Oral Glutamine Supplement Reduces Subjective Fatigue Ratings during Repeated Bouts of Firefighting Simulations

Wildland firefighting requires repetitive (e.g., consecutive work shifts) physical work in dangerous conditions (e.g., heat and pollution). Workers commonly enter these environments in a nonacclimated state, leading to fatigue and heightened injury risk. Strategies to improve tolerance to these stressors are lacking. Purpose: To determine if glutamine ingestion prior to and after consecutive days of firefighting simulations in the heat attenuates subjective ratings of fatigue, and evaluate if results were supported by glutamine-induced upregulation of biological stress responses. Methods: Participants (5 male, 3 female) ingested glutamine (0.15 g/kg/day) or a placebo before and after two consecutive days (separated by 24 h) of firefighter simulations in a heated chamber (35 degrees C, 35% humidity). Perceived fatigue and biological stress were measured pre-, post-, and 4 h postexercise in each trial. Results: Subjective fatigue was reduced pre-exercise on Day 2 in the glutamine group (p \u3c 0.05). Peripheral mononuclear cell expression of heat shock protein 70 (HSP70) and serum antioxidants were elevated at 4 h postexercise on Day 1 in the glutamine trial (p \u3c 0.05). Conclusions: Ingestion of glutamine before and after repeated firefighter simulations in the heat resulted in reduced subjective fatigue on Day 2, which may be a result of the upregulation of biological stress systems (antioxidants, HSPs). This response may support recovery and improve work performance

Effect of Branched-Chain Amino Acid Supplementation on Recovery Following Acute Eccentric Exercise

This study investigated the effect of branched-chain amino acid (BCAA) supplementation on recovery from eccentric exercise. Twenty males ingested either a BCAA supplement or placebo (PLCB) prior to and following eccentric exercise. Creatine kinase (CK), vertical jump (VJ), maximal voluntary isometric contraction (MVIC), jump squat (JS) and perceived soreness were assessed. No significant (p \u3e 0.05) group by time interaction effects were observed for CK, soreness, MVIC, VJ, or JS. CK concentrations were elevated above baseline (p \u3c 0.001) in both groups at 4, 24, 48 and 72 hr, while CK was lower (p = 0.02) in the BCAA group at 48 hr compared to PLCB. Soreness increased significantly from baseline (p \u3c 0.01) in both groups at all time-points; however, BCAA supplemented individuals reported less soreness (p \u3c 0.01) at the 48 and 72 hr time-points. MVIC force output returned to baseline levels (p \u3e 0.05) at 24, 48 and 72 hr for BCAA individuals. No significant difference between groups (p \u3e 0.05) was detected for VJ or JS. BCAA supplementation may mitigate muscle soreness following muscle-damaging exercise. However, when consumed with a diet consisting of ~1.2 g/kg/day protein, the attenuation of muscular performance decrements or corresponding plasma CK levels are likely negligible

Reply to “Programming may matter most.” Response to “Metabolic effects of two high-intensity circuit training protocols: Does sequence matter?”

We appreciate the interest that our study elicited and the comments from a reader. We commend the reader of our paper for critically evaluating the protocol and results of the study. Here, we would like to respond to the statement made in the letter. Indeed, the rest intervals were longer and time at VO2max was lower in our study than recommended by Bucheit and Larsen.1 However, because the reader is interested in the practical implications of our study, we ask that they consider the following

Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo

Meeting Abstracts: Proceedings of the Thirteenth International Society of Sports Nutrition (ISSN) Conference and Expo Clearwater Beach, FL, USA. 9-11 June 201

The use of a smart-textile garment during high-intensity functional training: a pilot study

BACKGROUND:Wearable devices are common in the health and fitness industry and provide valuable information to improve and achieve fitness goals. The Hexoskin shirt (Hx) is one such device that has been shown to be valid and reliable. The purpose of this pilot study was to compare the Hx to established methods during a maximal graded exercise test (TM) and a high-intensity functional training (HIFT) session. METHODS:Ten healthy individuals (31.0±7.6 years, 76.4±11.4 kg; 1.7±0.1 m) volunteered for this study and completed a TM and a HIFT exercise session. During both testing sessions, respiratory measures (respiratory rate [RR], and respiratory volume [RV]) were assessed using a portable metabolic system (Cosmed K4b2; K4), and heart rate (HR) was determined via ECG in a standard 12-lead configuration. The Hx was worn during both sessions. RESULTS:During TM, a 4% difference was noted for HR during cool down, while exercising HR and RV, along with RR during cool down were all under 10%. During HIFT, HR at rest and cool down, as well as RR during exercise were less than 10%. The variation between technologies for the remaining variables ranged between 12.3-39.9% and 10.9-41.1% for TM and HIFT, respectively. CONCLUSIONS:The Hx smart garment may be utilized to provide select cardiorespiratory data in a TM and HIFT session. We recommend that the validity and reliability be fully established before the Hx smart garment is entirely utilized for all cardiorespiratory data and research purposes in a field-based environment

Exercise-Based Cardiac Rehabilitation Improves Cognitive Function Among CVD Patients

Objective: Investigate the effects of cardiac rehabilitation (CR) exercise training on cognitive performance and if the changes are associated with alterations in prefrontal cortex (PFC) oxygenation among patients with cardiovascular disease (CVD). Design: A single group pre-post design. Setting: An outpatient CR program. Subjects: Twenty (15 male, 5 female; mean (SD) age 64.8 (11.6) yrs) patients from an outpatient CR program. Intervention: At least 18 individualized CR sessions (approximately 6 weeks). Main measures: Pre- and post-CR changes in cognitive performance (a measure of 5 constructs from the NIH Fluid Cognition test battery), left-PFC and right-PFC activation (measured using functional near-infrared spectroscopy (fNIRS)) and cardiorespiratory capacity (measured by a submaximal graded treadmill test). Results: Patients showed improvements in cardiorespiratory capacity and various cognitive constructs (processing speed, attention, executive function, and working memory scores). A significant increase in PFC oxygenation, primarily in the left-PFC region, occurred at post-CR test. Correlation analyses revealed negative associations between changes in cognition (executive function and fluid composite score) and PFC changes. The change in cardiorespiratory capacity was positively associated with the change in working memory score. Conclusions: CVD patients enrolled in CR showed significant improvements in multiple cognitive domains along with increased cortical activation. The negative associations between cognitive functioning and PFC oxygenation suggest an improved neural efficiency, which is identified as higher cognitive performance for a given (or reduced) amount of cortical activation

Autophagy response to acute high-intensity interval training and moderate-intensity continuous training is dissimilar in skeletal muscle and peripheral blood mononuclear cells and is influenced by sex

Autophagy is an evolutionary conserved cellular degradation system that underlies the positive effects of exercise. Currently, few human data exist investigating the autophagic response to exercise including the response to high-intensity interval training (HIIT), response in divergent tissues, and if sex differences exist. The purpose of this study was to investigate the autophagy response in skeletal muscle and peripheral blood mononuclear cells (PBMCs) following an acute bout of HIIT and moderate-intensity continuous training (MICT) with treadmill running in males and females. Using a crossover design, ten recreationally-active males (n = 5; 25.2 ± 1.1 yrs) and females (n = 5; 21.6 ± 3.6 yrs) performed a bout of MICT (60 min at 55% of max velocity [Vmax]]) and HIIT (12 bouts of 1 min at 100% Vmax and 1 min at 3 miles per hour) in a fasted state separated by ≥ 72 h. Muscle biopsy samples from the vastus lateralis and PBMCs were collected pre- and 3 h post-exercise and analyzed for differences in protein expression of LC3I, LC3II, and p62 via western blot analysis. Expression of LC3II:LC3I was significantly different from pre-exercise 3 h post-exercise in MICT in skeletal muscle (64.3 ± 47.3%; p = 0.024). A significant time effect was found for p62 3 h post-exercise compared to pre-exercise (135.23 ± 84.6%; p = 0.043) in skeletal muscle. No differences in markers of autophagy were observed in PBMCs. When sexes were analyzed separately there was a condition x time x sex interaction in LC3II (p = 0.007) and LC3II:LC3I (p = 0.043) in PBMCs. Post hoc analyses revealed a difference in LC3II pre vs. 3 h post exercise in males, but not females, in both HIIT (144.2 ± 89.7%; p = 0.024) and MICT (61.8 ± 36.1%; p = 0.043). Our findings show that HIIT results in changes in markers of autophagy and that the exercise-induced autophagy response varies in tissues and between sexes

Differential Effects of Exercise Programs on Neuregulin 4, Body Composition and Cardiometabolic Risk Factors in Men With Obesity

International audienceBACKGROUND: Neuregulin 4 (Nrg4) is an adipokine that is sensitive to energy expenditure and with a potential role in metabolic homeostasis and obesity. This study examined the effects of 12 weeks of three different exercise training protocols on Nrg4 levels, cardiometabolic risk factors, and body composition parameters in men with obesity. METHODS: Sixty adult men with obesity (Mean ± SD; age: 27.60 ± 8.4 yrs.; height: 168.4 ± 2.6 cm; weight: 96.7 ± 7.2 kg) were randomly allocated into four equal (n = 15) groups: High- Intensity Interval Training (HIIT), Circuit Resistance Training (CRT), Moderate Intensity Continuous Training (MICT) or a control group. The HIIT protocol involved six bouts of 3-min high-intensity exercise (90% VO(2peak) ) followed by 3-min low-intensity exercise (50% VO(2peak) ). The CRT group performed three circuits of resistance training, where each circuit included 11 exercises at 20% of one-repetition maximum (1RM) and 70% of VO(2peak) , and with a work-to-rest ratio of 2:1 (40-s exercise and 20-s rest) and 60-s recovery between circuits. The MICT group performed 36 min of exercise at 70% of VO(2peak) . All measurements were taken 72 h before and after the first and last training sessions. RESULTS: There were significant differences between the groups in fat-free mass (FFM), (effect size (ES): 0.78), fat mass (ES: 0.86), VO(2peak) (ES: 0.59), high-density lipoprotein cholesterol (HDL-C) (ES: 0.83), low-density lipoprotein (LDL-C) (ES: 0.79), total cholesterol (TC) (ES: 0.90), triglyceride (TG) (ES: 0.52) glucose (ES: 0.39), insulin (ES: 0.61), HOM-IR (ES: 0.91) and Nrg4 (ES: 0.98) (p < 0.05). There were no significant changes in very-low-density lipoprotein cholesterol (VLDL-C) (ES: 0.13) levels, or body weights (ES: 0.51) (p > 0.05). Levels of Nrg4 were negatively correlated with LDL-C, TC, TG, VLDL-C, glucose, insulin, HOMA-IR (p < 0.05) and positively with HDL-C (p < 0.05). CONCLUSION: Our results suggest that HIIT and CRT protocols have greater effects than MICT protocol on Nrg4 levels, metabolic and cardiovascular risk factors, and body composition variables in men with obesity