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Stuart Phillips, PhD, on Building Muscle with Resistance Exercise and Reassessing Protein IntakeProtein and exercise -
One of the main points of debate relative to protein intake and kidney function is the belief that habitual protein consumption in excess of the RDA promotes chronic renal disease through increased glomerular pressure and hyperfiltration [ 19 , 20 ].
The majority of scientific evidence cited by the authors [ 20 ] was generated from animal models and patients with co-existing renal disease. As such, the extension of this relationship to healthy individuals with normal renal function is inappropriate [ 21 ].
In a well designed prospective cohort study, it was surmised that high protein intake was not associated with renal functional decline in women with normally operating kidneys [ 22 ]. Also, it has been reported that there are no statistically significant differences in age, sex, weight, and kidney function between non-vegetarians and vegetarians a group demonstrated to have lower dietary protein intakes [ 23 , 24 ].
Both the non-vegetarian and vegetarian groups possessed similar kidney function, and displayed the same rate of progressive deterioration in renal physiology with age [ 24 ]. Preliminary clinical and epidemiological studies have suggested a benefit of relatively high protein diets on major risk factors for chronic kidney disease, such as hypertension, diabetes, obesity and metabolic syndrome.
Future studies are necessary to further examine the role of relatively high protein weight loss diets, dietary protein source quality and quantity on the prevalence and development of kidney disease in at risk patient populations [ 25 , 26 ].
While it appears that dietary protein intakes above the RDA are not deleterious for healthy, exercising individuals, those individuals with mild renal insufficiency need to closely monitor their protein intake as observational data from epidemiological studies provide evidence that dietary protein intake may be related to the progression of renal disease [ 21 , 26 ].
In addition to renal function, the relationship between dietary protein intake and bone metabolism has also served as the cause for some controversy. Specifically, there is concern that a high intake of dietary protein results in the leaching of calcium from bones, which may lead to osteopenia and predispose some individuals to osteoporosis.
This supposition stems from early studies reporting an increase in urine acidity from increased dietary protein that appeared to be linked to drawing calcium from the bones to buffer the acid load.
However, studies reporting this effect were limited by small sample sizes, methodological errors, and the use of high doses of purified forms of protein [ 27 ].
It is now known that the phosphate content of protein foods and supplements fortified with calcium and phosphorous negates this effect. In fact, some data suggest that elderly men and women the segment of the population most susceptible to osteoporosis should consume dietary protein above current recommendations 0.
In addition, data from stable calcium isotope studies is emerging, which suggests the main source of the increase in urinary calcium from a high-protein diet is intestinal dietary and not from bone resorption [ 29 ]. Also, given that exercise training supplies the stimulus for increasing skeletal muscle protein, levels in the range of 1.
More research needs to be conducted in adults and the elderly relative to exercise, skeletal muscle hypertrophy and protein intake and their cumulative effects on bone mass. Overall, there is a lack of scientific evidence linking higher dietary protein intakes to adverse outcomes in healthy, exercising individuals.
There is, however, a body of scientific literature which has documented a benefit of protein supplementation to the health of multiple organ systems. It is therefore the position of the International Society of Sport Nutrition that active elderly individuals require protein intakes ranging from 1.
To obtain supplemental dietary protein, exercising individuals often ingest protein powders. Powdered protein is convenient and, depending on the product, can be cost-efficient as well [ 32 ]. Common sources of protein include milk, whey, casein, egg, and soy-based powders.
Different protein sources and purification methods may affect the bioavailability of amino acids. The amino acid bioavailability of a protein source is best conceptualized as the amount and variety of amino acids that are digested and absorbed into the bloodstream after a protein is ingested.
Furthermore, amino acid bioavailability may also be reflected by the difference between the nitrogen content from a protein source that is ingested versus the nitrogen content that is subsequently present in the feces.
Consideration of the bioavailability of amino acids into the blood, as well as their delivery to the target tissue s , is of greatest importance when planning a regimen of pre- and post-exercise protein ingestion. A protein that provides an adequate circulating pool of amino acids before and after exercise is readily taken up by skeletal muscle to optimize nitrogen balance and muscle protein kinetics [ 33 ].
The quality of a protein source has previously been determined by the somewhat outdated protein efficiency ratio PER , and the more precise protein digestibility corrected amino acid score PDCAAS.
The former method was used to evaluate the quality of a protein source by quantifying the amount of body mass maturing rats accrue when fed a test protein. The latter method was established by the Food and Agriculture Organization FAO as a more appropriate scoring method which utilized the amino acid composition of a test protein relative to a reference amino acid pattern, which was then corrected for differences in protein digestibility [ 34 ].
The U. Dairy Export Council's Reference Manual for U. Whey and Lactose Products indicates that milk-derived whey protein isolate presents the highest PDCAAS out of all of the common protein sources due to its high content of essential and branched chain amino acids. Milk-derived casein, egg white powder, and soy protein isolate are also classified as high quality protein sources with all of them scoring a value of unity 1.
In contrast, lentils score a value of 0. Commercially, the two most popular types of proteins in supplemental form are whey and casein.
Recent investigations have detailed the serum amino acid responses to ingesting different protein types. Using amino acid tracer methodology, it was demonstrated that whey protein elicits a sharp, rapid increase of plasma amino acids following ingestion, while the consumption of casein induces a moderate, prolonged increase in plasma amino acids that was sustained over a 7-hr postprandial time period [ 35 ].
The differences in the digestibility and absorption of these protein types may indicate that the ingestion of "slow" casein and "fast" whey proteins differentially mediate whole body protein metabolism due to their digestive properties [ 35 ].
Other studies have shown similar differences in the peak plasma levels of amino acids following ingestion of whey and casein fractions i. Applied exercise science research has also demonstrated the differential effects that ingesting different proteins exerts on postprandial blood amino acid responses and muscle protein synthesis after exercise.
The data are equivocal relative to which type of protein increases net protein status breakdown minus synthesis to a greater extent after exercise. Some research has demonstrated that despite different patterns of blood amino acid responses, muscle protein net balance was similar in those ingesting casein or whey [ 33 ].
However, additional research has indicated that whey protein induced protein gain to a greater extent than casein [ 38 ]. In contrast, several other studies have shown that casein increased protein deposition at levels greater than whey proteins [ 35 , 37 ].
The recommendation of the International Society of Sport Nutrition is that individuals engaging in exercise attempt to obtain their protein requirements through whole foods.
When supplements are ingested, we recommend that the protein contain both whey and casein components due to their high protein digestibility corrected amino acid score and ability to increase muscle protein accretion.
It is generally recognized that active individuals require more dietary protein due to an increase in intramuscular protein oxidation [ 39 ] and protein breakdown [ 40 ] that occurs during exercise, as well as the need to further complement intramuscular protein resynthesis and attenuate proteolytic mechanisms that occur during the post-exercise recovery phases [ 41 — 43 ].
Thus, a strategically planned protein intake regimen timed around physical activity is integral in preserving muscle mass or eliciting muscular hypertrophy, ensuring a proper recovery from exercise, and perhaps even sustaining optimal immune function. Previously, high levels of blood amino acids following a bout of resistance training have been found to be integral in promoting muscle protein synthesis [ 44 ].
Evidence is accumulating that supports the benefits of the timing of protein intake and its effect on gains in lean mass during resistance exercise training [ 45 — 49 ]. Given that much of the research to date has been conducted on resistance exercise, more investigations are required to ascertain the effects of protein timing on other modes of exercise.
Research has also highlighted the positive immune and health-related effects associated with post-exercise protein ingestion. A previous investigation utilizing United States Marine subjects [ 50 ] examined the effects of an ingested supplement 8 g carbohydrate, 10 g protein, 3 g fat immediately after exercise on the status of various health markers.
These data were compared to subjects ingesting a non-protein supplement 8 g carbohydrate, 0 g protein, 3 g fat , and subjects ingesting placebo tablets 0 g carbohydrate, 0 g protein, 0 g fat.
Moreover, post-exercise muscle soreness was significantly reduced in subjects ingesting protein when compared to the control groups. Previous studies using animal models have demonstrated that whey protein elicits immuno-enhancing properties, likely due to its high content of cysteine; an amino acid that is needed for glutathione production [ 51 , 52 ].
Hence, previous research has indicated that ingesting a protein source that is rich in essential amino acids and is readily digestible immediately before and following exercise training is beneficial for increasing muscle mass, recovery following exercise, and sustaining immune function during high-volume training periods.
It is the position of the International Society of Sport Nutrition that exercising individuals should consume high quality protein within the time period encompassing their exercise session i. before, during, and after. The branched-chain amino acids i. leucine, isoleucine and valine constitute approximately one-third of skeletal muscle protein [ 53 ].
An increasing amount of literature suggests that of the three BCAAs, leucine appears to play the most significant role in stimulating protein synthesis [ 54 ]. In this regard, amino acid supplementation particularly the BCAAs may be advantageous for the exercising individual.
A few studies reported that when BCAAs were infused in humans at rest, protein balance increases by either decreasing the rate of protein breakdown, increasing the rate of protein synthesis or a combination of both [ 55 , 56 ]. Following resistance exercise in males it has been shown that the addition of free leucine combined with carbohydrate and protein led to a greater increase protein synthesis as compared to taking the same amount of carbohydrate and protein without leucine [ 57 ].
However, the majority of the research relative to leucine ingestion and protein synthesis has been conducted using animal models. Similar research needs to be conducted in healthy individuals engaging in resistance exercise. BCAA ingestion has been shown to be beneficial during aerobic exercise.
When BCAAs are taken during aerobic exercise the net rate of protein degradation has been shown to decrease [ 58 ]. Equally important, BCAA administration given before and during exhaustive aerobic exercise to individuals with reduced muscle glycogen stores may also delay muscle glycogen depletion [ 59 ].
When BCAAs were given to runners during a marathon it improved the performance of "slower" runners those who completed the race in 3. During prolonged aerobic exercise, the concentration of free tryptophan increases and the uptake of tryptophan into the brain increases.
When this occurs, 5-hydroxytryptamine a. serotonin , which is thought to play a role in the subjective feelings of fatigue, is produced. Similarly, BCAAs are transported into the brain by the same carrier system as tryptophan and thus "compete" with tryptophan to be transported into the brain.
Therefore, it is believed that when certain amino acids such as BCAAs are present in the plasma in sufficient amounts, it theoretically may decrease the uptake of tryptophan in the brain and ultimately decrease the feelings of fatigue [ 61 , 62 ].
Furthermore, there is also research to suggest that BCAA administration taken during prolonged endurance events may help with mental performance in addition to the aforementioned performance benefits [ 60 ]. However, not all research investigating BCAA supplementation has reported improvements in exercise performance.
Reasons for discrepant results are not clear at this time, but at the very minimum, it seems apparent that supplementation with BCAAs does not impair performance. Because BCAAs have been shown to aid in recovery processes from exercise such as stimulating protein synthesis, aiding in glycogen resynthesis, as well as delaying the onset of fatigue and helping maintain mental function in aerobic-based exercise, we suggest consuming BCAAs in addition to carbohydrates before, during, and following an exercise bout.
However, while more research is indicated, because BCAAs occur in nature i. This will ensure the ratio that appears often in animal protein [ 64 ]. Any deficiency in BCAA intake from whole foods can easily be remedied by consuming whey protein during the time frame encompassing the exercise session; however, an attempt should be made to obtain all recommended BCAAs from whole food protein sources.
It is the position of the International Society of Sports Nutrition that exercising individuals need approximately 1. The amount is dependent upon the mode and intensity of the exercise, the quality of the protein ingested, and the status of the energy and carbohydrate intake of the individual.
Concerns that protein intake within this range is unhealthy are unfounded in healthy, exercising individuals. An attempt should be made to obtain protein requirements from whole foods, but supplemental protein is a safe and convenient method of ingesting high quality dietary protein.
The timing of protein intake in the time period encompassing the exercise session has several benefits including improved recovery and greater gains in fat free mass. Protein residues such as branched chain amino acids have been shown to be beneficial for the exercising individual, including increasing the rates of protein synthesis, decreasing the rate of protein degradation, and possibly aiding in recovery from exercise.
In summary, exercising individuals need more dietary protein than their sedentary counterparts, which can be obtained from whole foods as well as from high quality supplemental protein sources such as whey and casein protein.
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Med Sci Sports Exerc. Tarnopolsky M: Protein requirements for endurance athletes. Rand WM, Pellett PL, Young VR: Meta-analysis of nitrogen balance studies for estimating protein requirements in healthy adults. Am J Clin Nutr. Forslund AH, El-Khoury AE, Olsson RM, Sjodin AM, Hambraeus L, Young VR: Effect of protein intake and physical activity on h pattern and rate of macronutrient utilization.
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Int J Sports Med. Those who aim for the higher end of the range may include:. One important caution is that people with chronic kidney conditions may need to limit protein to protect their kidneys. If you have kidney disease , consult your doctor about protein intake.
Another method calculates protein intake based on your specific daily calorie goal. Protein is an important part of a balanced, healthy diet that includes a variety of foods, including unlimited vegetables. You may choose to use protein supplements, such as powders, premixed drinks, bars, and gummies.
Plant-based protein powders can be particularly helpful for people who follow a vegetarian or vegan lifestyle, she adds. Wardlaw also recommends reading labels, finding substitutes for healthy eating , and avoiding products with:. Add protein-rich snacks throughout the day, such as protein bars, homemade protein balls made from protein powder, cottage cheese, or meat sticks.
Many people who exercise also wonder how much protein after a workout is best. Wardlaw recommends at least 15 to 25 grams of protein within 2 hours after exercise.
That helps stimulate muscle growth. Request an appointment, or learn more about Sports Medicine at Mass General Brigham and the teams we treat. This damage is responsible for muscle soreness and can ultimately reduce strength and function if the proteins are not replenished. Consuming protein in the diet can offset this effect.
Eating a high protein meal decreases muscle breakdown and increases muscle repair and synthesis Moore D et al. As a result, the American College of Sports Medicine advocates protein intakes higher than the RDA.
Individuals who take part in endurance sports runners, cyclists, swimmers are advised to consume between 1. A position paper from the International Society of Sports Nutrition came to a similar conclusion, suggesting ranges up to 2.
Scientific research shows that simply consuming enough protein will not optimise muscle repair and synthesis because not all types of protein are equally beneficial. In order to utilise the protein we eat, the body breaks it down into basic building blocks, called amino acids. The source of the protein influences our ability to digest it properly and, therefore, the availability of these crucial building blocks.
Protein from plants such as vegetables, nuts, seeds, grains, and legumes are not as well digested as protein from animal sources or soy protein. In addition, not all proteins contain all of the amino acids the human body needs.
Some amino acids, called essential amino acids, cannot be produced by the human body and must be consumed in the diet. Egg, milk and soy proteins are highly digestible and contain all of the essential amino acids, meaning they are considered the highest quality proteins for humans.
Recent scientific research has allowed us to refine this list even further for athletes because when it comes to building muscle, one specific amino acid, leucine, plays a critical role Layman D et al.
Whey protein contains more leucine than any other source of protein and clinical studies have shown that whey stimulates muscle synthesis more effectively than other high quality proteins, especially when consumed after exercise. This leucine trigger hypothesis has been found to be especially important for older adults , where the ability to digest and utilise protein is diminished.
Focusing on post-exercise whey supplementation is only part of a bigger picture. Optimal muscle repair and synthesis will not be achieved simply by drinking a protein shake after a workout. Frequent training is required to improve performance.
As a result, muscle breakdown, repair and synthesis becomes an ongoing process and regular intake of high quality protein is needed.
This means that consuming larger amounts of protein at that same meal offers no additional benefit. For this reason, spreading protein intake throughout the day, such that g of high quality protein is consumed at breakfast, lunch and dinner, is more beneficial.
Permanent weight loss the TREK Prottein the Protejn to hear about exercide new products! Sign Up. Protein is Protein and exercise for everyone who is hitting the gym, playing sports, going for runs or doing any other form of exercise, not just the pros. Protein is a macronutrient. To put it simply, protein is one of the main nutrients that every person needs to maintain a healthy body.
Journal of the International Protein and exercise of Sports Nutrition volume edercise Protein and exercise, Article number: 20 Cite this article. DIY lice treatment details. The Protein and exercise Society Proteih Sports Nutrition ISSN Protein and exercise amd objective Protein and exercise Android fat distribution review related to the intake of protein for healthy, exercising exsrcise. Based on exdrcise current available literature, the position of the Society is as follows:. An acute exercise stimulus, particularly resistance exercise, and protein ingestion both stimulate muscle protein synthesis MPS and are synergistic when protein consumption occurs before or after resistance exercise. For building muscle mass and for maintaining muscle mass through a positive muscle protein balance, an overall daily protein intake in the range of 1. Recommendations regarding the optimal protein intake per serving for athletes to maximize MPS are mixed and are dependent upon age and recent resistance exercise stimuli.
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