Pre-Sleep Protein Ingestion to Improve the Skeletal Muscle Adaptive Response to Exercise Training

Meal timing and its role in obesity and associated diseases

Meal timing emerges as a crucial factor influencing metabolic health that can be explained by the tight interaction between the endogenous circadian clock and metabolic homeostasis. Mistimed food intake, such as delayed or nighttime consumption, leads to desynchronization of the internal circadian clock and is associated with an increased risk for obesity and associated metabolic disturbances such as type 2 diabetes and cardiovascular diseases. Conversely, meal timing aligned with cellular rhythms can optimize the performance of tissues and organs. In this review, we provide an overview of the metabolic effects of meal timing and discuss the underlying mechanisms. Additionally, we explore factors influencing meal timing, including internal determinants such as chronotype and genetics, as well as external influences like social factors, cultural aspects, and work schedules. This review could contribute to defining meal-timing-based recommendations for public health initiatives and developing guidelines for effective lifestyle modifications targeting the prevention and treatment of obesity and associated metabolic diseases. Furthermore, it sheds light on crucial factors that must be considered in the design of future food timing intervention trials.

Effects of pre-sleep protein supplementation on plasma markers of muscle damage and inflammatory cytokines resulting from sprint interval training in trained swimmers

BACKGROUND

Pre-sleep protein has been shown to improve muscle recovery overnight following exercise-induced muscle damage. Whether such an approach affects recovery from sprint interval training (SIT) has yet to be elucidated. This study examined the effects of protein supplementation every night before sleep on early (45 min post-SIT) and late (24 and 48 h after SIT) responses of creatine kinase (CK) and inflammatory cytokines, including interleukin-6 and 10 (IL-6 and IL-10) and tumor necrosis factor-alpha (TNFα).

METHODS

Twenty trained swimmers underwent a 2-week in-water swimming SIT (two sets of 12 × 50-m all-out swims, interspersed by 1:1 recovery between each sprint and 3 min of rest between sets) and were randomized to two intervention groups receiving either 0.5 g kg-1 day-1 protein beverage (PRO) or the same amount of carbohydrate (CHO) preceding going to bed every night. For initial and final training sessions, CK and cytokine responses were analyzed at different time points, including resting, immediately after completion, 45 min post-SIT, and 24 and 48 h after SIT.

RESULTS

CK concentrations elevated from resting point to 24 and 48 h post-SIT for both PRO and CHO groups (p < 0.05). In both training groups, the peak levels of IL-6 and 10 were observed 45 min post-SIT on both occasions. TNFα levels significantly elevated from rest to immediately after SIT (p < 0.001) and returned to values equivalent to the baseline afterward in both groups and on both occasions. In both groups, swimming SIT also switched the cytokine response 48 hours after exercise to an anti-inflammatory status by decreasing the ratio of IL-6 to IL-10 (p < 0.04) in the last training session.

CONCLUSIONS

Pre-sleep protein ingestion failed to ameliorate blood markers of muscle damage. The late anti-inflammatory profile of cytokines and exercise-induced muscle damage improved after two weeks of swimming SIT with either protein or carbohydrate ingestion before sleep.

Pre-sleep feeding, sleep quality, and markers of recovery in division I NCAA female soccer players

Pre-sleep nutrition habits in elite female athletes have yet to be evaluated. A retrospective analysis was performed with 14 NCAA Division I female soccer players who wore a WHOOP, Inc. band - a wearable device that quantifies recovery by measuring sleep, activity, and heart rate metrics through actigraphy and photoplethysmography, respectively - 24 h a day for an entire competitive season to measure sleep and recovery. Pre-sleep food consumption data were collected via surveys every 3 days. Average pre-sleep nutritional intake (mean ± sd: kcals 330 ± 284; cho 46.2 ± 40.5 g; pro 7.6 ± 7.3 g; fat 12 ± 10.5 g) was recorded. Macronutrients and kcals were grouped into high and low categories based upon the 50^th percentile of the mean to compare the impact of a high versus low pre-sleep intake on sleep and recovery variables. Sleep duration (p = 0.10, 0.69, 0.16, 0.17) and sleep disturbances (p = 0.42, 0.65, 0.81, 0.81) were not affected by high versus low kcal, PRO, fat, CHO intake, respectively. Recovery (p = 0.81, 0.06, 0.81, 0.92), RHR (p = 0.84, 0.64, 0.26, 0.66), or HRV (p = 0.84, 0.70, 0.76, 0.93) were also not affected by high versus low kcal, PRO, fat, or CHO consumption, respectively. Consuming a small meal before bed may have no impact on sleep or recovery.

Pre-sleep protein supplementation does not improve performance, body composition, and recovery in British Army recruits (part 1)

Dietary protein is crucial for optimising physical training adaptations such as muscular strength and mass, which are key aims for athletic populations, including British Army recruits. New recruits fail to meet the recommended protein intake during basic training (BT), with negligible amounts consumed in the evening. This study assessed the influence of a daily bolus of protein prior to sleep on performance adaptations, body composition and recovery in British Army recruits. 99 men and 23 women [mean ± standard deviation (SD): age: 21.3 ± 3.5 years, height: 174.8 ± 8.4 cm, body mass 75.4 ± 12.2 kg] were randomised into a dietary control (CON), carbohydrate placebo (PLA), moderate (20 g) protein (MOD) or high (60 g) protein (HIGH) supplementation group. Supplements were isocaloric and were consumed on weekday evenings between 2000 and 2100 for 12 weeks during BT. Performance tests (mid-thigh pull, medicine ball throw, 2 km run time, maximal push-up, and maximal vertical jump) and body composition were assessed at the start and end of BT. Dietary intake, energy expenditure, salivary hormones, urinary nitrogen balance, perceived muscle soreness, rating of perceived exertion, mood, and fatigue were assessed at the start, middle and end of BT. Protein supplementation increased protein intake in HIGH (2.16 ± 0.50 g⸱kg-1⸱day-1) and MOD (1.71 ± 0.48 g⸱kg-1⸱day-1) compared to CON (1.17 ± 0.24 g⸱kg-1⸱day-1) and PLA (1.31 ± 0.29 g⸱kg-1⸱day-1; p < 0.001). Despite this, there was no impact of supplementation on mid-thigh pull performance (CON = 7 ± 19%, PLA = 7 ± 19%, MOD = 0 ± 16%, and HIGH = 4 ± 14%; p = 0.554) or any other performance measures (p > 0.05). Fat-free mass changes were also similar between groups (CON = 4 ± 3%, PLA = 4 ± 4%, MOD = 3 ± 3%, HIGH = 5 ± 4%, p = 0.959). There was no impact of protein supplementation on any other body composition or recovery measure. We conclude no benefits of pre-bed protein supplementation to improve performance, body composition and recovery during BT. It is possible the training stimulus was great enough, limiting the impact of protein supplementation. However, the high degree of inter-participant variability suggests an individualised use of protein supplementation should be explored, particularly in those who consume sub-optimal (<1.6 g⸱kg-1⸱day-1) habitual amounts of protein. Clinical trial registration: The study was registered with ClinicalTrials.gov, U.S. national institutes (identifier: NCT05998590).

Pre-sleep protein supplementation does not improve recovery from load carriage in British Army recruits (part 2)

British Army basic training (BT) is physically demanding with new recruits completing multiple bouts of physical activity each day with limited recovery. Load carriage is one of the most physically demanding BT activities and has been shown to induce acute exercise-induced muscle damage (EIMD) and impair muscle function. Protein supplementation can accelerate muscle recovery by attenuating EIMD and muscle function loss. This study investigated the impact of an additional daily bolus of protein prior to sleep throughout training on acute muscle recovery following a load carriage test in British Army recruits. Ninety nine men and 23 women (mean ± SD: age: 21.3 ± 3.5 yrs., height: 174.8 ± 8.4 cm, body mass 75.4 ± 12.2 kg) were randomized to dietary control (CON), carbohydrate placebo (PLA), moderate (20 g; MOD) or high (60 g; HIGH) protein supplementation. Muscle function (maximal jump height), perceived muscle soreness and urinary markers of muscle damage were assessed before (PRE), immediately post (POST), 24-h post (24 h-POST) and 40-h post (40 h-POST) a load carriage test. There was no impact of supplementation on muscle function at POST (p = 0.752) or 40 h-POST (p = 0.989) load carriage but jump height was greater in PLA compared to HIGH at 24 h-POST (p = 0.037). There was no impact of protein supplementation on muscle soreness POST (p = 0.605), 24 h-POST (p = 0.182) or 40 h-POST (p = 0.333). All groups had increased concentrations of urinary myoglobin and 3-methylhistidine, but there was no statistical difference between groups at any timepoint (p > 0.05). We conclude that pre-sleep protein supplementation does not accelerate acute muscle recovery following load carriage in British Army recruits during basic training. The data suggests that consuming additional energy in the form of CHO or protein was beneficial at attenuating EIMD, although it is acknowledged there were no statistical differences between groups. Although EIMD did occur as indicated by elevated urinary muscle damage markers, it is likely that the load carriage test was not arduous enough to reduce muscle function, limiting the impact of protein supplementation. Practically, protein supplementation above protein intakes of 1.2 g⸱kg-1⸱day-1 following load carriage over similar distances (4 km) and carrying similar loads (15-20 kg) does not appear to be warranted.

Sleep Duration and Sarcopenia: An Updated Systematic Review and Meta-Analysis

OBJECTIVES

In adults, short and long sleep duration has been associated with sarcopenia risk. Studies have shown that various factors, including biological and psychological factors, could be the underlying cause of the association between aberrant sleep duration and sarcopenia risk. In this study, we have qualitatively and quantitatively summarized previously published studies on sleep duration to assess the relationship between sleep duration and sarcopenia risk in adults. This would aid in enhancing our understanding of recent advancements in this field and the association between sleep duration and sarcopenia risk.

DESIGN

Systematic review and meta-analysis.

SETTING AND PARTICIPANTS

In this review, we included studies evaluating the association between the duration of sleep and sarcopenia in adults in observational studies.

METHODS

Five electronic databases (PubMed, EMBASE, Cochrane Library, China National Knowledge Infrastructure, and Web of Science) were searched to April 20, 2023, to identify studies related to sarcopenia and sleep duration. Next, we calculated the odds ratios (ORs) for sarcopenia prevalence based on the adjusted data from individual studies. Statistical analyses were performed using Stata 11.0.

RESULTS

Sarcopenia prevalence was high (18%) in adults with long sleep duration. Our results showed a significant association between short duration of sleep and high sarcopenia prevalence in older adults (OR 1.2, 95% CI 1.02-1.41, I2 = 56.6%). Furthermore, a significant association was observed between all participants with long-duration sleep and high sarcopenia prevalence (OR 1.53, 95% CI 1.34-1.75, I2 = 56.8%). We also observed significant heterogeneity in the adjusted ORs.

CONCLUSIONS AND IMPLICATIONS

There was a correlation between sarcopenia and short or long sleep duration, especially in older adults. In adults with a long duration of sleep, sarcopenia prevalence was relatively high.

Pre-sleep Protein Ingestion Increases Mitochondrial Protein Synthesis Rates During Overnight Recovery from Endurance Exercise: A Randomized Controlled Trial

BACKGROUND

Casein protein ingestion prior to sleep has been shown to increase myofibrillar protein synthesis rates during overnight sleep. It remains to be assessed whether pre-sleep protein ingestion can also increase mitochondrial protein synthesis rates. Though it has been suggested that casein protein may be preferred as a pre-sleep protein source, no study has compared the impact of pre-sleep whey versus casein ingestion on overnight muscle protein synthesis rates.

OBJECTIVE

We aimed to assess the impact of casein and whey protein ingestion prior to sleep on mitochondrial and myofibrillar protein synthesis rates during overnight recovery from a bout of endurance-type exercise.

METHODS

Thirty-six healthy young men performed a single bout of endurance-type exercise in the evening (19:45 h). Thirty minutes prior to sleep (23:30 h), participants ingested 45 g of casein protein, 45 g of whey protein, or a non-caloric placebo. Continuous intravenous L-[ring-13C6]-phenylalanine infusions were applied, with blood and muscle tissue samples being collected to assess overnight mitochondrial and myofibrillar protein synthesis rates.

RESULTS

Pooled protein ingestion resulted in greater mitochondrial (0.087 ± 0.020 vs 0.067 ± 0.016%·h-1, p = 0.005) and myofibrillar (0.060 ± 0.014 vs 0.047 ± 0.011%·h-1, p = 0.012) protein synthesis rates when compared with placebo. Casein and whey protein ingestion did not differ in their capacity to stimulate mitochondrial (0.082 ± 0.019 vs 0.092 ± 0.020%·h-1, p = 0.690) and myofibrillar (0.056 ± 0.009 vs 0.064 ± 0.018%·h-1, p = 0.440) protein synthesis rates.

CONCLUSIONS

Protein ingestion prior to sleep increases both mitochondrial and myofibrillar protein synthesis rates during overnight recovery from exercise. The overnight muscle protein synthetic response to whey and casein protein does not differ.

CLINICAL TRIAL REGISTRATION

NTR7251 .

Protein Ingestion in Reducing the Risk of Late-Onset Post-Exercise Hypoglycemia: A Pilot Study in Adolescents and Youth with Type 1 Diabetes

Dietary protein causes dose-dependent hyperglycemia in individuals with type 1 diabetes (T1D). This study investigated the effect of consuming 50 g of protein on overnight blood glucose levels (BGLs) following late-afternoon moderate-intensity exercise. Six participants (3M:3F) with T1D, HbA1c 7.5 ± 0.8% (58.0 ± 8.7 mmol/mol) and aged 20.2 ± 3.1 years exercised for 45 min at 1600 h and consumed a protein drink or water alone at 2000 h, on two separate days. A basal insulin euglycemic clamp was employed to measure the mean glucose infusion rates (m-GIR) required to maintain euglycemia on both nights. The m-GIR on the protein and water nights during the hypoglycemia risk period and overnight were 0.27 ± 043 vs. 1.60 ± 0.66 mg/kg/min (p = 0.028, r = 0.63) and 0.51 ± 0.16 vs. 1.34 ± 0.71 mg/kg/min (p = 0.028, r = 0.63), respectively. Despite ceasing intravenous glucose infusion on the protein night, the BGLs peaked at 9.6 ± 1.6 mmol/L, with a hypoglycemia risk period mean of 7.8 ± 1.5 mmol/L compared to 5.9 ± 0.4 mmol/L (p = 0.028) on the water night. The mean plasma glucagon levels were 51.5 ± 14.1 and 27.2 ± 10.1 ng/L (p = 0.028) on the protein and water night, respectively. This suggests that an intake of protein is effective at reducing the post-exercise hypoglycemia risk, potentially via a glucagon-mediated stimulation of glucose production. However, 50 g of protein may be excessive for maintaining euglycemia.

Phenomics in sport: Can emerging methodology drive advanced insights?

Methodologies in applied sport science have predominantly driven a reductionist grounding to component-specific mechanisms to drive athlete training and care. While linear mechanistic approaches provide useful insights, they have impeded progress in the development of more complex network physiology models that consider the temporal and spatial interactions of multiple factors within and across systems and subsystems. For this, a more sophisticated approach is needed and the development of such a methodological framework can be considered a Sport Grand Challenge. Specifically, a transdisciplinary phenomics-based scientific and modeling framework has merit. Phenomics is a relatively new area in human precision medicine, but it is also a developed area of research in the plant and evolutionary biology sciences. The convergence of innovative precision medicine, portable non-destructive measurement technologies, and advancements in modeling complex human behavior are central for the integration of phenomics into sport science. The approach enables application of concepts such as phenotypic fitness, plasticity, dose-response dynamics, critical windows, and multi-dimensional network models of behavior. In addition, profiles are grounded in indices of change, and models consider the athlete's performance or recovery trajectory as a function of their dynamic environment. This new framework is introduced across several example sport science domains for potential integration. Specific factors of emphasis are provided as potential candidate fitness variables and example profiles provide a generalizable modeling approach for precision training and care. Finally, considerations for the future are discussed, including scaling from individual athletes to teams and additional factors necessary for the successful implementation of phenomics.

Muscle-Related Effect of Whey Protein and Vitamin D3 Supplementation Provided before or after Bedtime in Males Undergoing Resistance Training

There is increasing evidence that dietary protein intake with leucine and vitamin D is an important factor in muscle protein synthesis. This study investigated the combined effects of consuming whey protein and vitamin D₃ in the evening before bedtime or in the morning after sleeping on muscle mass and strength. Healthy, untrained males (N = 42; Age = 18-24 year) were randomly assigned into three groups: before bedtime, after sleeping, and control. Subjects underwent a 6-week resistance training program in combination with supplements that provided 25 g whey protein and 4000 IU vitamin D₃ for the before bedtime and after sleeping groups and a 5 g maltodextrin placebo for the control group. A significant increase in serum vitamin D was observed in both before bedtime and after sleeping groups. All groups experienced a significant gain in leg press. However, the control group did not experience significant improvements in muscle mass and associated blood hormones that were experienced by the before bedtime and after sleeping groups. No significant differences in assessed values were observed between the before bedtime and after sleeping groups. These findings suggest that the combination of whey protein and vitamin D supplements provided either before or after sleep resulted in beneficial increases in muscle mass in young males undergoing resistance training that exceeded the changes observed without these supplements.

Sleep Quality: A Narrative Review on Nutrition, Stimulants, and Physical Activity as Important Factors

Sleep is a cyclically occurring, transient, and functional state that is controlled primarily by neurobiological processes. Sleep disorders and insomnia are increasingly being diagnosed at all ages. These are risk factors for depression, mental disorders, coronary heart disease, metabolic syndrome, and/or high blood pressure. A number of factors can negatively affect sleep quality, including the use of stimulants, stress, anxiety, and the use of electronic devices before sleep. A growing body of evidence suggests that nutrition, physical activity, and sleep hygiene can significantly affect the quality of sleep. The aim of this review was to discuss the factors that can affect sleep quality, such as nutrition, stimulants, and physical activity.

Pre-sleep Protein Supplementation Affects Energy Metabolism and Appetite in Sedentary Healthy Adults

Purpose

To assess the acute effect of pre-sleep protein supplementation combined with resistance exercise on energy metabolism (including 24-h total energy expenditure (TEE), sleep energy expenditure (SEE), basal energy expenditure (BEE), glycolipid oxidation, and appetite of sedentary adults.

Methods

A total of thirty-one sedentary participants completed this randomized, double-blind, crossover study. Participants completed the following 24-h experimental conditions in random order in the Human Calorimeter chamber: (1) 40-g protein supplementation with dinner before a nighttime resistance exercise, and followed by pre-sleep placebo intake (PRO-PLA); (2) placebo intake with dinner before a nighttime resistance exercise, and followed by pre-sleep 40-g protein supplementation (PLA-PRO); and (3) placebo supplementation both with dinner and pre-sleep combined with a nighttime resistance exercise (PLA). Subjective appetite score before breakfast the next day was evaluated using the visual analog scale.

Results

The SEE values were significantly higher by a mean of 21.7 kcal and 33.3 kcal in PRO-PLA (318.3 ± 44.3 kcal) and PLA-PRO (329.9 ± 45.2 kcal), respectively, than in PLA (296.6 ± 46.6 kcal). In addition, the SEE values for PLA-PRO was also significantly higher by 11.6 kcal than that for PRO-PLA. Further, the fullness the next morning was significantly higher by 30.8% in PLA-PRO (43.9 ± 23.5 mm) than in PLA (33.5 ± 26.6 mm). These effects remained after adjustment for 24-h energy intake.

Conclusion

Pre-sleep protein supplementation combined with resistance exercise can significantly increase the SEE and fullness in the next morning, indicating a possible strategy to improve sleep energy metabolism in the sedentary population.

Pre-sleep protein supplementation after an acute bout of evening resistance exercise does not improve next day performance or recovery in resistance trained men

Background

To evaluate the effect of pre-sleep protein supplementation after an acute bout of evening resistance training on next day performance and recovery the following day in physically active men.

Methods

Eighteen resistance trained men performed a single bout of resistance exercise then received either a pre-sleep protein (PRO) supplement containing 40 g of casein protein (PRO; n = 10; mean ± SD; age = 24 ± 4 yrs; height = 1.81 ± 0.08 m; weight = 84.9 ± 9.5 kg) or a non-caloric, flavor matched placebo (PLA; n = 8; age = 28 ± 10 yrs; height = 1.81 ± 0.07 m; weight = 86.7 ± 11.0 kg) 30 min before sleep (1 h after a standard recovery drink). Blood samples were obtained pre-exercise and the following morning (+12-h) to measure creatine kinase and C-reactive protein. Visual analog scales were utilized to assess perceived pain, hunger, and recovery. One-repetition maximum (1RM) tests for barbell bench press and squat were performed pre-exercise and the following morning (+12-h). Statistical analysis was performed using SPSS (V.23) and p ≤ 0.05 was considered statistically significant.

Results

There were no significant differences between the groups in next morning performance or muscle damage biomarkers. However, pre-sleep PRO resulted in a lower perception of hunger that approached significance the following morning when compared to PLA (PRO:43.6 ± 31.2, PLA: 69.4 ± 2.22; 95% C.I. = −53.6, 2.0; p = 0.07; d = 0.95).

Conclusions

Following an evening bout of exercise, pre-sleep PRO did not further improve next morning muscle damage biomarkers or maximal strength performance in resistance trained men compared to a non-caloric PLA. However, there may be implications for lower perceived hunger the next morning with pre-sleep PRO consumption compared to PLA.

“Food First but Not Always Food Only”: Recommendations for Using Dietary Supplements in Sport

The term “food first” has been widely accepted as the preferred strategy within sport nutrition, although there is no agreed definition of this and often limited consideration of the implications. We propose that food first should mean “where practically possible, nutrient provision should come from whole foods and drinks rather than from isolated food components or dietary supplements.” There are many reasons to commend a food first strategy, including the risk of supplement contamination resulting in anti-doping violations. However, a few supplements can enhance health and/or performance, and therefore a food only approach could be inappropriate. We propose six reasons why a food only approach may not always be optimal for athletes: (a) some nutrients are difficult to obtain in sufficient quantities in the diet, or may require excessive energy intake and/or consumption of other nutrients; (b) some nutrients are abundant only in foods athletes do not eat/like; (c) the nutrient content of some foods with established ergogenic benefits is highly variable; (d) concentrated doses of some nutrients are required to correct deficiencies and/or promote immune tolerance; (e) some foods may be difficult to consume immediately before, during or immediately after exercise; and (f) tested supplements could help where there are concerns about food hygiene or contamination. In these situations, it is acceptable for the athlete to consider sports supplements providing that a comprehensive risk minimization strategy is implemented. As a consequence, it is important to stress that the correct terminology should be “food first but not always food only.”

Determining the Influence of Habitual Dietary Protein Intake on Physiological Muscle Parameters in Youth and Older Age

Protein ingestion is a potent stimulator of skeletal muscle protein synthesis (MPS). However, older adults demonstrate resistance to anabolic stimuli. Some evidence has demonstrated that a larger acute protein dose is required in older compared to younger adults to elicit the same synthetic response, suggesting that older adults should be consuming higher habitual dietary protein to optimise muscle mass. However, limited research has explored dietary habits in different age groups or the relationship between habitual dietary intake and mechanistic physiological parameters associated with muscle mass and function. This work investigated the effect of habitual dietary intake in young (n = 10, 25.9 (3.2y)) and older (n = 16, 70.2 (3.2y)) community-dwelling adults (16:10 male: female) on physiological muscle parameters. Dietary intake was assessed using four-day diet diaries. Post-absorptive MPS and MPS responses to feeding (4.25x basal metabolic rate; 16% protein) were determined in muscle biopsies of the m. vastus lateralis via stable isotope tracer ([1, 2^-13C₂]-leucine) infusions with mass-spectrometric analyses. Body composition was measured by dual-energy x-ray absorptiometry. Whole body strength was assessed via 1-repetition maximum assessments. No significant differences in habitual dietary intake (protein, fat, carbohydrate and leucine as g.kgWBLM^-1.day^-1) were observed between age groups. Whole-body lean mass (61.8 ± 9.9 vs. 49.8 ± 11.9 kg, p = 0.01) and knee-extensor strength (87.7 ± 28.3 vs. 56.8 ± 16.4 kg, p = 0.002) were significantly higher in young adults. Habitual protein intake (g.kg^-1.day^-1) was not associated with whole-body lean mass, upper-leg lean mass, whole-body strength, knee-extensor strength, basal MPS or fed-state MPS across both age groups. These findings suggest that differences in muscle mass and strength parameters between youth and older age are not explained by differences in habitual dietary protein intake. Further research with a larger sample size is needed to fully explore these relationships and inform on interventions to mitigate sarcopenia development.

DIETARY SUPPLEMENTS FOR CONSIDERATION IN ELITE FEMALE FOOTBALLERS

The physical demands of professional female football have intensified in recent years. Supplements are only advised in addition to a healthy, balanced diet, but may warrant a greater prevalence in the professional game to support well-being, recovery, and performance. Supplements used by players should be safe, legal, and scientifically proven to be effective. An individual approach should be taken to using supplements dependant on the needs and goals of the player. Female players should aim to improve the frequency of protein intake throughout the day, whilst tailoring doses to individual body mass. Vitamin D supplementation is vital throughout the winter months in countries with limited sun exposure, however doses should be administered based on individual blood test results. Iron is likely to be important to the well-being of female athletes throughout the season, in particular during the menses. Omega-3 and collagen may be of greater benefit to female than male athletes during recovery from soft tissue injury, whilst probiotics and creatine are beneficial throughout the season for reducing risk of illness and optimising recovery, respectively. Ergogenic supplements for football include beta-alanine, nitrate and caffeine. Caution should be taken with caffeine use due to the varying tolerance of difference athletes and sleep impairments that can follow.

Branched chain amino acids selectively promote cardiac growth at the end of the awake period

Essentially all biological processes fluctuate over the course of the day, manifesting as time-of-day-dependent variations with regards to the way in which organ systems respond to normal behaviors. For example, basic, translational, and epidemiologic studies indicate that temporal partitioning of metabolic processes governs the fate of dietary nutrients, in a manner in which concentrating caloric intake towards the end of the day is detrimental to both cardiometabolic and cardiovascular parameters. Despite appreciation that branched chain amino acids impact risk for obesity, diabetes mellitus, and heart failure, it is currently unknown whether the time-of-day at which dietary BCAAs are consumed influence cardiometabolic/cardiovascular outcomes. Here, we report that feeding mice a BCAA-enriched meal at the end of the active period (i.e., last 4 h of the dark phase) rapidly increases cardiac protein synthesis and mass, as well as cardiomyocyte size; consumption of the same meal at the beginning of the active period (i.e., first 4 h of the dark phase) is without effect. This was associated with a greater BCAA-induced activation of mTOR signaling in the heart at the end of the active period; pharmacological inhibition of mTOR (through rapamycin) blocked BCAA-induced augmentation of cardiac mass and cardiomyocyte size. Moreover, genetic disruption of the cardiomyocyte circadian clock abolished time-of-day-dependent fluctuations in BCAA-responsiveness. Finally, we report that repetitive consumption of BCAA-enriched meals at the end of the active period accelerated adverse cardiac remodeling and contractile dysfunction in mice subjected to transverse aortic constriction. Thus, our data demonstrate that the timing of BCAA consumption has significant implications for cardiac health and disease.

The Effect of a Multi-ingredient Supplement on Resistance Training-induced Adaptations

INTRODUCTION

Resistance exercise training (RET) induces muscle hypertrophy that, when combined with co-temporal protein ingestion, is enhanced. However, fewer studies have been conducted when RET is combined with multi-ingredient supplements.

PURPOSE

We aimed to determine the effect of a high-quality multi-ingredient nutritional supplement (SUPP) versus an isonitrogenous (lower protein quality), isoenergetic placebo (PL) on RET-induced gains in lean body mass (LBM), muscle thickness, and muscle cross-sectional area (CSA). We hypothesized that RET-induced gains in LBM and muscle CSA would be greater in SUPP versus PL.

METHODS

In a double-blind randomized controlled trial, 26 (13 male, 13 female) healthy young adults (mean ± SD, 22 ± 2 yr) were randomized to either the SUPP group (n = 13; 20 g whey protein, 2 g leucine, 2.5 g creatine monohydrate, 300 mg calcium citrate, 1000 IU vitamin D) or the PL group (n = 13; 20 g collagen peptides, 1.4 g alanine, 0.6 g glycine) groups, ingesting their respective supplements twice daily. Measurements were obtained before and after a 10-wk linear progressive RET program.

RESULTS

Greater increases in LBM were observed for SUPP versus PL (SUPP: +4.1 ± 1.3 kg, PL: +2.8 ± 1.7 kg, P < 0.05). No additive effect of the supplement could be detected on vastus lateralis muscle CSA, but SUPP did result in increased biceps brachii muscle CSA and thickness (P < 0.05).

CONCLUSIONS

We conclude that when combined with RET, the consumption of SUPP increased LBM and upper-body CSA and thickness to a greater extent than to that observed in the PL group of healthy young adults.

Does Protein Supplementation Support Adaptations to Arduous Concurrent Exercise Training? A Systematic Review and Meta-Analysis with Military Based Applications

We evaluated the impact of protein supplementation on adaptations to arduous concurrent training in healthy adults with potential applications to individuals undergoing military training. Peer-reviewed papers published in English meeting the population, intervention, comparison and outcome criteria were included. Database searches were completed in PubMed, Web of science and SPORTDiscus. Study quality was evaluated using the COnsensus based standards for the selection of health status measurement instruments checklist. Of 11 studies included, nine focused on performance, six on body composition and four on muscle recovery. Cohen's d effect sizes showed that protein supplementation improved performance outcomes in response to concurrent training (ES = 0.89, 95% CI = 0.08-1.70). When analysed separately, improvements in muscle strength (SMD = +4.92 kg, 95% CI = -2.70-12.54 kg) were found, but not in aerobic endurance. Gains in fat-free mass (SMD = +0.75 kg, 95% CI = 0.44-1.06 kg) and reductions in fat-mass (SMD = -0.99, 95% CI = -1.43-0.23 kg) were greater with protein supplementation. Most studies did not report protein turnover, nitrogen balance and/or total daily protein intake. Therefore, further research is warranted. However, our findings infer that protein supplementation may support lean-mass accretion and strength gains during arduous concurrent training in physical active populations, including military recruits.

Nutrition for Older Athletes: Focus on Sex-Differences

Regular physical exercise and a healthy diet are major determinants of a healthy lifespan. Although aging is associated with declining endurance performance and muscle function, these components can favorably be modified by regular physical activity and especially by exercise training at all ages in both sexes. In addition, age-related changes in body composition and metabolism, which affect even highly trained masters athletes, can in part be compensated for by higher exercise metabolic efficiency in active individuals. Accordingly, masters athletes are often considered as a role model for healthy aging and their physical capacities are an impressive example of what is possible in aging individuals. In the present review, we first discuss physiological changes, performance and trainability of older athletes with a focus on sex differences. Second, we describe the most important hormonal alterations occurring during aging pertaining regulation of appetite, glucose homeostasis and energy expenditure and the modulatory role of exercise training. The third part highlights nutritional aspects that may support health and physical performance for older athletes. Key nutrition-related concerns include the need for adequate energy and protein intake for preventing low bone and muscle mass and a higher demand for specific nutrients (e.g., vitamin D and probiotics) that may reduce the infection burden in masters athletes. Fourth, we present important research findings on the association between exercise, nutrition and the microbiota, which represents a rapidly developing field in sports nutrition.

The role of protein hydrolysates for exercise-induced skeletal muscle recovery and adaptation: a current perspective

The protein supplement industry is expanding rapidly and estimated to have a multi-billion market worth. Recent research has centred on understanding how the manufacturing processes of protein supplements may impact muscle recovery and remodeling. The hydrolysed forms of protein undergo a further heating extraction process during production which may contribute to amino acids (AA) appearing in circulation at a slightly quicker rate, or greater amplitude, than the intact form. Whilst the relative significance of the rate of aminoacidemia to muscle protein synthesis is debated, it has been suggested that protein hydrolysates, potentially through the more rapid delivery and higher proportion of di-, tri- and smaller oligo-peptides into circulation, are superior to intact non-hydrolysed proteins and free AAs in promoting skeletal muscle protein remodeling and recovery. However, despite these claims, there is currently insufficient evidence to support superior muscle anabolic properties compared with intact non-hydrolysed proteins and/or free AA controls. Further research is warranted with appropriate protein controls, particularly in populations consuming insufficient amounts of protein, to support and/or refute an important muscle anabolic role of protein hydrolysates. The primary purpose of this review is to provide the reader with a current perspective on the potential anabolic effects of protein hydrolysates in individuals wishing to optimise recovery from, and maximise adaptation to, exercise training.

High Frequency Protein-Rich Meal Service to Promote Protein Distribution to Stimulate Muscle Function in Preoperative Patients

Apart from meeting daily protein requirements, an even distribution of protein consumption is proposed instrumental to optimizing protein muscle synthesis and preserving muscle mass. We assessed whether a high frequency protein-rich meal service for three weeks contributes to an even daily protein distribution and a higher muscle function in pre-operative patients. This study was a post-hoc analysis of a randomized controlled trial (RCT) in 102 patients. The intervention comprised six protein-rich dishes per day. Daily protein distribution was evaluated by a three-day food diary and muscle function by handgrip strength before and after the intervention. Protein intake was significantly higher in the intervention group at the in-between meals in the morning (7 ± 2 grams (g) vs. 2 ± 3 g, p < 0.05) and afternoon (8 ± 3 g vs. 2 ± 3 g, p < 0.05). Participants who consumed 20 g protein for at least two meals had a significantly higher handgrip strength compared to participants who did not. A high frequency protein-rich meal service is an effective strategy to optimize an even protein distribution across meals throughout the day. Home-delivered meal services can be optimized by offering more protein-rich options such as dairy or protein supplementation at breakfast, lunch and prior to sleep for a better protein distribution.

The Acute Effects of a Relative Dose of Pre-Sleep Protein on Recovery Following Evening Resistance Exercise in Active Young Men

The purpose of the present study was to assess the acute effects of pre-sleep consumption of isocaloric casein protein (CP), CP and whey protein (BLEND), or non-caloric control (CTRL) at a dose relative to lean body mass (LBM) on recovery following an evening lower-body resistance exercise (RE) bout. Fifteen active and previously resistance-trained males (age: 21 ± 1 years, body fat: 14.2 ± 2.7%) participated in this randomized, single-blind, crossover study. Participants performed an evening lower-body RE bout and were provided with 0.4 g/kg/LBM of whey protein (WP) supplement post-RE. A single dose of 0.6 g/kg/LBM of CP, 0.4 g/kg/LBM of CP and 0.2 g/kg/LBM WP (BLEND), or CTRL was consumed 30 min prior to sleep. Measurements of perceived recovery (visual analogue scales (VAS) for recovery, soreness, and fatigue), appetite (VAS for hunger, satiety, and desire to eat), as well as pressure-pain threshold (dolorimeter), average power, and peak torque (isokinetic dynamometry) of the right thigh muscles were assessed the following morning. Main effects of time were seen for all recovery variables (perceived recovery: F_2,28 = 96.753, p < 0.001, h_p² = 0.874; perceived fatigue: F_2,28 = 76.775, p < 0.001; h_p² = 0.846; perceived soreness: F_2,28 = 111.967, p < 0.001; h_p² = 0.889). A main effect of supplement was only seen for perceived recovery (F_2,28 = 4.869; p = 0.015; h_p² = 0.258), with recovery being 6.10 ± 2.58 mm greater in CP vs. BLEND (p = 0.033) and 7.51 ± 2.28 mm greater in CP than CTRL (p = 0.005). No main effects of supplement were seen in measures of perceived soreness, or fatigue (F_2,28 ≤ 2.291; p > 0.120; h_p² ≤ 0.141). No differences between supplements were found in perceived next-morning hunger (p = 0.06), satiety (p ≥ 0.227), or desire to eat (p = 0.528). Main effects of supplement were seen between BLEND and CP vs. CTRL for measures of pain-pressure threshold at the rectus femoris (F_2,28 = 9.377; p = 0.001; h_p² = 0.401), the vastus lateralis (F_2,28 = 10.887; p < 0.001; h_p² = 0.437), and the vastus medialis (F_2,28 = 12.113, p < 0.001; h_p² = 0.464). Values of peak torque and average power were similar between all supplement groups at 60°/sec (F_1.309,18.327 ≤ 1.994; p ≥ 0.173; h_p² ≤ 0.125), 180°/s (F_2,28 ≤ 1.221; p ≥ 0.310; h_p² ≤ 0.080), and 300°/sec (F_2,28 ≤ 2.854; p ≥ 0.074; h_p² ≤ 0.169). Pre-sleep consumption of CP and BLEND at a dose relative to LBM may enhance perceived overnight recovery to a greater extent than CTRL as a result of less muscle soreness the following morning after an acute evening RE bout.

The Effect of Protein Supplementation versus Carbohydrate Supplementation on Muscle Damage Markers and Soreness Following a 15-km Road Race: A Double-Blind Randomized Controlled Trial

We assessed whether a protein supplementation protocol could attenuate running-induced muscle soreness and other muscle damage markers compared to iso-caloric placebo supplementation. A double-blind randomized controlled trial was performed among 323 recreational runners (age 44 ± 11 years, 56% men) participating in a 15-km road race. Participants received milk protein or carbohydrate supplementation, for three consecutive days post-race. Habitual protein intake was assessed using 24 h recalls. Race characteristics were determined and muscle soreness was assessed with the Brief Pain Inventory at baseline and 1-3 days post-race. In a subgroup (n = 149) muscle soreness was measured with a strain gauge algometer and creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations were measured. At baseline, no group-differences were observed for habitual protein intake (protein group: 79.9 ± 26.5 g/d versus placebo group: 82.0 ± 26.8 g/d, p = 0.49) and muscle soreness (protein: 0.45 ± 1.08 versus placebo: 0.44 ± 1.14, p = 0.96). Subjects completed the race with a running speed of 12 ± 2 km/h. With the Intention-to-Treat analysis no between-group differences were observed in reported muscle soreness. With the per-protocol analysis, however, the protein group reported higher muscle soreness 24 h post-race compared to the placebo group (2.96 ± 2.27 versus 2.46 ± 2.38, p = 0.039) and a lower pressure muscle pain threshold in the protein group compared to the placebo group (71.8 ± 30.0 N versus 83.9 ± 27.9 N, p = 0.019). No differences were found in concentrations of CK and LDH post-race between groups. Post-exercise protein supplementation is not more preferable than carbohydrate supplementation to reduce muscle soreness or other damage markers in recreational athletes with mostly a sufficient baseline protein intake running a 15-km road race.

Acute Effects of Cheddar Cheese Consumption on Circulating Amino Acids and Human Skeletal Muscle

Cheddar cheese is a protein-dense whole food and high in leucine content. However, no information is known about the acute blood amino acid kinetics and protein anabolic effects in skeletal muscle in healthy adults. Therefore, we conducted a crossover study in which men and women (n = 24; ~27 years, ~23 kg/m2) consumed cheese (20 g protein) or an isonitrogenous amount of milk. Blood and skeletal muscle biopsies were taken before and during the post absorptive period following ingestion. We evaluated circulating essential and non-essential amino acids, insulin, and free fatty acids and examined skeletal muscle anabolism by mTORC1 cellular localization, intracellular signaling, and ribosomal profiling. We found that cheese ingestion had a slower yet more sustained branched-chain amino acid circulation appearance over the postprandial period peaking at ~120 min. Cheese also modestly stimulated mTORC1 signaling and increased membrane localization. Using ribosomal profiling we found that, though both milk and cheese stimulated a muscle anabolic program associated with mTORC1 signaling that was more evident with milk, mTORC1 signaling persisted with cheese while also inducing a lower insulinogenic response. We conclude that Cheddar cheese induced a sustained blood amino acid and moderate muscle mTORC1 response yet had a lower glycemic profile compared to milk.

Nutritional Practice and Nitrogen Balance in Elite Japanese Swimmers during a Training Camp

The protein requirement in athletes increases as a result of exercise-induced changes in protein metabolism. In addition, the frequency, quantity, and quality (i.e., leucine content) of the protein intake modulates the protein metabolism. Thus, this study aimed to investigate whether nutritional practice (particularly, protein and amino acid intake at each eating occasion) meets the protein needs required to achieve zero nitrogen balance in elite swimmers during a training camp. Eight elite swimmers (age 21.9 ± 2.3 years, body weight 64.2 ± 7.1 kg, sex M:2 F:6) participated in a four-day study. The nitrogen balance was calculated from the dietary nitrogen intake and urinary nitrogen excretion. The amino acid intake was divided over six eating occasions. The nitrogen balance was found to be positive (6.7 ± 3.1 g N/day, p < 0.05) with protein intake of 2.96 ± 0.74 g/kg/day. The frequency and quantity of leucine and the protein intake were met within the recommended range established by the International Society of Sports Nutrition. Thus, a protein intake of 2.96 g/kg/day with a well-designated pattern (i.e., frequency throughout the day, as well as quantity and quality) of protein and amino acid intake may satisfy the increased need for protein in an elite swimmer.

UEFA expert group statement on nutrition in elite football. Current evidence to inform practical recommendations and guide future research

Football is a global game which is constantly evolving, showing substantial increases in physical and technical demands. Nutrition plays a valuable integrated role in optimising performance of elite players during training and match-play, and maintaining their overall health throughout the season. An evidence-based approach to nutrition emphasising, a 'food first' philosophy (ie, food over supplements), is fundamental to ensure effective player support. This requires relevant scientific evidence to be applied according to the constraints of what is practical and feasible in the football setting. The science underpinning sports nutrition is evolving fast, and practitioners must be alert to new developments. In response to these developments, the Union of European Football Associations (UEFA) has gathered experts in applied sports nutrition research as well as practitioners working with elite football clubs and national associations/federations to issue an expert statement on a range of topics relevant to elite football nutrition: (1) match day nutrition, (2) training day nutrition, (3) body composition, (4) stressful environments and travel, (5) cultural diversity and dietary considerations, (6) dietary supplements, (7) rehabilitation, (8) referees and (9) junior high-level players. The expert group provide a narrative synthesis of the scientific background relating to these topics based on their knowledge and experience of the scientific research literature, as well as practical experience of applying knowledge within an elite sports setting. Our intention is to provide readers with content to help drive their own practical recommendations. In addition, to provide guidance to applied researchers where to focus future efforts.

Whey protein supplementation does not accelerate recovery from a single bout of eccentric exercise

The current double blind, randomized, placebo-controlled trial with two parallel groups aimed to assess the impact of whey protein supplementation on recovery of muscle function and muscle soreness following eccentric exercise. During a 9-day period, forty recreationally active males received twice daily supplementation with either whey protein (PRO; 60 g/day) or an iso-energetic amount of carbohydrate (CON). Muscle function and soreness were assessed before, and 0, 3, 24, 48, and 72 h after performing 100 drop jumps. Recovery of isometric maximal voluntary contraction (MVC) did not significantly differ between groups (timextreatment, P = 0.56). In contrast, the recovery of isokinetic MVC at 90°·s^-1 was faster in CON as opposed to PRO (timextreatment interaction, P = 0.044). Recovery of isokinetic MVC at 180°·s^-1 was also faster in CON as opposed to PRO (timextreatment interaction, P = 0.011). Recovery of countermovement jump performance did not differ between groups (timextreatment interaction, P = 0.52). Muscle soreness, CK and CRP showed a transient increase over time (P < 0.001), with no differences between groups. In conclusion, whey protein supplementation does not accelerate recovery of muscle function or attenuate muscle soreness and inflammation during 3 days of recovery from a single bout of eccentric exercise.

Rehabilitation Nutrition for Injury Recovery of Athletes: The Role of Macronutrient Intake

An adequate and balanced diet is of utmost importance in recovery and rehabilitation. "Rehabilitation nutrition" for injury recovery of athletes is similar to sports nutrition, except for the differences that concern the prevention of the risk or presence of sarcopenia, malnutrition, or dysphagia. Rehabilitation nutrition also aims, combined with training, to an adequate long-term nutritional status of the athlete and also in physical condition improvement, in terms of endurance and resistance. The aim of this paper is to define the proper nutrition for athletes in order to hasten their return to the sports after surgery or injury. Energy intake should be higher than the energy target in order to fight sarcopenia-that is 25-30 kcal/kg of body weight. Macro- and micro-nutrients play an important role in metabolism, energy production, hemoglobin synthesis, lean mass and bone mass maintenance, immunity, health, and protection against oxidative damage. Nutritional strategies, such as supplementation of suboptimal protein intake with leucine are feasible and effective in offsetting anabolic resistance. Thus, maintaining muscle mass, without gaining fat, becomes challenging for the injured athlete. A dietary strategy should be tailored to the athlete's needs, considering amounts, frequency, type and, most of all, protein quality. During rehabilitation, simultaneous carbohydrates and protein intake can inhibit muscle breakdown and muscle atrophy. The long-term intake of omega-3 fatty acids enhances anabolic sensitivity to amino acids; thus, it may be beneficial to the injured athlete. Adequate intakes of macronutrients can play a major role supporting athletes' anabolism.

Effects of pre-sleep protein consumption on muscle-related outcomes - A systematic review

OBJECTIVES

The timing of protein intake over the day on muscle mass and strength gains have received interest in the literature. Thus, the aim of this systematic review is to analyze clinical studies that evaluated the acute effects of pre-sleep protein consumption on overnight muscle protein synthesis and the chronic effects on muscle mass and strength.

DESIGNS

Systematic review.

METHODS

A literature search was conducted up to June 2020 according to PRISMA statement and nine articles were included to analyze.

RESULTS

The consumption of 20-40 g of casein approximately 30 min before sleep stimulates whole-body protein synthesis rates over a subsequent overnight period in young and elderly men (preceded or not by resistance exercise, respectively). In addition, pre-sleep protein consumption can augment the muscle adaptive response (muscle fiber cross-sectional area, strength and muscle mass) during 10-12 weeks of resistance exercise in young, but not in elderly men.

CONCLUSIONS

Based on current evidence, the consumption of 20-40 g of casein approximately 30 min before sleep improves protein synthetic response during an overnight recovery period in healthy young adult men, with possible positive effects on muscle mass and strength following prolonged resistance exercise. In elderly, despite the initial evidence regarding the pre-sleep protein enhances overnight muscle protein synthesis rates, the current available evidence is limited precluding to conclude about the chronic effects on skeletal muscle mass or strength. These conclusions need to be taken with caution due to uneven protein intakes between experimental groups. Therefore, more data are needed before further considering pre-sleep protein as an effective nutritional intervention.

Protein Supplementation in Sport: Source, Timing, and Intended Benefits

PURPOSE OF REVIEW

The purpose of this review is to provide background on the present literature regarding the utility and effectiveness of protein supplements, including protein source and nutrient timing.

RECENT FINDINGS

In the setting of adequate dietary protein consumption, research suggests some benefit particularly in sport or exercise activities. Protein supplements command a multi-billion-dollar market with prevalent use in sports. Many individuals, including athletes, do not consume optimal dietary protein on a daily basis. High-protein diets are remarkably safe in healthy subjects, especially in the short term. Some objective outcomes are physiologic and may not translate to clinically relevant outcomes. Athletes should, however, consider long-term implications when consuming high quantities of protein in dietary or supplement form.

Effects of Pre-Sleep Whey vs. Plant-Based Protein Consumption on Muscle Recovery Following Damaging Morning Exercise

Pre-sleep whey protein intake has been shown to improve overnight muscle protein synthesis, muscle size and strength, and muscle recovery. Despite a growing interest in alternative protein sources, such as plant-based protein, there is no evidence regarding the efficacy of plant-based proteins consumed pre-sleep. Therefore, we aimed to compare whey vs. plant-based pre-sleep protein dietary supplementation on muscle recovery in middle-aged men. Twenty-seven recreationally active, middle-aged men performed 5 sets of 15 repetitions of maximal eccentric voluntary contractions (ECC) for the knee extensors (ext) and flexors (flex), respectively, in the morning. Participants consumed 40 g of either whey hydrolysate (WH, n = 9), whey isolate (WI, n = 6), rice and pea combination (RP, n = 6), or placebo (PL, n = 6) 30 min pre-sleep on the day of ECC and the following two nights. Catered meals (15% PRO, 55% CHO, 30% Fat) were provided to participants for 5 days to standardize nutrition. Plasma creatine kinase (CK), interleukin-6 (IL-6), and interleukin-10 (IL-10) were measured at pre, immediately post (+0), +4, +6, +24, +48, and +72 h post-ECC. Isometric (ISOM) and isokinetic (ISOK) maximal voluntary contraction force were measured at pre, immediately post (+0), +24, +48, and +72 h post-ECC. Muscle soreness, thigh circumference, and HOMA-IR were measured at pre, +24, +48, and +72 h post-ECC. CK was increased at +4 h post-ECC, remained elevated at all time points compared to baseline (p < 0.001), and was significantly greater at +72 h compared to all other time points (p < 0.001). IL-6 was increased at +6 h (p = 0.002) with no other time differing from baseline. ISOMext was reduced after ECC (p = 0.001) and remained reduced until returning to baseline at +72 h. ISOMflex, ISOKext, and ISOKflex were reduced after ECC and remained reduced at +72 h (p < 0.001). Muscle soreness increased post-ECC (p < 0.001) and did not return to baseline. Thigh circumference (p = 0.456) and HOMA-IR (p = 0.396) did not change post-ECC. There were no significant differences between groups for any outcome measure. These data suggest that middle-aged men consuming 1.08 ± 0.02 g/kg/day PRO did not recover from damaging eccentric exercise at +72 h and that pre-sleep protein ingestion, regardless of protein source, did not aid in muscle recovery when damaging eccentric exercise was performed in the morning.

Nutrient Timing: A Garage Door of Opportunity?

Nutrient timing involves manipulation of nutrient consumption at specific times in and around exercise bouts in an effort to improve performance, recovery, and adaptation. Its historical perspective centered on ingestion during exercise and grew to include pre- and post-training periods. As research continued, translational focus remained primarily on the impact and outcomes related to nutrient consumption during one specific time period to the exclusion of all others. Additionally, there seemed to be increasing emphasis on outcomes related to hypertrophy and strength at the expense of other potentially more impactful performance measures. As consumption of nutrients does not occur at only one time point in the day, the effect and impact of energy and macronutrient availability becomes an important consideration in determining timing of additional nutrients in and around training and competition. This further complicates the confining of the definition of “nutrient timing” to one very specific moment in time at the exclusion of all other time points. As such, this review suggests a new perspective built on evidence of the interconnectedness of nutrient impact and provides a pragmatic approach to help frame nutrient timing more inclusively. Using this approach, it is argued that the concept of nutrient timing is constrained by reliance on interpretation of an “anabolic window” and may be better viewed as a “garage door of opportunity” to positively impact performance, recovery, and athlete availability.

The Effects of Timing of a Leucine-Enriched Amino Acid Supplement on Body Composition and Physical Function in Stroke Patients: A Randomized Controlled Trial

The combination of exercise and nutritional intervention is widely used for stroke patients, as well as frail or sarcopenic older persons. As previously shown, supplemental branched chain amino acids (BCAAs) or protein to gain muscle mass has usually been given just after exercise. This study investigated the effect of the timing of supplemental BCAAs with exercise intervention on physical function in stroke patients. The participants were randomly assigned to two groups based on the timing of supplementation: breakfast (n = 23) and post-exercise (n = 23). The supplement in the breakfast group was provided at 08:00 with breakfast, and in the post-exercise group it was provided just after the exercise session in the afternoon at 14:00-18:00. In both groups, the exercise intervention was performed with two sessions a day for two months. The main effects were observed in body fat mass (p = 0.02, confidence interval (CI): 13.2-17.7), leg press strength (p = 0.04, CI: 94.5-124.5), and Berg balance scale (p = 0.03, CI: 41.6-52.6), but no interaction with intake timing was observed. Although the effect of the timing of supplementation on skeletal muscle mass was similar in both groups, BCAA intake with breakfast was effective for improving physical performance and decreasing body fat mass. The results suggest that a combination of BCAA intake with breakfast and an exercise program was effective for promoting rehabilitation of post-stroke patients.

Effects of Dietary Protein on Body Composition in Exercising Individuals

Protein is an important component of a healthy diet and appears to be integral to enhancing training adaptations in exercising individuals. The purpose of this narrative review is to provide an evidence-based assessment of the current literature examining increases in dietary protein intake above the recommended dietary allowance (RDA: 0.8 g/kg/d) in conjunction with chronic exercise on body composition (i.e., muscle, fat and bone). We also highlight acute and chronic pre-sleep protein studies as well as the influence of exercise timing on body composition. Overall, a high-protein diet appears to increase muscle accretion and fat loss and may have beneficial effects on bone when combined with exercise. Pre-sleep protein is a viable strategy to help achieve total daily protein goals. Importantly, there appears to be no deleterious effects from a high-protein diet on muscle, fat or bone in exercising individuals.

Nutritional Strategies to Optimize Performanceand Recovery in Rowing Athletes

Rowing is a high-intensity sport requiring a high level of aerobic and anaerobic capacity. Although good nutrition is essential for successful performance in a rowing competition, its significance is not sufficiently established. This review aimed to provide nutritional strategies to optimize performance and recovery in rowing athletes based on a literature review. Following the guidelines given in the Preferred Reporting Items for Systematic Review and Meta-Analyses (PRISMA), we performed web searches using online databases (Pubmed, Web of Science, Wiley Online Library, ACS Publications, and SciFinder). Typically, a rowing competition involves a 6–8-min high-intensity exercise on a 2000-m course. The energy required for the exercise is supplied by muscle-stored glycogens, which are derived from carbohydrates. Therefore, rowing athletes can plan their carbohydrate consumption based on the intensity, duration, and type of training they undergo. For effective and safe performance enhancement, rowing athletes can take supplements such as β-alanine, caffeine, β-hydroxy-β-methylbutyric acid (HMB), and beetroot juice (nitrate). An athlete may consume carbohydrate-rich foods or use a carbohydrate mouth rinse. Recovery nutrition is also very important to minimize the risk of injury or unexplained underperformance syndrome (UUPS) from overuse. It must take into account refueling (carbohydrate), rehydration (fluid), and repair (protein). As lightweight rowing athletes often attempt acute weight loss by limiting food and fluid intake to qualify for a competition, they require personalized nutritional strategies and plans based on factors such as their goals and environment. Training and competition performance can be maximized by including nutritional strategies in training plans.

Nitrogen Balance in Female Japanese National Handball Players During Training Camp

Protein requirements for athletes are affected by various factors, including distribution and quality (i. e., amino acid composition) of protein ingestion throughout the day. However, little is known about the protein requirements of elite female athletes engaging in team sports. This study aimed to determine the nitrogen balance and distribution of protein and amino acid intake in elite female handball athletes during training camp. In observational study design, 11 female Japanese national handball players (age 26.9 ± 4.9 years) participated in a 5-days experiment. Nitrogen balance was calculated from the daily protein intake assessed by dietary records and urinary nitrogen excretion. Amino acid intake amounts were organized based on six eating occasions. The average and population-safe protein intake for zero nitrogen balance were estimated as 1.57 and 1.93 g/kg/day, respectively. The protein intake at breakfast, lunch, and dinner and the leucine intake in the three main meals and the morning snack were higher than is recommended by current guidelines for maximizing muscle protein synthesis. The population-safe protein intake in elite female handball athletes was within the range of the current recommendations for athletes (1.2–2.0 g/kg/day). Our results show that it may be possible to improve the distribution and quality of protein ingestion after exercise and before sleep.

Effects of dietary supplementation in sport and exercise: a review of evidence on milk proteins and amino acids

Dietary supplements, especially protein, are used by athletes to achieve the exercise and training daily demands, and have been receiving research focus on their role regarding recovery and performance. Protein supplements are preferred over traditional protein sources because of their ease of availability and use. In addition to consuming a complete protein supplement, such as whey protein, the ingestion of a supplement containing only amino acids has been of interest for promoting skeletal muscle anabolism and high-quality weight loss. The aim of this study was to review the existing evidence on the effects of protein and amino acid supplementation on exercise. The preponderance of evidence suggests that protein supplementation, especially milk proteins, potentiate muscle protein synthesis, lean mass and exercise recovery. Unlike proteins, amino acids supplementation (branched-chain amino acids, glutamine or leucine) results from research are equivocal and are not warranted.

Pre-Sleep Casein Protein Ingestion Does Not Impact Next-Day Appetite, Energy Intake and Metabolism in Older Individuals

Maintaining adequate daily protein intake is important to maintain muscle mass throughout the lifespan. In this regard, the overnight period has been identified as a window of opportunity to increase protein intake in the elderly. However, it is unknown whether pre-sleep protein intake affects next-morning appetite and, consequently, protein intake. Therefore, the purpose of the current study was to investigate the effects of a pre-sleep protein drink on next-morning appetite, energy intake and metabolism. Twelve older individuals (eight males, four females; age: 71.3 ± 4.2 years) took part in a single-blind randomised cross-over study. After a standardised dinner, participants consumed either a 40-g protein drink, isocaloric maltodextrin drink, or placebo water control before bedtime. Next-morning appetite, energy intake, resting metabolic rate (RMR), respiratory exchange rate (RER), and plasma acylated ghrelin, leptin, glucose, and insulin concentrations were assessed. No between-group differences were observed for appetite and energy intake at breakfast. Furthermore, RMR, RER, and assessed blood markers were not significantly different between any of the treatment groups. Pre-sleep protein intake does not affect next-morning appetite and energy intake and is therefore a viable strategy to increase daily protein intake in an older population.

Ingestion of a Pre-bedtime Protein Containing Beverage Prevents Overnight Induced Negative Whole Body Protein Balance in Healthy Middle-Aged Men: A Randomized Trial

Age related muscle wasting leads to overall reductions of lean body mass, reduced muscle strength, and muscle function resulting in compromised quality of life. Utilizing novel nutritional strategies to attenuate such losses is of great importance in elderly individuals. We aimed to test if a complete dietary supplement containing 25 g of milk proteins and ingested in the evening before bed would improve protein metabolism in terms of whole body protein balance over a 10 h overnight period following ingestion of the test drink in healthy middle-aged male subjects. In addition we also assessed the rates of muscle protein synthesis during the second half of the night in order to see if previously reported extended amino acidemia during sleep results in increased rates of muscle protein synthesis. Seventeen healthy middle-aged male subjects (59.4 ± 3.2 year) consumed a dietary supplement drink at 21:00 containing either 25 g milk protein concentrate, 25 g maltodextrin, 7.75 g canola oil (treatment group), or an isocaloric protein void drink (placebo group). Muscle protein synthesis was assessed from a muscle biopsy following the continuous intravenous infusion of ¹³C-phenylalanine for 5 h (from 03:00 to 08:00). Whole body protein balance was greater in the treatment group (−0.13 ± 11.30 g prot/10 h) compared to placebo (−12.22 ± 6.91 g prot/10 h) (P ≤ 0.01). In contrast, no changes were observed on rates of muscle protein synthesis during the second half of the night. Ingestion of a dietary supplement containing 25 g of milk proteins significantly reduced the negative protein balance observed during the night. Therefore, pre-bedtime protein ingestion may attenuate overnight losses of lean tissue in healthy elderly men. Despite increases in aminoacidemia during the second part of the night, no changes were observed in the rates of muscle protein synthesis during this time.

Clinical Trial Registration:www.ClinicalTrials.gov, identifier: NCT02041143.

Dietary Protein and Physical Activity Interventions to Support Muscle Maintenance in End-Stage Renal Disease Patients on Hemodialysis

End-stage renal disease patients have insufficient renal clearance capacity left to adequately excrete metabolic waste products. Hemodialysis (HD) is often employed to partially replace renal clearance in these patients. However, skeletal muscle mass and strength start to decline at an accelerated rate after initiation of chronic HD therapy. An essential anabolic stimulus to allow muscle maintenance is dietary protein ingestion. Chronic HD patients generally fail to achieve recommended protein intake levels, in particular on dialysis days. Besides a low protein intake on dialysis days, the protein equivalent of a meal is extracted from the circulation during HD. Apart from protein ingestion, physical activity is essential to allow muscle maintenance. Unfortunately, most chronic HD patients have a sedentary lifestyle. Yet, physical activity and nutritional interventions to support muscle maintenance are generally not implemented in routine patient care. To support muscle maintenance in chronic HD patients, quantity and timing of protein intake should be optimized, in particular throughout dialysis days. Furthermore, implementing physical activity either during or between HD sessions may improve the muscle protein synthetic response to protein ingestion. A well-orchestrated combination of physical activity and nutritional interventions will be instrumental to preserve muscle mass in chronic HD patients.

Acute and sustained effects of a periodized carbohydrate intake using the sleep-low model in endurance-trained males

Repeated periodization of carbohydrate (CHO) intake using a diet-exercise strategy called the sleep-low model can potentially induce mitochondrial biogenesis and improve endurance performance in endurance-trained individuals. However, more studies are needed to confirm the performance-related effects and to investigate the sustained effects on maximal fat oxidation (MFO) rate and proteins involved in intramuscular lipid metabolism. Thirteen endurance-trained males (age 23-44 years; V ˙ O₂ -max, 63.9 ± 4.6 mL·kg^-1 ·min^-1 ) were randomized into two groups: sleep-low (LOW-CHO) or high CHO availability (HIGH-CHO) in three weekly training blocks over 4 weeks. The acute metabolic response was investigated during 60 minutes of exercise within the last 3 weeks of the intervention. Pre- and post-intervention, 30-minute time-trial performance was investigated after a 90-minute pre-load, which as a novel approach included nine intense intervals (and estimation of MFO). Additionally, muscle biopsies (v. lateralis) were obtained to investigate expression of proteins involved in intramuscular lipid metabolism using Western blotting. During acute exercise, average fat oxidation rate was ~36% higher in LOW-CHO compared to HIGH-CHO (P = .03). This did not translate into sustained effects on MFO. Time-trial performance increased equally in both groups (overall time effect: P = .005). We observed no effect on intramuscular proteins involved in lipolysis (ATGL, G0S2, CGI-58, HSL) or fatty acid transport and β-oxidation (CD-36 and HAD, respectively). In conclusion, the sleep-low model did not induce sustained effects on MFO, endurance performance, or proteins involved in intramuscular lipid metabolism when compared to HIGH-CHO. Our study therefore questions the transferability of acute effects of the sleep-low model to superior sustained adaptations.

Timing of Food Intake: Identifying Contributing Factors to Design Effective Interventions

Observations that mistimed food intake may have adverse metabolic health effects have generated interest in personalizing food timing recommendations in interventional studies and public health strategies for the purpose of disease prevention and improving overall health. Small, controlled, and short-termed intervention studies suggest that food timing may be modified as it is presumed to be primarily regulated by choice. Identifying and evaluating social and biological factors that explain variability in food timing may determine whether changes in food timing in uncontrolled, free-living environments are sustainable in the long term, and may facilitate design of successful food timing-based interventions. Based on a comprehensive literature search, we summarize 1) cultural and environmental factors; 2) behavioral and personal preference factors; and 3) physiological factors that influence the time when people consume foods. Furthermore, we 1) highlight vulnerable populations who have been identified in experimental and epidemiological studies to be at risk of mistimed food intake and thus necessitating intervention; 2) identify currently used food timing assessment tools and their limitations; and 3) indicate other important considerations for the design of food timing interventions based on successful strategies that address timing of other lifestyle behaviors. Conclusions drawn from this overview may help design practical food timing interventions, develop feasible public health programs, and establish guidelines for effective lifestyle recommendations for prevention and treatment of adverse health outcomes attributed to mistimed food intake.

Greek Yogurt and 12 Weeks of Exercise Training on Strength, Muscle Thickness and Body Composition in Lean, Untrained, University-Aged Males

Milk and/or whey protein plus resistance exercise (RT) increase strength and muscle size, and optimize body composition in adult males and females. Greek yogurt (GY) contains similar muscle-supporting nutrients as milk yet it is different in several ways including being a semi-solid food, containing bacterial cultures and having a higher protein content (mostly casein) per serving. GY has yet to be investigated in the context of a RT program. The purpose of this study was to assess the effects of GY consumption plus RT on strength, muscle thickness and body composition in lean, untrained, university-aged males. Thirty untrained, university-aged (20.6 ± 2.2 years) males were randomized to 2 groups (n = 15/group): fat-free, plain GY or a Placebo Pudding (PP; isoenergetic carbohydrate-based pudding) and underwent a combined RT/plyometric training program 3 days/week for 12 weeks. They consumed either GY (20 g protein/dose) or PP (0 g protein/dose) daily, 3 times on training days and 2 times on non-training days. After 12 weeks, both groups significantly increased strength, muscle thickness and fat-free mass (FFM) (p < 0.05). The GY group gained more total strength (GY; 98 ± 37 kg, PP; 57 ± 15 kg), more biceps brachii muscular thickness (GY; 0.46 ± 0.3 cm, PP; 0.12 ± 0.2 cm), more FFM (GY; 2.4 ± 1.5 kg, PP; 1.3 ± 1.3 kg), and reduced % body fat (GY; −1.1 ± 2.2%, PP; 0.1 ± 2.6%) than PP group (p < 0.05 expressed as absolute change). Thus, consumption of GY during a training program resulted in improved strength, muscle thickness and body composition over a carbohydrate-based placebo. Given the results of our study, the general benefits of consuming GY and its distinctiveness from milk, GY can be a plausible, post-exercise, nutrient-rich alternative for positive strength, muscle, and body composition adaptations.

A bedtime milk snack does not impact RMR, substrate utilisation and appetite the following morning in mildly overweight males

Nighttime eating is often associated with a negative impact on weight management and cardiometabolic health. However, data from recent acute metabolic studies have implicated a benefit of ingesting a bedtime snack for weight management. The present study compared the impact of ingesting a milk snack containing either 10 (BS10) or 30 g (BS30) protein with a non-energetic placebo (BS0) 30 min before bedtime on next morning metabolism, appetite and energy intake in mildly overweight males (age: 24·3 (sem 0·8) years; BMI: 27·4 (sem 1·1) kg/m2). Next morning measurements of RMR, appetite and energy intake were measured using indirect calorimetry, visual analogue scales and an ad libitum breakfast, respectively. Bedtime milk ingestion did not alter next morning RMR (BS0: 7822 (sem 276) kJ/d, BS10: 7482 (sem 262) kJ/d, BS30: 7851 (sem 261) kJ/d, P=0·19) or substrate utilisation as measured by RER (P=0·64). Bedtime milk ingestion reduced hunger (P=0·01) and increased fullness (P=0·04) during the evening immediately after snack ingestion, but elicited no effect the next morning. Next morning breakfast (BS0: 2187 (sem 365) kJ, BS10: 2070 (sem 336) kJ, BS30: 2582 (sem 384) kJ, P=0·21) and 24 h post-trial (P=0·95) energy intake was similar between conditions. To conclude, in mildly overweight adults, compared with a non-energetic placebo, a bedtime milk snack containing 10 or 30 g of protein does not confer changes in next morning whole-body metabolism and appetite that may favour weight management.

The Impact of Pre-sleep Protein Ingestion on the Skeletal Muscle Adaptive Response to Exercise in Humans: An Update

This review provides an update on recent research assessing the effect of pre-sleep protein ingestion on muscle protein synthesis rates during overnight sleep and the skeletal muscle adaptive response to exercise training. Protein ingested prior to sleep is effectively digested and absorbed during overnight sleep, thereby increasing overnight muscle protein synthesis rates. Protein consumption prior to sleep does not appear to reduce appetite during breakfast the following day and does not change resting energy expenditure. When applied over a prolonged period of resistance-type exercise training, pre-sleep protein supplementation has a beneficial effect on the increase in muscle mass and strength. Protein ingestion before sleep is hypothesized to represent an effective nutritional strategy to preserve muscle mass in the elderly, especially when combined with physical activity or muscle contraction by means of neuromuscular electrical stimulation. In conclusion, protein ingestion prior to sleep is an effective interventional strategy to increase muscle protein synthesis rates during overnight sleep and can be applied to support the skeletal muscle adaptive response to resistance-type exercise training.

Nutritional Considerations for Sport Participation in Children and Adolescents With Obesity

There is a high prevalence of children with obesity who are participating in sports. Appropriate nutritional considerations are important to optimize health and training adaptations. This review focuses on macronutrient recommendations and their effect on weight management and/or benefits for athletic training for children ages 5 to 18 years. Equal distribution of protein intake throughout the day (~25-30 g/meal) and during postexercise recovery is recommended. Special attention should be given to increasing protein intake during breakfast because it is often the meal with the least protein intake. Both postexercise recommendations for protein (~0.3 g/kg of body weight) and carbohydrate (~1.0-1.2 g/kg/h) were not determined in children with obesity, and require future verification. Individual carbohydrate needs of training to meet fuel costs are recommended, but ~200 to 500 g/day of carbohydrate may be required depending on a child's level of sport participation and competition. Fat intake should follow general recommendations to meet the accepted macronutrient distribution range in children (25% to 35%) and reduce saturated fat intake. No evidence suggests that additional dietary fat modifications would improve training adaptations in children. Longitudinal studies are required to further our understanding of age and sex effects and confirm the appropriate quantity of macronutrients for active children with obesity.

Dietary Protein for Training Adaptation and Body Composition Manipulation in Track and Field Athletes

Track and field athletes engage in vigorous training that places stress on physiological systems requiring nutritional support for optimal recovery. Of paramount importance when optimizing recovery nutrition are rehydration and refueling which are covered in other papers in this volume. Here, we highlight the benefits for dietary protein intake over and above requirements set out in various countries at ∼0.8-1.0 g·kg body mass (BM)^-1·day^-1 for training adaptation, manipulating body composition, and optimizing performance in track and field athletes. To facilitate the remodeling of protein-containing structures, which are turning over rapidly due to their training volumes, track and field athletes with the goal of weight maintenance or weight gain should aim for protein intakes of ∼1.6 g·kg BM^-1·day^-1. Protein intakes at this level would not necessarily require an overemphasis on protein-containing foods and, beyond convenience, does not suggest a need to use protein or amino acid-based supplements. This review also highlights that optimal protein intakes may exceed 1.6 g·kg BM^-1·day^-1 for athletes who are restricting energy intake and attempting to minimize loss of lean BM. We discuss the underpinning rationale for weight loss in track and field athletes, explaining changes in metabolic pathways that occur in response to energy restriction when manipulating protein intake and training. Finally, this review offers practical advice on protein intakes that warrant consideration in allowing an optimal adaptive response for track and field athletes seeking to train effectively and to lose fat mass while energy restricted with minimal (or no) loss of lean BM.