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Enhanced Endurance Performance by Periodization of CHO Intake: "Sleep Low" Strategy
Abstract and Figures
Purpose:
We investigated the effect of a chronic dietary periodization strategy on endurance performance in trained athletes.
Methods:
21 triathletes (V[Combining Dot Above]O2max: 58.7 ± 5.7 mL·min·kg) were divided into 2 groups: a "sleep-low" (SL, n = 11) and a control group (CON, n = 10) consumed the same daily carbohydrate (CHO) intake (6 g·kg·d) but with different timing over the day to manipulate CHO availability before and after training sessions. The "sleep low" strategy consisted of a 3-week training/diet intervention comprising three blocks of diet/exercise manipulations: 1) "train-high" interval training sessions (HIT) in the evening with high-CHO availability; 2) overnight CHO restriction ("sleeping-low"), and 3) "train-low" sessions with low endogenous and exogenous CHO availability. The CON group followed the same training program but with high CHO availability throughout training sessions (no CHO restriction overnight, training sessions with exogenous CHO provision).
Results:
There was a significant improvement in delta efficiency during submaximal cycling for SL versus CON (CON: +1.4 ± 9.3 %, SL: +11 ± 15 %, P<0.05). SL also improved supra-maximal cycling to exhaustion at 150% of peak aerobic power (CON: +1.63 ± 12.4 %, SL: +12.5 ± 19.0 %; P = 0.06) and 10 km running performance (CON: -0.10 ± 2.03 %, SL: -2.9 ± 2.15 %; P < 0.05). Fat mass was decreased in SL (CON: -2.6 ± 7.4; SL: -8.5 ± 7.4 %PRE, P < 0.01), but not lean mass (CON: -0.22 ± 1.0; SL: -0.16 ± 1.7 %PRE).
Conclusion:
Short-term periodization of dietary CHO availability around selected training sessions promoted significant improvements in submaximal cycling economy, as well as supra-maximal cycling capacity and 10 km running time in trained endurance athletes.
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... Previous reports have suggested these techniques may enhance cellular adaptations to endurance exercise like mitochondrial density [116,117]. However, longitudinal evidence is mixed as to whether these practices result in increased exercise performance [118,119]. A 2016 investigation by Marquet et al. [119] noted significant improvements in submaximal cycling efficiency and 10 km running performance when triathletes underwent 3 weeks of carbohydrate periodization which included performing some sessions fasted prior to the morning meal compared to controls who consumed the same daily amount of carbohydrates (6 g/kg/day) spread equally throughout the day. ...
... However, longitudinal evidence is mixed as to whether these practices result in increased exercise performance [118,119]. A 2016 investigation by Marquet et al. [119] noted significant improvements in submaximal cycling efficiency and 10 km running performance when triathletes underwent 3 weeks of carbohydrate periodization which included performing some sessions fasted prior to the morning meal compared to controls who consumed the same daily amount of carbohydrates (6 g/kg/day) spread equally throughout the day. However, Burke and colleagues failed to detect similar improvements in Olympic-caliber race walkers after 3 weeks of a similar dietary protocol [118], although neither investigation stated the length of time of the overnight fast along with the length of time between finishing the exercise session and the resumption of eating, which are both important considerations and can potentially impact outcomes. ...
... Additionally, performing low-intensity "recovery" sessions fasted prior to consuming breakfast has previously been found to improve mitochondrial density and metabolic adaptations to endurance exercise [116,117]. However, the literature regarding whether these improvements result in better performance is mixed [118,119]. ...
Background: Breakfast is often termed the most important meal of the day. However, its importance to acute and chronic adaptations to exercise is currently not well summarized throughout the literature. Methods: A narrative review of the experimental literature regarding breakfast consumption’s impact on acute and chronic exercise performance and alterations in body composition prior to November 2024 was conducted. To be included in this review, the selected investigations needed to include some aspect of either endurance or resistance training performance and be conducted in humans. Results: These findings suggest that breakfast consumption may benefit acute long-duration (>60 min) but not short-duration (<60 min) morning endurance exercise. Evening time trial performance was consistently inhibited following breakfast omission despite the resumption of eating midday. No or minimal impact of breakfast consumption was found when examining acute morning or afternoon resistance training or the longitudinal adaptations to either resistance or endurance training. Favorable changes in body composition were often noted following the omission of breakfast. However, this was primarily driven by the concomitant reduced kilocalorie intake. Conclusions: Consuming breakfast may aid endurance athletes regularly performing exercise lasting >60 min in length. However, the morning meal’s impact on resistance training and changes in body composition appears to be minimal. Although, as the body of literature is limited, future investigations are needed to truly ascertain the dietary practice’s impact.
... Moreover, several studies have demonstrated that repeated exposures to low CHO availability training over a 3-to 10-week period enhanced the activity and/or content of proteins involved in oxidative metabolism (e.g. citrate synthase, β-HAD, succinate dehydrogenase, COXIV) and, in some cases, translate to improvements in exercise performance [110][111][112][113]. While these findings provide experimental evidence to support the practical application of the 'train low' (muscle glycogen) paradigm for endurance athletes, recent scientific interest has focussed on how the protein needs of endurance athletes should be modified during periods of CHO-restricted endurance training. ...
The purpose of this narrative review is to provide an evidence-based update on the protein needs of endurance athletes with a focus on high-quality metabolic studies conducted on the topics of recovery and training adaptation over the past decade. We use the term ‘protein needs’ to delineate between the concepts of a daily protein requirement and per meal protein recommendations when devising scientific evidence-based protein guidelines for the endurance athlete to promote post-exercise recovery, enhance the adaptive response to endurance training and improve endurance performance. A habitual protein intake of 1.5 g/kg of body mass (BM)⁻¹·day⁻¹ is typical in male and female endurance athletes. Based on findings from a series of contemporary protein requirement studies, the evidence suggests a daily protein intake of ~ 1.8 g·kgBM⁻¹·day⁻¹ should be advocated for endurance athletes, with the caveat that the protein requirement may be further elevated in excess of 2.0 g·kgBM⁻¹·day⁻¹ during periods of carbohydrate-restricted training and on rest days. Regarding protein recommendations, the current lack of metabolic studies that determine the dose response of muscle protein synthesis to protein ingestion in relation to endurance exercise makes it difficult to present definitive guidelines on optimal per meal protein intakes for endurance athletes. Moreover, there remains no compelling evidence that co-ingesting protein with carbohydrate before or during endurance exercise confers any performance advantage, nor facilitates the resynthesis of liver or muscle glycogen stores during recovery, at least when carbohydrate recommendations are met. However, recent evidence suggests a role for protein nutrition in optimising the adaptive metabolic response to endurance training under conditions of low carbohydrate and/or energy availability that represent increasingly popular periodised strategies for endurance athletes.
... Studies of Tier 2-3 endurance athletes have shown that those who undertook strategic periodization of carbohydrate availability over a one week [152] or three week [153] training block achieved greater performance outcomes compared to groups training undertaken with sustained high carbohydrate availability. Meanwhile, studies in Tier 3-5 athletes have failed to show a superior performance outcome with periodized versus sustained high CHO availability [135,154,155]. ...
... There are many examples in sport science research where adaptations or performance improvements with trained athletes following an intervention are not replicated with highly trained or elite athletes. For example, in moderately trained athletes, changes in endurance performance following a training block with periodised carbohydrate availability were greater than those of a control group whose diet provided continuous high carbohydrate availability (Marquet et al., 2016). Meanwhile, no such advantage was reported when elite athletes followed equivalent interventions (Burke et al., 2017). ...
Sport science practitioners utilise findings from peer reviewed research to inform practice. Fewer studies are conducted with high performance athletes, however, than those involving recreationally active participants. Noting that research findings from recreational athletes may not be generalisable to the elite, there is a need to engage the latter cohort in research with better potential to influence health and performance. This study identified methods used to engage and recruit highly trained, elite and world class athletes as research participants. A document analysis was conducted using a purposive sample of peer‐reviewed sport science literature. All articles published in 2022 from 18 highly ranked sport science journals were screened for inclusion. Studies investigating athletes ranked as highly trained/national level or above were included. All details related to participant recruitment were extracted from included articles, with the content being coded and thematically analysed using an interpretivist approach. A total of 439 studies from the 2356 screened were included in the analysis. Five primary themes of recruitment strategies were identified, beneath an overarching strategy of purposeful, convenience sampling. Recruitment themes related to the use of a gatekeeper, the research environment providing convenient access to athletes, promoting the study electronically, utilising professional networks and recruiting at training or competition. Engaging athletes through a gatekeeper is a prominent strategy to involve elite athletes in research. It is suggested that researchers work collaboratively with team or organisation personnel to promote recruitment, creating co‐designed approaches that address issues most relevant to athletes and staff.
... Each of these methods is subject to underreported dietary intake; however, the 24-h recall with multi-pass interview exhibits the lowest error from doubly labeled water comparisons [88]. See the CHO timing study by Marquet et al. for an example of well-controlled, but feasible monitoring of diet intake [130]; notably participants recorded their diet at multiple points throughout the study with multi-pass interviewing and single-investigator dietary analysis. Nonetheless, implementing rigorous nutrition controls does significantly increase the workload to execute a study; therefore, utilizing automated and self-administered multi-pass methods such as the National Institute for Health's Automated Self-Administered Dietary Assessment Tool (ASA24) may reduce researcher burden, though the validity of the tool is still in question depending on the variable(s) of interest [131]. ...
In addition to its established thermoregulatory and cardiovascular effects, heat stress provokes alterations in macronutrient metabolism, gastrointestinal integrity, and appetite. Inadequate energy, carbohydrate, and protein intake have been implicated in reduced exercise and heat tolerance. Classic exercise heat acclimation (HA) protocols employ low-to-moderate–intensity exercise for 5–14 days, while recent studies have evolved the practice by implementing high-intensity and task-specific exercise during HA, which potentially results in impaired post-HA physical performance despite adequate heat adaptations. While there is robust literature demonstrating the performance benefit of various nutritional interventions during intensive training and competition, most HA studies implement few nutritional controls. This review summarizes the relationships between heat stress, HA, and intense exercise in connection with substrate metabolism, gastrointestinal function, and the potential consequences of reduced energy availability. We discuss the potential influence of macronutrient manipulations on HA study outcomes and suggest best practices to implement nutritional controls.
... The general consensus from the wealth of studies undertaken in the past 40 years is that CHO loading can improve performance and capacity especially when the exercise is greater than 90 min in duration. The enhanced performance effect is likely initially mediated by a delay in the time-point at which energy availability becomes limiting to the maintenance of the desired workload, which in the case of race pace is dependent on sustained and high rates of CHO oxidation (18). ...
This research was done with the aim of studying cell signaling processes in the process of body metabolism in 2024. Methodology: The research method of the present study is descriptive-survey in nature, and applied in terms of research purpose and cross-sectional in terms of time. The research design used in this research is the pre-test-post-test design. The statistical population of this research consists of 3 men and 3 women who are engaged in cycling professionally. In this research, to reach a representative sample, a non-random sampling method was used. In this research, two library and field methods were used to collect data. Sports exercises have been used in the field section. Results: The findings of this research show that the metabolic process regulates many cells signaling processes that are related to human health and performance. Now that the specific regulatory checkpoints for CHO metabolism are well documented, the precision of the molecular mechanisms regulating CHO transport, storage, and utilization that have not yet been fully identified can be increased. In the process of metabolism, consumed nutrients are analyzed and converted into smaller molecules. Conclusion: These molecules ultimately contribute to cellular structures such as proteins and nucleic acids. Also, this stored energy is released and transferred to all body activities, including movements and chemical compounds, in signaling processes.
Background
Carbohydrate restriction can alter substrate utilization and potentially impair endurance performance in female athletes. Caffeine intake may mitigate this performance decrements.
Objectives
The aim of this study was to test the hypothesis that maximal fat oxidation (MFO) rate would be enhanced in the carbohydrate (CHO) restricted state in trained females. Additionally, the impact of caffeine intake before exercise under conditions of low CHO availability was examined on time-trial performance.
Methods
By using a randomized, double-blinded, placebo-controlled, crossover design, 17 female endurance athletes completed 3 experimental blocks. Each block consisted of high-intensity-interval–training (HIT) in the evening, followed by a fat oxidation test to measure MFO rate and a 20-min time trial (20TT) performance the next morning. The females received standardized, isoenergetic diets with different timing of CHO intake: No CHO between exercise sessions without (FASTED) or with 300 mg caffeine (4.1–4.9 mg/kg body mass) (FASTED+CAFF) before morning exercise tests or CHO ingestion after HIT (FED).
Results
MFO rate was higher in FASTED+CAFF (0.57 ± 0.04 g/min) than that in FED (0.50 ± 0.04 g/min, P = 0.039) but not different from FASTED condition. Power output performed during the 20TT was higher after FASTED+CAFF (189 ± 9 W) than that after FASTED (+6.9%, P = 0.022) and FED (+4.2%, P = 0.054).
Conclusions
CHO restriction during recovery from HIT enhances MFO rate during subsequent exercise compared with the condition where CHOs were consumed during the recovery period, but the effect was only significant when CHO restriction was combined with caffeine supplementation before the MFO test. In addition, caffeine ingestion before exercise in the CHO-restricted state compensates for the decreased work capacity associated with the CHO-restricted state.
Este estudo revisa a literatura para avaliar o efeito da periodização nutricional no desempenho de atletas voltados para força e hipertrofia muscular, destacando sua contribuição para a recuperação e adaptação ao treinamento. A periodização nutricional refere-se à adaptação planejada da ingestão de nutrientes conforme as demandas específicas de cada fase do treinamento, promovendo um consumo estratégico de macronutrientes e micronutrientes para apoiar os objetivos atléticos. Com base na análise de estudos, observou-se que essa prática favorece a maximização de força, o aumento da massa muscular e o controle da composição corporal, comparando positivamente com estratégias nutricionais não periodizadas. Entre os benefícios, incluem-se o suporte ao volume e à intensidade dos treinos, além da prevenção de lesões e redução da fadiga. Contudo, sua implementação apresenta desafios, como a complexidade do planejamento e a necessidade de constante monitoramento, exigindo alto nível de conhecimento dos profissionais envolvidos. A revisão também identificou lacunas e a necessidade de maior aprofundamento na investigação de variáveis individuais, como metabolismo e resposta adaptativa. Este estudo sugere que a periodização nutricional, quando aplicada estrategicamente e ajustada às características do atleta, oferece um caminho promissor para melhorar a performance e o bem-estar, além de promover a longevidade na prática esportiva. Em conclusão, recomenda-se uma abordagem personalizada e colaborativa entre atletas, treinadores e nutricionistas, com o objetivo de aplicar diretrizes baseadas em evidências para o esporte de alto rendimento.
in Japanese]
Graphical Abstract Fullsize Image
We determined the effects of 'periodized nutrition' on skeletal muscle and whole-body responses to a bout of prolonged exercise the following morning. Seven cyclists completed two trials receiving isoenergetic diets differing in the timing of ingestion: They consumed either 8 g•kg(-1) BM of CHO before undertaking an evening session of high-intensity training (HIT) and slept without eating (FASTED), or 4 g•kg(-1) BM of CHO before HIT then 4 g•kg(-1) BM of CHO before sleeping (FED). The next morning subjects completed 2 h cycling (120SS) while overnight fasted. Muscle biopsies were taken on day 1 (D1) before and 2 h after HIT and on Day 2 (D2) pre-, post-, and 4 h after 120SS. Muscle [glycogen] was higher in FED at all times post-HIT (P< 0.001). HIT increased PGC1α mRNA (P< 0.01) while PDK4 mRNA was elevated to a greater extent in FASTED (P< 0.05). Resting phosphorylation of AMPK(Thr172), p38MAPK(Thr180/Tyr182) and p-ACC(Ser79) (D2) was greater in FASTED (P< 0.05). Fat oxidation during 120SS was higher in FASTED (P< 0.01) coinciding with increases in ACC(Ser79) and CPT1, as well as mRNA expression of CD36 and FABP3 (P< 0.05). Methylation on the gene promoter for COX4I1 and FABP3 increased 4 h after 120SS in both trials, while methylation of the PPARδ promoter increased only in FASTED. We provide evidence for shifts in DNA methylation that correspond with inverse changes in transcription for metabolically adaptive genes, although delaying post-exercise feeding failed to augment markers of mitochondrial biogenesis.
Copyright © 2014, Journal of Applied Physiology.
No literature reviews have systematically identified and evaluated research on the psychological determinants of endurance performance, and sport psychology performance enhancement guidelines for endurance sports are not founded on a systematic appraisal of endurance-specific research.
A systematic literature review was conducted to identify practical psychological interventions that improve endurance performance and to identify additional psychological factors that affect endurance performance. Additional objectives were to evaluate the research practices of the included studies, to suggest theoretical and applied implications, and to guide future research.
Electronic databases, forward-citation searches and manual searches of reference lists were used to locate relevant studies. Peer-reviewed studies were included when they chose an experimental or quasi-experimental research design; a psychological manipulation; endurance performance as the dependent variable; and athletes or physically active, healthy adults as participants.
Consistent support was found for using imagery, self-talk and goal setting to improve endurance performance, but it is unclear whether learning multiple psychological skills is more beneficial than learning one psychological skill. The results also demonstrated that mental fatigue undermines endurance performance, and verbal encouragement and head-to-head competition can have a beneficial effect. Interventions that influenced perception of effort consistently affected endurance performance.
Psychological skills training could benefit an endurance athlete. Researchers are encouraged to compare different practical psychological interventions, to examine the effects of these interventions for athletes in competition and to include a placebo control condition or an alternative control treatment. Researchers are also encouraged to explore additional psychological factors that could have a negative effect on endurance performance. Future research should include psychological mediating variables and moderating variables. Implications for theoretical explanations for endurance performance and evidence-based practice are described.
Abstract Traditional nutritional approaches to endurance training have typically promoted high carbohydrate (CHO) availability before, during and after training sessions to ensure adequate muscle substrate to meet the demands of high daily training intensities and volumes. However, during the past decade, data from our laboratories and others have demonstrated that deliberately training in conditions of reduced CHO availability can promote training-induced adaptations of human skeletal muscle (i.e. increased maximal mitochondrial enzyme activities and/or mitochondrial content, increased rates of lipid oxidation and, in some instances, improved exercise capacity). Such data have led to the concept of 'training low, but competing high' whereby selected training sessions are completed in conditions of reduced CHO availability (so as to promote training adaptation), but CHO reserves are restored immediately prior to an important competition. The augmented training response observed with training-low strategies is likely regulated by enhanced activation of key cell signalling kinases (e.g. AMPK, p38MAPK), transcription factors (e.g. p53, PPARδ) and transcriptional co-activators (e.g. PGC-1α), such that a co-ordinated up-regulation of both the nuclear and mitochondrial genomes occurs. Although the optimal practical strategies to train low are not currently known, consuming additional caffeine, protein, and practising CHO mouth-rinsing before and/or during training may help to rescue the reduced training intensities that typically occur when 'training low', in addition to preventing protein breakdown and maintaining optimal immune function. Finally, athletes should practise 'train-low' workouts in conjunction with sessions undertaken with normal or high CHO availability so that their capacity to oxidise CHO is not blunted on race day.
Recovery from the demands of daily training is an essential element of a scientifically based periodized program whose twin goals are to maximize training adaptation and enhance performance. Prolonged endurance training sessions induce substantial metabolic perturbations in skeletal muscle, including the depletion of endogenous fuels and damage/disruption to muscle and body proteins. Therefore, increasing nutrient availability (i.e., carbohydrate and protein) in the post-training recovery period is important to replenish substrate stores and facilitate repair and remodelling of skeletal muscle. It is well accepted that protein ingestion following resistance-based exercise increases rates of skeletal muscle protein synthesis and potentiates gains in muscle mass and strength. To date, however, little attention has focused on the ability of dietary protein to enhance skeletal muscle remodelling and stimulate adaptations that promote an endurance phenotype. The purpose of this review is to critically discuss the results of recent studies that have examined the role of dietary protein for the endurance athlete. Our primary aim is to consider the results from contemporary investigations that have advanced our knowledge of how the manipulation of dietary protein (i.e., amount, type, and timing of ingestion) can facilitate muscle remodelling by promoting muscle protein synthesis. We focus on the role of protein in facilitating optimal recovery from, and promoting adaptations to strenuous endurance-based training.
Laboratory-based studies demonstrate that fueling (carbohydrate; CHO) and fluid strategies can enhance training adaptations and race-day performance in endurance athletes. Thus, the aim of this case study was to characterize several periodized training and nutrition approaches leading to individualized race-day fluid and fueling plans for 3 elite male marathoners. The athletes kept detailed training logs on training volume, pace, and subjective ratings of perceived exertion (RPE) for each training session over 16 wk before race day. Training impulse/load calculations (TRIMP; min x RPE = load [arbitrary units; AU]) and 2 central nutritional techniques were implemented: periodic low-CHO-availability training and individualized CHO- and fluid-intake assessments. Athletes averaged ∼13 training sessions per week for a total average training volume of 182 km/wk and peak volume of 231 km/wk. Weekly TRIMP peaked at 4,437 AU (Wk 9), with a low of 1,887 AU (Wk 16) and an average of 3,082 ± 646 AU. Of the 606 total training sessions, ∼74%, 11%, and 15% were completed at an intensity in Zone 1 (very easy to somewhat hard), Zone 2 (at lactate threshold) and Zone 3 (very hard to maximal), respectively. There were 2.5 ± 2.3 low-CHO-availability training bouts per week. On race day athletes consumed 61 ± 15 g CHO in 604 ± 156 ml/hr (10.1% ± 0.3% CHO solution) in the following format: ∼15 g CHO in ∼150 ml every ∼15 min of racing. Their resultant marathon times were 2:11:23, 2:12:39 (both personal bests), and 2:16:17 (a marathon debut). Taken together, these periodized training and nutrition approaches were successfully applied to elite marathoners in training and competition.
Commencing some training sessions with reduced carbohydrate (CHO) availability has been shown to enhance skeletal muscle adaptations, but the effect on exercise performance is less clear. We examined whether restricting CHO intake between twice daily sessions of high-intensity interval training (HIIT) augments improvements in exercise performance and mitochondrial content. Eighteen active but not highly trained subjects [peak oxygen uptake (VO2peak) = 44 ± 9 ml/kg/min], matched for age, sex, and fitness, were randomly allocated to two groups. On each of six days over 2 wk, subjects completed two training sessions, each consisting of 5 x 4-min cycling intervals (60% of peak power), interspersed by 2 min of recovery. Subjects ingested either 195 g of CHO ("HI-HI" group: ~2.3 g/kg) or 17 g of CHO ("HI-LO" group: ~0.3 g/kg) during the 3-h period between sessions. The training-induced improvement in 250-kJ time trial performance was greater (p = 0.02) in the HI-LO group (211 ± 66 W to 244 ± 75 W) compared to the HI-HI group (203 ± 53 W to 219 ± 60 W); however, the increases in mitochondrial content was similar between groups, as reflected by similar increases in citrate synthase maximal activity, citrate synthase protein content and cytochrome c oxidase subunit IV protein content (p > 0.05 for interaction terms). This is the first study to show that a short-term 'train low, compete high' intervention can improve whole-body exercise capacity. Further research is needed to determine whether this type of manipulation can also enhance performance in highly-trained subjects.
Mitochondrial biogenesis in skeletal muscle results from the cumulative effect of transient increases in mRNA transcripts encoding mitochondrial proteins in response to repeated exercise sessions. This process requires the coordinated expression of both nuclear and mitochondrial (mt) DNA genomes and is regulated, for the most part, by the peroxisome proliferator-activated receptor γ coactivator 1α. Several other exercise-inducible proteins also play important roles in promoting an endurance phenotype, including AMP-activated protein kinase, p38 mitogen-activated protein kinase and tumour suppressor protein p53. Commencing endurance-based exercise with low muscle glycogen availability results in greater activation of many of these signalling proteins compared with when the same exercise is undertaken with normal glycogen concentration, suggesting that nutrient availability is a potent signal that can modulate the acute cellular responses to a single bout of exercise. When exercise sessions are repeated in the face of low glycogen availability (i.e. chronic training), the phenotypic adaptations resulting from such interventions are also augmented.
Recovery from the demands of daily training is an essential element of a scientifically based periodized program whose twin goals are to maximize training adaptation and enhance performance. Prolonged endurance training sessions induce substantial metabolic perturbations in skeletal muscle, including the depletion of endogenous fuels and damage/disruption to muscle and body proteins. Therefore, increasing nutrient availability (i.e., carbohydrate and protein) in the post-training recovery period is important to replenish substrate stores and facilitate repair and remodelling of skeletal muscle. It is well accepted that protein ingestion following resistance-based exercise increases rates of skeletal muscle protein synthesis and potentiates gains in muscle mass and strength. To date, however, little attention has focused on the ability of dietary protein to enhance skeletal muscle remodelling and stimulate adaptations that promote an endurance phenotype. The purpose of this review is to critically discuss the results of recent studies that have examined the role of dietary protein for the endurance athlete. Our primary aim is to consider the results from contemporary investigations that have advanced our knowledge of how the manipulation of dietary protein (i.e., amount, type, and timing of ingestion) can facilitate muscle remodelling by promoting muscle protein synthesis. We focus on the role of protein in facilitating optimal recovery from, and promoting adaptations to strenuous endurance-based training.
The synthesis of new protein is necessary for both strength and endurance adaptations. While the proteins that are made might differ, myofibrillar proteins following resistance exercise and mitochondrial proteins and metabolic enzymes following endurance exercise, the basic premise of shifting to a positive protein balance after training is thought to be the same. What is less clear is the contribution of nutrition to the adaptive process. Following resistance exercise, proteins rich in the amino acid leucine increase the activation of mTOR, the rate of muscle protein synthesis (MPS), and the rate of muscle mass and strength gains. However, an effect of protein consumption during acute post-exercise recovery on mitochondrial protein synthesis has yet to be demonstrated. Protein ingestion following endurance exercise does facilitate an increase in skeletal MPS, supporting muscle repair, growth and remodeling. However, whether this results in improved performance has yet to be demonstrated. The current literature suggests that a strength athlete will experience an increased sensitivity to protein feeding for at least 24 h after exercise, but immediate consumption of 0.25 g/kg bodyweight of rapidly absorbed protein will enhance MPS rates and drive the skeletal muscle hypertrophic response. At rest, ∼0.25 g/kg bodyweight of dietary protein should be consumed every 4-5 h and another 0.25-0.5 g/kg bodyweight prior to sleep to facilitate the postprandial muscle protein synthetic response. In this way, consuming dietary protein can complement intense exercise training and facilitate the skeletal muscle adaptive response. Copyright © 2013 Nestec Ltd., Vevey/S. Karger AG, Basel.