Cold Ambient Temperature Does Not Alter Subcutaneous Abdominal Adipose Tissue Lipolysis and Blood Flow in Endurance-Trained Cyclists.

This study sought to investigate the effect of cold ambient temperature on subcutaneous abdominal adipose tissue (SCAAT) lipolysis and blood flow during steady-state endurance exercise in endurance-trained cyclists. Ten males (age: 23 ± 3 years; peak oxygen consumption: 60.60 ± 4.84 ml·kg-1·min-1; body fat: 18.4% ± 3.5%) participated in baseline lactate threshold (LT) and peak oxygen consumption testing, two familiarization trials, and two experimental trials. Experimental trials consisted of cycling in COLD (3 °C; 42% relative humidity) and neutral (NEU; 19 °C; 39% relative humidity) temperatures. Exercise consisted of 25 min cycling at 70% LT and 25 min at 90% LT. In situ SCAAT lipolysis and blood flow were measured via microdialysis. Heart rate, core temperature, carbohydrate and fat oxidation, blood glucose, and blood lactate were also measured. Heart rate, core temperature, oxygen consumption, and blood lactate increased with exercise but were not different between COLD and NEU. SCAAT blood flow did not change from rest to exercise or between COLD and NEU. Interstitial glycerol increased during exercise (p < .001) with no difference between COLD and NEU. Fat oxidation increased (p < .001) at the onset of exercise and remained elevated thereafter with no difference between COLD and NEU. Carbohydrate oxidation increased with increasing exercise intensity and was greater at 70% LT in COLD compared to NEU (p = .030). No differences were observed between conditions for any other variable. Cycling exercise increased SCAAT lipolysis but not blood flow. Ambient temperature did not alter SCAAT metabolism, SCAAT blood flow, or fat oxidation in well-trained cyclists, though cold exposure increased whole-body carbohydrate oxidation at lower exercise intensities.

International Society of Sports Nutrition Position Stand: Effects of essential amino acid supplementation on exercise and performance.

Position Statement: The International Society of Sports Nutrition (ISSN) presents this position based on a critical examination of literature surrounding the effects of essential amino acid (EAA) supplementation on skeletal muscle maintenance and performance. This position stand is intended to provide a scientific foundation to athletes, dietitians, trainers, and other practitioners as to the benefits of supplemental EAA in both healthy and resistant (aging/clinical) populations. EAAs are crucial components of protein intake in humans, as the body cannot synthesize them. The daily recommended intake (DRI) for protein was established to prevent deficiencies due to inadequate EAA consumption. The following conclusions represent the official position of the Society: 1. Initial studies on EAAs' effects on skeletal muscle highlight their primary role in stimulating muscle protein synthesis (MPS) and turnover. Protein turnover is critical for replacing degraded or damaged muscle proteins, laying the metabolic foundation for enhanced functional performance. Consequently, research has shifted to examine the effects of EAA supplementation - with and without the benefits of exercise - on skeletal muscle maintenance and performance. 2. Supplementation with free-form EAAs leads to a quick rise in peripheral EAA concentrations, which in turn stimulates MPS. 3. The safe upper limit of EAA intake (amount), without inborn metabolic disease, can easily accommodate additional supplementation. 4. At rest, stimulation of MPS occurs at relatively small dosages (1.5-3.0 g) and seems to plateau at around 15-18 g. 5. The MPS stimulation by EAAs does not require non-essential amino acids. 6. Free-form EAA ingestion stimulates MPS more than an equivalent amount of intact protein. 7. Repeated EAA-induced MPS stimulation throughout the day does not diminish the anabolic effect of meal intake. 8. Although direct comparisons of various formulas have yet to be investigated, aging requires a greater proportion of leucine to overcome the reduced muscle sensitivity known as "anabolic resistance." 9. Without exercise, EAA supplementation can enhance functional outcomes in anabolic-resistant populations. 10. EAA requirements rise in the face of caloric deficits. During caloric deficit, it's essential to meet whole-body EAA requirements to preserve anabolic sensitivity in skeletal muscle.

The effects of betaine supplementation on fluid balance and heat tolerance during passive heat stress in men.

INTRODUCTION: Consuming intracellular osmolytes, like betaine (BET), may attenuate symptoms of heat stress. The purpose of this study was to examine the effects of BET supplementation on fluid balance and heat tolerance after a 7-day loading period and during passive heat exposure. METHODS: A double-blind, placebo controlled, crossover study compared BET or placebo consumption (50 mg·kg-1 , twice daily) for 7 days in young, recreationally active men (N = 11). RESULTS: During the loading period, no significant interactions were found for any marker of fluid balance between or within conditions. During heat exposure, significant time effects but no condition x time interactions, were found for plasma characteristics (i.e., volume, osmolality, sodium, albumin, and total protein). Plasma volume was significantly increased by min 30 in both conditions (PLA: +6.9. ± 5.0%, BET: +10.2 ± 7.4%) and remained elevated for the remainder of the experimental trial, but was not significantly different between conditions. After 60 min of passive heat exposure, both conditions experienced a similar increase in core temperature (PLA: +0.32 ± 0.22°C, BET: +0.31 ± 0.21°C; p = 0.912). CONCLUSIONS: Supplemental BET did not improve markers of fluid balance or heat tolerance during 7 days of loading or during passive heat exposure.

Collagen peptides supplementation improves function, pain, and physical and mental outcomes in active adults.

INTRODUCTION: Chronic pain affects 19% of adults in the United States, with increasing prevalence in active and aging populations. Pain can limit physical activity and activities of daily living (ADLs), resulting in declined mental and social health. Nutritional interventions for pain currently target inflammation or joint health, but few influence both. Collagen, the most abundant protein in the human body and constituent of the extra cellular matrix, is such a nutraceutical. While there have been reports of reductions in pain with short-term collagen peptide (CP) supplementation, there are no long-term studies specifically in healthy middle-aged active adults. PURPOSE: To determine the effects of daily CP consumption over 3, 6, and 9 months on survey measures of pain, function, and physical and mental health using The Knee Injury & Osteoarthritis Outcomes Score (KOOS) and Veterans Rand 12 (VR-12) in middle-aged active adults. METHODS: This study was a double-blind randomized control trial with three treatment groups (Placebo, 10 g/d CP, and 20 g/d CP). RESULTS: Improvements in ADLs (p = .031, ηp2 = .096) and pain (p = .037, ηp2 = .164) were observed with 10 g/d CP over 6 months, although pain only improved in high frequency exercisers (>180 min/week). Additionally, VR-12 mental component scores (MCS) improved with 10 g/d of CP over 3-9 months (p = .017, ηp2 = .309), while physical component scores (PCS) improved with 20 g/d of CP over 3-9 months, but only in females (p = .013, ηp2= .582). CONCLUSION: These findings suggest 10 to 20 g/d of CP supplementation over 6 to 9 months may improve ADLs, pain, MCS, and PCS in middle-aged active adults.

Early Detection of COVID-19 in Female Athletes Using Wearable Technology.

BACKGROUND: Heart rate variability (HRV), respiratory rate (RR), and resting heart rate (RHR) are common variables measured by wrist-worn activity trackers to monitor health, fitness, and recovery in athletes. Variations in RR are observed in lower-respiratory infections, and preliminary data suggest changes in HRV and RR are linked to early detection of COVID-19 infection in nonathletes. HYPOTHESIS: Wearable technology measuring HRV, RR, RHR, and recovery will be successful for early detection of COVID-19 in NCAA Division I female athletes. STUDY DESIGN: Cohort study. LEVEL OF EVIDENCE: Level 2. METHODS: Female athletes wore WHOOP, Inc. bands through the 2020 to 2021 competitive season. Of the athletes who tested positive for COVID (n = 33), 14 had enough data to be assessed (N = 14; 20.0 ± 1.3 years; 69.8 ± 7.2 kg; 172.0 ± 8.3 cm). Roughly 2 weeks of noninfected days were used to set baseline levels of HRV, RR, recovery, and RHR to compare with -3, -2, and -1 days before a positive COVID-19 result. RESULTS: Increases in RR (P = 0.02) were detected on day -3. RHR (P < 0.01) and RR increased (P < 0.01), while HRV decreased (P < 0.05) on day -1, compared with baseline. Differences were noted in all variables on the day of the positive COVID-19 result: decreased HRV (P < 0.05) and recovery scores (P < 0.01), and increased RHR (P < 0.01) and RR (P < 0.01). CONCLUSION: In female athletes, wearable technology was successful in predicting COVID-19 infection through changes in RR 3 days before a positive test, and also HRV and RHR the day before a positive test. CLINICAL RELEVANCE: Wearable technology may be used, as part of a multifaceted approach, for the early detection of COVID-19 in elite athletes through monitoring of HRV, RR, and RHR for overall team health.

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 50th 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.

International society of sports nutrition position stand: nutritional concerns of the female athlete.

Based on a comprehensive review and critical analysis of the literature regarding the nutritional concerns of female athletes, conducted by experts in the field and selected members of the International Society of Sports Nutrition (ISSN), the following conclusions represent the official Position of the Society: 1. Female athletes have unique and unpredictable hormone profiles, which influence their physiology and nutritional needs across their lifespan. To understand how perturbations in these hormones affect the individual, we recommend that female athletes of reproductive age should track their hormonal status (natural, hormone driven) against training and recovery to determine their individual patterns and needs and peri and post-menopausal athletes should track against training and recovery metrics to determine the individuals' unique patterns. 2. The primary nutritional consideration for all athletes, and in particular, female athletes, should be achieving adequate energy intake to meet their energy requirements and to achieve an optimal energy availability (EA); with a focus on the timing of meals in relation to exercise to improve training adaptations, performance, and athlete health. 3. Significant sex differences and sex hormone influences on carbohydrate and lipid metabolism are apparent, therefore we recommend first ensuring athletes meet their carbohydrate needs across all phases of the menstrual cycle. Secondly, tailoring carbohydrate intake to hormonal status with an emphasis on greater carbohydrate intake and availability during the active pill weeks of oral contraceptive users and during the luteal phase of the menstrual cycle where there is a greater effect of sex hormone suppression on gluconogenesis output during exercise. 4. Based upon the limited research available, we recommend that pre-menopausal, eumenorrheic, and oral contraceptives using female athletes should aim to consume a source of high-quality protein as close to beginning and/or after completion of exercise as possible to reduce exercise-induced amino acid oxidative losses and initiate muscle protein remodeling and repair at a dose of 0.32-0.38 g·kg-1. For eumenorrheic women, ingestion during the luteal phase should aim for the upper end of the range due to the catabolic actions of progesterone and greater need for amino acids. 5. Close to the beginning and/or after completion of exercise, peri- and post-menopausal athletes should aim for a bolus of high EAA-containing (~10 g) intact protein sources or supplements to overcome anabolic resistance. 6. Daily protein intake should fall within the mid- to upper ranges of current sport nutrition guidelines (1.4-2.2 g·kg-1·day-1) for women at all stages of menstrual function (pre-, peri-, post-menopausal, and contraceptive users) with protein doses evenly distributed, every 3-4 h, across the day. Eumenorrheic athletes in the luteal phase and peri/post-menopausal athletes, regardless of sport, should aim for the upper end of the range. 7. Female sex hormones affect fluid dynamics and electrolyte handling. A greater predisposition to hyponatremia occurs in times of elevated progesterone, and in menopausal women, who are slower to excrete water. Additionally, females have less absolute and relative fluid available to lose via sweating than males, making the physiological consequences of fluid loss more severe, particularly in the luteal phase. 8. Evidence for sex-specific supplementation is lacking due to the paucity of female-specific research and any differential effects in females. Caffeine, iron, and creatine have the most evidence for use in females. Both iron and creatine are highly efficacious for female athletes. Creatine supplementation of 3 to 5 g per day is recommended for the mechanistic support of creatine supplementation with regard to muscle protein kinetics, growth factors, satellite cells, myogenic transcription factors, glycogen and calcium regulation, oxidative stress, and inflammation. Post-menopausal females benefit from bone health, mental health, and skeletal muscle size and function when consuming higher doses of creatine (0.3 g·kg-1·d-1). 9. To foster and promote high-quality research investigations involving female athletes, researchers are first encouraged to stop excluding females unless the primary endpoints are directly influenced by sex-specific mechanisms. In all investigative scenarios, researchers across the globe are encouraged to inquire and report upon more detailed information surrounding the athlete's hormonal status, including menstrual status (days since menses, length of period, duration of cycle, etc.) and/or hormonal contraceptive details and/or menopausal status.

Collagen peptide supplementation for pain and function: is it effective?

PURPOSE OF REVIEW: Connective tissue injuries are prevalent in active and aging populations, leading to chronic pain and decreased function. Turnover of this tissue is not well understood, especially as it relates to aging and injury. Supplementation of collagen peptides has been shown to improve connective tissue recovery and pain through increased collagen production. RECENT FINDINGS: Collagen peptide supplementation improves pain and function, and upregulates metabolic pathways associated with muscle and tendon growth. Literature from the past 12-18 months supports that these pathways are also involved with increased synthesis and degradation of collagen and other elements of the extracellular matrix. Improvements in body composition and strength have been noted with collagen peptide supplementation when paired with resistance training. Collagen peptide supplements are hydrolyzed into small peptides, termed bioactive peptides, and individual amino acids. These bioactive peptides are associated with the benefits observed with collagen peptide supplementation and may play a critical role in the collagen turnover. SUMMARY: Collagen peptide supplementation has been shown to promote recovery, decrease pain, and improve strength and body composition when paired with resistance training. These benefits may be attributed to bioactive peptides in collagen peptide supplements. Additional research is warranted to examine the specific effects of these bioactive peptides.

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.

Sleep Duration Correlates With Performance in Ultra-Endurance Triathlon.

The relationship between sleep duration, sleep quality, and race completion time during each stage of a 3-day ultra-endurance triathlon (stage 1: 10-km swim, 146-km cycle; stage 2: 276-km cycle; and stage 3: 84.4-km run) was investigated. Seventeen triathletes partook in sleep analysis throughout the ultra-endurance multiday triathlon using an actigraphy wristband. The participants wore the band to record objective sleep outcomes for approximately 4 days (1-2 d prerace, 3 race days, and 1 d postrace), except while racing. The total sleep time (TST; prerace: 414.1 [95.3] min, prestage 1: 392.2 [138.3] min, prestage 2: 355.6 [62.5] min, and prestage 3: 299.7 [107.0] min) significantly decreased over time (P < .05). Significant Pearson moment-product correlations were found between TST and subsequent race-day performance for race stage 1 (r = -.577; P = .019) and stage 3 (r = -.546; P = .035), with further analysis revealing that TST explained 33% and 30% of the variation in performance for stages 1 and 3, respectively. During a 3-day ultra-endurance triathlon, the TST was reduced and had a significant negative correlation to exercise performance, indicating that sleep loss was associated with slower performances. Sleep onset latency, wake episodes, and sleep efficiency did not significantly change over the course of this investigation, which may stem from the close proximity of exercise to sleep.

Prevalence of Normal Weight Obesity and Health Risk Factors for the Female Collegiate Dancer.

ABSTRACT: Brown, AF, Alfiero, CJ, Brooks, SJ, Kviatkovsky, SA, Smith-Ryan, AE, and Ormsbee, MJ. Prevalence of normal weight obesity and health risk factors for the female collegiate dancer. J Strength Cond Res 35(8): 2321-2326, 2021-The purpose of this study was to investigate the prevalence of normal weight obesity (NWO) and evaluate the relationship between NWO and health risk factors in a collegiate dancer population. Reanalysis of data of female dancers (N = 42) from 2 larger studies was used to assess prevalence and health risk factors of NWO. Dancers completed a dual-energy x-ray absorptiometry scan to assess fat mass (FM), lean mass (LM), and visceral adipose tissue (VAT) and a 3-day food record. Normal weight obesity was defined as a body mass index (BMI) of 18.5-24.9 kg·m-2 and body fat (BF) ≥30%. Twenty-five (60%) dancers were classified as normal weight lean (NWL), and 17 dancers (40%) were classified as NWO. Significant differences were observed for BMI (NWL: 21.1 ± 1.7, NWO: 23.1 ± 1.6, p < 0.001), LM (NWL: 71.0 ± 2.9%, NWO: 62.5 ± 2.7%, p < 0.001), %BF (NWL: 24.8 ± 3.1%, NWO: 33.9 ± 2.6%, p < 0.001), and VAT (NWL: 130.6 ± 43.0 g, NWO: 232.3 ± 70.8 g, p < 0.001) between NWL and NWO. A significant difference was observed for carbohydrate intake (NWL: 4.7 ± 1.8 g·kg-1, NWO: 3.7 ± 1.0 g·kg-1, p = 0.020) between groups. Significant positive correlations with FM were observed between carbohydrate (kcal, p = 0.048), fat (kcal, p = 0.018; g·kg-1, p = 0.040), and total calories (p = 0.019) in NWO. Normal weight obesity in collegiate dancers may be more prevalent than previously perceived and may be significantly related to important health risk factors. The current study demonstrates the need for body composition assessments and emphasizing on promoting overall health in collegiate dancers.

Gastrointestinal pathophysiology during endurance exercise: endocrine, microbiome, and nutritional influences.

Gastrointestinal symptoms are abundant among athletes engaging in endurance exercise, particularly when exercising in increased environmental temperatures, at higher intensities, or over extremely long distances. It is currently thought that prolonged ischemia, mechanical damage to the epithelial lining, and loss of epithelial barrier integrity are likely contributors of gastrointestinal (GI) distress during bouts of endurance exercise, but due to the many potential causes and sporadic nature of symptoms this phenomenon has proven difficult to study. In this review, we cover known factors that contribute to GI distress symptoms in athletes during exercise, while further attempting to identify novel avenues of future research to help elucidate mechanisms leading to symptomology. We explore the link between the intestinal microbiome, the integrity of the gut epithelia, and add detail on gut hormone and peptide secretion that could potentially contribute to GI distress symptoms in athletes. The influence of nutrition and dietary supplementation strategies are also detailed, where much research has opened up new ideas and potential mechanisms for understanding gut pathophysiology during exercise. The etiology of gastrointestinal symptoms during endurance exercise is multi-factorial with neuroendocrine, microbial, and nutritional factors likely contributing to specific, individualized symptoms. Recent work in previously unexplored areas of both microbiome and gut peptide secretion are pertinent areas for future work, and the numerous supplementation strategies explored to date have provided insight into physiological mechanisms that may be targetable to reduce the incidence and severity of gastrointestinal symptoms in athletes.

The Potential Role of Creatine in Vascular Health.

Creatine is an organic compound, consumed exogenously in the diet and synthesized endogenously via an intricate inter-organ process. Functioning in conjunction with creatine kinase, creatine has long been known for its pivotal role in cellular energy provision and energy shuttling. In addition to the abundance of evidence supporting the ergogenic benefits of creatine supplementation, recent evidence suggests a far broader application for creatine within various myopathies, neurodegenerative diseases, and other pathologies. Furthermore, creatine has been found to exhibit non-energy related properties, contributing as a possible direct and in-direct antioxidant and eliciting anti-inflammatory effects. In spite of the new clinical success of supplemental creatine, there is little scientific insight into the potential effects of creatine on cardiovascular disease (CVD), the leading cause of mortality. Taking into consideration the non-energy related actions of creatine, highlighted in this review, it can be speculated that creatine supplementation may serve as an adjuvant therapy for the management of vascular health in at-risk populations. This review, therefore, not only aims to summarize the current literature surrounding creatine and vascular health, but to also shed light onto the potential mechanisms in which creatine may be able to serve as a beneficial supplement capable of imparting vascular-protective properties and promoting vascular health.

Effect of Functional Impact Training on Body Composition, Bone Mineral Density, and Strength in Breast Cancer Survivors.

PURPOSE: The purpose of this study was to examine the effects of 24 wk of functional impact training (FIT) that consisted of resistance and high-impact exercises in comparison with yin yoga on body composition, bone mineral density (BMD), blood biomarkers for bone metabolism, and strength in breast cancer survivors (BCS). METHODS: Forty-four BCS (60.3 ± 8.3 yr) were randomly assigned to the FIT or yin yoga group. Body composition and BMD were measured via dual energy x-ray absorptiometry. Blood biomarkers for bone metabolism were analyzed via enzyme-linked immunosorbent assays. Upper and lower body strength was assessed using a one-repetition maximum chest press and isokinetic knee extension/flexion using the Biodex System 3, respectively. Participants completed 45-min FIT or yin yoga sessions twice weekly for 24 wk. Changes in dependent variables over time were analyzed using repeated-measures ANOVA. Significance was accepted at P ≤ 0.05. RESULTS: There were no group-time effects for body composition, BMD, or blood biomarkers. Main effects were observed for left femoral neck (0.883 ± 0.138 to 0.870 ± 0.131 g·cm) and left forearm (0.465 ± 0.078 to 0.457 ± 0.069 g·cm) BMD. The FIT group improved upper body strength (73.2 ± 18.1 to 83.2 ± 22.3 kg), whereas the yin yoga group did not (59.8 ± 14.8 to 59.3 ± 15.6 kg). Main time effects were observed for peak isokinetic knee extension and flexion at all speeds with an average improvement of 13.2% and 16.2%, respectively. CONCLUSION: Both FIT and yin yoga may be beneficial exercise modes for improving lower body strength, although only FIT improved upper body strength. Additional research is needed to examine the effectiveness of FIT programs of longer duration and/or higher intensity on body composition and BMD in BCS.

Adrenal stress hormone action in skeletal muscle during exercise training: An old dog with new tricks?

Exercise is a key component of a healthy lifestyle as it helps maintain a healthy body weight and reduces the risk of various morbidities and co-morbidities. Exercise is an acute physiological stress that initiates a multitude of processes that attempt to restore physiological homeostasis and promote adaptation. A component of the stress response to exercise is the rapid release of hormones from the adrenal gland including glucocorticoids, the catecholamines and aldosterone. While each hormone targets several tissues throughout the body, skeletal muscle is of interest as it is central to physical function and various metabolic processes. Indeed, adrenal stress hormones have been shown to elicit specific performance benefits on the muscle. However, how the acute, short-lived release of these stress hormones during exercise influences adaptations of skeletal muscle to long-term training remains largely unknown. Thus, the objective of this review was to briefly highlight the known impact of adrenal stress hormones on skeletal muscle metabolism and function (Old Dog), and critically examine the current evidence supporting a role for these endogenous hormones in mediating long-term training adaptations in skeletal muscle (New Tricks).

Betaine Supplementation May Improve Heat Tolerance: Potential Mechanisms in Humans.

Betaine has been demonstrated to increase tolerance to hypertonic and thermal stressors. At the cellular level, intracellular betaine functions similar to molecular chaperones, thereby reducing the need for inducible heat shock protein expression. In addition to stabilizing protein conformations, betaine has been demonstrated to reduce oxidative damage. For the enterocyte, during periods of reduced perfusion as well as greater oxidative, thermal, and hypertonic stress (i.e., prolonged exercise in hot-humid conditions), betaine results in greater villi length and evidence for greater membrane integrity. Collectively, this reduces exercise-induced gut permeability, protecting against bacterial translocation and endotoxemia. At the systemic level, chronic betaine intake has been shown to reduce core temperature, all-cause mortality, markers of inflammation, and change blood chemistry in several animal models when exposed to heat stress. Despite convincing research in cell culture and animal models, only one published study exists exploring betaine's thermoregulatory function in humans. If the same premise holds true for humans, chronic betaine consumption may increase heat tolerance and provide another avenue of supplementation for those who find that heat stress is a major factor in their work, or training for exercise and sport. Yet, this remains speculative until data demonstrate such effects in humans.

Pre-Sleep Low Glycemic Index Modified Starch Does Not Improve Next-Morning Fuel Selection or Running Performance in Male and Female Endurance Athletes.

To determine the effects of pre-sleep supplementation with a novel low glycemic index (LGI) carbohydrate (CHO) on next-morning substrate utilization, gastrointestinal distress (GID), and endurance running performance (5-km time-trial, TT). Using a double-blind, randomized, placebo (PLA) controlled, crossover design, trained participants (n = 14; 28 ± 9 years, 8/6 male/female, 55 ± 7 mL/kg/min) consumed a LGI, high glycemic index (HGI), or 0 kcal PLA supplement ≥ 2 h after their last meal and <30 min prior to sleep. Upon arrival, resting energy expenditure (REE), substrate utilization, blood glucose, satiety, and GID were assessed. An incremental exercise test (IET) was performed at 55, 65, and 75% peak volume of oxygen consumption (VO2peak) with GID, rating of perceived exertion (RPE) and substrate utilization recorded each stage. Finally, participants completed the 5-km TT. There were no differences in any baseline measure. During IET, CHO utilization tended to be greater with LGI (PLA, 56 ± 11; HGI, 60 ± 14; LGI, 63 ± 14%, p = 0.16, η2 = 0.14). GID was unaffected by supplementation at any point (p > 0.05). Performance was also unaffected by supplement (PLA, 21.6 ± 9.5; HGI, 23.0 ± 7.8; LGI, 24.1 ± 4.5 min, p = 0.94, η2 = 0.01). Pre-sleep CHO supplementation did not affect next-morning resting metabolism, BG, GID, or 5-km TT performance. The trend towards higher CHO utilization during IET after pre-sleep LGI, suggests that such supplementation increases morning CHO availability.

The Evolving Applications of Creatine Supplementation: Could Creatine Improve Vascular Health?

Creatine is a naturally occurring compound, functioning in conjunction with creatine kinase to play a quintessential role in both cellular energy provision and intracellular energy shuttling. An extensive body of literature solidifies the plethora of ergogenic benefits gained following dietary creatine supplementation; however, recent findings have further indicated a potential therapeutic role for creatine in several pathologies such as myopathies, neurodegenerative disorders, metabolic disturbances, chronic kidney disease and inflammatory diseases. Furthermore, creatine has been found to exhibit non-energy-related properties, such as serving as a potential antioxidant and anti-inflammatory. Despite the therapeutic success of creatine supplementation in varying clinical populations, there is scarce information regarding the potential application of creatine for combatting the current leading cause of mortality, cardiovascular disease (CVD). Taking into consideration the broad ergogenic and non-energy-related actions of creatine, we hypothesize that creatine supplementation may be a potential therapeutic strategy for improving vascular health in at-risk populations such as older adults or those with CVD. With an extensive literature search, we have found only four clinical studies that have investigated the direct effect of creatine on vascular health and function. In this review, we aim to give a short background on the pleiotropic applications of creatine, and to then summarize the current literature surrounding creatine and vascular health. Furthermore, we discuss the varying mechanisms by which creatine could benefit vascular health and function, such as the impact of creatine supplementation upon inflammation and oxidative stress.

Nutritional Supplementation Concurrent with Nutrition Education Accelerates the Wound Healing Process in Patients with Diabetic Foot Ulcers.

Trials on nutritional supplements for the treatment of diabetic foot ulcer (DFU) have only evaluated the effects of supplementation with specific nutrients. Additionally, nutrition education has not been a systematic part of these studies. The aim of this study was to evaluate the effects of a nutrient-dense formula combined with nutrition education on wound healing in DFU patients. Twenty-nine patients were randomly assigned to the treatment group (n = 15) receiving two servings of supplements daily plus nutrition education or control group (n = 14) that received the standard of care but no additional nutritional or educational intervention. Both groups were followed for a maximum of 12 weeks. Wound healing, as measured by planimetry, was examined at baseline and every four weeks until complete wound closure or up to 12 weeks. There were no significant differences between groups for BMI, age, duration of diabetes, wound age estimation, or wound area at baseline. The treatment group experienced a faster wound healing rate (6.43 mm2/week more reduction in the wound area) than the control group. The mean reduction in the wound area during the first four weeks of the study was almost 13-fold greater in the treatment group compared to the control group (18.0 mm2/week vs. 1.4 mm2/week, respectively). Our findings showed that nutrition supplementation plus nutrition education significantly accelerated wound healing in DFU patients compared to those who just received a standard-of-care regimen.

Effects of Creatine Supplementation during Resistance Training Sessions in Physically Active Young Adults.

The purpose was to examine the effects of creatine supplementation during resistance training sessions on skeletal muscle mass and exercise performance in physically active young adults. Twenty-two participants were randomized to supplement with creatine (CR: n = 13, 26 ± 4 yrs; 0.0055 g·kg-1 post training set) or placebo (PLA: n = 9, 26 ± 5 yrs; 0.0055 g·kg-1 post training set) during six weeks of resistance training (18 sets per training session; five days per week). Prior to and following training and supplementation, measurements were made for muscle thickness (elbow and knee flexors/extensors, ankle plantarflexors), power (vertical jump and medicine ball throw), strength (leg press and chest press one-repetition maximum (1-RM)) and muscular endurance (one set of repetitions to volitional fatigue using 50% baseline 1-RM for leg press and chest press). The creatine group experienced a significant increase (p < 0.05) in leg press, chest press and total body strength and leg press endurance with no significant changes in the PLA group. Both groups improved total body endurance over time (p < 0.05), with greater gains observed in the creatine group. In conclusion, creatine ingestion during resistance training sessions is a viable strategy for improving muscle strength and some indices of muscle endurance in physically active young adults.