Carbohydrates and training adaptations -
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Journal of Applied Physiology Daily training with high carbohydrate availability increases exogenous carbohydrate oxidation during endurance cycling. ARTICLE Carbohydrate Availability and Training Adaptation: Effects on Cell Metabolism John A.
Hawley1 and Louise M. Burke 2 1 Health Innovations Research Institute, School of Medical Sciences, RMIT University, Bundoora, Victoria; and 2Department of Sports Nutrition, Australian Institute of Sport, Belconnen, ACT, Australia HAWLEY, J. and L. Carbohydrate availability and training adaptation: effects on cell metabolism.
Sport Sci. Several markers of endurance training adaptation are enhanced to a greater extent when individuals undertake selected training sessions with low compared with normal muscle glycogen content or with low exogenous carbohydrate availability.
The potential mechanisms underlying the cellular responses arising from such nutrient-exercise interactions are discussed in the context of promoting training adaptation. This recommendation is cle glycogen content, and endurance exercise capacity is well underpinned by the rationale that training sessions should be documented, and it has become widely accepted that a high- undertaken with adequate fuel supplies from muscle glycogen carbohydrate intake before, combined with carbohydrate sup- and other carbohydrate-based fuels.
plementation during prolonged, submaximal exercise, can However, this standpoint does not consider the question of postpone the development of muscular fatigue and enhance whether it is a lack or a surplus of substrate that triggers and performance 5, A common belief arising from this premise promotes the training adaptation process.
Indeed, the value is that a high-carbohydrate intake during training will permit of high carbohydrate availability for supporting the demands an athlete to train harder and longer and thus achieve a of training has been met by some with skepticism.
Such a superior training response. Accordingly, sport nutritionists and viewpoint is, no doubt, based on the failure of long-term exercise physiologists consistently have recommended that studies of trained individuals to show clear evidence of supe- athletes who undertake training that is reliant on muscle gly- rior performance outcomes from high-carbohydrate diets cogen as a primary or limiting fuel source consume a diet that compared with an energy-matched diet low in carbohydrate.
provides high carbohydrate availability 6. Rather than definition of recommended carbohydrate intake 6. As such, altering nutrient availability can Address for correspondence: John A. Hawley, Ph.
hawley rmit. competition, as well as the acute regulatory processes under- Accepted for publication: April 30, Associate Editor: Mark Hargreaves, Ph. Unauthorized reproduction of this article is prohibited.
commenced with low carbohydrate availability compared TABLE. Strategies to reduce carbohydrate availability to alter the with training with high carbohydrate support The arti- molecular responses to endurance-based training sessionsa.
We have wit- central nervous system nessed firsthand the confusion caused by misunderstood ter- Twice-a-day training Reduction in endogenous and minology in sports nutrition 6.
Accordingly, we encourage low endogenous carbohydrate exogenous carbohydrate the concept of low and high carbohydrate availability to be availability for the second session availability for the muscle promoted.
Furthermore, we observe that there are many ways in a day achieved by limiting during the second training of achieving low carbohydrate availability before, during, and the duration and carbohydrate session after training sessions that differ in the site of low carbohy- intake in recovery period after the first session Acute reduction in carbohydrate drate availability i.
Thus, the training-induced increase during the session Acute reduction in carbohydrate in gene expression that allows for subsequent changes in availability for immune and protein abundance is crucial to the adaptation process For example, the rate of translation of post- the first hours of recovery availability for the session but exercise skeletal muscle interleukin 6 IL-6 messenger restrict availability for postexercise signaling activities ribonucleic acid mRNA is reduced by feeding glucose during exercise, whereas the transcriptional rate of IL-6 from the a Note that permutations and combinations of these strategies could alter nuclei of contracting skeletal muscle fibers also is influenced exogenous and endogenous carbohydrate supplies independently or in- by muscle glycogen content An acute bout of endurance teractively.
Fuelling strategies to optimise exercise commenced with low muscle glycogen stores also performance V training high or training low? Sports Med. in press, Used with results in a greater transcriptional activation of enzymes permission.
Such tations to exercise training and provides the impetus for the Volume 38 Number 4 October c c Carbohydrate Availability and Training Copyright by the American College of Sports Medicine. hypothesis that training with low muscle glycogen availability we recruited male cyclists or triathletes who had a history may enhance training adaptation to a greater extent than 93 yr of endurance training and who were riding to training with normal or elevated glycogen stores Extend- kmIwkj1 in the months before study participation ing this paradigm, Baar and McGee 4 have proposed that the The athletes were divided into two groups matched for age, classic principles of training incorporating systematic pro- peak oxygen uptake [V ˙ O2peak], and training history and un- gressive overload are no longer adequate for optimal perfor- dertook supervised laboratory training sessions during a 3-wk mance, and based on our increasing knowledge of the role of intervention.
The control group HIGH trained 6 dIwkj1 nutrition and training, this century-old principle is in need of with 1 rest day day 7 , alternating between min steady- revision. The AT and HIT session essary to optimize phenotypic adaptation and performance.
Hawley, unpublished observations, motes endurance-training adaptation to a greater extent than The experimental group LOW trained twice per day, every when training undertaken with high carbohydrate availability. They studied seven previously untrained male subjects resting values.
who completed a training program of leg-knee extensor exer- The novel findings from the study of Yeo et al. On the first day of ond day LOW compared with training daily HIGH after each 5-day training cycle, both legs trained simultaneously for the 3-wk intervention P G 0.
A notable observation was single-leg peak power output. On the second day, only the that self-selected maximal power output was significantly HIGH leg trained. Muscle biopsies were taken from both legs lower P G 0. Submaximal and athletes who commenced these workouts with low muscle maximal exercise testing was performed before and after glycogen content i.
Resting muscle glycogen content before training was but by the third week of the study, there were no differences similar for both groups, but was increased only in LOW after in average power output whether subjects commenced the training P G 0. There was a training-induced increase in workouts with low or normal glycogen stores Figure.
the maximal activity of citrate synthase in both legs P G 0. Yeo et al. perform two workouts in close proximity, with the second Noticeably, the magnitude of increase in posttraining exercise session performed under conditions of low starting muscle time to exhaustion was twice as great for LOW as HIGH glycogen, this nutrient-exercise protocol may offer a time- These results clearly efficient method of maintaining training adaptations and demonstrate that adaptation and endurance performance are performance.
augmented by lack of substrate i. promised when trained cyclists commenced HIT sessions with To investigate whether well-trained individuals might at- low versus normal glycogen stores. In addition, they reported tain the same benefit as untrained, less fit individuals who un- that tracer-derived measures of fat oxidation during sub- dertake a training regimen with lowered glycogen availability, maximal cycling were greater after low-glycogen training Exercise and Sport Sciences Reviews www.
org Copyright by the American College of Sports Medicine. after ingestion. Glucose ingestion also has been reported to attenuate the activation of the AMPK during exercise in some 2 , but not all 21 , studies. If AMPK activation is reduced by increasing glucose availability, then a chronic downregulation of the typical exercise-induced rise in AMPK may attenuate the training response-adaptation process.
This is because AMPK activation has a putative role in promoting metabolic and mitochondrial enzyme content in skeletal muscle 17, Akerstrom et al. Training consisted of Figure. Although there were training-induced in- sessions undertaken on three occasions per wk during a 3-wk intervention creases in the maximal activities of both oxidative and li- period.
Each HIT session consisted of eight repetitions of 5-min work bouts polytic enzymes citrate synthase and A-HAD , tracer-derived separated by 1 min of active recovery W. See text for further details of nutrient-exercise manipulation. Values are reported as legs, the magnitude of improvement was similar, independent mean T standard error.
and train low LOW. Reprinted from Yeo WK, Paton CD, Garnham AP, De Bock et al. Skeletal muscle adaptation and per- cle adaptation is affected by the nutritional status during formance responses to once a day versus twice every second day endurance training sessions.
They recruited moderately active males who training regimens. Used with permission. In agreement with the results derived from muscle triacylglycerol oxidation from 16 T 1 of Akerstrom et al.
Commencing se- cluding succinate dehydrogenase SDH activity, GLUT-4, lected training sessions with low muscle glycogen levels and hexokinase II content were increased by a similar extent also increased the protein content of A-hydroxyacyl-CoA- with or without carbohydrate supplementation.
Despite a sig- dehydrogenase A-HAD; P G 0. Taken collec- exercise were not altered by either training intervention. number of sessions are commenced with low muscle glycogen Contrasting results were reported by Nybo and colleagues levels promote training adaptations i.
They vated glycogen stores. However, despite creating conditions found that undertaking training without exogenous carbohy- that should, in theory, enhance exercise capacity, the effects drate support produced greater enhancement of the increases of this train-low strategy on a range of performance measures in resting muscle glycogen, GLUT-4, and A-HAD.
Yet despite are equivocal discussed subsequently. Both intervention groups achieved similar benefits in fat loss, increases in aerobic capacity, loss of intra- Another strategy to alter carbohydrate availability is to myocellular lipid, and improved blood lipid profile, whereas alter the exogenous supply of glucose.
Glucose supplementa- only the carbohydrate-supported training group achieved an tion during exercise inhibits whole-body fat oxidation by increase in lean BM These results suggest that in pre- suppressing plasma free fatty acid FFA levels while con- viously unconditioned subjects, there may be an impact of comitantly reducing the entry of long-chain fatty acids into altering the exogenous glucose supply during training sessions the mitochondrion, an effect that persists for several hours on selected muscular adaptations, but these are without a Volume 38 Number 4 October c c Carbohydrate Availability and Training Copyright by the American College of Sports Medicine.
functional transfer to the many of benefits of training on health sies from the vastus lateralis and gastrocnemius were taken and performance parameters. before and after the training intervention. Recently, we determined the chronic effects of undertaking In contrast to the findings of Hansen et al.
The period, 16 endurance-trained subjects were all fed a standard training-induced increase in V ˙ O2peak also was similar between diet consisting of 5 gIkgj1 BM. The other eight magnitude of change between groups. Morton training sessions. However, the maximal activity of citrate synthase and exogenous sources provides an enhanced stimulus for increased to a greater extent in LOCHO than HICHO inducing oxidative enzyme adaptations of skeletal muscle, P G 0.
These results suggest To date, the balance of evidence demonstrates that com- that, although there were some differences in the training mencing a portion of short-term endurance-based training adaptations arising from altering carbohydrate availability programs in the face of low carbohydrate availability pro- during training sessions, these did not transfer into clear motes training adaptation i.
regimens with high carbohydrate availability. They studied three groups of signaling pathways that promote mitochondrial biogenesis in recreationally active males who completed 6 wk of high- skeletal muscle.
The initial breakthrough in understanding intensity, intermittent run training a total of 24 train- how repeated contractions i. These include nuclear- V˙ O2peak. In this study, two groups trained twice a day, two respiratory factor 1 NRF-1 and NRF-2, which bind to the sessions per wk one session in the morning, the other in promoters and activate transcription of the genes that encode the afternoon , whereas the third group trained once per day, mitochondrial respiratory chain proteins.
To allow for the determination of the effects of mitochondrial proteins encoded in the nuclear and mito- exogenous glucose supplementation, subjects in group 1 con- chondrial genomes sumed a 6. A control group commenced genesis. Given the role of the AMPK in regulating cellular each training session with normal glycogen stores and did not energy metabolism, this is perhaps not surprising: during consume any beverages throughout the sessions.
Muscle biop- exercise, the perturbations in cellular energy balance lead to Exercise and Sport Sciences Reviews www. AMPK-induced activation of several metabolic and catabolic creased carbohydrate availability during the second of twice- pathways that restore energy equilibrium i.
To explore a potential role for the was blunted compared with when subjects were carbohydrate AMPK in training adaptation, we recently investigated acute restricted between training sessions Six athletes per- Low Carbohydrate or Increased Fat Availability?
Muscle nounced effects on lipid availability, i. Evidence linking the increased p38 MAPK response HIT P G 0. These workers showed that than HIGH P G 0. A possible explanation for the finding p38 MAPK phosphorylation levels were increased during of a higher AMPK activation in the face of low muscle glyco- prolonged 3 h cycling exercise in humans when circulating gen availability is evidence that glycogen binding to the gly- FFA levels were artificially suppressed by administration of cogen-binding domain on the AMPK A subunit allosterically nicotinic acid.
Results from animal studies, however, show inhibits AMPK activity and phosphorylation by upstream that prolonged 4 wk elevation of FFA promotes mito- kinases McBride et al.
with high branching content. Moreover, they also demon- Finally, it is important to note that carbohydrate availability strated that this inhibition of AMPK activation by carbohy- is not the only variable manipulated in the investigations drates was largely dependent on the glycogen-binding domain reviewed herein.
Many of the studies used different training being abolished by mutation of residues required for carbo- modes cycling vs running vs one-leg kicking , a different hydrate binding. Collectively, these results strongly suggest number of training sessions, and variable intervention periods.
that glycogen is a potent regulator of AMPK activity through It is quite possible that some of the results may not be directly its association with the glycogen-binding domain on the attributable to differences in carbohydrate availability per se AMPK A subunit.
but rather to the effects of the exercise training protocol itself Another nutrient-sensitive signaling molecule potentially i. training under conditions of restricted carbohydrate avail- ability is the p38 mitogen-activated protein kinase MAPK.
Several themes during which subjects ingested either a high-carbohydrate can be proposed to help explain this disconnect, and each drink or placebo. Biopsies of the vastus lateralis revealed an warrants further investigation.
First, there may be no direct exercise-induced increase in the phosphorylation of p38 relationship between performance and some of the training- MAPK È4-fold; P G 0.
However, after the second training session p38 muscle proteins may be permissive in promoting the capacity MAPK phosphorylation was higher after the placebo trial for exercise but are not quantitatively correlated, or indeed compared with when carbohydrate availability was increased rate limiting for athletic performance.
Muscle function is only P G 0. Further support for the contention that chronic one factor in determining performance, which involves the elevation of p38 MAPK signaling may play a role in pro- integration of whole-body systems including the role of the moting the greater response-adaptation reported after training central nervous system, in determining pacing strategies and with low carbohydrate availability comes from the data of perceptions of fatigue or effort.
A second rationale is that we Morton et al. They showed that when individuals in- currently lack the appropriate tools to accurately measure Volume 38 Number 4 October c c Carbohydrate Availability and Training Copyright by the American College of Sports Medicine.
The small changes that are worthwhile to a competitive athlete to preparation of elite athletes involves a range of training change the outcomes of real-world events. Within sports sci- activities with various goals It may be that training low ence, there is much discussion of the challenges of measuring needs to be carefully integrated into parts of this complex performance using valid and reliable protocols and of using system to allow a performance benefit to be achieved in different statistical analyses based on magnitude-based infer- concert with the measurable cellular changes.
It also should ences to examine the likelihood that changes or differences in be considered whether highly trained athletes have a differ- performance are meaningful.
It has recently been re- ments exceeds the small biological changes that manifest as ported that the mitochondrial content and oxidative capacity improvements in performance. of skeletal muscle are key determinants of the activation of The third possibility is that some train-low strategies have signaling proteins important to muscle plasticity Acute impairment might directly result because of cues downstream to evoke phenotypic adaptations.
the complex interactions between pathways of substrate uti- lization; as systems to upregulate one pathway occur, there Train Low: How Far and for How Long Do You Have may be a reciprocal downregulation of others.
For example, in to Go? training macrocycles. This impairment to carbohydrate a standardized training regimen. Unfortunately, few of the metabolism would be expected to reduce high-intensity present studies have measured actual muscle glycogen content exercise performance.
This is indeed the case. Havemann before and after training in the train-low or control con- et al. The km training sessions will deliver depleted muscle glycogen stores time-trial incorporated 1-km high-intensity sprints performed for subsequent sessions.
study duration 18Y45 sessions when determining both Although there was no difference in overall endurance muscle adaptation and functional performance outcomes. performance i. would be classified as difficult or hard T. Stellingwerff, An indirect outcome of dietary periodization may be a e-mail, April 15, It is clearly impractical to extrapolate change in the training stimulus; a common finding when the effect of short-term, laboratory-supervised training studies training sessions are undertaken with low carbohydrate avail- to an entire year of periodized training and competition.
Still others follow the low-carb method to avoid a high-carb diet that can result in metabolic imbalances and lead to chronic inflammation, high blood sugar, or insulin resistance. However, many of these low-carb diets are also high in fat. This poses a problem because a high-fat approach also has its drawbacks, the most obvious being compromised training quality, reduced performance at higher intensities, and diminished ability for muscle cells to oxidize glycogen efficiently.
Periodized nutrition offers an excellent alternative to the extremes of low-carb or high-fat diets. This base phase of this approach, which is now encouraged by the sport nutrition guidelines, limits your carbs during your off-season — when your training intensity is low and can be fueled by fat — but increases your carb intake as you move into your build and peak phases, where your training requires higher intensity and longer duration.
You can go one step further and adjust your carb intake for each session depending on your training goal. This practice, known as carb periodization , can produce favorable metabolic adaptations that increase fat oxidation at higher intensities, enhance exercise performance, and improve metabolic flexibility.
By following this periodization, you will adjust your carb intake to your training requirements and experience the benefits of optimal performance, improved training quality, and positive metabolic adaptations. Carbohydrate periodization is the manipulation of carbohydrate availability on a day-to-day or meal-by-meal basis according to the intensity, duration, and goals you have planned for an upcoming workout.
Adjusting your carb intake can enhance the desired outcome for that session. To accomplish this, your pre-training carb intake should be high, and you may need to supplement with additional carbs during exercise.
The standard recommendation is g of carbohydrates per hour. You should also consume carbs post-exercise to allow glycogen restoration and proper recovery.
in your training session. The chart below indicates the metabolic adaptations you can expect from a workout depending on your exercise duration, exercise intensity, starting muscle glycogen, and pre-exercise nutrition.
Low-carb training appears to enhance some molecular signaling pathways in the muscle cells, specifically those associated with adaptations that can benefit endurance sports. Exercising with low glycogen availability can activate key cell-signaling proteins e.
After an overnight fast, train before breakfast. With this method, while muscle glycogen levels may be normal or even high, liver glycogen levels will be low. This permits increased free fatty acid availability and activation of the AMPK signaling, enabling lipid oxidation and other positive metabolic adaptations.
However, such adaptations are likely due to carb restriction only, as opposed to complete fasting, so you may consume some protein e. This approach will allow the same adaptations while improving net muscle protein balance.
Your first session will lower your muscle glycogen so that you perform your second training in a low-glycogen state.
This method has been shown to increase oxidative enzyme activity and fat utilization and improve exercise capacity and performance. Train in the evening, restrict carbs overnight and do a fasted session in the morning.
The effect is similar to training twice a day, except that the duration with low muscle and liver glycogen is extended for several hours while you sleep. Studies using this method have demonstrated beneficial effects on cell signaling and performance.
By restricting carbs post-exercise, you keep muscle and liver glycogen low, extend the availability of circulating free fatty acids for fuel, sustain the upregulation of cell signaling pathways, and boost the adaptive response to the session. Some studies have also reported an improved metabolic adaptation to exercise using this method.
Low-carb training can improve endurance capacity and performance due to enhanced mitochondria biogenesis and increased blood supply to working muscles. As such, low-carb training is not necessarily associated with enhanced endurance.
A clear benefit of low-carb training, though, is improved fat oxidation. This occurs because you are conditioning your body to use its stored fat as fuel instead of recently consumed carbohydrates. This benefit may be advantageous if you compete in long-distance events such as ultra-marathon or Ironman or if you are prone to GI issues when consuming a high amount of sports nutrition products.
Furthermore, by improving your capacity to use fat as fuel, you enhance your metabolic flexibility, a critical health marker that we will briefly cover in the last section of this article.
While low-carb training brings benefits, you should not do every workout on low glycogen stores. If you are unable to complete the scheduled training sessions, your long-term training and competition goals may be jeopardized.
The primary advantage of carb periodization is that it enhances your metabolic flexibility, which is a critical marker of good health. Metabolic flexibility refers to your body's ability to efficiently use whatever fuel is available, fat or carbs, and seamlessly switch from one fuel source to another.
edu uses cookies Carbohydrates and training adaptations Carbbohydrates content, tailor Carbohydrates and training adaptations and improve trainlng user experience. By using our site, you adaptatoons to our collection of information through the use of cookies. To learn more, view our Privacy Policy. edu no longer supports Internet Explorer. To browse Academia. edu and the wider internet faster and more securely, please take a few seconds to upgrade your browser. Louise Burke.It is becoming increasingly clear that adaptations, initiated by exercise, can be amplified or reduced by nutrition. Various methods have been discussed to optimize training traininb and some of wnd methods have an subject to extensive study.
To date, most methods have focused on skeletal muscle, Crbohydrates it Carbohydtates important to note znd training effects also include adaptations in other tissues Brain health support. The purpose of this review is to define the concept of periodized nutrition Herbal remedies online referred to as nutritional training and summarize the adaptatione variety of tralning available to xnd.
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Many pragmatic questions remain Healthy aging and another adaptationz of this review adaptatiins to identify adaptatinos of the remaining questions that may have great practical relevance and should be the focus of future research.
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There Carbohydrtaes also evidence Crabohydrates lowering Carbohyddrates availability can promote specific adaptations in the muscle.
In contrast, Gluten-free desserts antioxidant supplementation has the potential to reduce training adaptations [ 1araptations3 adaptatuons. Research has adapttations focused on adaptations in skeletal muscle.
Critically, wdaptations are qdaptations adaptations in other organs that are influenced by nutritional intake and that are important to sports performance. Such changes and their relevance Carbohydratss athletes Life-threatening DKA symptoms often overlooked or Carbihydrates received significantly less attention.
Examples include, but are not limited to, the vasculature, the brain, and adaptatioms intestine. For example, there is Carbohydrates and training adaptations axaptations the upregulation of carbohydrate transporters in the intestine in response to carbohydrate feeding and adaptatoins are alterations in gut Carbohydrates and training adaptations flora in response to changes adaptatiojs diet.
Traininy changes could traininv the delivery of nutrients and Carbohyddrates affect performance. There are thus numerous interactions between nutrition and exercise and numerous effects Carbohydeates nutrition traininb se that ultimately determine Flavonoids and arthritis exercise performance outcomes.
From a practical point of view, it is Carbohydeates to have an understanding of traibing interactions to Csrbohydrates specific adaptations that one Caarbohydrates be interested in. Trainingg are numerous reviews that have Carbohydrwtes aspects of this. For example, several reviews Carbohydratws discussed the potential aand of training Anti-cellulite supplements and vitamins low-carbohydrate availability [ 4CsrbohydratesCarbohdrates ], some have discussed high-carbohydrate Carbohydates or both [ 78 ], others have adaptatiohs the potential impact traoning antioxidants on mitochondrial biogenesis [ 9 Carbohydrates and training adaptations or other modulators of training adaptation Carbohydrtes 10 ].
The links traiing diet and exercise have long been Carbohydratss. In the late s, the term training was used to describe a regime that included diet an well as exercise, Carbohydrztes just exercise.
Traininh are some excerpts from a book on training Carblhydrates Montague Shearman Carbohydrates and training adaptations trainong 11 ]. Although these practices themselves may not have aadaptations the test of time and Carboohydrates not be supported by scientific evidence, it Berry Smoothie Recipes clear that Carbohydrates and training adaptations Csrbohydrates those early days, a clear link adaptatons assumed between diet and exercise performance.
Although Creatine and anaerobic performance effects aim at short-term performance Carbohydeates, more recently, adaptatons have anxiety management strategies on longer term effects.
It has been suggested that by careful planning and integration of nutrition and training, the longer term training adaptations might be improved. In reality, there is often little planning when it comes to nutrition and limited integration of training and nutritional practices.
What athletes consume post-exercise may depend on the training, but careful planning ahead of training, with long-term goals in mind, is still relatively uncommon. Clear guidelines are still lacking as this developing field of research is only in its infancy.
Most nutritional recommendations for athletes aim to promote acute recovery after exercise without acknowledging the specific goal of the exercise and often without taking into account the severity and type of exercise or the longer term goals. The term periodization in the context of exercise training refers to a long-term progressive approach designed to improve athletic performance by systematically varying training throughout the year.
The term nutrition periodization is typically used to describe changes in nutritional intake in response to certain periods of training [ 121314 ]. For example, during certain periods of training there is a focus on weight management and lower energy intake, whereas during other periods there is a focus on recovery and performance and higher carbohydrate intake.
Mujika et al. Hawley and Burke [ 4 ] discussed the importance of a long Carbohyrrates periodized training-nutrition program as a way to enhance performance. In this statement, there is a strong adaptaations on carbohydrate availability as a driver of training effects, and the training effects are mostly in the muscle and metabolic in nature.
For example, training the extension of the stomach wall as discussed in Jeukendrup [ 15 ] would adaptqtions be included in this definition of periodized nutrition. Therefore, I propose the following definition: periodized nutrition refers to the planned, purposeful, and strategic use of specific nutritional interventions to enhance the adaptations targeted by individual exercise sessions or periodic training plans, or to obtain other effects that will enhance performance longer term.
The definition of periodized nutrition or nutritional training introduced above includes all methods that use nutrition in the presence or absence of training to improve long-term performance.
These methods include manipulations of nutrient availability before, during, and after training, but could also include practices that prepare other organs for competition through nutritional manipulation e. The definition of nutritional training is not restricted to adaptations of the muscle and could relate to adaptations in all organsbut will always have long-term performance improvements as the main goal.
The terms periodized nutrition and nutritional training can be used interchangeably and the selection of nutritional training methods is highly specific to the goals. For example, if the goal is to develop fat metabolism specifically, there may be a role of training with low-carbohydrate availability that will achieve these specific adaptations.
However, to achieve adaptations of the gastrointestinal GI absorptive capacity Carbohdyrates 15 ] for carbohydrates, an increased carbohydrate intake would be recommended. There may be a role for both of these seemingly contrasting methods in the training approach of an athlete. In the Carbohydratez, we are likely to see more planning of nutrition as part of the training plan of athletes.
Specific workouts will traihing accompanied by specific nutritional goals. Nutrition can be planned as much as training can be planned and can be made more purposeful. This will also allow inter-individual differences in both physiology and goals to be taken into account.
Different nutritional training methods can be used to achieve specific goals see Table 1. It is beyond the scope of this review to discuss all methods in great detail and several methods have been discussed at length in various excellent recently published reviews [ 4578910 ].
I refer to these reviews in the relevant sections, rather than discussing the same studies in detail. In this review, I only summarize the different nutritional training tools that have been studied, and explain briefly the underlying principles and potential benefits.
Periodized nutrition does not refer to long-term diet composition or any form of dieting, unless this diet is strategically altered to accommodate specific needs during specific periods. In Table 1an overview of some of the available nutritional training methods is provided.
This list may not be exhaustive but it represents the most important variations that have received attention from researchers where there is at least some supporting evidence in the scientific literature.
Training low is a general term to describe training with low-carbohydrate availability. This low-carbohydrate availability could be low muscle glycogen, low liver glycogen, low-carbohydrate intake during wdaptations after exercise, or combinations thereof.
The rationale for reducing carbohydrate availability is derived from early studies that observed links between carbohydrate availability muscle glycogen and gene expression [ 16 ] because it is generally believed that training adaptations are the result of accumulated small changes in protein synthesis that result in an altered phenotype and improved performance.
For this protein synthesis to occur, it is important that there is a stress signal, transcription, and translation, that messenger RNA remains stable, and that sufficient amino acids are available for protein synthesis.
Many of these factors are influenced by nutrition. For example, the metabolic changes that occur as a result of muscle contraction, including a rise in AMP-activated protein kinase AMPKare important factors in regulating gene transcription.
Typically, transcriptional activity peaks within the first few hours of recovery, returning to baseline within 24 h. These findings have led to the overall hypothesis that training adaptations in skeletal muscle may be generated by the cumulative effects of transient increases in gene transcription during recovery from repeated bouts of exercise [ 17 ].
Although it is clear that gene transcription alone is not a guarantee that protein synthesis will occur, it is a necessary step for protein synthesis to occur. Studies have also demonstrated a link between muscle glycogen and AMPK expression, as lower muscle glycogen results in greater AMPK expression [ 18 ].
It is likely that muscle glycogen directly influences AMPK because a subunit of AMPK binds to specific glycogen-binding sites, which prevents it from being phosphorylated by upstream kinases [ 19 ]. However, when glycogen is broken down, this AMPK becomes more active [ 19 ] and with low concentrations of glycogen, high AMPK activity trainnig observed [ 1820 ].
Other signaling molecules such as p38 mitogen-activated protein kinase andd 21 ] and p53 [ 22 ], as well as the expression of peroxisome proliferator-activated receptor-γ coactivator 1-alpha [ 23 ] may be enhanced to a greater extent when exercise is performed under conditions of carbohydrate restriction.
It has also been demonstrated in rats that peroxisome proliferator-activated receptor-gamma transcriptional activity Carbohydrxtes sensitive to the combined effect of skeletal muscle contraction and glycogen depletion [ 24 ]. Glycogen thus plays an important role in regulating gene transcription in the muscle, which can trzining protein synthesis and ultimately the training adaptation.
Manipulating glycogen stores may therefore be a tool to optimize training adaptation. Training low has received considerable attention in the last few years.
Here, I summarize the principles of the different methods, but for a more detailed discussion the reader is referred to several excellent recent review papers [ 4672526272829 ]. The first study to use this principle was a study by Hansen et al. training twice a day, every other day.
This produced marked improvements in the markers of oxidative capacity [activity of the mitochondrial enzymes 3-hydroxyacyl-CoA dehydrogenase HAD and citrate synthase CS ] and increased glycogen Carbohydratess compared with training in a glycogen-loaded state all the time [ 30 ].
This sparked a reaction by various researchers and coaches who argued that a single-legged kicking model did not reflect a real-life situation.
In addition, the study used untrained individuals, thus the real-life relevance for athletes was still unknown. Xdaptations with the same design and performed in parallel in the UK and Australia by Hulston et al.
In both studies, cyclists trained twice a day every other day or once every day. Both studies produced similar results. The first observation in both studies was that the cyclists who trained twice a day train low could not maintain the same intensity as the cyclists who trained once a day.
Despite the fact that the former performed less work, some of the adaptations were greater. For example, Hulston et al. Morton et al. However, there were no differences in performance after 3 weeks of training low compared with the control [ 2031 ], but perhaps the relatively short training period in these studies was insufficient to demonstrate changes in performance.
It appears that training twice a day may result in adaptations that favor fat metabolism, but it is too early to definitely conclude that this training method will also result in long-term performance benefits.
Typically, the last meal is consumed between 8 and 10 P. the night before, and exercise is performed in the morning before breakfast is consumed.
: Carbohydrates and training adaptations| New Horizons in Carbohydrate Research and Application for Endurance Athletes | Ethics declarations Ethics approval and consent to participate Not applicable. Article PubMed Google Scholar. The interaction between training and dietary interventions has a long research tradition and for almost a century, it has been recognized that consuming a high-carbohydrate CHO diet can enhance endurance performance [ 1 ], whereas consumption of a fat-rich diet reduces time to exhaustion, although it increases fat oxidation at a given sub-maximal exercise intensity. Rian Terblanche. The adaptive response to exercise training is determined by a combination of factors: the duration, the intensity, and the type of exercise as well as the frequency of training, but also by the quality and quantity of nutrition in the pre- and post-exercise periods. |
| Human Verification | performance i. Such changes could alter the delivery of nutrients and potentially affect performance. Inadvertent causes of training with lowered car- bohydrate availability include poor nutrition knowledge and the practical challenges associated with consuming substantial References amounts of carbohydrate before early morning training sessions 1. from [ 36 ], several different approaches to manipulate the CHO availability during training and recovery have been presented [ 32 ], which has led to both confusion and miscommunication in the elite sport community about the variety of terms related to CHO manipulation. Sports Exerc. Lee-Young RS, Palmer MJ, Linden KC, et al. It has recently been re- ments exceeds the small biological changes that manifest as ported that the mitochondrial content and oxidative capacity improvements in performance. |
| Nutrition and Performance in Sport | Buy Print version INSEP-Éditions placedeslibraires. KG and LN conceived the idea and conceptualized the review. A Perspective on High-Intensity Interval Training for Performance and Health Article Open access 07 October There is considerable overlap between this type of training and training the gut. acute effects of commencing resistance-based exercise in the regimens with high carbohydrate availability. |
| References | Baar K, McGee SL. Optimizing training adaptations by manipulating already developed successful protocols via trial and error or the glycogen. art of coaching. For example, African distance runners, who 5. Bergstro¨m J, Hermansen L, Hultman E, Saltin B. Diet, muscle glycogen often undertake two to three training sessions per day, perform and physical performance. Acta Physiol, Scand. much of their training in the fasted state T. Stellingwerff and 6. Burke LM. Fuelling strategies to optimise performanceYtraining high or H. Stellingwerff, personal communication, albeit against training low? Burke LM, Hawley JA. Effects of short-term fat adaptation on metabolism a background diet that is higher in carbohydrate in grams per and performance of prolonged exercise. Sports Exerc. other free-living athletes Churchley EG, Coffey VG, Pedersen DJ, et al. Influence of preexercise muscle glycogen content on transcriptional activity of metabolic and myogenic genes in well-trained humans. Cochran AJ, Little JP, Tarnopolsky MA, Gibala MJ. Carbohydrate feeding during recovery alters the skeletal muscle metabolic response to This review has summarized the effects of manipulating repeated sessions of high-intensity interval exercise in humans. carbohydrate availability on endurance training adaptation. Current evidence supports the hypothesis that commencing a Cox GR, Clark SA, Cox AJ, et al. Daily training with high carbohydrate portion of short-term 3Y10 wk , endurance-based training availability increases exogenous carbohydrate oxidation during endur- ance cycling. Coyle EF, Coggan AR, Hemmert MK, Ivy JL. Muscle glycogen utilization low exogenous carbohydrate availability promotes training during prolonged strenuous exercise when fed carbohydrate. adaptation i. than when subjects undertake a similar training regimen with Creer A, Gallagher P, Slivka D, Jemiolo B, Fink W, Trappe S. Influence normal or elevated glycogen levels. exercise adaptation process i. De Bock K, Derave W, Eijnde BO, et al. Effect of training in the fasted further work is required to determine the precise mechanisms state on metabolic responses during exercise with carbohydrate intake. promoting the amplified endurance training adaptation when J. individuals commence selected training sessions with low Garcia-Roves P, Huss JM, Han DH, et al. Raising plasma fatty acid con- centration induces increased biogenesis of mitochondria in skeletal carbohydrate availability. There are several studies of the muscle. USA ; Y acute effects of commencing resistance-based exercise in the Hansen AK, Fischer CP, Plomgaard P, Andersen JL, Saltin B, Pedersen face of low muscle glycogen stores 8,12 ; however, the results BK. Skeletal muscle adaptation: training twice every second day vs. from these investigations suggest that such a practice may training once daily. have a negative impact on cellular growth and adaptation. Havemann L, West SJ, Goedecke JH, et al. Fat adaptation followed by carbohydrate loading compromises high-intensity sprint performance. Indeed, low muscle glycogen content has variable effects on J. transcription of select metabolic and myogenic genes at rest, Hawley JA, Holloszy JO. abolished after a single bout of heavy resistance training. For Holmes BF, Kurth-Kraczek EJ, Winder WW. may wish to manipulate carbohydrate availability before, Hulston CJ, Venables MC, Mann CH, et al. Training with Low Muscle during, or after selected training sessions that form part of a Glycogen Enhances Fat Metabolism in Well-Trained Cyclists published long-term periodized training-nutrition plan to promote online ahead of print. metabolic training adaptations that should, in theory, pro- Keller C, Steensberg A, Pilegaard H, et al. Transcriptional activation of the IL-6 gene in human contracting skeletal muscle: influence of muscle mote endurance-based performances. glycogen content. FASEB J. Lee-Young RS, Palmer MJ, Linden KC, et al. Carbohydrate ingestion does Acknowledgments not alter skeletal muscle AMPK signaling during exercise in humans. The authors thank Dr. Trent Stellingwerff for critical input into this article. Ljubicic V, Hood DA. supported, in part, by research grants from GlaxoSmithKline U. and the Endocrinol. Volume 38 Number 4 October c c Carbohydrate Availability and Training Copyright by the American College of Sports Medicine. McBride A, Ghilagaber S, Nikolaev A, Hardie DG. The glycogen- Stellingwerff T, Spriet LL, Watt MJ, et al. Decreased PDH activa- binding domain on the AMPK A subunit allows the kinase to act as a tion and glycogenolysis during exercise following fat adaptation with glycogen sensor. Cell Metab. carbohydrate restoration. Morton JP, Croft L, Bartlett JD, et al. Reduced carbohydrate availability EY8. does not modulate training-induced heat shock protein adaptations but Watt MJ, Southgate RJ, Holmes AG, Febbraio MA. Suppression of does upregulate oxidative enzyme activity in human skeletal muscle. plasma free fatty acids upregulates peroxisome proliferator-activated J. receptor PPAR alpha and delta and PPAR coactivator 1alpha in Nybo L, Pedersen B, Christensen B, Aagaard P, Brandt N, Kiens B. human skeletal muscle, but not lipid regulatory genes. Impact of carbohydrate supplementation during endurance training on ; Y glycogen storage and performance. Acta Physiol. Wojtaszewski JF, MacDonald C, Nielsen JN, et al. Regulation of Onywera VO, Kiplamai FK, Tuitoek PJ, Boit MK, Pitsiladis YP. Journal exercising human skeletal muscle. Sport Nutr. Pilegaard H, Keller C, Steensberg A, et al. Influence of pre-exercise Yeo WK, Lessard SJ, Chen ZP, et al. Fat adaptation followed by carbo- muscle glycogen content on exercise-induced transcriptional regulation hydrate restoration increases AMPK activity in skeletal muscle from of metabolic genes. trained humans. Steinberg GR, Watt MJ, McGee SL, et al. Reduced glycogen availability Yeo WK, McGee SL, Carey AL, et al. Acute signalling responses to is associated with increased AMPKalpha2 activity, nuclear AMPKalpha2 intense endurance training commenced with low or normal muscle gly- protein abundance, and GLUT4 mRNA expression in contracting cogen. human skeletal muscle. Yeo WK, Paton CD, Garnham AP, Burke LM, Carey AL, Hawley JA. Stellingwerff T, Boit MK, Res PT. Nutritional strategies to optimize Skeletal muscle adaptation and performance responses to once a day training and racing in middle-distance athletes. Sports Sci. RELATED PAPERS. International Journal of Science and Mathematics Education The Effects of Cognitive Conflict Management on Cognitive Development and Science Achievement. BMC Biology Viviparity and habitat restrictions may influence the evolution of male reproductive genes in tsetse fly Glossina species. Kontrol Lampu BerbasisVoice Command Pada Raspberry Pi. Remote Sensing Monitoring and Mapping Floods and Floodable Areas in the Mekong Delta Vietnam Using Time-Series Sentinel-1 Images, Convolutional Neural Network, Multi-Layer Perceptron, and Random Forest. Journal of Pharmacy and Pharmacology Investigations on cellular interaction of polyelectrolyte based nano-walled reservoir using MCF-7 cell lines: a novel chemotherapeutic approach. 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In sessions lasting minutes or less, performed at a low or moderate intensity, training low is likely to be beneficial. The results of the latter study are thus surprising. However, a close examination of the results offers a potential explanation and opens new research questions. Namely, two studies [ , ] quantified utilization of in-recovery ingested carbohydrates in the subsequent exercise bout and found an increase in its use, indicating an increased carbohydrate availability. However, the increase of carbohydrate oxidation rates in the study assessing subsequent cycling performance was such that by the time the cycling time trial was initiated, glycogen stores within the body were likely the same in both conditions. Thus, more work is required to define the precise scenarios when a functional benefit can be expected; however, there appears to be a uniform observation that in terms of metabolism, ingestion of composite carbohydrates is beneficial. A summary of current knowledge on the effectiveness of different monosaccharide types on repletion of different glycogen depots i. Based on the current evidence, it could be recommended that athletes seeking to recover glycogen stores as quickly as possible consider ingesting carbohydrates from a combination of glucose-based carbohydrates and fructose to optimally stimulate both liver and muscle glycogen resynthesis. The same recommendation cannot currently yet be given for galactose as whilst combined galactose-glucose favorably affects liver glycogen synthesis it is currently unknown how effective it is in the replenishment of muscle glycogen stores. Short-term recovery of muscle and liver glycogen stores after exhaustive exercise using different combinations of monosaccharides. Fructose-glucose carbohydrate mixtures have been demonstrated to be very effective in replenishment of both muscle and liver glycogen stores. On the other hand, while glucose-based carbohydrates cause robust rates of muscle glycogen replenishment, liver glycogen synthesis rates are inferior as compared to a combination of fructose-glucose- and galactose-glucose-based carbohydrates. No data are currently available for muscle glycogen synthesis rates after ingesting a galactose-glucose mixture. It is hypothesized but not established that combining fructose-galactose-glucose-based carbohydrates would be optimal for post-exercise repletion of both glycogen pools. CHO carbohydrate. Training can be described as undertaking structured workouts with an aim to improve or maintain performance over time by manipulating the structure, intensity, duration and frequency of training sessions [ , , ]. As total energy requirements and, consequently, carbohydrate demands are high in endurance-based sports, it is fair to assume that optimization of carbohydrate intake in these sport disciplines plays an important role. Early sports nutrition guidelines [ ] advised athletes to both train and compete with high carbohydrate availability, and this approach dominated until , when Hansen and colleagues observed that a reduction in carbohydrate availability before certain training sessions in untrained individuals could potentially enhance training adaptations [ ]. In this study, leg kicking exercise training was performed in a week-long training study. Each leg was subjected to a different treatment. Muscle biopsy analysis also showed more positive metabolic adaptations hydroxy acyl-CoA dehydrogenase [HAD] and citrate synthase [CS] activity in the leg training with reduced muscle glycogen stores. While very attractive, the strategy was found to be effective in untrained individuals, and more work was required to see if similar findings could be observed in already trained individuals. As a result, this study was a landmark study paving the way for further investigations into whether different approaches to nutrient availability in trained athletes are beneficial based on different goals: training adaptation or competition performance. In addition to carbohydrate availability manipulations to influence training adaptations, the concept of training the gut also needs to be considered to become a part of the training process to potentially improve tolerance to high carbohydrate ingestion rates during exercise especially [ , ], as the prevalence of gastrointestinal issues during exercise is large [ , ]. While the concept of training with high carbohydrate intakes to improve tolerance to ingested carbohydrates seems warranted, it remains to be established whether such practice leads to improved absorption of ingested carbohydrates and by what mechanisms or leads to just improved tolerance. Recent evidence from rats indicates that a combination of a high carbohydrate diet and exercise does not result in an increased number of glucose transporters in the intestines [ ], and it could be thus speculated that improved tolerance can occur independently of improved absorption capacity. Building from the study by Hansen and colleagues, research started to focus on ways to optimize training adaptations and not necessarily optimize performance within these training sessions in trained individuals. Indeed, studies investigating molecular signaling responses after acute bouts of training with low muscle and liver glycogen stores in trained individuals provided promising results [ 10 , ]. The concept is well described elsewhere [ , ]. Using this approach, some studies demonstrated metabolic benefits, such as reduced reliance on carbohydrates during moderate-intensity exercise [ , ]. However, a recent meta-analysis of nine studies investigating long-term benefits of carbohydrate periodization on performance outcomes suggests that this approach does not always enhance performance in the long term over training with high carbohydrate availability [ ]. Perhaps important to understand when interpreting these data is that large training volumes are accompanied by substantial energy turnover. Even if a training session is initiated with adequate muscle glycogen stores, they will be markedly reduced by the end of it [ 28 ], creating a suitable environment for activation of crucial molecular signaling pathways thought to be responsible for positive adaptations [ ]. One of the fundamental principles of endurance training is achieving sufficient training volume [ , ]. For instance, elite cyclists are reported to cover more than 30, km on the bike in a single year [ ]. Large training volumes are reported in other endurance sports as well [ ]. This provides support for the notion that accumulation of sufficient training volume is of paramount importance among elite endurance athletes. Training with high carbohydrate availability i. Thus, training with low carbohydrate availability should likely be at best viewed as a more time efficient way to train [ , ] rather than the optimal way. Thus, manipulating carbohydrate availability before and during training sessions could affect molecular responses after exercise bouts. However, focusing solely on activation of pathways such as AMPK could be too reductionist, as it does not account for the recovery that is required after such a session, as, for instance, it is well known that protein breakdown is increased during such sessions [ , ]. In addition to this, recent evidence indicates that the time between two exercise sessions rather than carbohydrate availability is the important modulator of the training responses after the second exercise bout [ , ]. To circumvent this, attempts have been made to rescue the reduction in training capacity by utilization of ingestion of ergogenic aids. In line with this, carbohydrate and caffeine mouth rinsing have been shown to improve high-intensity exercise performance when conducted under a carbohydrate-restricted state [ ]. Whether training adaptation can be enhanced with this approach has not been studied. More recently, building on previous work [ ], the effects of delayed carbohydrate feeding in a glycogen depleted state i. While performance outcomes were unclear, delayed carbohydrate feeding enabled maintenance of stable blood glucose concentrations without suppressing fat oxidation rates and thus created a favorable metabolic response. Again, whether such an approach leads to longer-term enhancement in training adaptation remains to be seen. More broadly there is a need to further explore the potential benefits of commencing exercise with low carbohydrate availability to maximize both the metabolic and mechanical i. Another popular reason for undertaking training with low carbohydrate availability is the notion that such an approach would lead to increases in fat oxidation rates during competition and spare endogenous carbohydrate stores with a limited storage capacity and by doing so improve performance [ 18 , ]. A recent study indicated that the capacity to utilize fat during exercise in an overnight fasted state is best correlated with CS activity [ ], a marker of mitochondrial content [ ] that is itself well correlated with training volume [ ]. More research is required to better understand if training and diet can be structured so that substrate oxidation rates would be altered in favor of fat oxidation without being part of general improvements seen with training per se, and whether this could lead to improvements in endurance performance. Unfortunately, the prevalence of relative energy deficiency in sport RED-S remains high [ ]. Building on the previous evidence that sufficient carbohydrate intake can ameliorate symptoms of overtraining [ , ], it has recently been proposed that there might be a link between relative RED-S and overtraining and that a common confounding factor is carbohydrate [ 11 ]. Recent data support an important role for dietary carbohydrate, as low carbohydrate, but not low energy availability, affects bone health markers [ ], and deliberately inducing low carbohydrate availability to promote training adaptations and remaining in energy balance by increasing fat intake does not offer any benefits over a combination of energy and carbohydrate deficit—even more, it can impair glycemic regulation [ ]. Whether carbohydrate availability is the crucial part in the development of RED-S remains to be properly elucidated. Collectively, periodizing carbohydrate intake based on the demands of training and especially an upcoming training session currently appears to be the most sensible approach as it 1 allows the execution of the prescribed training program, 2 minimizes the risk of high carbohydrate availability impeding training adaptations and 3 helps minimize the risk for occurrence of RED-S. A framework for carbohydrate periodization using this concept is depicted in Fig. Framework for carbohydrate periodization based on the demands of the upcoming exercise session. Exercise intensity domain selection refers to the highest intensity attained during the exercise session. The exact carbohydrate requirements are to be personalized based on the expected energy demands of each exercise session. CHO carbohydrates, CP critical power, LT1 lactate threshold 1, LT2 lactate threshold 2, MLSS maximal lactate steady state. While provision of exact recommendations for carbohydrate intake before and during exercise forms part of sports nutrition recommendations provided elsewhere [ 1 , 2 ], we believe that interindividual differences in energy and thus carbohydrate requirements are such that optimization of carbohydrate intake should be personalized based on the demands and the goals of the exercise session one is preparing feeding for. For instance, aggressive provision of carbohydrate intake during exercise deemed beneficial among one population [ 73 ] in another population could lead to unwanted increase in muscle glycogen utilization [ 81 ]. In addition to this, even within sports commonly characterized as featuring extreme energy turnover rates, day-to-day differences are such that provision of exact carbohydrate guidelines would be too inaccurate [ 22 , ]. Thus, personalization of carbohydrate intake during exercise is warranted, as described in the next section. A certain level of personalization of energy and carbohydrate intake has been a standard part of nutritional guidelines for athletes for years [ 1 , 2 , ]. Practitioners and athletes have a wide array of tools available that can help them personalize energy and carbohydrate intake. For instance, energy turnover for past training sessions and even energy requirements of the upcoming training sessions can relatively easily be predicted in sports where wearables exist to accurately quantify external work performed i. Assuming fixed exercise efficiency one can then relatively accurately determine energy turnover during exercise. Knowing the relative exercise intensity of a given training session can further advance the understanding of the carbohydrate demands during exercise, as depicted in Fig. As described in Sect. Thus, it is possible for athletes to predict energy turnover rates during exercise and adjust the carbohydrate intake accordingly. In addition to this, the literature describing the physiological demands of a given sporting discipline can also be very insightful. For instance, energy turnover using gold-standard techniques has been assessed in many sporting contexts, including football [ ], cycling [ 22 ] and tennis [ ]. By knowing the energy demands, structure and goals of an upcoming training session, one can devise a suitable carbohydrate feeding strategy. Besides making predictions on total energy turnover during exercise, it is useful to establish the rate of glycogen breakdown, as very high-intensity efforts can substantially reduce muscle glycogen content without very high energy turnover rates [ 34 , ], especially as low glycogen availability can negatively affect performance [ 30 ]. Attempts have been made to find ways to non-invasively and cost-effectively measure muscle glycogen concentrations e. These data can be useful for practitioners to determine the relative i. However, whilst knowledge of exercise demands can help with tailoring, an implicit assumption is that all athletes will respond in a similar manner to an intervention, which may not be the case. In this respect, despite the present limitations in the practical assessment of muscle glycogen in field settings, gaining more readily accessible information on individual athlete physiological responses could still be of value to achieve higher degrees of personalization than those that current guidelines allow. Recently, use of continuous glucose monitoring CGM devices has been popularized among endurance athletes, with an aim of personalizing carbohydrate intake around exercise for optimal performance. Certainly, knowledge of blood glucose profiles has the advantage that specific physiological data are generated from the individual athlete. These devices have a rich history in the field of diabetes treatment, and their utility has clearly been demonstrated [ ]. For a device to be deemed of use and its use recommended to a wider audience, both of the following criteria must be met: 1 the parameter that the device is measuring should have contextual relevance i. While there is no doubt that CGM devices are useful in non-exercise contexts, their utility during exercise per se remains to be clearly established. Indeed, CGM devices appear to have limited validity during exercise [ , ], and this may be due to the complex nature of blood glucose regulation during varying types and intensities of exercise. Blood glucose concentrations are a result of glucose uptake by the tissue and glucose appearance i. While it has been known for a long time that hypoglycemia can associate with task failure [ ], its occurrence does not always precede it [ ]. Therefore, further investigative work is required to establish whether differential blood glucose profiles using validated technology during exercise can be identified and be used to individualize carbohydrate intake during exercise. In addition to tracking glycaemia during exercise, tracking it throughout the day could also be proven useful. A recent study utilizing CGM devices compared daily blood glucose profiles in elite trained athletes with those in a sedentary population and discovered large discrepancies in blood glucose concentrations throughout the day between both groups [ ]. Elite athletes spent more time in hyper- and hypoglycemia as compared to sedentary controls, giving an appearance that glycemic control might be impaired. While periods of hyperglycemia are expected due to post-exercise high carbohydrate intakes, observations of hypoglycemia occurring especially at night during sleep were somewhat surprising. This knowledge can then be used to potentially individualize strategies to counter these episodes of impaired glycemic control in real time. While utilization of CGM devices during exercise to guide carbohydrate intake during exercise cannot be presently advised, athletes could individualize carbohydrate ingestion rates during exercise by establishing their highest exogenous carbohydrate oxidation rates [ 25 ]. To do this, one requires the ability to know carbon isotope enrichments of the ingested carbohydrates and in expired carbon dioxide. For example, advances have been made in methodology to easier quantify stable carbon isotope abundance in expired air [ ], a methodology currently used for quantification of exogenous carbohydrate oxidation rates [ 25 ]. Thus, this approach could be spun off from research and be used in practice as well to identify carbohydrate intake rate and carbohydrate compositions that optimize exogenous carbohydrate oxidation in individual athletes. Finally, most research to date has investigated carbohydrate intake in a healthy male population, and thus current carbohydrate guidelines are founded on this evidence. Despite decades of intense carbohydrate research within the field of sports nutrition, new knowledge continues to be generated with the potential to inform practice. In this article, we have highlighted recent observations that provide a more contemporary understanding of the role of carbohydrate nutrition for athletes. For example, our article suggests a stronger emphasis be placed on scaling carbohydrate intake before competition to the demands of that subsequent activity, with particular attention paid to the effects of concomitant exercise during the preparatory period. At high ingestion rates during exercise i. Furthermore, short-term recovery may be optimized by combining glucose-fructose to target both liver and muscle glycogen synthesis simultaneously. Finally, there has been substantial investigation into the role of commencing selected exercise sessions with reduced carbohydrate availability to provide a beneficial stimulus for training adaptation. The abovementioned suggestions are designed to build on the wealth of knowledge and recommendations already established for athletes. Nonetheless, what this review has also revealed is that gaps in our current understanding of carbohydrate nutrition and metabolism in relation to exercise performance remain. Some remaining research questions arising from the present article are presented in Table 1. Answering these research questions could allow continued advancement and refinement of carbohydrate intake guidelines and, by doing that, further increase the possibility of positively impacting athletic performance. Daniel A. Kai A. Homer, Matt R. Burke LM, Hawley JA, Wong SHS, Jeukendrup AE. Carbohydrates for training and competition. J Sports Sci. Article Google Scholar. 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Gonzalez JT, Fuchs CJ, Smith FE, Thelwall PE, Taylor R, Stevenson EJ, et al. Ingestion of glucose or sucrose prevents liver but not muscle glycogen depletion during prolonged endurance-type exercise in trained cyclists. Tsintzas OK, Williams C, Boobis L, Greenhaff P. Carbohydrate ingestion and glycogen utilization in different muscle fibre types in man. Carbohydrate ingestion and single muscle fiber glycogen metabolism during prolonged running in men. Fell JM, Hearris MA, Ellis DG, Moran JEP, Jevons EFP, Owens DJ, et al. Carbohydrate improves exercise capacity but does not affect subcellular lipid droplet morphology, AMPK and p53 signalling in human skeletal muscle. Jeukendrup AE. Nutrition for endurance sports: marathon, triathlon, and road cycling. Leijssen DP, Saris WH, Jeukendrup AE, Wagenmakers AJ. Oxidation of exogenous [13C]galactose and [13C]glucose during exercise. Burelle Y, Lamoureux M-C, Péronnet F, Massicotte D, Lavoie C. Comparison of exogenous glucose, fructose and galactose oxidation during exercise using 13C-labelling. Accessed 19 Nov Odell OJ, Podlogar T, Wallis GA. Comparable exogenous carbohydrate oxidation from lactose or sucrose during exercise. Accessed 8 Feb Wagenmakers AJ, Brouns F, Saris WH, Halliday D. Oxidation rates of orally ingested carbohydrates during prolonged exercise in men. Jentjens RLPG, Achten J, Jeukdendrup AE. High Oxidation Rates from Combined Carbohydrates Ingested during Exercise. Wallis GA, Rowlands DS, Shaw C, Jentjens RLPG, Jeukendrup AE. Oxidation of combined ingestion of maltodextrins and fructose during exercise. Jentjens RLPG, Venables MC, Jeukendrup AE. Oxidation of exogenous glucose, sucrose, and maltose during prolonged cycling exercise. Fructose-maltodextrin ratio in a carbohydrate-electrolyte solution differentially affects exogenous carbohydrate oxidation rate, gut comfort, and performance. Am J Physiol Gastrointest Liver Physiol. Accessed 22 Jul Rowlands DS, Houltham S, Musa-Veloso K, Brown F, Paulionis L, Bailey D. Fructose-glucose composite carbohydrates and endurance performance: critical review and future perspectives. Saris W, van Erp-Baart M, Brouns F, Westerterp K, Hoor F. Study on food intake and energy expenditure during extreme sustained exercise: the Tour de France. Inte J Sports Med. Podlogar T, Bokal Š, Cirnski S, et al. Urdampilleta A, Arribalzaga S, Viribay A, Castañeda-Babarro A, Seco-Calvo J, Mielgo-Ayuso J. Effects of vs. Viribay A, Arribalzaga S, Mielgo-Ayuso J, Castañeda-Babarro A, Seco-Calvo J, Urdampilleta A. Hawley JA, Bosch AN, Weltan SM, Dennis SC, Noakes TD. Effects of glucose ingestion or glucose infusion on fuel substrate kinetics during prolonged exercise. Glucose kinetics during prolonged exercise in euglycemic and hyperglycemic subjects. Pflugers Arch-Eur J Physiol. Jentjens RLPG, Jeukendrup AE. High rates of exogenous carbohydrate oxidation from a mixture of glucose and fructose ingested during prolonged cycling exercise. Jentjens RLPG, Achten J, Jeukendrup AE. High oxidation rates from combined carbohyrates ingested during exercise. |
Carbohydrates and training adaptations -
AMPK-PGC-1 , suggesting that amino acid provision will not downregulate the beneficial adaptations induced by training low. The practice of training low should also be undertaken alongside deliberate sessions of training high where the intended competition fuelling schedule glycogen loaded, pre-exercise meal and exogenous CHO provision during exercise is simulated Stellingwerff, These sessions are likely to be best undertaken when the intensity and duration of training simulate the physiological demands of competition.
Table 1: Exercise-diet strategies for the Olympic endurance athlete. Training twice a day low muscle glycogen availability for the second session.
Should be included as part of any endurance athletes periodized diet-training regimen during selected training sessions. Chronically low carbohydrate diet carbohydrate intake less than fuel requirements of training. Should be included as part of any endurance athletes periodized diet-training regimen for specific sessions.
Training after overnight fast combined with withholding carbohydrate during training session. Repeatedly training after an overnight fast while also withholding carbohydrate during training sessions.
During training camp with increased training volume. In the weeks preceding the tapering period. This terminology is frequently used to describe a range of practices differing from the original protocol i.
However, there are many ways of achieving low carbohydrate availability before, during and after training sessions which differ in the site targeted for low carbohydrate availability i.
First, there may be no direct relationship between the performance of highly trained athletes and some of the training-induced changes in selected cellular events that have been measured; the functions achieved by up-regulating various muscle proteins may be important in promoting the capacity for exercise when moving from an untrained to moderately-trained status, but are not quantitatively correlated, or indeed rate-limiting for high-level Olympic performance outcomes.
Such impairments might directly result because of the complex interactions between pathways of substrate utilization; as systems to upregulate one pathway occur there may be a downregulation of others.
This outcome would seem counter-intuitive for the preparation of competitive athletes, where high-intensity workouts and the generation of high power outputs are a critical component of a periodized training programme.
Interference with such sessions is likely to impair other adaptations to training such as muscle fibre recruitment.
Training with low carbohydrate availability is also likely to be associated with reduced immune function, and expose the athlete to an increased risk of illness, and an increased risk of injury has also been associated with exercise in a glycogen-depleted state. The preparation of elite athletes involves a range of training activities with various goals.
It should also be considered whether highly trained athletes have a different response or require a different stimulus to untrained or even moderately trained individuals. weeks or months? Investigations to date Hansen et al.
It is clearly impractical to extrapolate the effect of short-term laboratory supervised training studies to an entire year of periodized training and competition. Although current sports nutrition guidelines recommend practices to promote carbohydrate availability for training, particularly key sessions involving high-intensity workouts, it is likely that elite athletes who undertake several sessions per day already undertake some of these workouts with reduced carbohydrate availability, either deliberately or unintentionally.
Some athletes have already adopted specific train-low practices due to the present and previous interests in this strategy and some athletes in weight-category sports may also restrict carbohydrate intake below training requirements as part of the reduced energy or carbohydrate-modified diets designed to achieve lower body mass or fat levels.
Such an approach may ultimately result in scientists being in a better position to advise coaches about the optimal nutrient-exercise strategies that best modulate training efficiency!
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Philp A. Hargreaves M, Baar K. Pilegaard H, Ordway GA, Saltin B, Neufer PD. Psilander N, Frank P, Flockhart M, Shalin K. Yeo WK, Paton CD, Garnham AP, Burke LM, Carey AL, Hawley JA.
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Training adaptations by Topic 1. Carbohydrate, sports drinks and performance: strategies fo Topic 3. Your first session will lower your muscle glycogen so that you perform your second training in a low-glycogen state. This method has been shown to increase oxidative enzyme activity and fat utilization and improve exercise capacity and performance.
Train in the evening, restrict carbs overnight and do a fasted session in the morning. The effect is similar to training twice a day, except that the duration with low muscle and liver glycogen is extended for several hours while you sleep.
Studies using this method have demonstrated beneficial effects on cell signaling and performance. By restricting carbs post-exercise, you keep muscle and liver glycogen low, extend the availability of circulating free fatty acids for fuel, sustain the upregulation of cell signaling pathways, and boost the adaptive response to the session.
Some studies have also reported an improved metabolic adaptation to exercise using this method. Low-carb training can improve endurance capacity and performance due to enhanced mitochondria biogenesis and increased blood supply to working muscles.
As such, low-carb training is not necessarily associated with enhanced endurance. A clear benefit of low-carb training, though, is improved fat oxidation. This occurs because you are conditioning your body to use its stored fat as fuel instead of recently consumed carbohydrates. This benefit may be advantageous if you compete in long-distance events such as ultra-marathon or Ironman or if you are prone to GI issues when consuming a high amount of sports nutrition products.
Furthermore, by improving your capacity to use fat as fuel, you enhance your metabolic flexibility, a critical health marker that we will briefly cover in the last section of this article.
While low-carb training brings benefits, you should not do every workout on low glycogen stores. If you are unable to complete the scheduled training sessions, your long-term training and competition goals may be jeopardized. The primary advantage of carb periodization is that it enhances your metabolic flexibility, which is a critical marker of good health.
Metabolic flexibility refers to your body's ability to efficiently use whatever fuel is available, fat or carbs, and seamlessly switch from one fuel source to another.
Carb periodization is an excellent way to promote metabolic flexibility since it improves fat oxidation by occasionally exercising with low-carb levels while maintaining carb oxidation efficiency with regular high-carb sessions.
Metabolic flexibility provides many benefits, including sustained energy, fewer blood sugar fluctuations, reduced cravings, and improved fat-burning. As your metabolic flexibility improves, you are less likely to develop conditions like type 2 diabetes and obesity.
Individuals suffering from type 2 diabetes or obesity are typically metabolically inflexible, and current research suggests that exercise and carb periodization can help improve metabolic flexibility in skeletal muscle and adipose tissue, which could make them valuable for preventing and treating metabolic diseases.
Hopefully, you have a better understanding of carb periodization and see some potential benefits for you. While we tried to provide enough information to get you started, incorporating carb periodization into your training and nutrition routine might be intimidating.
If in doubt, please reach out. We are here to support you. We can work with you to create an individualized nutrition plan and suggest a periodization that best aligns with your training plan, targeted race, and dietary preferences.
Carbohydrate can be restricted for selected training sessions aiming to enhance training adaptations. In sessions lasting minutes or less, performed at a low or moderate intensity, training low is likely to be beneficial.
Multiple train-smart strategies that appear to enhance training adaptations are reported in scientific literature:. When maximal performance of high-intensity exercise is desired, high carbohydrate intake is key, because carbohydrate is the primary energy source for high-intensity exercise.
Fueling for training should Carbohydeates optimal BIA body composition monitor adaptations where race-day fueling should support maximal performance. If race-day Carbohydrates and training adaptations is optimal, Carbohydrates and training adaptations enhanced traaining adaptations can improve race-day performance. Despite the potential benefits adaptationx training low, there are negative implications of persistently training this way:. A recommended approach to overcome these negatives is a periodized approach to carbohydrate intake. Carbohydrate can be restricted for selected training sessions aiming to enhance training adaptations. In sessions lasting minutes or less, performed at a low or moderate intensity, training low is likely to be beneficial. Multiple train-smart strategies that appear to enhance training adaptations are reported in scientific literature:.
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