One week post-marathon, most biomarkers of damage and stress were still significantly lower in the whey protein group compared to the maltodextrin group Together, these results indicate that whey protein supplementation during marathon preparation and recovery, and that the supplement aids in attenuating metabolic and muscular damage.

Daily dietary assessments were not included in this study 54 , thus limiting possible practical applications or recommendations. Further studies are necessary to elucidate the potential contribution of peri-workout whey protein ingestion on makers of muscle damage, recovery, and subsequent performance measures in endurance athletes.

In real-world sport performance situations, recovery and performance must be evaluated in the context of an accumulated effect. The ability to train consistently while remaining healthy is critical for continued progression and optimal performance.

Endurance athletes in particular are at increased risk for upper respiratory tract infections Kephart et al. Additionally, Rowlands et al. Post-exercise consumption of protein at levels thought to maximally stimulate MPS would potentially not have this same impact.

Post-exercise protein consumption affects other systems and pathways and should not be considered only in terms of stimulating MPS. As further evidence of this notion, Levenhagen et al.

Although this supplementation protocol stimulated MPS, subjects were found to be in negative whole-body protein balance. Because prolonged bouts of endurance exercise i. Because of this, protein requirements and recommendations for endurance athletes must consider more than MPS, especially since short-term increases in MPS do not fully explain the dynamics of long-term whole-body net protein balance and various training adaptations.

Overall, total daily energy and protein intake over the long term play the most crucial dietary roles in facilitating adaptations to exercise. However, once these factors are accounted for, it appears that peri-exercise protein intake plays a potentially useful role in optimizing physical performance and positively influencing the subsequent recovery processes.

Difficulties also arise in attempting to define and quantify the concept of recovery. Additionally, both performance and recovery must be viewed in context depending on whether the emphasis is an immediate, short-term effect i.

It should also be noted that protein timing, whether it is pre-, during, or post-workout, is often framed within the context of bodybuilding i. It is evident that to use such a narrow frame of reference ignores the potential utility of protein timing within the context of endurance events i.

For instance, if one competes in a weight-class sport e. In these situations, protein timing in particular may serve a useful role in recovery. Translating research into practical application requires differentiation between novice or trained individuals, healthy normal weight or healthy overweight individuals, special populations, or those with certain metabolic or disease states.

Here, we specifically focus on healthy, exercising individuals and limit our conclusions to these individuals. It is important moving forward that the study populations used are appropriate for the goals of the study and desired applications.

For example, it is of little use to have a sample of recreationally-trained individuals if the goal is to understand performance in high-level athletes.

Though protein-containing meals result in increase of MPS on their own, as does resistance training, the timing of ingestion of protein around exercise further enhances this increase of MPS 63 , It is worth noting that an upper limit for this acute dosing has not really been established, though there is evidence that 40 g of protein stimulates MPS to a greater degree than 20 g following whole-body resistance training A dose higher than this, however, has not been included using the same timing paradigm.

With regard to endurance exercise, protein consumption during exercise may not confer an immediate ergogenic benefit, especially when carbohydrate consumption is adequate. It may, however, aid in delaying central fatigue, reducing MPB, and contributing to a more positive, whole-body nitrogen balance.

Additionally, protein consumption in and around intense or prolonged endurance activity may aid in reduction of upper respiratory tract infection incidence and improved immune system function.

It may also aid in upregulating gene expression of proteins necessary for improving bioenergetic pathways. The impact of this on subsequent training sessions should not be dismissed and is an important part of improving performance.

The effect of protein consumption on resistance training is highly dependent on many variables not related to protein. The combination of peri-training protein consumption with inadequate or ineffective resistance training protocols will not maximize improvements in strength or hypertrophy.

Resistance training protocol interventions must be of adequate intensity, volume, and frequency with an emphasis on progressive overload to produce results. Additionally, adequate training interventions coupled with calorie-restricted nutrition protocols may require increased protein intake of 2.

Consideration must also be made for the age of resistance-trained individuals, as older adults require protein intake over and above that of their younger counterparts to receive the same benefits noted above In order to fully understand the role of protein or any substrate for that matter on performance, the practical application beyond the contrived training or recovery interventions presented must be addressed.

Daily training schedules of athletes require an ongoing ability to recover and perform. As an example, most of the studies included in this area utilized a training protocol that took ~3—4 h per week, typically in moderately-trained individuals.

For comparative purposes, a competitive athlete may spend 3—10 times this amount of time training per week if not more. Protein dosing strategies need to take this into account. This becomes even more apparent when considering that the uniform distribution of protein throughout the day results in greater MPS than an uneven distribution even when total daily protein intake is equal Arciero et al.

These results suggest that the pattern of daily protein ingestion may also impact results from resistance training protocols and provides further evidence that we must look beyond the few hours following training to determine the impact that protein may have on performance and recovery.

Madzima et al. While no statistically significant changes were observed between groups, protein groups trended toward greater increases when compared to the carbohydrate group while morning fat oxidation was greatest in the casein supplemented group.

Taken together, these data demonstrate the need for a more comprehensive view and methods of measuring recovery. Increased sensitization of muscle to protein and nutrients for 24—72 h following training coupled with multiple weekly training sessions results in an on-going state of recovery.

Because of this, we need to begin considering this longer stimulus window as an opportunity to maximize feeding, rather than as a reason why immediate post-workout ingestion may not be particularly important. In other words, consuming nothing post-workout would be an unwise strategy if the goal is to potentially optimize the adaptive response to exercise training.

Overall, there appears to be no adaptive advantage to avoiding protein intake in the peri-workout period. Stimulation of MPS in the acute period following training may not result in improvements in strength, hypertrophy, body composition, or performance without deliberate implementation of additional strategies during the prolonged recovery period.

As such, this much broader view should be considered with regard to future investigations. SA is on the Advisory Panel for Dymatize. JA is the CEO of the International Society of Sports Nutrition—an academic non-profit that receives grants in part from companies that sell dietary protein. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

The reviewer CK declared a past co-authorship with several of the authors SA and JA to the handling Editor. Jager R, Kerksick CM, Campbell BI, Cribb PJ, Wells SD, Skwiat TM, et al. International society of sports nutrition position stand: protein and exercise.

J Int Soc Sports Nutr. doi: PubMed Abstract CrossRef Full Text Google Scholar. The Statistics Portal. Cermak NM, Res PT, de Groot LC, Saris WH, van Loon LJ.

Protein supplementation augments the adaptive response of skeletal muscle to resistance-type exercise training: a meta-analysis. Am J Clin Nutr. Pasiakos SM, Lieberman HR, McLellan TM. Effects of protein supplements on muscle damage, soreness and recovery of muscle function and physical performance: a systematic review.

Sports Med. Reidy PT, Rasmussen BB. Role of ingested amino acids and protein in the promotion of resistance exercise—induced muscle protein anabolism. J Nutr. Morton RW, Murphy KT, McKellar SR, Schoenfeld BJ, Henselmans M, Helms E, et al. A systematic review, meta-analysis and meta-regression of the effect of protein supplementation on resistance training-induced gains in muscle mass and strength in healthy adults.

Br J Sports Med. Haff GG, Triplett NT. Essentials of Strength Training and Conditioning. Champaign, IL: Human Kinetics Google Scholar.

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Int J Sport Nutr Exerc Metab. Antonio J, Peacock CA, Ellerbroek A, Fromhoff B, Silver T. The effects of consuming a high protein diet 4.

Thomson RL, Brinkworth GD, Noakes M, Buckley JD. Muscle strength gains during resistance exercise training are attenuated with soy compared with dairy or usual protein intake in older adults: a randomized controlled trial.

Clin Nutr. CrossRef Full Text Google Scholar. Volpi E, Campbell WW, Dwyer JT, Johnson MA, Jensen GL, Morley JE, et al. Is the optimal level of protein intake for older adults greater than the recommended dietary allowance?

J Gerontol A Biol Sci Med Sci. Cockburn E, Hayes PR, French DN, Stevenson E, St Clair Gibson A. Acute milk-based protein-CHO supplementation attenuates exercise-induced muscle damage. Appl Physiol Nutr Metab.

Cockburn E, Stevenson E, Hayes PR, Robson-Ansley P, Howatson G. Effect of milk-based carbohydrate-protein supplement timing on the attenuation of exercise-induced muscle damage. Cockburn E, Bell PG, Stevenson E. Effect of milk on team sport performance after exercise-induced muscle damage.

Med Sci Sports Exerc. West DWD, Abou Sawan S, Mazzulla M, Williamson E, Moore DR. Whey protein supplementation enhances whole body protein metabolism and performance recovery after resistance exercise: a double-blind crossover study.

Nutrients Tang JE, Phillips SM. Maximizing muscle protein anabolism: the role of protein quality. Curr Opin Clin Nutr Metab Care — Hulmi JJ, Lockwood CM, Stout JR. Nutr Metab. Millward DJ, Layman DK, Tome D, Schaafsma G.

Protein quality assessment: impact of expanding understanding of protein and amino acid needs for optimal health. Garlick PJ. The role of leucine in the regulation of protein metabolism.

Fabre M, Hausswirth C, Tiollier E, Molle O, Louis J, Durguerian A, et al. Effects of postexercise protein intake on muscle mass and strength during resistance training: is there an optimal ratio between fast and slow proteins? Naclerio F, Larumbe-Zabala E, Ashrafi N, Seijo M, Nielsen B, Allgrove J, et al.

Effects of protein-carbohydrate supplementation on immunity and resistance training outcomes: a double-blind, randomized, controlled clinical trial. Eur J Appl Physiol. Schoenfeld BJ, Aragon A, Wilborn C, Urbina SL, Hayward SE, Krieger J.

Pre- vs. post-exercise protein intake has similar effects on muscular adaptations. PeerJ 5:e Burd NA, Gorissen SH, van Vliet S, Snijders T, van Loon LJ.

Differences in postprandial protein handling after beef compared with milk ingestion during postexercise recovery: a randomized controlled trial. Naclerio F, Larumbe-Zabala E. Effects of whey protein alone or as part of a multi-ingredient formulation on strength, fat-free mass, or lean body mass in resistance-trained individuals: a meta-analysis.

Schoenfeld BJ, Aragon AA, Krieger JW. The effect of protein timing on muscle strength and hypertrophy: a meta-analysis. Cribb PJ, Hayes A. Effects of supplement timing and resistance exercise on skeletal muscle hypertrophy.

Nosaka K, Newton M, Sacco P. Delayed-onset muscle soreness does not reflect the magnitude of eccentric exercise-induced muscle damage. Scand J Med Sci Sports — In addition to helping to promote satiety, protein can also help increase metabolism, which can aid in burning calories more efficiently, which is important for anyone trying to change their body composition.

Protein, when consumed throughout the day, also helps you maintain your muscle mass. Having adequate muscle mass also is essential in maintaining your metabolism. Not only does eating protein help prevent muscle breakdown, but it can also help build muscles. Combining regular activity and exercise with protein intake promotes muscle growth.

High-quality proteins contain all of the essential amino acids and are rich in branched-chain amino acids BCAAs.

Leucine, one of these BCAAs, plays a major role in promoting muscle growth and recovery after resistance and endurance exercise. These high-quality proteins exist in animal-based protein foods such as lean poultry, beef, fish, dairy, egg products, and whole eggs.

Protein shakes are extremely convenient, making them useful for active individuals and athletes who are constantly on the go. If choosing a protein powder supplement, whey protein and plant-based proteins such as soy or pea have been shown to most effectively promote muscle growth and recovery.

Timing of protein intake is especially important for athletes or anyone trying to build muscle. Exercise stresses the muscles. They concluded that the lowest intake compromised protein synthesis when compared to the moderate and high intakes and that while the moderate protein intake amounted to a neutral protein balance, they recommended one standard deviation above at 1.

Other studies have also suggested that protein intakes ranging from 1. The International Society of Sports Nutrition ISSN has also published position statements on the protein requirements of athletes, and they note 1.

And a consensus statement from ACSM et al. A fascinating and recent study was a systematic review, meta-analysis, and meta-regression by Morton et al. Data from the review, including 49 previous studies and participants, showed that protein supplementation significantly improved fat-free mass gains, maximal strength, muscle fibre diameter, and cross-sectional area of femur thigh mass The authors also noted that a protein intake higher than 1.

Two other studies by Antonio et al. Their first intervention had 30 resistance-trained individuals continue following their typical exercise training program alongside either a control or high-protein diet 4.

While the 30 participants were at a caloric surplus for 8 weeks, no changes in body mass, fat mass, fat-free mass, or per cent body fat were found when compared to the control group.

The participants followed either their normal diet of 2. Ultimately, the researchers found similar changes in strength, and the control group saw a significant increase in body mass. In contrast, the high-protein group saw a greater decrease in fat mass and per cent body fat 3. They theorised that those changes in fat-free mass they saw in both of the groups were the result of a different training stimulus.

Intermediate Strength Athletes 6 months — 2 years training : 1. And what is also important to consider is the speed at which an athlete loses body mass. To read the Research Review on making weight the wrong way, click here. They found that the higher protein diet lost significantly less fat-free mass, and both groups lost similar amounts of fat mass and performed similarly in all physical tasks assessed.

Pasiakos et al. Following the week intervention, the two groups that consumed higher amounts of protein 1. Lastly, a more recent study conducted by Longland et al. Following 8 weeks, those in the higher protein group were able to gain more fat-free mass and lose fat mass simultaneously often called body recomposition.

Now that daily protein requirements across many studies have been thoroughly analysed and noted, what is next important is protein intake on a per-meal basis as well as timing around training.

The most common strategy involves consuming protein in and around a training session to repair muscular damage and enhance post-exercise strength and hypertrophy-related adaptations Furthermore, pre-training nutrition may function as both a pre- and immediate post-exercise meal as digestion can persist well into the recovery period following exercise The effects of protein timing for increasing muscle protein synthesis related to exercise is a hotly debated subject in the literature.

Borsheim et al. Tipton et al. As well as their notion of the next scheduled protein-rich meal whether it occurs immediately or hours post-exercise is likely sufficient for maximising recovery and anabolism 4. Lastly, within a meta-analysis of 20 studies and participants by Schoenfeld et al.

They note that if an anabolic window does exist, it would appear to be greater than the currently held allotment of one hour. They go on further to state that any positive effects they saw within the studies they analysed were most likely due to overall daily protein intake and not the timing of protein intake Alex holds a BSc in Kinesiology from the University of Ottawa Canada.

He is now completing an MSc in Diabetes Medicine He is type 1 myself at the University of Dundee Scotland. Learn how to improve your athletes' agility. This free course also includes a practical coaching guide to help you design and deliver your own fun and engaging agility sessions.

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Contents Determining Protein Requirements Protein Requirements for Athletes Energy Restriction Protein Timing Main Takeaways About the Author References Comments. Alex St.

John Alex holds a BSc in Kinesiology from the University of Ottawa Canada. More content by Alex. American College of Sports Medicine, American Dietetic Association, and Dietitians of Canada.

Nutrition and Athletic Performance. The effects of consuming a high protein diet 4. Journal of the International Society of Sports Nutrition , 11 1 , A high protein diet 3. Journal of the International Society of Sports Nutrition, 12 1 , Nutrient timing revisited: Is there a post-exercise anabolic window?

Journal of the International Society of Sports Nutrition, 10 1 , 5.

However, as the Eat-Lancet is a universal recommendation, it is necessary to adapt the EAT-Lancet reference diet to national preferences and contexts, as well as local food availability, nutritional content of foods, and national dietary recommendations The CF and WF relative to Eat-Lancet reference food groups were not surprising, as animal protein is known to have a high environmental impact, high CF and WF as compared to that of plant protein This is especially important because, in Brazil, there is a tradition of appreciating meat, and people consider animal protein essential for health and nutrition However, such a high intake of dairy was not expected, which might be associated with adolescent consumption of yogurts, sandwiches, and pizza, which are very common in this age group We expected to observe a higher intake of legumes, as beans are a staple food in Brazil and are traditionally consumed twice a day along with rice, vegetables, and a source of meat 37 , Beans were the second-most consumed food No association was found between income levels and food groups or between income levels and CF and WF.

Meat consumption may vary according to income, increasing proportionally to income until it reaches a plateau and then drops slightly On the other hand, it is expected that people with greater purchasing power will be more aware about sustainability.

Therefore, this group would be more susceptible to adopting a diet with low environmental impact In our study, male participants had higher CF, WF, and energy intakes than female participants. It is well-documented that footprints are associated with energy intake The older age groups also had higher footprints than the younger group, which is probably due to the higher energy intake among older athletes.

Maintaining a diet within the energy recommendations is a possible way to stimulate healthy and sustainable diets However, athletes have a high total energy expenditure, and this procedure is not suitable for athletes.

Among the different sports modalities, artistic swimming participants had lower values of CF and WF; these athletes also had lower energy intake, and in the group studied, all were female. Therefore, the lower environmental impact of this modality is likely associated with sex and lower energy intake.

Garzillo 10 evaluated the environmental impact CF and WF of average Brazilian food consumption based on data from the Pesquisa de Orçamentos Familiares — POF—Household Budget Survey — The estimated WF value is 4, liters of water per day.

The average energy intake was 1, kcal and the median protein intake was 76 g. Red meat represented Regarding WF, red meat's contribution was In comparison with the study carried out by Garzillo 10 , the adolescent athletes in our study had a higher WF 4, Meat's contribution to WF and CF, If these values were used, the diet of participants in the first quartile of CF could be considered sustainable.

However, the other quartiles were high-intensity emissions. CF estimates for the fourth quartile were superior to the average dietary emissions from high-emission countries such as the USA The different methodologies used to estimate the environmental impact of food consumption make it difficult to compare results between studies.

The food consumption of adolescent athletes presented in this study had higher values for CF 4, The values found for WF 4, However, the footprint database used by these authors has a different methodology than that used in the present study because they did not consider the cooking techniques.

Travassos et al. Arrieta and Gonzáles 45 estimated that GHG emissions related to the current diet in Argentina are 5. Temme et al. Girls had an average of 3. A study carried out in Sweden used linear programming to design nutritionally adequate and climate-friendly diets for omnivorous, pescatarian, vegetarian, and vegan adolescents The results showed that an affordable and nutritionally adequate diet with considerably reduced GHG can be achieved for adolescents.

For omnivorous adolescents, the diet was associated with a reduction in meat, dairy, and processed foods, and an increase in cereals and tubers, pulses, eggs, and seafood We observed a considerable disproportion between the percentage of energy contribution In the first quartile, the plant-to-animal protein was In the quartile with the highest CF, the ratio of plant-to-animal protein was , reinforcing the need to reduce animal protein consumption to decrease the environmental impact of the diet.

Reducing the intake of animal protein and reducing energy intake should be ranked as the first and second steps to steer current food consumption in a sustainable direction, and reducing household food waste should be ranked third Therefore, it is evident that vegetarian and vegan diets do not impair sports performance.

Lynch 19 compared vegetarian and omnivorous endurance athletes and found that their ability to generate strength was equivalent, and vegetarians showed better cardiorespiratory fitness than omnivorous athletes. Nebl et al.

Thus, it is possible to note that adopting a vegetarian diet does not bring any harm to sports performance, and there are still benefits to the health of these individuals reducing the risk of developing chronic diseases It is worth mentioning that for athletes to be able to reduce the environmental impact of their diet, they do not need to become vegetarian or vegan.

Reguant-Closa et al. There are several ways to introduce sustainable strategies in sports nutrition, such as adopting a flexible diet with a greater intake of plant-based protein than animal protein, not exceeding the daily protein intake needs, reducing the consumption of animal protein, reducing food waste, prioritizing the production of local and seasonal foods, reducing the consumption of processed foods, and prioritizing sustainable packaging.

These guidelines can aid in reconciling sports nutrition, performance, and food sustainability. However, nutritional recommendations that consider sustainability are still scarce 1 , 22 , Therefore, it is important to reinforce the scientific evidence of the environmental impact of the diet of athletes, especially adolescents, which highlights the importance of the present study, since adolescent athletes have different consumption patterns and nutritional needs compared to other groups.

To the best of our knowledge, no previous study has calculated the environmental impact of the diets of adolescent athletes. This area of research needs further studies to provide insights into the environmental boundaries of diets, food and nutrient intakes and sports performance.

We also emphasize the importance of providing nutritional guidance for sustainability. Discussions about sustainable diets are still very incipient in Brazil, and different initiatives and clarification campaigns are necessary to encourage the reduction of animal protein consumption.

The median of the protein was within the range recommended by ADA 2 , even in the lowest quartile of CF, which demonstrates that it is viable to have a lower environmental impact while meeting the protein recommendations.

Furthermore, our findings show some discrepancies between the diet of athletes and the reference planetary diet of the EAT-Lancet.

This may be explained by the fact that the EAT-Lancet reference diet was conceived as a recommendation for the general population and not for specific groups. Therefore, it could be used as a roadmap and is not strictly followed by athletes because it has many stress points.

Athletes have higher protein and energy recommendations than the general population. Although athletes can follow a plant-based diet, nutritional guidance is not always available. Our results demonstrated that it is possible to have athletes on a low-carbon diet and simultaneously meet protein recommendations, with a plant-to-animal protein ratio of 3 × 1.

However, they also had a lower calorie intake, which can compromise sports performance; therefore, future research should evaluate athletes' diets in terms of sustainability and sports performance.

PF and CG: conceptualization, methodology, investigation, writing—original draft, and visualization. TO: formal analysis, investigation, writing—original draft, and writing.

TF: writing—review and editing. LL: formal analysis, investigation, writing—original draft, and editing. RS: writing—original draft. AP: conceptualization, methodology, resources, writing—review and editing, project administration. All authors contributed to the article and approved the submitted version.

We would like to thank CAPES, FAPERJ, and CNPq for granting graduate and post-graduate scholarships and for the financial support that allowed the realization of this study. We would also like to thank the sports associations Academia Luta Pela Paz, Fluminense Futebol Clube, Tijuca Tênis Clube, Jequiá Iate Clube, and all volunteers who participated in the study.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers.

Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher. Meyer N, Reguant-Closa A. Eat as if you could save the planet and win! Sustainability integration into nutrition for exercise and sport.

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Int J Life Cycle Assess. CrossRef Full Text Google Scholar. Jeukendrup A, Cronin L. Nutrition and elite young athletes. Med Sport Sci. Reinaldo JM, Silva da DG, Matos RC, Leite MMR, Mendes-Netto RS. Inadequação nutricional na dieta de atletas adolescentes.

ABCS Health Sci. Pendrill F, Persson UM, Godar J, Kastner T, Moran D, Schmidt S, et al. Agricultural and forestry trade drives large share of tropical deforestation emissions. Global Environ Change.

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São Paulo: Faculdade de Saúde Pública da Universidade de São Paulo Google Scholar. IPCC- Intergovernmental Panel on Climate Change. Climate Change Mitigation. Contribution of Working Group III to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.

Special Report on Climate Change, Desertification, Land Degradation, Sustainable Land Management, Food Security, and Greenhouse Gas Fluxes in Terrestrial Ecosystems.

Intergovernmental Panel on Climate Change Geneva, Switzerland. WWP - World Wildlife Fund. One Planet Plate - Criteria and Background. World Wildlife Fund. pdf accessed August 8, Romaguera M, Hoekstra AY, Su Z, Krol MS, Salama MS. Potential of using remote sensing techniques for global assessment of water footprint of crops.

Remote Sensing. Feng K, Siu YL, Guan D, Hubacek K. Assessing regional virtual water flows and water footprints in the yellow river Basin, China: a consumption based approach. Appl Geograp. Athletes should consider focusing on whole food sources of protein that contain all of the EAAs i.

Endurance athletes should focus on achieving adequate carbohydrate intake to promote optimal performance; the addition of protein may help to offset muscle damage and promote recovery. Pre-sleep casein protein intake 30—40 g provides increases in overnight MPS and metabolic rate without influencing lipolysis.

In , the International Society of Sports Nutrition ISSN published its first position stand devoted to the science and application of dietary protein intake [ 1 ]. Subsequently, this paper has been accessed more than , times and continues to serve as a key reference on the topic.

In the past ten years, there have been continued efforts to advance the science and application of dietary protein intake for the benefit of athletes and fitness-minded individuals. This updated position stand includes new information and addresses the most important dietary protein categories that affect physically active individuals across domains such as exercise performance, body composition, protein timing, recommended intakes, protein sources and quality, and the preparation methods of various proteins.

Most of the scientific research investigating the effects of protein intake on exercise performance has focused on supplemental protein intake. From a broad perspective, the dependent measures of these studies can be categorized into two domains:. Very few studies have investigated the effects of prolonged periods one week or more of dietary protein manipulation on endurance performance.

The trained cyclists ingested each diet for a 7-day period in a randomized, crossover fashion. Before and following the 7-day diet intervention, a self-paced cycling endurance time trial was conducted as the primary measure of exercise performance. It should be noted however that a 7-day treatment period is exceedingly brief.

It is unknown what the effect of a higher protein diet would be over the course of several weeks or months. Although the number of investigations is limited, it appears as if increasing protein intakes above recommended intakes does not enhance endurance performance [ 2 , 4 , 5 ].

In addition to these studies that spanned one to three weeks, several acute-response single feeding and exercise sessions studies exist, during which protein was added to a carbohydrate beverage prior to or during endurance exercise.

Similarly, most of these interventions also reported no added improvements in endurance performance when protein was added to a carbohydrate beverage as compared to carbohydrate alone [ 6 , 7 , 8 , 9 ]. An important research design note, however, is that those studies which reported improvements in endurance performance when protein was added to a carbohydrate beverage before and during exercise all used a time-to-exhaustion test [ 10 , 11 , 12 ].

When specifically interested in performance outcomes, a time trial is preferred as it better mimics competition and pacing demands. In conclusion, added protein does not appear to improve endurance performance when given for several days, weeks, or immediately prior to and during endurance exercise.

For these reasons, it seems prudent to recommend for endurance athletes to ingest approximately 0. Another important consideration relates to the impact of ingesting protein along with carbohydrate on rates of protein synthesis and balance during prolonged bouts of endurance exercise.

Beelen and colleagues [ 14 ] determined that adding protein to carbohydrate consumption throughout a prolonged bout of endurance exercise promotes a higher whole body net protein balance, but the added protein does not exert any further impact on rates of MPS.

While performance outcomes were not measured, these results shift the focus of nutrient ingestion during prolonged bouts of endurance exercise to the ingestion of carbohydrate. When adequate carbohydrate is delivered, adding protein to carbohydrate does not appear to improve endurance performance over the course of a few days or weeks.

Adding protein during or after an intensive bout of endurance exercise may suppress the rise in plasma proteins linked to myofibrillar damage and reduce feelings of muscle soreness. There are relatively few investigations on the effects of protein supplementation on endurance performance.

The extent to which protein supplementation, in conjunction with resistance training, enhances maximal strength is contingent upon many factors, including:. Co-ingestion of additional dietary ingredients that may favorably impact strength e. creatine, HMB. Taking each of these variables into consideration, the effects of supplemental protein consumption has on maximal strength enhancement are varied, with a majority of the investigations reporting no benefit [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ] and a few reporting improvements in maximal strength [ 26 , 27 , 28 , 29 ].

With limited exceptions [ 16 , 18 , 23 , 27 ], most of the studies utilized young, healthy, untrained males as participants. In one investigation examining college football athletes supplementing with a proprietary milk protein supplement two servings of 42 g per day for 12 weeks, a These differences were statistically significant.

When females were the only sex investigated, the outcomes consistently indicated that supplemental protein does not appear to enhance maximal strength at magnitudes that reach statistical significance.

Hida et al. An important note for this study is that 15 g of egg protein is considered by many to be a sub-optimal dose [ 31 ]. However, others have advocated that the total daily intake of protein might be as important or more important [ 32 ].

In another study, Josse et al. In summary, while research investigating the addition of supplemental protein to a diet with adequate energy and nutrient intakes is inconclusive in regards to stimulating strength gains in conjunction with a resistance-training program to a statistically significant degree, greater protein intakes that are achieved from both dietary and supplemental sources do appear to have some advantage.

Hoffman and colleagues [ 29 ] reported that in athletes consuming daily protein intakes above 2. Cermak and colleagues [ 35 ] pooled the outcomes from 22 separate clinical trials to yield subjects in their statistical analysis and found that protein supplementation with resistance training resulted in a A similar conclusion was also drawn by Pasiakos et al.

Results from many single investigations indicate that in both men and women protein supplementation exerts a small to modest impact on strength development. Pooled results of multiple studies using meta-analytic and other systematic approaches consistently indicate that protein supplementation 15 to 25 g over 4 to 21 weeks exerts a positive impact on performance.

Andersen et al. When the blend of milk proteins was provided, significantly greater increases in fat-free mass, muscle cross-sectional area in both the Type I and Type II muscle fibers occurred when compared to changes seen with carbohydrate consumption. Collectively, a meta-analysis by Cermak and colleagues [ 35 ] reported a mean increase in fat-free mass of 0.

Other reviews by Tipton, Phillips and Pasiakos, respectively, [ 36 , 38 , 39 ] provide further support that protein supplementation 15—25 g over 4—14 weeks augments lean mass accretion when combined with completion of a resistance training program.

Beyond accretion of fat-free mass, increasing daily protein intake through a combination of food and supplementation to levels above the recommended daily allowance RDA RDA 0. The majority of this work has been conducted using overweight and obese individuals who were prescribed an energy-restricted diet that delivered a greater ratio of protein relative to carbohydrate.

Greater amounts of fat were lost when higher amounts of protein were ingested, but even greater amounts of fat loss occurred when the exercise program was added to the high-protein diet group, resulting in significant decreases in body fat.

Each person was randomly assigned to consume a diet that contained either 1× 0. Participants were measured for changes in body weight and body composition. While the greatest body weight loss occurred in the 1× RDA group, this group also lost the highest percentage of fat-free mass and lowest percentage of fat mass.

Collectively, these results indicate that increasing dietary protein can promote favorable adaptations in body composition through the promotion of fat-free mass accretion when combined with a hyperenergetic diet and a heavy resistance training program and can also promote the loss of fat mass when higher intakes of daily protein × the RDA are combined with an exercise program and a hypoenergetic diet.

When combined with a hyperenergetic diet and a heavy resistance-training program, protein supplementation may promote increases in skeletal muscle cross-sectional area and lean body mass.

When combined with a resistance-training program and a hypoenergetic diet, an elevated daily intake of protein 2 — 3× the RDA can promote greater losses of fat mass and greater overall improvements in body composition.

In the absence of feeding, muscle protein balance remains negative in response to an acute bout of resistance exercise [ 48 ]. Tipton et al. Later, Burd et al. Subsequently, these conclusions were supported by Borsheim [ 52 ] and Volpi [ 53 ].

The study by Borsheim also documented a dose-response outcome characterized by a near doubling of net protein balance in response to a three to six gram dose of the EAAs [ 52 ].

Building on this work, Tipton et al. These findings formed the theoretical concept of protein timing for resistance exercise that has since been transferred to not only other short-duration, high-intensity activities [ 56 ] but also endurance-based sports [ 57 ] and subsequent performance outcomes [ 58 ].

The strategic consumption of nutrition, namely protein or various forms of amino acids, in the hours immediately before and during exercise i.

While earlier investigations reported positive effects from consumption of amino acids [ 37 , 46 , 61 ], it is now clear that intact protein supplements such as egg, whey, casein, beef, soy and even whole milk can evoke an anabolic response that can be similar or greater in magnitude to free form amino acids, assuming ingestion of equal EAA amounts [ 62 , 63 , 64 ].

For instance, whey protein ingested close to resistance exercise, promotes a higher activation phosphorylation of mTOR a key signaling protein found in myocytes that is linked to the synthesis of muscle proteins and its downstream mRNA translational signaling proteins i. Moreover, it was found that the increased mTOR signaling corresponded with significantly greater muscle hypertrophy after 10 weeks of training [ 65 ].

However, the hypertrophic differences between protein consumption and a non-caloric placebo appeared to plateau by week 21, despite a persistently greater activation of this molecular signaling pathway from supplementation. Results from other research groups [ 56 , 57 , 58 , 66 ] show that timing of protein near ± 2 h aerobic and anaerobic exercise training appears to provide a greater activation of the molecular signalling pathways that regulate myofibrillar and mitochondrial protein synthesis as well as glycogen synthesis.

It is widely reported that protein consumption directly after resistance exercise is an effective way to acutely promote a positive muscle protein balance [ 31 , 55 , 67 ], which if repeated over time should translate into a net gain or hypertrophy of muscle [ 68 ].

Pennings and colleagues [ 69 ] reported an increase in both the delivery and incorporation of dietary proteins into the skeletal muscle of young and older adults when protein was ingested shortly after completion of exercise.

These findings and others add to the theoretical basis for consumption of post-protein sooner rather than later after exercise, since post workout MPS rates peak within three hours and remain elevated for an additional 24—72 h [ 50 , 70 ].

This extended time frame also provides a rationale for both immediate and sustained i. These temporal considerations would also capture the peak elevation in signalling proteins shown to be pivotal for increasing the initiation of translation of muscle proteins, which for the most part appears to peak between 30 and 60 min after exercise [ 71 ].

However, these differences may be related to the type of protein used between the studies. The studies showing positive effects of protein timing used milk proteins, whereas the latter study used a collagen based protein supplement. While a great deal of work has focused on post-exercise protein ingestion, other studies have suggested that pre-exercise and even intra-exercise ingestion may also support favorable changes in MPS and muscle protein breakdown [ 14 , 54 , 75 , 76 , 77 , 78 ].

Initially, Tipton and colleagues [ 54 ] directly compared immediate pre-exercise and immediate post-exercise ingestion of a mixture of carbohydrate 35 g and EAAs 6 g combination on changes in MPS. They reported that pre-exercise ingestion promoted higher rates of MPS while also demonstrating that nutrient ingestion prior to exercise increased nutrient delivery to a much greater extent than other immediate or one hour post-exercise time points.

These results were later challenged by Fujita in who employed an identical study design with a different tracer incorporation approach and concluded there was no difference between pre- or post-exercise ingestion [ 75 ].

Subsequent work by Tipton [ 79 ] also found that similar elevated rates of MPS were achieved when ingesting 20 g of a whey protein isolate immediately before or immediately after resistance exercise.

At this point, whether any particular time of protein ingestion confers any unique advantage over other time points throughout a h day to improve strength and hypertrophy has yet to be adequately investigated.

To date, although a substantial amount of literature discusses this concept [ 60 , 80 ], a limited number of training studies have assessed whether immediate pre- and post-exercise protein consumption provides unique advantages compared to other time points [ 72 , 73 , 81 ].

Each study differed in population, training program, environment and nutrition utilized, with each reporting a different result. What is becoming clear is that the subject population, nutrition habits, dosing protocols on both training and non-training days, energy and macronutrient intake, as well as the exercise bout or training program itself should be carefully considered alongside the results.

In particular, the daily amount of protein intake seems to operate as a key consideration because the benefits of protein timing in relation to the peri-workout period seem to be lessened for people who are already ingesting appropriate amounts of protein e.

A literature review by Aragon and Schoenfeld [ 83 ] determined that while compelling evidence exists showing muscle is sensitized to protein ingestion following training, the increased sensitivity to protein ingestion might be greatest in the first five to six hours following exercise.

Thus, the importance of timing may be largely dependent on when a pre-workout meal was consumed, the size and composition of that meal and the total daily protein in the diet. In this respect, a pre-exercise meal will provide amino acids during and after exercise and therefore it stands to reason there is less need for immediate post-exercise protein ingestion if a pre-exercise meal is consumed less than five hours before the anticipated completion of a workout.

A meta-analysis by Schoenfeld et al. The authors concluded that total protein intake was the strongest predictor of muscular hypertrophy and that protein timing likely influences hypertrophy to a lesser degree.

However, the conclusions from this meta-analysis may be questioned because the majority of the studies analyzed were not protein timing studies but rather protein supplementation studies.

In that respect, the meta-analysis provides evidence that protein supplementation i. While a strong rationale remains to support the concept that the hours immediately before or after resistance exercise represents an opportune time to deliver key nutrients that will drive the accretion of fat-free mass and possibly other favorable adaptations, the majority of available literature suggests that other factors may indeed be operating to a similar degree that ultimately impact the observed adaptations.

In this respect, a key variable that must be accounted for is the absolute need for energy and protein required to appropriately set the body up to accumulate fat-free mass. Thus, the most practical recommendation is to have athletes consume a meal during the post-workout or pre-workout time period since it may either help or have a neutral effect.

In younger subjects, the ingestion of 20—30 g of any high biological value protein before or after resistance exercise appears to be sufficient to maximally stimulate MPS [ 21 , 64 ].

More recently, Macnaughton and colleagues [ 85 ] reported that 40 g of whey protein ingestion significantly increased the MPS responses compared to a 20 g feeding after an acute bout of whole-body resistance exercise, and that the absolute protein dose may operate as a more important consideration than providing a protein dose that is normalized to lean mass.

Free form EAAs, soy, milk, whey, caseinate, and other protein hydrolysates are all capable of activating MPS [ 86 ]. However, maximal stimulation of MPS, which results in higher net muscle protein accretion, is the product of the total amount of EAA in circulation as well as the pattern and appearance rate of aminoacidemia that modulates the MPS response [ 86 ].

Recent work has clarified that whey protein provides a distinct advantage over other protein sources including soy considered another fast absorbing protein and casein a slower acting protein source on acute stimulation of MPS [ 86 , 87 ].

Importantly, an elegant study by West and investigators [ 87 ] sought to match the delivery of EAAs in feeding patterns that replicated how whey and casein are digested. The authors reported that a 25 g dose of whey protein that promoted rapid aminoacidemia further enhanced MPS and anabolic signaling when compared to an identical total dose of whey protein when delivered as ten separate 2.

The advantages of whey protein are important to consider, particularly as all three sources rank similarly in assessments of protein quality [ 88 ].

In addition to soy, other plant sources e. have garnered interest as potential protein sources to consider. Unfortunately, research that examines the ability of these protein sources to modulate exercise performance and training adaptations is limited at this time.

The investigators concluded that gains in strength, muscle thickness and body composition were similar between the two protein groups, suggesting that rice protein may be a suitable alternative to whey protein at promoting resistance training adaptations.

Furthermore, differences in absorption kinetics, and the subsequent impact on muscle protein metabolism appear to extend beyond the degree of hydrolysis and amino acid profiles [ 69 , 86 , 90 , 91 , 92 , 92 ]. For instance, unlike soy more of the EAAs from whey proteins hydrolysates and isolates survive splanchnic uptake and travel to the periphery to activate a higher net gain in muscle [ 86 ].

These characteristics yield a high concentration of amino acids in the blood aminoacidemia [ 69 , 87 ] that facilitates greater activation of MPS and net muscle protein accretion, in direct comparison to other protein choices [ 50 , 69 , 91 ].

The addition of creatine to whey protein supplementation appears to further augment these adaptations [ 27 , 72 , 95 ]; however, an optimal timing strategy for this combination remains unclear.

The timing of protein-rich meals consumed throughout a day has the potential to influence adaptations to exercise. Using similar methods, other studies over recent decades [ 53 , 62 , 87 , 91 , 96 , 97 , 98 , 99 , ] have established the following:.

The anabolic response to feeding is pronounced but transient. During the post-prandial phase 1—4 h after a meal MPS is elevated, resulting in a positive muscle protein balance.

In contrast, MPS rates are lower in a fasted state and muscle protein balance is negative. Protein accretion only occurs in the fed state. The concentration of EAA in the blood plasma regulates protein synthesis rates within muscle at rest and post exercise.

More recent work has established that protein-carbohydrate supplementation after strenuous endurance exercise stimulates contractile MPS via similar signaling pathways as resistance exercise [ 56 , 57 ]. That is, the consumption of a protein-containing meal up to 24 h after a single bout of resistance exercise results in a higher net stimulation of MPS and protein accretion than the same meal consumed after 24 h of inactivity [ 50 ].

The effect of insulin on MPS is dependent on its ability to increase amino acid availability, which does not occur when insulin is systematically increased e. Taken together, these results seem to indicate that post-workout carbohydrate supplementation offers very little contribution from a muscle development standpoint provided adequate protein is consumed.

Importantly, these results are not to be interpreted to mean that carbohydrate administration offers no potential effect for an athlete engaging in moderate to high volumes of training, but rather that benefits derived from carbohydrate administration appear to more favorably impact aspects of muscle glycogen recovery as opposed to stimulating muscle protein accretion.

Eating before sleep has long been controversial [ , , ]. However, a methodological consideration in the original studies such as the population used, time of feeding, and size of the pre-sleep meal confounds firm conclusions about benefits or drawbacks.

Results from several investigations indicate that 30—40 g of casein protein ingested min prior to sleep [ ] or via nasogastric tubing [ ] increased overnight MPS in both young and old men, respectively. Likewise, in an acute setting, 30 g of whey protein, 30 g of casein protein, and 33 g of carbohydrate consumed min prior to sleep resulted in an elevated morning resting metabolic rate in young fit men compared to a non-caloric placebo [ ].

Interestingly, Madzima et al. This infers that casein protein consumed pre-sleep maintains overnight lipolysis and fat oxidation.

This finding was further supported by Kinsey et al. Similar to Madzima et al. Interestingly, the pre-sleep protein and carbohydrate ingestion resulted in elevated insulin concentrations the next morning and decreased hunger in this overweight population.

Of note, it appears that exercise training completely ameliorates any rise in insulin when eating at night before sleep [ ], while the combination of pre-sleep protein and exercise has been shown to reduce blood pressure and arterial stiffness in young obese women with prehypertension and hypertension [ ].

In athletes, evening chocolate milk consumption has also been shown to influence carbohydrate metabolism in the morning, but not running performance [ ]. In addition, data supports that exercise performed in the evening augments the overnight MPS response in both younger and older men [ , , ].

To date, only a few studies involving nighttime protein ingestion have been carried out for longer than four weeks. Snijders et al.

The group receiving the protein-centric supplement each night before sleep had greater improvements in muscle mass and strength over the week study.

Of note, this study was non-nitrogen balanced and the protein group received approximately 1. More recently, in a study in which total protein intake was equal, Antonio et al.

They examined the effects on body composition and performance [ ]. All subjects maintained their usual exercise program. The authors reported no differences in body composition or performance between the morning and evening casein supplementation groups.

However, it is worth noting that, although not statistically significant, the morning group added 0. Although this finding was not statistically significant, it supports data from Burk et al.

It should be noted that the subjects in the Burk et al. study were resistance training. A retrospective epidemiological study by Buckner et al. Thus, it appears that protein consumption in the evening before sleep might be an underutilized time to take advantage of a protein feeding opportunity that can potentially improve body composition and performance.

In addition to direct assessments of timed administration of nutrients, other studies have explored questions that center upon the pattern of when certain protein-containing meals are consumed. Paddon-Jones et al. In this study, participants were given an EAA supplement three times a day for 28 days.

Results indicated that acute stimulation of MPS provided by the supplement on day 1 resulted in a net gain of ~7. When extrapolated over the entire day study, the predicted change in muscle mass corresponded to the actual change in muscle mass ~ g measured by dual-energy x-ray absorptiometry DEXA [ 97 ].

While these findings are important, it is vital to highlight that this study incorporated a bed rest model with no acute exercise stimulus while other work by Mitchell et al.

Interestingly, supplementation with 15 g of EAAs and 30 g of carbohydrate produced a greater anabolic effect increase in net phenylalanine balance than the ingestion of a mixed macronutrient meal, despite the fact that both interventions contained a similar dose of EAAs [ 96 ].

Most importantly, the consumption of the supplement did not interfere with the normal anabolic response to the meal consumed three hours later [ 96 ].

Areta et al. The researchers compared the anabolic responses of three different patterns of ingestion a total of 80 g of protein throughout a h recovery period after resistance exercise. Using a group of healthy young adult males, the protein feeding strategies consisted of small pulsed 8 × 10 g , intermediate 4 × 20 g , or bolus 2 × 40 g administration of whey protein over the h measurement window.

Results showed that the intermediate dosing 4 × 20 g was superior for stimulating MPS for the h experimental period. Specifically, the rates of myofibrillar protein synthesis were optimized throughout the day of recovery by the consumption of 20 g protein every three hours compared to large 2 × 40 g , less frequent servings or smaller but more frequent 8 × 10 g patterns of protein intake [ 67 ].

Previously, the effect of various protein feeding strategies on skeletal MPS during an entire day was unknown. This study provided novel information demonstrating that the regulation of MPS can be modulated by the timing and distribution of protein over 12 h after a single bout of resistance exercise.

However, it should be noted that an 80 g dose of protein over a h period is quite low. The logical next step for researchers is to extend these findings into longitudinal training studies to see if these patterns can significantly affect resistance-training adaptations.

Indeed, published studies by Arnal [ ] and Tinsley [ ] have all made some attempt to examine the impact of adjusting the pattern of protein consumption across the day in combination with various forms of exercise.

Collective results from these studies are mixed. Thus, future studies in young adults should be designed to compare a balanced vs. skewed distribution pattern of daily protein intake on the daytime stimulation of MPS under resting and post-exercise conditions and training-induced changes in muscle mass, while taking into consideration the established optimal dose of protein contained in a single serving for young adults.

Without more conclusive evidence spanning several weeks, it seems pragmatic to recommend the consumption of at least g of protein ~0. In the absence of feeding and in response to resistance exercise, muscle protein balance remains negative.

Skeletal muscle is sensitized to the effects of protein and amino acids for up to 24 h after completion of a bout of resistance exercise. A protein dose of 20—40 g of protein 10—12 g of EAAs, 1—3 g of leucine stimulates MPS, which can help to promote a positive nitrogen balance.

The EAAs are critically needed for achieving maximal rates of MPS making high-quality, protein sources that are rich in EAAs and leucine the preferred sources of protein.

Studies have suggested that pre-exercise feedings of amino acids in combination with carbohydrate can achieve maximal rates of MPS, but protein and amino acid feedings during this time are not clearly documented to increase exercise performance.

Total protein and calorie intake appears to be the most important consideration when it comes to promoting positive adaptations to resistance training, and the impact of timing strategies immediately before or immediately after to heighten these adaptations in non-athletic populations appears to be minimal.

Proteins provide the building blocks of all tissues via their constituent amino acids. Athletes consume dietary protein to repair and rebuild skeletal muscle and connective tissues following intense training bouts or athletic events.

A report in by Phillips [ ] summarized the findings surrounding protein requirements in resistance-trained athletes.

Using a regression approach, he concluded that a protein intake of 1. A key consideration regarding these recommended values is that all generated data were obtained using the nitrogen balance technique, which is known to underestimate protein requirements. Interestingly, two of the included papers had prescribed protein intakes of 2.

All data points from these two studies also had the highest levels of positive nitrogen balance. For an athlete seeking to ensure an anabolic environment, higher daily protein intakes might be needed. Another challenge that underpins the ability to universally and successfully recommend daily protein amounts are factors related to the volume of the exercise program, age, body composition and training status of the athlete; as well as the total energy intake in the diet, particularly for athletes who desire to lose fat and are restricting calories to accomplish this goal [ ].

For these reasons, and due to an increase of published studies in areas related to optimal protein dosing, timing and composition, protein needs are being recommended within this position stand on a per meal basis.

For example, Moore [ 31 ] found that muscle and albumin protein synthesis was optimized at approximately 20 g of egg protein at rest. Witard et al. Furthermore, while results from these studies offer indications of what optimal absolute dosing amounts may be, Phillips [ ] concluded that a relative dose of 0.

Once a total daily target protein intake has been achieved, the frequency and pattern with which optimal doses are ingested may serve as a key determinant of overall changes in protein synthetic rates. Research indicates that rates of MPS rapidly rise to peak levels within 30 min of protein ingestion and are maintained for up to three hours before rapidly beginning to lower to basal rates of MPS even though amino acids are still elevated in the blood [ ].

Using an oral ingestion model of 48 g of whey protein in healthy young men, rates of myofibrillar protein synthesis increased three-fold within 45—90 min before slowly declining to basal rates of MPS all while plasma concentration of EAAs remained significantly elevated [ ].

While largely unexplored in a human model, these authors relied upon an animal model and were able to reinstate increases in MPS using the consumption of leucine and carbohydrate min after ingestion of the first meal.

As such, it is suggested that individuals attempting to restrict caloric intake should consume three to four whole meals consisting of 20—40 g of protein per meal.

While this recommendation stems primarily from initial work that indicated protein doses of 20—40 g favorably promote increased rates of MPS [ 31 , , ], Kim and colleagues [ ] recently reported that a 70 g dose of protein promoted a more favorable net balance of protein when compared to a 40 g dose due to a stronger attenuation of rates of muscle protein breakdown.

For those attempting to increase their calories, we suggest consuming small snacks between meals consisting of both a complete protein and a carbohydrate source. This contention is supported by research from Paddon-Jones et al.

These researchers compared three cal mixed macronutrient meals to three cal meals combined with three cal amino acid-carbohydrate snacks between meals. Additionally, using a protein distribution pattern of 20—25 g doses every three hours in response to a single bout of lower body resistance exercise appears to promote the greatest increase in MPS rates and phosphorylation of key intramuscular proteins linked to muscle hypertrophy [ ].

This simple addition could provide benefits for individuals looking to increase muscle mass and improve body composition in general while also striving to maintain or improve health and performance.

The current RDA for protein is 0. While previous recommendations have suggested a daily intake of 1. Daily and per dose needs are combinations of many factors including volume of exercise, age, body composition, total energy intake and training status of the athlete.

Daily intakes of 1. Even higher amounts ~70 g appear to be necessary to promote attenuation of muscle protein breakdown.

Pacing or spreading these feeding episodes approximately three hours apart has been consistently reported to promote sustained, increased levels of MPS and performance benefits.

There are 20 total amino acids, comprised of 9 EAAs and 11 non-essential amino acids NEAAs. EAAs cannot be produced in the body and therefore must be consumed in the diet. Several methods exist to determine protein quality such as Chemical Score, Protein Efficiency Ratio, Biological Value, Protein Digestibility-Corrected Amino Acid Score PDCAAS and most recently, the Indicator Amino Acid Oxidation IAAO technique.

Ultimately, in vivo protein quality is typically defined as how effective a protein is at stimulating MPS and promoting muscle hypertrophy [ ]. Overall, research has shown that products containing animal and dairy-based proteins contain the highest percentage of EAAs and result in greater hypertrophy and protein synthesis following resistance training when compared to a vegetarian protein-matched control, which typically lacks one or more EAAs [ 86 , 93 , ].

Several studies, but not all, [ ] have indicated that EAAs alone stimulate protein synthesis in the same magnitude as a whole protein with the same EAA content [ 98 ]. For example, Borsheim et al. Moreover, Paddon-Jones and colleagues [ 96 ] found that a cal supplement containing 15 g of EAAs stimulated greater rates of protein synthesis than an cal meal with the same EAA content from a whole protein source.

While important, the impact of a larger meal on changes in circulation and the subsequent delivery of the relevant amino acids to the muscle might operate as important considerations when interpreting this data. In contrast, Katsanos and colleagues [ ] had 15 elderly subjects consume either 15 g of whey protein or individual doses of the essential and nonessential amino acids that were identical to what is found in a g whey protein dose on separate occasions.

Whey protein ingestion significantly increased leg phenylalanine balance, an index of muscle protein accrual, while EAA and NEAA ingestion exerted no significant impact on leg phenylalanine balance. This study, and the results reported by others [ ] have led to the suggestion that an approximate 10 g dose of EAAs might serve as an optimal dose to maximally stimulate MPS and that intact protein feedings of appropriate amounts as opposed to free amino acids to elderly individuals may stimulate greater improvements in leg muscle protein accrual.

Based on this research, scientists have also attempted to determine which of the EAAs are primarily responsible for modulating protein balance.

The three branched-chain amino acids BCAAs , leucine, isoleucine, and valine are unique among the EAAs for their roles in protein metabolism [ ], neural function [ , , ], and blood glucose and insulin regulation [ ]. Additionally, enzymes responsible for the degradation of BCAAs operate in a rate-limiting fashion and are found in low levels in splanchnic tissues [ ].

Thus, orally ingested BCAAs appear rapidly in the bloodstream and expose muscle to high concentrations ultimately making them key components of skeletal MPS [ ]. Furthermore, Wilson and colleagues [ ] have recently demonstrated, in an animal model, that leucine ingestion alone and with carbohydrate consumed between meals min post-consumption extends protein synthesis by increasing the energy status of the muscle fiber.

Multiple human studies have supported the contention that leucine drives protein synthesis [ , ]. Moreover, this response may occur in a dose-dependent fashion, plateauing at approximately two g at rest [ 31 , ], and increasing up to 3.

However, it is important to realize that the duration of protein synthesis after resistance exercise appears to be limited by both the signal leucine concentrations , ATP status, as well as the availability of substrate i. As such, increasing leucine concentration may stimulate increases in muscle protein, but a higher total dose of all EAAs as free form amino acids or intact protein sources seems to be most suited for sustaining the increased rates of MPS [ ].

It is well known that exercise improves net muscle protein balance and in the absence of protein feeding, this balance becomes more negative. When combined with protein feeding, net muscle protein balance after exercise becomes positive [ ]. Norton and Layman [ ] proposed that consumption of leucine, could turn a negative protein balance to a positive balance following an intense exercise bout by prolonging the MPS response to feeding.

In support, the ingestion of a protein or essential amino acid complex that contains sufficient amounts of leucine has been shown to shift protein balance to a net positive state after intense exercise training [ 46 , ].

Even though leucine has been demonstrated to independently stimulate protein synthesis, it is important to recognize that supplementation should not be with just leucine alone. For instance, Wilson et al. In summary, athletes should focus on consuming adequate leucine content in each of their meals through selection of high-quality protein sources [ ].

Protein sources containing higher levels of the EAAs are considered to be higher quality sources of protein. The body uses 20 amino acids to make proteins, seven of which are essential nine conditionally , requiring their ingestion to meet daily needs.

EAAs appear to be uniquely responsible for increasing MPS with doses ranging from 6 to 15 g all exerting stimulatory effects. In addition, doses of approximately one to three g of leucine per meal appear to be needed to stimulate protein translation machinery.

The BCAAs i. However, the extent to which these changes are aligned with changes in MPS remains to be fully explored. While greater doses of leucine have been shown to independently stimulate increases in protein synthesis, a balanced consumption of the EAAs promotes the greatest increases.

Milk proteins have undergone extensive research related to their potential roles in augmenting adaptations from exercise training [ 86 , 93 ]. For example, consuming milk following exercise has been demonstrated to accelerate recovery from muscle damaging exercise [ ], increase glycogen replenishment [ ], improve hydration status [ , ], and improve protein balance to favor synthesis [ 86 , 93 ], ultimately resulting in increased gains in both neuromuscular strength and skeletal muscle hypertrophy [ 93 ].

Moreover, milk protein contains the highest score on the PDCAAS rating system, and in general contains the greatest density of leucine [ ].

Milk can be fractionated into two protein classes, casein and whey. While both are high in quality, the two differ in the rate at which they digest as well as the impact they have on protein metabolism [ , , ]. Whey protein is water soluble, mixes easily, and is rapidly digested [ ]. In contrast, casein is water insoluble, coagulates in the gut and is digested more slowly than whey protein [ ].

Casein also has intrinsic properties such as opioid peptides, which effectively slow gastric motility [ ]. Original research investigating the effects of digestion rate was conducted by Boirie, Dangin and colleagues [ , , ].

These researchers gave a 30 g bolus of whey protein and a 43 g bolus of casein protein to subjects on separate occasions and measured amino acid levels for several hours after ingestion. They reported that the whey protein condition displayed robust hyperaminoacidemia min after administration.

However, by min, amino acid concentrations had returned to baseline. In contrast, the casein condition resulted in a slow increase in amino acid concentrations, which remained elevated above baseline after min.

Over the study duration, casein produced a greater whole body leucine balance than the whey protein condition, leading the researcher to suggest that prolonged, moderate hyperaminoacidemia is more effective at stimulating increases in whole body protein anabolism than a robust, short lasting hyperaminoacidemia.

While this research appears to support the efficacy of slower digesting proteins, subsequent work has questioned its validity in athletes. The first major criticism is that Boire and colleagues investigated whole body non-muscle and muscle protein balance instead of skeletal myofibrillar MPS.

These findings suggest that changes in whole body protein turnover may poorly reflect the level of skeletal muscle protein metabolism that may be taking place. Trommelen and investigators [ ] examined 24 young men ingesting 30 g of casein protein with or without completion of a single bout of resistance exercise, and concluded that rates of MPS were increased, but whole-body protein synthesis rates were not impacted.

More recently, Tang and colleagues [ 86 ] investigated the effects of administering 22 g of hydrolyzed whey isolate and micellar casein 10 g of EAAs at both rest and following a single bout of resistance training in young males.

Moreover, these researchers reported that whey protein ingestion stimulated greater MPS at both rest and following exercise when compared to casein. In comparison to the control group, both whey and casein significantly increased leucine balance, but no differences were found between the two protein sources for amino acid uptake and muscle protein balance.

Additional research has also demonstrated that 10 weeks of whey protein supplementation in trained bodybuilders resulted in greater gains in lean mass 5. These findings suggest that the faster-digesting whey proteins may be more beneficial for skeletal muscle adaptations than the slower digesting casein.

Skeletal muscle glycogen stores are a critical element to both prolonged and high-intensity exercise. In skeletal muscle, glycogen synthase activity is considered one of the key regulatory factors for glycogen synthesis. Research has demonstrated that the addition of protein in the form of milk and whey protein isolate 0.

Further, the addition of protein facilitates repair and recovery of the exercised muscle [ 12 ]. These effects are thought to be related to a greater insulin response following the exercise bout. Intriguingly, it has also been demonstrated that whey protein enhances glycogen synthesis in the liver and skeletal muscle more than casein in an insulin-independent fashion that appears to be due to its capacity to upregulate glycogen synthase activity [ ].

Therefore, the addition of milk protein to a post-workout meal may augment recovery, improve protein balance, and speed glycogen replenishment.

While athletes tend to view whey as the ideal protein for skeletal muscle repair and function it also has several health benefits. In particular, whey protein contains an array of biologically active peptides whose amino acids sequences give them specific signaling effects when liberated in the gut.

Furthermore, whey protein appears to play a role in enhancing lymphatic and immune system responses [ ]. In addition, α-lactalbumin contains an ample supply of tryptophan which increases cognitive performance under stress [ ], improves the quality of sleep [ , ], and may also speed wound healing [ ], properties which could be vital for recovery from combat and contact sporting events.

In addition, lactoferrin is also found in both milk and in whey protein, and has been demonstrated to have antibacterial, antiviral, and antioxidant properties [ ].

Moreover, there is some evidence that whey protein can bind iron and therefore increase its absorption and retention [ ]. Egg protein is often thought of as an ideal protein because its amino acid profile has been used as the standard for comparing other dietary proteins [ ].

Due to their excellent digestibility and amino acid content, eggs are an excellent source of protein for athletes. While the consumption of eggs has been criticized due to their cholesterol content, a growing body of evidence demonstrates the lack of a relationship between egg consumption and coronary heart disease, making egg-based products more appealing [ ].

One large egg has 75 kcal and 6 g of protein, but only 1. Research using eggs as the protein source for athletic performance and body composition is lacking, perhaps due to less funding opportunities relative to funding for dairy.

Egg protein may be particularly important for athletes, as this protein source has been demonstrated to significantly increase protein synthesis of both skeletal muscle and plasma proteins after resistance exercise at both 20 and 40 g doses.

Leucine oxidation rates were found to increase following the 40 g dose, suggesting that this amount exceeds an optimal dose [ 31 ].

In addition to providing a cost effective, high-quality source of protein rich in leucine 0. Functional foods are defined as foods that, by the presence of physiologically active components, provide a health benefit beyond basic nutrition [ ]. According to the Academy of Nutrition and Dietetics, functional foods should be consumed as part of a varied diet on a regular basis, at effective levels [ ].

Thus, it is essential that athletes select foods that meet protein requirements and also optimize health and prevent decrements in immune function following intense training.

Eggs are also rich in choline, a nutrient which may have positive effects on cognitive function [ ].

Moreover, eggs provide an excellent source of the carotenoid-based antioxidants lutein and zeaxanthin [ ]. Also, eggs can be prepared with most meal choices, whether at breakfast, lunch, or dinner. With regard to endurance exercise, protein consumption during exercise may not confer an immediate ergogenic benefit, especially when carbohydrate consumption is adequate.

It may, however, aid in delaying central fatigue, reducing MPB, and contributing to a more positive, whole-body nitrogen balance. Additionally, protein consumption in and around intense or prolonged endurance activity may aid in reduction of upper respiratory tract infection incidence and improved immune system function.

It may also aid in upregulating gene expression of proteins necessary for improving bioenergetic pathways. The impact of this on subsequent training sessions should not be dismissed and is an important part of improving performance. The effect of protein consumption on resistance training is highly dependent on many variables not related to protein.

The combination of peri-training protein consumption with inadequate or ineffective resistance training protocols will not maximize improvements in strength or hypertrophy.

Resistance training protocol interventions must be of adequate intensity, volume, and frequency with an emphasis on progressive overload to produce results. Additionally, adequate training interventions coupled with calorie-restricted nutrition protocols may require increased protein intake of 2.

Consideration must also be made for the age of resistance-trained individuals, as older adults require protein intake over and above that of their younger counterparts to receive the same benefits noted above In order to fully understand the role of protein or any substrate for that matter on performance, the practical application beyond the contrived training or recovery interventions presented must be addressed.

Daily training schedules of athletes require an ongoing ability to recover and perform. As an example, most of the studies included in this area utilized a training protocol that took ~3—4 h per week, typically in moderately-trained individuals.

For comparative purposes, a competitive athlete may spend 3—10 times this amount of time training per week if not more. Protein dosing strategies need to take this into account. This becomes even more apparent when considering that the uniform distribution of protein throughout the day results in greater MPS than an uneven distribution even when total daily protein intake is equal Arciero et al.

These results suggest that the pattern of daily protein ingestion may also impact results from resistance training protocols and provides further evidence that we must look beyond the few hours following training to determine the impact that protein may have on performance and recovery. Madzima et al.

While no statistically significant changes were observed between groups, protein groups trended toward greater increases when compared to the carbohydrate group while morning fat oxidation was greatest in the casein supplemented group. Taken together, these data demonstrate the need for a more comprehensive view and methods of measuring recovery.

Increased sensitization of muscle to protein and nutrients for 24—72 h following training coupled with multiple weekly training sessions results in an on-going state of recovery. Because of this, we need to begin considering this longer stimulus window as an opportunity to maximize feeding, rather than as a reason why immediate post-workout ingestion may not be particularly important.

In other words, consuming nothing post-workout would be an unwise strategy if the goal is to potentially optimize the adaptive response to exercise training. Overall, there appears to be no adaptive advantage to avoiding protein intake in the peri-workout period. Stimulation of MPS in the acute period following training may not result in improvements in strength, hypertrophy, body composition, or performance without deliberate implementation of additional strategies during the prolonged recovery period.

As such, this much broader view should be considered with regard to future investigations. SA is on the Advisory Panel for Dymatize. JA is the CEO of the International Society of Sports Nutrition—an academic non-profit that receives grants in part from companies that sell dietary protein.

The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. The reviewer CK declared a past co-authorship with several of the authors SA and JA to the handling Editor.

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However, the dietary recommendations state that most only need 0. This is approximately 55 grams of protein per day for someone who weighs pounds.

This may seem quite low to most physically active individuals and is not difficult to meet as most sedentary individuals consume more than the recommendation.

So, what is the correct protein intake to optimize performance and body composition? A recent position statement from the Academy of Nutrition and Dietetics, Dieticians of America, and the American College of Sports Medicine summarizes the evidence for numerous sports nutrition recommendations including dietary protein intake.

The current data suggests that physically active individuals should consume 1. The upper end of that protein intake is recommended for individuals during periods of higher training frequency and greater intensity and during periods of calorie restriction to maintain muscle mass.

In regards to the timing of protein intake, the position statement recommends that individuals consume 0. Furthermore, that same amount is recommended every 3 to 5 hours over multiple meals throughout the day to maximize muscular adaptation.

Although the current evidence states that athletes need more than the current recommendations, it is not quite as high as what is observed in some gym circles. This article was published by Michigan State University Extension. Many of those reading this will be aware of the general recommendation of 1 gram g of protein per pound lb of body mass However, it can be challenging to determine the specific protein requirements for athletes, as many factors can change the advised ranges.

Whether it is training status, individual sport, or dietary intake, many factors can influence recommendations for protein intake for athletes. Most data discussed in this article will deal with studies that used nitrogen balance to assess adequate protein requirements.

From a physiological standpoint, to be in nitrogen protein balance means that protein nitrogen intake is equal to protein nitrogen loss While nitrogen balance is an accepted measure for assessing protein requirements, it has some drawbacks, which might result in recommendations that are too low Along with nitrogen balance and protein quantity recommendations, it is also vital to keep a note of the quality of protein athletes are ingesting.

Protein Type and Quality As many protein types exist, there is a range of protein quality and completeness that needs to be addressed when it comes to protein requirements Milk proteins whey and casein are typically rated as two of the highest qualities of proteins available while varying plant sources usually score the lowest Protein sources from eggs, beef, poultry, fish, and dairy are regularly viewed as excellent sources of protein A protein source with all of the essential amino acids in the correct amounts and proportions to increase muscle protein synthesis is known as a complete protein Dietary protein sources of animal origin are broadly classified as complete protein sources, while sources of plant origin are commonly missing one or more of the essential amino acids and must be combined with complementary incomplete protein sources The current recommended dietary allowance RDA of protein is 0.

However, a more recent analysis of the same data notes a value of 1. Also, further analysis of daily requirements for sedentary adults using a more accurate amino acid analysis technique Indicator Amino Acid Oxidation found a value of 1.

So overall, there exists a range in the literature when it comes to sedentary adults 0. This should be the absolute bare minimum that athletes ingest daily, but as athletes require more than the typical sedentary adult, read on to the next sections to determine individual needs based upon various situations.

Endurance athletes are no different; protein requirements vary depending upon training status, exercise intensity, workout duration, and dietary intake The best way to approach these variations is to classify athletes as recreational athletes those predominantly performing low- to moderate-intensity endurance exercise , modestly trained athletes, and elite endurance athletes Multiple studies have found that a recreational level of endurance training does not alter the amount of protein needed for that athlete 31, One such study by el-Khoury et al.

For modestly trained athletes, multiple studies have reported protein intakes of 0. These protein intakes resulted in net negative protein balances following exercise. Recommendations of In terms of elite endurance athletes, a small collection of studies has examined their protein requirements.

One found that 1. Another advised that 1. A further study by Brouns et al. If an endurance athlete is interested in improving their endurance exercise performance, diets high in protein appear to offer no benefit.

Still, they may help reduce psychological stress and declines in performance commonly seen during blocks on high-intensity training And ingestion of protein following resistance exercise is required for a positive protein balance Regular resistance exercise is also a source of stress and trauma that requires greater protein availability to recover A meta-analysis involving participants across 22 published studies has also demonstrated a positive impact of protein supplementation on improvements in fat-free mass and leg strength when compared to a placebo in both young and old populations 8.

An example of this is the near-universal finding of untrained or unaccustomed individuals needing increased amounts of dietary protein. Tarnopolsky et al. They concluded that the lowest intake compromised protein synthesis when compared to the moderate and high intakes and that while the moderate protein intake amounted to a neutral protein balance, they recommended one standard deviation above at 1.

Other studies have also suggested that protein intakes ranging from 1. The International Society of Sports Nutrition ISSN has also published position statements on the protein requirements of athletes, and they note 1.

And a consensus statement from ACSM et al. A fascinating and recent study was a systematic review, meta-analysis, and meta-regression by Morton et al. Data from the review, including 49 previous studies and participants, showed that protein supplementation significantly improved fat-free mass gains, maximal strength, muscle fibre diameter, and cross-sectional area of femur thigh mass The authors also noted that a protein intake higher than 1.

Two other studies by Antonio et al. Their first intervention had 30 resistance-trained individuals continue following their typical exercise training program alongside either a control or high-protein diet 4.

While the 30 participants were at a caloric surplus for 8 weeks, no changes in body mass, fat mass, fat-free mass, or per cent body fat were found when compared to the control group. The participants followed either their normal diet of 2. Ultimately, the researchers found similar changes in strength, and the control group saw a significant increase in body mass.

In contrast, the high-protein group saw a greater decrease in fat mass and per cent body fat 3. They theorised that those changes in fat-free mass they saw in both of the groups were the result of a different training stimulus.

Intermediate Strength Athletes 6 months — 2 years training : 1. And what is also important to consider is the speed at which an athlete loses body mass. To read the Research Review on making weight the wrong way, click here. They found that the higher protein diet lost significantly less fat-free mass, and both groups lost similar amounts of fat mass and performed similarly in all physical tasks assessed.

Pasiakos et al. You can use it to keep track of your calories as well as macronutrients such as protein. I know most athletes as well as parents are busy, but tracking protein intake as well as other nutritional intake is one of the most beneficial habits one can develop.

Another option is to seek out a professional such as a licensed nutritionist to help with a structured diet plan specifically made for your athlete. A good amount of high school athletes could benefit from keeping track of their daily nutritional intake as well as increasing their protein intake.

If you have an athlete who seems to be struggling when it comes to building muscle, then they may need to start monitoring their diet to make sure they are taking in the appropriate amounts of protein.

If you need more help with the dietary needs of your athlete, seeking out the help of a licensed professional could be beneficial. Learn about how MUSC Sports Medicine can help all athletes. Categories: Sports Medicine , Orthopaedics. Advance with MUSC Health. Advance Library Protein in Athlete Diet.

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