Acute and chronic resistance training downregulates select LINE-1 retrotransposon activity markers in human skeletal muscle.

Herein, we examined if acute or chronic resistance exercise affected markers of skeletal muscle long interspersed nuclear element-1 (LINE-1) retrotransposon activity. In study 1, 10 resistance-trained college-aged men performed three consecutive daily back squat sessions, and vastus lateralis biopsies were taken before (Pre), 2 h following session 1 (Post1), and 3 days following session 3 (Post2). In study 2, 13 untrained college-aged men performed a full-body resistance training program (3 days/wk), and vastus lateralis biopsies were taken before ( week 0) and ~72 h following training cessation ( week 12). In study 1, LINE-1 mRNA decreased 42-48% at Post1 and 2 ( P < 0.05), and reverse transcriptase (RT) activity trended downward at Post2 (-37%, P = 0.067). In study 2, LINE-1 mRNA trended downward at week 12 (-17%, P = 0.056) while LINE-1 promoter methylation increased (+142%, P = 0.041). Open reading frame (ORF)2p protein expression (-24%, P = 0.059) and RT activity (-26%, P = 0.063) also trended downward by week 12. Additionally, changes in RT activity versus satellite cell number were inversely associated ( r = -0.725, P = 0.008). Follow-up in vitro experiments demonstrated that 48-h treatments with lower doses (1 µM and 10 µM) of efavirenz and nevirapine (non-nucleoside RT inhibitors) increased myoblast proliferation ( P < 0.05). However, we observed a paradoxical decrease in myoblast proliferation with higher doses (50 µM) of efavirenz and delavirdine. This is the first report suggesting that resistance exercise downregulates markers of skeletal muscle LINE-1 activity. Given our discordant in vitro findings, future research is needed to thoroughly assess whether LINE-1-mediated RT activity enhances or blunts myoblast, or primary satellite cell, proliferative capacity.

Effects of Hydrolyzed Whey versus Other Whey Protein Supplements on the Physiological Response to 8 Weeks of Resistance Exercise in College-Aged Males.

OBJECTIVE: The objective of this study was to compare the chronic effects of different whey protein forms on body composition and performance when supplemented with resistance training. METHODS: Resistance-trained men (N = 56, 21.4 ± 0.4 years, 79.5 ± 1.0 kg) participated in an 8-week resistance training regimen (2 upper-body sessions and 2 lower-body sessions per week) and received one of 4 double-blinded treatments: 30 g/serving carbohydrate placebo (PLA) or 30 g/serving protein from either (a) 80% whey protein concentrate (WPC), (b) high-lactoferrin-containing WPC (WPC-L), or (c) extensively hydrolyzed WPC (WPH). All subjects consumed 2 servings of treatment per day; specifically, once immediately before and after training and between meals on nontraining days. Blood collection, one repetition maximum (1RM) testing for bench press and hack squat, and body composition assessment using dual-energy x-ray absorptiometry (DXA) occurred prior to training and 48 hours following the last training session. RESULTS: Total body skeletal muscle mass increased in all groups (p < 0.0125). There were similar between-group increases in upper-body (4%-7%, analysis of covariance [ANCOVA] interaction p = 0.73) and lower-body (24%-35%, ANCOVA interaction p = 0.85) 1RM strength following the intervention. Remarkably, WPH reduced fat mass (-6%), which was significantly different from PLA (+4.4%, p < 0.0125). No time or between-group differences were present for serum markers of health, metabolism, or muscle damage, with the exception of blood urea nitrogen being significantly lower for WPH than WPC (p < 0.05) following the intervention. CONCLUSIONS: WPH may augment fat loss but did not provide any other advantages when used in combination with resistance training. More mechanistic research is needed to examine how WPH affects adipose tissue physiology.

Whey protein-derived exosomes increase protein synthesis and hypertrophy in C2-C12 myotubes.

We sought to examine potential amino acid independent mechanisms whereby hydrolyzed whey protein (WP) affects muscle protein synthesis (MPS) and anabolism in vitro. Specifically, we tested (1) whether 3-h and 6-h treatments of WP, essential amino acids, or l-leucine (Leu) affected MPS, and whether 6-h treatments with low-, medium-, or high doses of WP versus Leu affected MPS; (2) whether knockdown of the primary Leu transporter affected WP- and Leu-mediated changes in MPS, mammalian target of rapamycin (mTOR) signaling responses, or both, following 6-h treatments; (3) whether exosomes isolated from WP (WP-EXO) affected MPS, mTOR signaling responses, or both, compared with untreated (control) myotubes, following 6-h, 12-h, and 24-h treatments, and whether they affected myotube diameter following 24-h and 48-h treatments. For all treatments, 7-d post-differentiated C2C12 myotubes were examined. In experiment 1, 6-h WP treatments increased MPS compared with control (+46%), Leu (+24%), and essential amino acids (+25%). Moreover, the 6-h low-, medium-, and high WP treatments increased MPS by approximately 40 to 50% more than corresponding Leu treatments. In experiment 2 (LAT short hairpin RNA-transfected myotubes), 6-h WP treatments increased MPS compared with control (+18%) and Leu (+19%). In experiment 3, WP-EXO treatments increased MPS over controls at 12h (+18%) and 24h (+45%), and myotube diameters increased with 24-h (+24%) and 48-h (+40%) WP-EXO treatments compared with controls. The WP-EXO treatments did not appear to operate through mTOR signaling; instead, they increased mRNA and protein levels o eukaryotic initiation factor 4A. Bovine-specific microRNA following 24-h WP-EXO treatments were enriched in myotubes (chiefly miR-149-3p, miR-2881), but were not related to hypertrophic gene targets. To summarize, hydrolyzed WP-EXO increased skeletal MPS and anabolism in vitro, and this may be related to an unknown mechanism that increases translation initiation factors rather than enhancing mTOR signaling or the involvement of bovine-specific microRNA.

Western diet-induced hepatic steatosis and alterations in the liver transcriptome in adult Brown-Norway rats.

BACKGROUND: The purpose of this study was to investigate the effects of sub-chronic high fat, high sucrose diet (also termed 'Westernized diet' or WD) feeding on the liver transcriptome during early nonalcoholic fatty liver disease (NAFLD) development. METHODS: Brown Norway male rats (9 months of age) were randomly assigned to receive ad libitum access to a control (CTL; 14 % kcal fat, 1.2 % sucrose by weight) diet or WD (42 % kcal from fat, 34 % sucrose by weight) for 6 weeks. RESULTS: Six weeks of WD feeding caused hepatic steatosis development as evidenced by the 2.25-fold increase in liver triacylglycerol content, but did not induce advanced liver disease (i.e., no overt inflammation or fibrosis) in adult Brown Norway rats. RNA deep sequencing (RNA-seq) revealed that 94 transcripts were altered in liver by WD feeding (46 up-, 48 down-regulated, FDR < 0.05). Specifically, the top differentially regulated gene network by WD feeding was 'Lipid metabolism, small molecular biochemistry, vitamin and mineral metabolism' (Ingenuity Pathway Analysis (IPA) score 61). The top-regulated canonical signaling pathway in WD-fed rats was the 'Superpathway of cholesterol biosynthesis' (10/29 genes regulated, p = 1.68E-17), which coincides with a tendency for serum cholesterol levels to increase in WD-fed rats (p = 0.09). Remarkably, liver stearoyl-CoA desaturase (Scd) mRNA expression was by far the most highly-induced transcript in WD-fed rats (approximately 30-fold, FDR = 0.01) which supports previous literature underscoring this gene as a crucial target during NAFLD development. CONCLUSIONS: In summary, sub-chronic WD feeding appears to increase hepatic steatosis development over a 6-week period but only induces select inflammation-related liver transcripts, mostly acute phase response genes. These findings continue to outline the early stages of NAFLD development prior to overt liver inflammation and advanced liver disease.

Novel Energy Drink Improves Cognitive Function and Mood, without Influencing Myocardial Oxygen Demand or Ventricular Repolarization in Adult Gamers: A Randomized, Double-Blind, Placebo-Controlled, Crossover Trial.

OBJECTIVES: To examine the efficacy of acute consumption of a novel energy drink (C4S) versus placebo for improving cognitive and gaming performance and mood. Secondarily, we examined the cardiovascular safety profile of acute C4S consumption. METHODS: Forty-five healthy, young adult video gamers completed two experimental visits in randomized order where they consumed either C4S or a placebo and then completed a validated battery of neurocognitive tests, played five video games, and completed a mood state survey. Blood pressure (BP), heart rate (HR), oxygen saturation, and electrocardiogram measurements were taken at baseline and repeated throughout each visit. RESULTS: Acute consumption of C4S improved cognitive flexibility (absolute mean or median difference [95% CI] = +4.3 [2.2-6.4]; p < 0.001; d = 0.63), executive function (+4.3 [2.3-6.3]; p < 0.001; d = 0.63), sustained attention (+2.1 [0.6-3.6]; p = 0.01; d = 0.44), motor speed (+2.9 [0.8-4.9]; p < 0.001; d = 0.44), psychomotor speed (+3.9 [0.1-7.7]; p = 0.04; d = 0.32) working memory (+1.0 [0.1-1.9]; p = 0.02; d = 0.35), and performance in the two-dimensional visuospatial game Tetris (+463 [-419-2,065] pts; p = 0.049; d = 0.30) compared to placebo. C4S also improved Fatigue-Inertia (-1 [-3-0]; p = 0.004; d = 0.45), Vigor-Activity (+2.4 [1.3-3.6]; p < 0.001; d = 0.64), Friendliness (+0 [0-1]; p = 0.04; d = 0.32), and Total Mood Disturbance (-3 [-6-0]; p = 0.002; d = 0.44). BP increased slightly in C4S versus placebo, while HR decreased from baseline to post-drink in the C4S condition. Rate-pressure-product was higher in C4S versus placebo independent of time but did not increase from baseline. There was no effect on corrected QT interval. CONCLUSION: Acute consumption of C4S was efficacious for cognitive performance, visuospatial gaming performance, and mood enhancement, and had no effect on myocardial oxygen demand or ventricular repolarization, despite being associated with increases in BP.

The effects of a sugar-free amino acid-containing electrolyte beverage on 5-kilometer performance, blood electrolytes, and post-exercise cramping versus a conventional carbohydrate-electrolyte sports beverage and water.

OBJECTIVE: The purpose of this study was to examine the acute effects of a multi-ingredient, low calorie dietary supplement (MIDS, XTEND® Healthy Hydration) on 5-kilometer (5-km) time trial performance and blood electrolyte concentrations compared to a carbohydrate-electrolyte beverage (CE, GATORADE® Thirst Quencher) and distilled water (W). METHODS: During visit 1 (V1), participants (10 men and 10 women, 20-35 years old, BMI ≤ 29 kg/m2, recreationally active) reported to the laboratory whereby the following tests were performed: i) height and weight measurements, ii) body composition analysis, iii) treadmill testing to measure maximal aerobic capacity, and iv) 5-km time trial familiarization. The second visit (V2) was one week after V1 in the morning (0600 - 0900) and participants arrived 12-14 h fasted (no food or drink). The first battery of assessments (V2-T1) included nude body mass, urine specific gravity (USG), a profile of mood states (POMS) questionnaire, and the completion of a visual analogue scale (VAS) questionnaire to quantify cramping. Then heart rate (HR), blood pressure (BP), total body hydration (via bioelectrical impedance spectroscopy [BIS]) were examined. Finally, a measurement of blood markers via finger stick was performed. Participants consumed a randomized beverage (16 fl. oz. of MIDS, 16 fl. oz. of W, or 16 fl. oz. of CE) within 3 min followed by a 45-min rest. Following the rest period, a second battery (V2-T2) was performed whereby participants' USG was assessed and they completed the POMS and VAS questionnaires, and HR, BP, and blood markers were measured. The participants then performed a 5-km treadmill time trial. Immediately following the 5-km time trial, participants completed a third testing battery (V2-T3) that began with blood markers, HR and BP assessments, followed by nude body weight assessment, and the POMS and VAS questionnaires. After 60 min, a fourth battery (V2-T4) was performed that included HR, BP, and blood markers. After sitting quietly for another 60 min a fifth battery assessment was performed (V2-T5) that included participants' USG, POMS and VAS questionnaires, HR, BP, blood markers, and total body hydration. Visits 3 (V3) and 4 (V4) followed the same protocol except a different randomized drink (16 oz. of CE, MIDS, or W) was consumed; all of which were separated by approximately one week. RESULTS: No differences occurred between conditions for 5-km time trial completion, indirect calorimetry outcomes during 5-km time trials, USG, or nude mass measurements (p > 0.05 for all relevant statistical tests). However, blood potassium and the sodium/potassium ratio displayed significant interactions (p < 0.05), and post hoc testing indicated these values were better maintained in the MIDS versus other conditions. Post-exercise cramp prevalence was greater in the CE (p < 0.05) and trended higher with W (p = 0.083) compared to the MIDS condition. Post-exercise cramp severity was also elevated with the W and CE beverages (p < 0.05) but not the MIDS (p = 0.211). CONCLUSIONS: The MIDS did not affect 5-km time trial performance but exhibited favorable effects on blood electrolyte and post-exercise self-reporting cramp outcomes compared to the CE and W drinks.

Acute effects of commercial energy drink consumption on exercise performance and cardiovascular safety: a randomized, double-blind, placebo-controlled, crossover trial.

The aim of this study was to examine the acute effects of a non-caloric energy drink (C4E) compared to a traditional sugar-containing energy drink (MED) and non-caloric placebo (PLA) on exercise performance and cardiovascular safety. Thirty healthy, physically active males (25 ± 4 y) completed three experimental visits under semi-fasted conditions (5-10 h) and in randomized order, during which they consumed C4E, MED, or PLA matched for volume, appearance, taste, and mouthfeel. One hour after drink consumption, participants completed a maximal, graded exercise test (GXT) with measurement of pulmonary gases, an isometric leg extension fatigue test (ISOFTG), and had their cardiac electrical activity (ECG), leg blood flow (LBF), and blood pressure (BP) measured throughout the visit. Neither MED nor C4E had an ergogenic effect on maximal oxygen consumption, time to exhaustion, or peak power during the GXT (p > 0.05). Compared to PLA, MED reduced fat oxidation (respiratory exchange ratio (RER) +0.030 ± 0.01; p = 0.026) during the GXT and did not influence ISOFTG performance. Compared to PLA, C4E did not alter RER (p = 0.94) and improved impulse during the ISOFTG (+0.658 ± 0.25 V·s; p = 0.032). Relative to MED, C4E did not significantly improve gas exchange threshold (p = 0.05-0.07). Both MED and C4E increased systolic BP at rest (+7.1 ± 1.2 mmHg; p < 0.001 and + 5.7 ± 1.0 mmHg; p < 0.001, respectively), C4E increased SBP post-GXT (+13.3 ± 3.8 mmHg; p < 0.001), and MED increased SBP during recovery (+3.2 ± 1.1 mmHg; p < 0.001). Neither MED nor C4E influenced ECG measures (p ≥ 0.08) or LBF (p = 0.37) compared to PLA. C4E may be more efficacious for improving performance in resistance-type tasks without altering fat oxidation under semi-fasted conditions during fatiguing exercise bouts, but promotes similar changes in BP and HR to MED.

Mechanical scale and load cell underwater weighing: a comparison of simultaneous measurements and the reliability of methods.

Both load cell and mechanical scale-based hydrostatic weighing (HW) systems are used for the measurement of underwater weight. However, there has been no direct comparison of the 2 methods. The purpose of the current investigation was to simultaneously compare a load cell and mechanical scale for use in HW. Twenty-seven men and women (mean ± SD, age: 22 ± 2 years) participated in the 2-day investigation. Each subject completed 2 HW assessments 24 hours apart. Single-day comparisons of all trials for both days revealed no significant difference between the mechanical scale and the load cell (mean difference < 0.016 kg, p > 0.05). True underwater weight values were not significantly different between methods for either days (mean difference < 0.014 kg, p > 0.05) and accounted for a mean difference in percent fat (%FAT) of <0.108%. The 95% limits of agreement indicated a maximum difference between methods of 0.53% FAT. Both methods produced similar reliability SEM values (mechanical SEM < 0.72%FAT, load cell SEM < 0.75%FAT). In conclusion, there was no difference between mechanical scale and load cell measurements of underwater weights and the added precision of the load cell only marginally (<0.16%FAT) improved day-to-day reliability. Either a mechanical scale or load cell can be used for HW with similar accuracy and reliability in young adults with a body mass index of 18.7-34.4 (5-25%FAT).

Reproducibility and validity of bioimpedance spectroscopy for tracking changes in total body water: implications for repeated measurements.

Bioimpedance spectroscopy (BIS) has been used to track changes in total body water (TBW). Accurate TBW estimations can be influenced by both methodological and biological factors. One methodological variation that contributes to BIS TBW errors is the electrode placement. The purpose of the present study was to compare the reproducibility and validity of fixed-distance electrode placements (5 cm) with the standard single-site electrode placements. Twenty-nine subjects (fifteen men and fourteen women) participated in the reproducibility study, while sixty-nine subjects (thirty-three men and thirty-six women) participated in the validity study. The reproducibility study included two measurements that were taken 24 h apart, while the validity study consisted of a 12-week exercise intervention with measurements taken at weeks 1 and 12. TBW was estimated using BIS and 2H techniques. Reproducibility results indicated that fixed-distance electrodes reduced the day-to-day standard error of the measurement in men (from 1·13 to 0·81 litres) but not in women (0·47 litres). sem values were lower for women than for men, suggesting that BIS TBW estimates are sex dependent. Validity results produced similar accurate findings (mean difference < 0·21 litres). However, fixed-distance electrodes improved delta TBW errors (mean difference improvements>0·04 litres in men, women, and men and women combined). When tracking changes in TBW, fixed-distance electrodes may reduce reproducibility errors and allow for smaller changes to be detected. However, the reduction of reproducibility errors may be greater for men than for women. Therefore, reproducibility calculations should be based on the sex of the sample population.

Low-calorie energy drink improves physiological response to exercise in previously sedentary men: a placebo-controlled efficacy and safety study.

Energy drink use has grown despite limited research to support efficacy or safety and amid concerns when combined with exercise. The purpose of this study was to assess the effects of 10 weeks of once-daily energy drink consumption or energy drink consumption with exercise on measures of body composition, cardiorespiratory fitness, strength, mood, and safety in previously sedentary males. Thirty-eight males were randomly assigned to energy drink + exercise (EX-A), energy drink (NEX-A), placebo + exercise (EX-B), or placebo (NEX-B). All participants consumed 1 drink per day for 10 weeks; EX-A and EX-B participated in 10 weeks of resistance and endurance exercise. Testing was performed before (PRE) and after (POST) the 10-week intervention. No significant (p > 0.05) changes were observed for body composition, fitness, or strength in NEX-A; however, significantly greater decreases in fat mass and percentage body fat and increases in VO2peak were observed in EX-A versus EX-B. Ventilatory threshold (VT), minute ventilation, VO2 at VT, and power output at VT improved significantly PRE to POST in EX-A but not in EX-B or nonexercising groups. Clinical markers for hepatic, renal, cardiovascular, and immune function, as determined by PRE and POST blood work revealed no adverse effects in response to the energy drink. Mood was not affected by energy drink use. Absent energy restriction or other dietary controls, chronic ingestion of a once-daily low-calorie energy drink appears ineffective at improving body composition, cardiorespiratory fitness, or strength in sedentary males. However, when combined with exercise, preworkout energy drink consumption may significantly improve some physiological adaptations to combined aerobic and resistance training.

Validity of electromyographic fatigue threshold as a noninvasive method for tracking changes in ventilatory threshold in college-aged men.

The submaximal electromyographic fatigue threshold test (EMG(FT)) has been shown to be highly correlated to ventilatory threshold (VT) as determined from maximal graded exercise tests (GXTs). Recently, a prediction equation was developed using the EMG(FT) value to predict VT. The aim of this study, therefore, was to determine if this new equation could accurately track changes in VT after high-intensity interval training (HIIT). Eighteen recreationally trained men (mean +/- SD; age 22.4 +/- 3.2 years) performed a GXT to determine maximal oxygen consumption rate (V(O2)peak) and VT using breath-by-breath spirometry. Participants also completed a discontinuous incremental cycle ergometer test to determine their EMGFT value. A total of four 2-minute work bouts were completed to obtain 15-second averages of the electromyographic amplitude. The resulting slopes from each successive work bout were used to calculate EMG(FT). The EMG(FT) value from each participant was used to estimate VT from the recently developed equation. All participants trained 3 days a week for 6 weeks. Training consisted of 5 sets of 2-minute work bouts with 1 minute of rest in between. Repeated-measures analysis of variance indicated no significant difference between actual and predicted VT values after 3 weeks of training. However, there was a significant difference between the actual and predicted VT values after 6 weeks of training. These findings suggest that the EMG(FT) may be useful when tracking changes in VT after 3 weeks of HIIT in recreationally trained individuals. However, the use of EMG(FT) to predict VT does not seem to be valid for tracking changes after 6 weeks of HIIT. At this time, it is not recommended that EMG(FT) be used to predict and track changes in VT.

The effects of beta-alanine supplementation and high-intensity interval training on neuromuscular fatigue and muscle function.

The purpose of this study was to determine the effects of beta-alanine supplementation and high-intensity interval training (HIIT) on electromyographic fatigue threshold (EMG(FT)) and efficiency of electrical activity (EEA). A total of 46 men completed four, 2-min work bouts on a cycle ergometer. Using bipolar surface electrodes, the EMG amplitude was averaged and plotted over the 2-min. The resulting slopes were used to calculate EMG(FT) and EEA. Following initial testing, all participants were randomly assigned to either placebo (PL; n = 18), beta-alanine (BA; n = 18) or control groups (CON; n = 10). Following randomization, participants engaged in 6 weeks of HIIT training. Significant improvements in EMG(FT) and EEA resulted for both training groups. In conclusion, HIIT appeared to be the primary stimulus effecting EMG(FT) or EEA, suggesting adaptations from HIIT may be more influential than increasing skeletal muscle carnosine levels on delaying fatigue in recreationally active men.

Estimating body fat in NCAA Division I female athletes: a five-compartment model validation of laboratory methods.

The purpose of the present study was to determine the validity of various laboratory methods for estimating percent body fat (%fat) in NCAA Division I college female athletes (n = 29; 20 +/- 1 year). Body composition was assessed via hydrostatic weighing (HW), air displacement plethysmography (ADP), and dual-energy X-ray absorptiometry (DXA), and estimates of %fat derived using 4-compartment (C), 3C, and 2C models were compared to a criterion 5C model that included bone mineral content, body volume (BV), total body water, and soft tissue mineral. The Wang-4C and the Siri-3C models produced nearly identical values compared to the 5C model (r > 0.99, total error (TE) < 0.40%fat). For the remaining laboratory methods, constant error values (CE) ranged from -0.04%fat (HW-Siri) to -3.71%fat (DXA); r values ranged from 0.89 (ADP-Siri, ADP-Brozek) to 0.93 (DXA); standard error of estimate values ranged from 1.78%fat (DXA) to 2.19%fat (ADP-Siri, ADP-Brozek); and TE values ranged from 2.22%fat (HW-Brozek) to 4.90%fat (DXA). The limits of agreement for DXA (-10.10 to 2.68%fat) were the largest with a significant trend of -0.43 (P < 0.05). With the exception of DXA, all of the equations resulted in acceptable TE values (<3.08%fat). However, the results for individual estimates of %fat using the Brozek equation indicated that the 2C models that derived BV from ADP and HW overestimated (5.38, 3.65%) and underestimated (5.19, 4.88%) %fat, respectively. The acceptable TE values for both HW and ADP suggest that these methods are valid for estimating %fat in college female athletes; however, the Wang-4C and Siri-3C models should be used to identify individual estimates of %fat in this population.

The relationships among endurance performance measures as estimated from VO2PEAK, ventilatory threshold, and electromyographic fatigue threshold: a relationship design.

BACKGROUND: The use of surface electromyography has been accepted as a valid, non-invasive measure of neuromuscular fatigue. In particular, the electromyographic fatigue threshold test (EMG(FT)) is a reliable submaximal tool to identify the onset of fatigue. This study examined the metabolic relationship between VO(2PEAK), ventilatory threshold (VT), and the EMGFT, as well as compared the power output at VO(2PEAK), VT, and EMG(FT). METHODS: Thirty-eight college-aged males (mean +/- SD = 22.5 +/- 3.5 yrs) performed an incremental test to exhaustion on an electronically-braked cycle ergometer for the determination of VO(2PEAK) and VT. Each subject also performed a discontinuous incremental cycle ergometer test to determine their EMG(FT) value, determined from bipolar surface electrodes placed on the longitudinal axis of the vastus lateralis of the right thigh. Subjects completed a total of four, 2-minute work bouts (ranging from 75-325 W). Adequate rest was given between bouts to allow for subjects' heart rate to drop within 10 beats of their resting heart rate. The EMG amplitude was averaged over 10-second intervals and plotted over the 2-minute work bout. The resulting slopes from each successive work bout were used to calculate EMG(FT). RESULTS: Power outputs and VO2 values from each subject's incremental test to exhaustion were regressed. The linear equations were used to compute the VO2 value that corresponded to each fatigue threshold. Two separate one-way repeated measure ANOVAs indicated significant differences (p < 0.05) among metabolic parameters and power outputs. However, the mean metabolic values for VT (1.90 +/- 0.50 l.min-1) and EMG(FT)VO2(1.84 +/- 0.53 l.min-1) were not significantly different (p > 0.05) and were highly correlated (r = 0.750). Furthermore, the mean workload at VT was 130.7 +/- 37.8 W compared with 134.1 +/- 43.5 W at EMG(FT) (p > 0.05) with a strong correlation between the two variables (r = 0.766). CONCLUSION: Metabolic measurements, as well as the power outputs at VT and EMG(FT), were strongly correlated. The significant relationship between VT and EMG(FT) suggests that both procedures may reflect similar physiological factors associated with the onset of fatigue. As a result of these findings, the EMG(FT) test may provide an attractive alternative to estimating VT.

Impact of Protein and Carbohydrate Supplementation on Musculoskeletal Injuries in Army Initial Entry Training Soldiers.

This project investigated whey protein and/or carbohydrate supplementation effects on musculoskeletal injury (MSI) outcomes. Four groups of Initial Entry Training soldiers consumed either: (1) one protein (38.6 g, 293 kcal); (2) one carbohydrate (63.4 g, 291 kcal); (3) two protein (77.2 g, 586 kcal); or (4) two carbohydrate servings/day (126.8 g, 582 kcal) after physical training and before bed, or before bed only. Odds Ratio, Chi-square and Wilcoxon ranked-sum test compared supplementation/no supplementation, number of servings, and protein/carbohydrate for MSI and limited/missed duty rates and limited/missed training days. Non-matched pairs group averages were compared to 2015/2016 historical data. Non-supplemented soldiers were approximately 5× more likely to sustain a MSI (χ2 = 58.48, p < 0.001) and 4× more likely to miss training (χ2 = 9.73, p = 0.003) compared to two servings. Non-supplemented soldiers missed five additional training days compared to two servings (W = 6059.5, p = 0.02). Soldiers consuming one serving were approximately 3× more likely to sustain a MSI than two servings (χ2 = 9.55, p = 0.002). There was no difference in limited/missed duty rates or limited/missed training days between consuming one or two servings. There was no difference between consuming one serving versus no supplementation or protein versus carbohydrate supplementation for any outcome variable. Soldiers consuming 2 servings/day of protein or carbohydrate had lower MSI rates, limited/missed duty rates, and limited/ missed training days compared to non-supplemented soldiers.

Effect of Whey Protein Supplementation on Physical Performance and Body Composition in Army Initial Entry Training Soldiers.

We investigated the effects of whey protein (WP) supplementation on body composition and physical performance in soldiers participating in Army Initial Entry Training (IET). Sixty-nine, male United States Army soldiers volunteered for supplementation with either twice daily whey protein (WP, 77 g/day protein, ~580 kcal/day; n = 34, age = 19 ± 1 year, height = 173 ± 6 cm, weight = 73.4 ± 12.7 kg) or energy-matched carbohydrate (CHO) drinks (CHO, 127 g/day carbohydrate, ~580 kcal/day; n = 35, age = 19 ± 1 year, height = 173 ± 5 cm, weight = 72.3 ± 10.9 kg) for eight weeks during IET. Physical performance was evaluated using the Army Physical Fitness Test during weeks two and eight. Body composition was assessed using 7-site skinfold assessment during weeks one and nine. Post-testing push-up performance averaged 7 repetitions higher in the WP compared to the CHO group (F = 10.1, p < 0.001) when controlling for baseline. There was a significant decrease in fat mass at post-training (F = 4.63, p = 0.04), but no significant change in run performance (F = 3.50, p = 0.065) or fat-free mass (F = 0.70, p = 0.41). Effect sizes for fat-free mass gains were large for both the WP (Cohen's d = 0.44) and CHO (Cohen's d = 0.42) groups. WP had a large effect on fat mass (FM) loss (Cohen's d = -0.67), while CHO had a medium effect (Cohen's d = -0.40). Twice daily supplementation with WP improved push-up performance and potentiated reductions in fat mass during IET training in comparison to CHO supplementation.

Skeletal muscle mitochondrial volume and myozenin-1 protein differences exist between high versus low anabolic responders to resistance training.

BACKGROUND: We sought to examine how 12 weeks of resistance exercise training (RET) affected skeletal muscle myofibrillar and sarcoplasmic protein levels along with markers of mitochondrial physiology in high versus low anabolic responders. METHODS: Untrained college-aged males were classified as anabolic responders in the top 25th percentile (high-response cluster (HI); n = 13, dual x-ray absorptiometry total body muscle mass change (Δ) = +3.1 ± 0.3 kg, Δ vastus lateralis (VL) thickness = +0.59 ± 0.05 cm, Δ muscle fiber cross sectional area = +1,426 ± 253 µm2) and bottom 25th percentile (low-response cluster (LO); n = 12, +1.1 ± 0.2 kg, +0.24 ± 0.07 cm, +5 ± 209 µm2; p < 0.001 for all Δ scores compared to HI). VL muscle prior to (PRE) and following RET (POST) was assayed for myofibrillar and sarcoplasmic protein concentrations, myosin and actin protein content, and markers of mitochondrial volume. Proteins related to myofibril formation, as well as whole lysate PGC1-α protein levels were assessed. RESULTS: Main effects of cluster (HI > LO, p = 0.018, Cohen's d = 0.737) and time (PRE > POST, p = 0.037, Cohen's d = -0.589) were observed for citrate synthase activity, although no significant interaction existed (LO PRE = 1.35 ± 0.07 mM/min/mg protein, LO POST = 1.12 ± 0.06, HI PRE = 1.53 ± 0.11, HI POST = 1.39 ± 0.10). POST myofibrillar myozenin-1 protein levels were up-regulated in the LO cluster (LO PRE = 0.96 ± 0.13 relative expression units, LO POST = 1.25 ± 0.16, HI PRE = 1.00 ± 0.11, HI POST = 0.85 ± 0.12; within-group LO increase p = 0.025, Cohen's d = 0.691). No interactions or main effects existed for other assayed markers. DISCUSSION: Our data suggest myofibrillar or sarcoplasmic protein concentrations do not differ between HI versus LO anabolic responders prior to or following a 12-week RET program. Greater mitochondrial volume in HI responders may have facilitated greater anabolism, and myofibril myozenin-1 protein levels may represent a biomarker that differentiates anabolic responses to RET. However, mechanistic research validating these hypotheses is needed.

Biomarkers associated with low, moderate, and high vastus lateralis muscle hypertrophy following 12 weeks of resistance training.

We sought to identify biomarkers which delineated individual hypertrophic responses to resistance training. Untrained, college-aged males engaged in full-body resistance training (3 d/wk) for 12 weeks. Body composition via dual x-ray absorptiometry (DXA), vastus lateralis (VL) thickness via ultrasound, blood, VL muscle biopsies, and three-repetition maximum (3-RM) squat strength were obtained prior to (PRE) and following (POST) 12 weeks of training. K-means cluster analysis based on VL thickness changes identified LOW [n = 17; change (mean±SD) = +0.11±0.14 cm], modest (MOD; n = 29, +0.40±0.06 cm), and high (HI; n = 21, +0.69±0.14 cm) responders. Biomarkers related to histology, ribosome biogenesis, proteolysis, inflammation, and androgen signaling were analyzed between clusters. There were main effects of time (POST>PRE, p<0.05) but no cluster×time interactions for increases in DXA lean body mass, type I and II muscle fiber cross sectional area and myonuclear number, satellite cell number, and macronutrients consumed. Interestingly, PRE VL thickness was ~12% greater in LOW versus HI (p = 0.021), despite POST values being ~12% greater in HI versus LOW (p = 0.006). However there was only a weak correlation between PRE VL thickness scores and change in VL thickness (r2 = 0.114, p = 0.005). Forced post hoc analysis indicated that muscle total RNA levels (i.e., ribosome density) did not significantly increase in the LOW cluster (351±70 ng/mg to 380±62, p = 0.253), but increased in the MOD (369±115 to 429±92, p = 0.009) and HI clusters (356±77 to 470±134, p<0.001; POST HI>POST LOW, p = 0.013). Nonetheless, there was only a weak association between change in muscle total RNA and VL thickness (r2 = 0.079, p = 0.026). IL-1ß mRNA levels decreased in the MOD and HI clusters following training (p<0.05), although associations between this marker and VL thickness changes were not significant (r2 = 0.0002, p = 0.919). In conclusion, individuals with lower pre-training VL thickness values and greater increases muscle total RNA levels following 12 weeks of resistance training experienced greater VL muscle growth, although these biomarkers individually explained only ~8-11% of the variance in hypertrophy.

Author Correction: Soy protein supplementation is not androgenic or estrogenic in college-aged men when combined with resistance exercise training.

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Soy protein supplementation is not androgenic or estrogenic in college-aged men when combined with resistance exercise training.

It is currently unclear as to whether sex hormones are significantly affected by soy or whey protein consumption. Additionally, estrogenic signaling may be potentiated via soy protein supplementation due to the presence of phytoestrogenic isoflavones. Limited also evidence suggests that whey protein supplementation may increase androgenic signaling. Therefore, the purpose of this study was to examine the effects of soy protein concentrate (SPC), whey protein concentrate (WPC), or placebo (PLA) supplementation on serum sex hormones, androgen signaling markers in muscle tissue, and estrogen signaling markers in subcutaneous (SQ) adipose tissue of previously untrained, college-aged men (n = 47, 20 ± 1 yrs) that resistance trained for 12 weeks. Fasting serum total testosterone increased pre- to post-training, but more so in subjects consuming WPC (p < 0.05), whereas serum 17ß-estradiol remained unaltered. SQ estrogen receptor alpha (ERα) protein expression and hormone-sensitive lipase mRNA increased with training regardless of supplementation. Muscle androgen receptor (AR) mRNA increased while ornithine decarboxylase mRNA (a gene target indicative of androgen signaling) decreased with training regardless of supplementation (p < 0.05). No significant interactions of supplement and time were observed for adipose tissue ERα/ß protein levels, muscle tissue AR protein levels, or mRNAs in either tissue indicative of altered estrogenic or androgenic activity. Interestingly, WPC had the largest effect on increasing type II muscle fiber cross sectional area values (Cohen's d = 1.30), whereas SPC had the largest effect on increasing this metric in type I fibers (Cohen's d = 0.84). These data suggest that, while isoflavones were detected in SPC, chronic WPC or SPC supplementation did not appreciably affect biomarkers related to muscle androgenic signaling or SQ estrogenic signaling. The noted fiber type-specific responses to WPC and SPC supplementation warrant future research.