Context : Short daily surveys are common in elite sports to capture psychological outcomes, but there is no information on the surveys convergent validity and test–retest reliability. Therefore, the purpose of this study is to determine the validity and test–retest reliability of daily athlete health surveys in collegiate athletes. Design : Descriptive study. Methods : Participants (n = 193, 74 males and 119 females; age = 20.3 [1.4] y) responded daily to sliding scale questions regarding readiness (scored from 0 to 100), fatigue, stress, and sleep quality (−5 [indicating low or poor scores] to +5 [indicating high or “good” scores]). At pre- and midseason times, participants completed the Perceived Stress Scale, Pittsburgh Sleep Quality Index, Athlete Sleep Screening Questionnaire, Overuse Injury Scale, and the Acute Recovery and Stress Scale. To assess validity, Spearman rho ( ρ ) correlation coefficients were used to assess the relationship between each athlete health variable and the corresponding validated survey. Reliability and precision were assessed with the intraclass correlation coefficient and the standard error of measurement, respectively. Results : Daily stress was correlated with the Perceived Stress Scale ( ρ = −.40, P < .001); daily sleep quality was associated with the Pittsburgh Sleep Quality Index ( ρ = −.44, P < .001) and the Athlete Sleep Screening Questionnaire ( ρ = −0.46, P < .001), and daily readiness was associated with the Overuse Injury Scale ( ρ = −.21, P = .003). Daily fatigue was associated with the recovery ( ρ = .37, P < .001) and stress dimensions ( ρ = −.36, P < .001) of the Acute Recovery and Stress Scale. All daily athlete health variables demonstrated either good or excellent reliability (intraclass correlation coefficient = .85–.94; standard error of measurement = 0.87–4.94). Conclusions : All daily health variables demonstrated acceptable reliability and precision. Sleep quality and stress were most strongly correlated with the outcome scores of their validated surveys. Fatigue was related to the Acute Recovery and Stress Scale, and readiness demonstrated a weak correlation to the Overuse Injury Scale. Clinicians should feel comfortable using these single-question daily health surveys in clinical care but exert caution when using readiness, and fatigue.

OBJECTIVE:To compare soreness location and intensity between male and female soccer athletes across 2 competitive seasons. DESIGN:Descriptive Cohort Study. SETTING:Collegiate Sports Medicine Facility. PARTICIPANTS:Forty male and 42 female collegiate soccer athletes. INTERVENTION:Season-long soccer trainings and games. MAIN OUTCOME MEASURES:Athletes reported perceived soreness location and intensity daily. χ 2 analysis and linear mixed effect models were used to compare soreness locations and intensities by sex. RESULTS:Male and female soccer athletes reported similar number of soreness instances, but male soccer athletes reported soreness more frequently at the ankle, foot, hip, pelvis, and posterior thigh. Female soccer athletes reported soreness more frequently at the anterior leg, anterior thigh, and knee. There was no significant difference in soreness intensity between sexes at any body location ( P = 0.86). When collapsed across sex, the frequency of anterior thigh soreness was higher at preseason (7.49%, CI: 5.46-9.52) than at midseason (4.55%, CI: 2.52-6.57; t = -2.94, P = 0.023) and at postseason (3.00%, CI: 0.76-5.23; t = -3.74, P < 0.001). There was also a significant difference in hip soreness frequency between the preseason (2.35%, CI: 1.32-3.33) and the postseason time points (0.52%, CI: -0.73% to 1.67%; t = -2.68, P = 0.023). CONCLUSIONS:Male and female athletes differ in the locations of their lower extremity soreness. However, lower extremity soreness intensity does not differ between sexes. Soccer athletes report soreness more frequently during the preseason and midseason than during the postseason. With tools to measure daily soreness location and intensity, clinicians could create targeted interventions to reduce soreness and limit its negative affect.

OBJECTIVE:This study investigated reliability and validity of muscle cross-sectional area and echo intensity using an automatic image analysis program. METHODS:Twenty-two participants completed two data collection trials consisting of ultrasound imaging of the vastus lateralis (VL) at 10 and 12 MHz. Images were analyzed manually and with Deep Anatomical Cross-Sectional Area (DeepACSA). Reliability statistics (i.e., intraclass correlation coefficient [ICC] model 2,1, standard error of measure expressed as a percentage of the mean [SEM%], minimal differences [MD] values needed to be considered real) and validity statistics (i.e., constant error [CE], total error [TE], standard error of the estimate [SEE]) were calculated. RESULTS:Automatic analyses of ACSA and EI demonstrated good reliability (10 MHz: ICC2,1 = 0.83 - 0.90; 12 MHz: ICC2,1 = 0.87-0.88), while manual analyses demonstrated moderate to excellent reliability (10 MHz: ICC2,1 = 0.82-0.99; 12 MHz: ICC2,1 = 0.73-0.99). Automatic analyses of ACSA presented greater error at 10 (CE = -0.76 cm2, TE = 4.94 cm2, SEE = 3.65 cm2) than 12 MHz (CE = 0.17 cm2, TE = 3.44 cm2, SEE = 3.11 cm2). Analyses of EI presented greater error at 10 (CE = 3.35 a.u., TE = 2.70 a.u., SEE = 2.58 a.u.) than at 12 MHz (CE = 3.21 a.u., TE = 2.61 a.u., SEE = 2.34 a.u.). CONCLUSION:The results suggest the DeepACSA program may be less reliable compared to manual analysis for VL ACSA but displayed similar reliability for EI. In addition, the results demonstrated the automatic program had low error for 10 and 12 MHz.

ABSTRACT:Cabre, HE, Ladan, AN, Moore, SR, Joniak, KE, Blue, MNM, Pietrosimone, BG, Hackney, AC, and Smith-Ryan, AE. Effects of hormonal contraception and the menstrual cycle on fatigability and recovery from an anaerobic exercise test. J Strength Cond Res 38(7): 1256-1265, 2024-This study sought to evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with a eumenorrheic (EUM) cycle, on fatigability and recovery between hormone the phases. Peak power (PP), average power (AP), fatigue index (FI), blood lactate, vessel diameter, and blood flow (BF) were measured from a repeated sprint cycle test (10 × 6 seconds) in 60, healthy, active women (mean ± SD ; age: 26.5 ± 7.0 years, BMI: 22.5 ± 3.7 kg·m -2 ) who used monophasic OC (≥6 months; n = 21), had a H-IUD (≥6 months; n = 20), or had regular naturally occurring menstrual cycle (≥3 months) or had a nonhormonal IUD (EUM; n = 19). Subjects were randomly assigned to begin in either the low-hormone phase (LHP) or high-hormone phase (HHP) and were tested once in each phase. Separate univariate analyses of covariances assessed the change from HHP to LHP between the groups, covaried for progesterone, with significance set at p ≤ 0.05. All groups demonstrated similar changes in PP, AP, FI, blood lactate, vessel diameter, and BF between the phases ( p > 0.05). Although not significant, AP was higher in LHP for OC (Δ -248.2 ± 1,301.4 W) and EUM (Δ -19.5 ± 977.7 W) and higher in HHP for H-IUD (Δ 369.3 ± 1,123.0 W). Oral contraceptive group exhibited a higher FI (Δ 2.0%) and reduced blood lactate clearance (Δ 2.5%) in HHP. In recreationally active women, hormonal contraception and hormone phases may minimally impact fatigue and recovery. Individual elite female athletes may benefit from understanding hormonal contraception type as performance and recovery may slightly vary across the cycle.

INTRODUCTION:To evaluate the effects of oral contraceptive (OC) and hormonal intrauterine device (H-IUD) use, compared with an eumenorrheic (EUM) cycle, on maximal strength and power between hormone phases. METHODS:One-repetition maximum (1RM) leg press and bench press, peak force from knee extension and upright row isometric dynamometry, and power from vertical jump height and reactive strength index (cm·s -1 ) were measured in 60 healthy, active women (mean ± SD; age: 26.5 ± 7.0 yr, body mass index: 23.8 ± 3.0 kg·m -2 ) who were monophasic OC users for ≥6 months ( n = 21), had an H-IUD for ≥6 months ( n = 20), or had regularly naturally occurring menstrual cycle for ≥3 months or were using a nonhormonal IUD (EUM; n = 19). Participants were randomly assigned to begin in the follicular phase/placebo pill (low hormone phase (LHP)) or in the luteal phase/active pill (high hormone phase (HHP)) and were tested once in each phase. Estimates of total lean mass (LM), leg LM, and arm LM were measured via dual energy x-ray absorptiometry. Separate univariate ANCOVAs were used to assess the change from HHP to LHP between groups, with LM and progesterone as covariates. RESULTS:Leg press 1RM was significantly different across phases between groups ( P = 0.037), with higher leg press 1RM in the HHP for the OC group (mean difference [∆ HHP - LHP] ± standard error: ∆ 7.4 ± 15.9 kg; P = 0.043) compared with the H-IUD group (∆ -8.9 ± 23.8 kg; P = 0.043). All groups demonstrated similar bench press 1RM, peak force, vertical jump height, and reactive strength index between phases ( P > 0.05). CONCLUSIONS:Lower body strength was greater in the HHP for OC users (5.6% increase) suggesting that lower body maximal strength outcomes may be influenced by hormonal contraception type.

Background & aims: Total body water (TBW) is the largest component of fat free mass and therefore is commonly used in multi-compartment body composition models and as a stand-alone method to assess body composition. Previous literature has not validated bioelectrical impedance spectroscopy device estimates of TBW in racial and ethnic minority populations; previous studies have focused on bioelec-trical impedance analysis devices that rely on proprietary algorithms and participant characteristics for accuracy. The purpose of this study was to assess the validity of two bioelectrical impedance spectros-copy devices for measures of TBW compared to a deuterium dilution criterion in a multi-ethnic sample. Methods: 109 individuals (55% female, Age: 26.6 +/- 6.9 yrs, BMI: 25.3 +/- 4.0 kg/m2) identifying as Asian, African American/Black, Caucasian/White, Hispanic, and Multi-racial were enrolled. After a 12 h fast, participants provided a saliva sample for the criterion baseline TBW measure and completed two bioelectrical impedance device (BIS, IB) measurements of TBW. Participants then ingested deuterium oxide (D2O). After an equilibration period, participants provided a second saliva sample for analysis of TBW. Results: For the total multi-ethnic sample, BIS estimates demonstrated good to fairly good agreement (Total error [TE] = 2.56 L, R2 = 0.951) and IB estimates were excellent to very good (TE = 1.95 L, R2 = 0.975). Validity results did not vary meaningfully between race and ethnicity. Conclusions: The results suggest the BIS and IB devices evaluated can produce valid TBW estimates compared to D2O in a multi-ethnic sample. TBW estimates from the IB may have better agreement with D2O compared to the BIS when using the default settings. (c) 2023 European Society for Clinical Nutrition and Metabolism. Published by Elsevier Ltd. All rights reserved.

Impedance (Z), resistance (R), reactance (Xc), and phase angle (PhA) are sensitive to shifts in fluid between intra- and extracellular compartments, as would occur with nutrient uptake into skeletal muscle, but remains largely unexplored. To explore the sensitivity of whole-body and segmental (arms, legs, trunk) bioimpedance to acute feeding, 27 young adults completed three feeding conditions on separate occasions in randomized, cross-over design [high-carbohydrate (CHO), high-protein (PRO), fasted (FAST); standardized for fluid]. Bioimpedance was completed one-hour post-meal. Differences between feeding conditions at 5, 50, 250 kHz were evaluated. At 5 kHz, whole-body Xc and PhA were significantly different with CHO (p = .017), but not PRO (p = .152), compared to FAST; there were no significant differences at 50 or 250 kHz (p > .05). Segmental bioimpedance was significantly different with CHO and PRO compared to FAST [5 kHz: (Arms: Z, R, Xc,PhA; Trunk: Z, R; p <= .002), 50 kHz:(Arms: Z, R, Xc; Trunk: Z, R, Xc; p < .02), 250 kHz:(Arms: Z, R; Trunk: Z, R; Legs: PhA; p <= .009)]. Results suggest segmental bioimpedance at 5 kHz is sensitive to acute nutrition. Further exploration is warranted.

Abstract Few investigations have evaluated the validity of current body composition technology among racially and ethnically diverse populations. This study assessed the validity of common body composition methods in a multi-ethnic sample stratified by race and ethnicity. One hundred and ten individuals (55 % female, age: 26·5 (sd 6·9) years) identifying as Asian, African American/Black, Caucasian/White, Hispanic, Multi-racial and Native American were enrolled. Seven body composition models (dual-energy X-ray absorptiometry (DXA), air displacement plethysmography (ADP), two bioelectrical impedance devices (BIS, IB) and three multi-compartment models) were evaluated against a four-compartment criterion model by assessing total error (TE) and standard error of the estimate. For the total sample, measures of % fat and fat-free mass (FFM) from multi-compartment models were all excellent to ideal (% fat: TE = 0·94–2·37 %; FFM: TE = 0·72–1·78 kg) compared with the criterion. % fat measures were very good to excellent for DXA, ADP and IB (TE = 2·52–2·89 %) and fairly good for BIS (TE = 4·12 %). For FFM, single device estimates were good (BIS; TE = 3·12 kg) to ideal (DXA, ADP, IB; TE = 1·21–2·15 kg). Results did not vary meaningfully between each race and ethnicity, except BIS was not valid for African American/Black, Caucasian/White and Multi-racial participants for % fat (TE = 4·3–4·9 %). The multi-compartment models evaluated can be utilised in a multi-ethnic sample and in each individual race and ethnicity to obtain highly valid results for % fat and FFM. Estimates from DXA, ADP and IB were also valid. The BIS may demonstrate greater TE for all racial and ethnic cohorts and results should be interpreted cautiously.

Objective To explore the effects of essential amino acid (EAA) supplementation on high-intensity interval training (HIIT) fatigue, perceived exertion, and training progression in overweight and obese adults. A secondary aim was to explore potential sex-differences on these outcomes. Methods Thirty-seven untrained adults (51% female; 36.2 +/- 5.9 yrs; 35.5 +/- 6.7% body fat) completed eight weeks of HIIT, 2d/wk on a cycle ergometer, either with EAA supplementation (HIIT + EAA; 3.6 g of EAA twice daily, 30 minutes pre and post HIIT) or without supplementation (HIIT). Heart rate (HR) and ratings of perceived exertion (RPE) were recorded throughout each session as indices of within training fatigue. Time to exhaustion (TTE) was recorded for the final interval of each session. Workload progression was determined by change in watts. Differences between groups (with and without EAA) were evaluated at 1wk, 4wks, and 8wks by repeated measure ANOVAs (alpha = 0.05). Results There were no differences in TTE (p = 0.983) or workload progression (p = 0.655) with EAA supplementation at any time point. HR and RPE within HIIT sessions were not significantly different with EAA supplementation at any time point (p > 0.05). Results were similar when evaluating males and females separately, but in females, RPE was significantly lower with EAA supplementation at 4wks (Delta: 1.1-2.2; p = 0.016). Conclusion EAA supplementation did not extend TTE during exercise or enhance workload progression across eight weeks of HIIT in untrained, overweight and obese adults. However, EAA consumed 30 minutes before exercise may reduce perceived exertion during the first four weeks of training in women, which may have implications for overall exercise enjoyment and long-term adherence.

BACKGROUNDThe COVID-19 pandemic forced collegiate athletes to train at home, without access to facilities. The purpose of this study was to evaluate the effect of the COVID-19 stay-at-home order on body composition of Division I football players, with a secondary aim to evaluate these changes between players with 'higher' (>25 kg/m2) and 'lower' (<25 kg/m2) fat-free mass index (kg/m2).METHODSBody composition of 29 NCAA Division I football players (Age=21.0±10 yr, Ht=186.7±5.6 cm, body mass=110.5±22.8 kg) were measured Spring season (February) and prior to pre-season (June). Whole body dual-energy x-ray absorptiometry scans were used to determine regional (arms, legs, trunk) and total body fat mass (FM), lean mass (LM), and fat-free mass (FFM). Fat-free mass index (FFMI) was calculated as [LM+Bone Mineral Content (BMC)]/Height2); participants were stratified by FFMI higher (n=16) and lower (n=13).RESULTSTotal LM (Mean Difference ± Standard Error: 0.80 ± 1.65 kg, p=0.016) increased from pre- to post-COVID stay-at-home. No significant changes in total FM were seen. Players with lower FFMI showed a significant decrease in trunk FM (-0.55± 0.19 kg, p=0.016). Players with higher FFMI showed a significant increase in total LM (0.96±0.42 kg, p=0.038).CONCLUSIONSThese results suggest no detrimental effect on body composition.

Segmental body composition analyses provide estimates of limb-specific regional tissue distribution, and can indicate between limb asymmetries. Multifrequency bioelectrical impedance analysis (MF-BIA) is a portable method with less cost and radiation exposure than is presented by dual-energy x-ray absorptiometry (DXA). However, it is unclear if MF-BIA can identify leg fat free mass (FFM) asymmetries similar to DXA. PURPOSE: The purpose of this study was to evaluate leg FFM asymmetry between limbs as measured from MF-BIA and DXA in career firefighters. METHODS: Fifty-nine male career firefighters (mean ± SD; age 31.62 ± 7.36 yrs, stature 179.05 ± 7.60 cm, body mass 90.15 ± 17.50 kg, body mass index 28.16 ± 5.11 kg/m2) volunteered for this study. All participants were free of any neuromuscular, cardiovascular, or metabolic diseases, and had not sustained any recent or previous (within the past 3 months) musculoskeletal injuries to the lower extremity. All participants were instructed to refrain from caffeine and smokeless tobacco for 12 hours, and vigorous lower body exercise for 48 hours. Following an 8 hour fast, leg FFM was assessed via MF-BIA and a daily calibrated DXA. Paired-samples t-tests were used to determine differences between MF-BIA and the DXA criterion. Asymmetry was defined as ±3% difference between limbs as a cutoff point. Frequency of detecting asymmetry (% difference in limbs) was calculated and McNemar’s test was performed to compare asymmetry frequencies with MF-BIA and DXA. Significance was set at an alpha level of 0.05. RESULTS: MF-BIA significantly underestimated FFM of the legs (mean difference = RL: -1.4 kg; LL: -1.4 kg; BOTH: -2.7 kg; P < 0.001). MF-BIA detected 2 cases of asymmetry while DXA detected 11 cases. McNemar’s test revealed the MF-BIA and DXA (P = 0.003) asymmetry detection is different between methods. CONCLUSION: The significant underestimation of leg FFM and limited ability of the MF-BIA to detect asymmetry in career firefighters may suggest that alternative field assessments of limb muscle mass (e.g. ultrasonography) are warranted, especially in populations with high levels of FFM. Supported by the National Strength and Conditioning Association Foundation

American football linemen are at an increased risk for developing obesity-related diseases. This study evaluated the impact of race and position on abdominal fat (visceral adipose tissue and android fat percentage) in football linemen. Thirty-four offensive and defensive linemen (%fat: 27.1 +/- 7.2%) completed a total body dual-energy X-ray absorptiometry scan to estimate visceral fat and android fat percentage. Participants were stratified by race [Black: n=23; White: n=11] and position (Offense: n=18; Defense: n=16). Two separate two-way ANOVA tests [race x position] were completed. For visceral adipose tissue, there was no interaction (p=0.056), but there was an effect of race (Black: 0.57 +/- 0.34kg; White: 1.51 +/- 0.56kg; p <0.001) and position (Offense: 1.220.60kg; Defense: 0.49 +/- 0.34kg; p<0.001). For android fat percentage, there was no interaction (p=0.855) or race effect (Black: 31.511.3%; White: 40.9 +/- 8.6%; p=0.123); there was a position effect (Offense: 42.1 +/- 5.6%; Defense: 26.0 +/- 9.9%; p<0.001). Offensive linemen, regardless of race, had greater visceral adipose tissue and android fat percent compared to defensive linemen. White linemen had greater visceral adipose tissue, regardless of position. These results suggest football linemen, especially offensive linemen with increased abdominal adiposity, may benefit from tracking metabolic health during their collegiate career to mitigate obesity-related disease risk once retired from sport.

Analysis of Brightness-mode ultrasound-captured fascicle angle (FA) and fascicle length (FL) can be completed manually with computer-based programs or by automated programs. Insufficient data exists regarding reliability and accuracy of automated tools. Therefore, the purpose of this study was to determine the test-retest reliability of automatic and manual ultrasound analyses, while determining accuracy of the automatic tool against the manual equivalent. Twenty-three participants (mean ± SD; age = 24 ± 4 years; height = 172.2 ± 10.5 cm; body mass = 73.1 ± 16.1 kg) completed one laboratory visit consisting of two trials where vastus lateralis muscle architecture was assessed with ultrasound. Images were taken at both lower (10 MHz) and higher frequency (12 MHz). Images were analyzed manually in an open-source imaging program and automatically using a separate open-source macro function. Test-retest reliability statistics were calculated for automatic and manual analyses. Accuracy was determined with validity statistics and were calculated for automatic analyses. The results show that manual ultrasound analyses for FA and FL for both lower and higher frequency displayed good reliability (ICC2,1 = 0.75–0.86). However, automatic ultrasound analyses for FA and FL revealed moderate reliability (ICC2,1 = 0.61–0.72) for the lower frequency images and poor reliability (ICC2,1 = 0.16–0.27) for higher frequency images. When assessed against manual techniques, automatic analyses presented greater total error (TE) and standard error of the estimate (SEE) for FA at lower frequency (constant error (CE) = −3.91°, TE = 5.57°, SEE = 3.45°) than higher (CE = −2.78°, TE = −4.54°, SEE = 2.45°). For FL, the higher frequency error (CE = 0.92 cm, TE = 2.12 cm, SEE = 1.15 cm) was similar to lower frequency error (CE = 1.98 cm, TE = 3.66 cm, SEE = 1.57 cm). The findings overall show that manual analyses had good reliability and low absolute error, while demonstrating the automated counterpart had poor to moderate reliability and large errors in analyses. These findings may be impactful as they highlight the good reliability and low error associated with manually analyzed ultrasound images and validate a novel automatic tool for analyzing ultrasound images. Future work should focus on improving reliability and decreasing error in automated image analysis tools. Automated tools are promising for the field as they eliminate biases between analysts and may be more time efficient than manual techniques.

The purpose of this study was to compare the independent and combined effects of high‐intensity interval training (HIIT) and essential amino acids (EAA) on lean mass, muscle characteristics of the quadriceps, and 24‐hr whole‐body protein turnover (WBPT) in overweight and obese adults. An exploratory aim was to evaluate potential modulatory effects of sex. Sixty‐six adults (50% female; Age: 36.7 ± 6.0 yrs; %BF: 36.0 ± 7.8%) were assigned to 8 wks of: (a) HIIT, 2 days/wk; (b) EAA supplementation, 3.6 g twice daily; (c) HIIT + EAA; or (d) control. At baseline, 4 wks, and 8 wks, total body, thigh LM and muscle characteristics were measured via dual‐energy x‐ray absorptiometry and B‐mode ultrasound, respectively. In a subsample, changes in WBPT was measured using [N15]alanine. Differences between groups were assessed using linear mixed models adjusted for baseline values, followed by 95% confidence intervals on adjusted mean change scores (Δ). HIIT and HIIT + EAA improved thigh LM (Δ: +0.17 ± 0.05 kg [0.08, 0.27]; +0.22 ± 0.05 kg [0.12,0.31]) and vastus lateralis cross‐sectional area (Δ: +2.73 ± 0.52 cm2 [1.69,3.77]; +2.64 ± 0.53 cm2 [1.58,3.70]), volume (Δ: +54.50 ± 11.69 cm3 [31.07, 77.92]; +62.39 ± 12.05 cm3 [38.26, 86.52]), and quality (Δ: −5.46 ± 2.68a.u. [−10.84, −0.09]; −7.97 ± 2.76a.u.[−13.49, −2.45]). Protein synthesis, breakdown, and flux were greater with HIIT + EAA and EAA compared to HIIT (p < .05). Sex differences were minimal. Compared to women, men tended to respond more to HIIT, with or without EAA. For women, responses were greater with HIIT + EAA than HIIT. In overweight and obese adults, 8 weeks of HIIT, with or without EAA, improved thigh LM size and quality; EAA may enhance muscular adaptation via increases in protein turnover, supporting greater improvements in muscular size and quality.

High-intensity interval training (HIIT) promotes positive cardiometabolic and body composition changes. Essential amino acids (EAA) may support changes associated with HIIT, but evaluation of potential synergistic effects is lacking. The purpose of this study was to compare independent and combined effects of HIIT and EAA on total body composition and metabolism in men and women considered overweight/obese; an exploratory aim was to evaluate the modulatory effects of sex. Sixty-six healthy adults (50% female; Age: 36.7 ± 6.0 years; BMI: 32.0 ± 4.2 kg/m2) completed 8 weeks of: (1) HIIT, 2 days/weeks; (2) EAA supplementation, 3.6 g twice daily; (3) HIIT + EAA; or (4) control. Body composition, resting metabolic rate (RMR), substrate metabolism (respiratory exchange ratio; RER), and cardiorespiratory fitness were measured at baseline, 4 weeks, and 8 weeks; cardiometabolic blood markers were measured at baseline and 8 weeks. Differences between groups were assessed by linear mixed models covaried for baseline values, followed by 95% confidence intervals (CI) on adjusted mean change scores. There were no significant changes in body composition (p > 0.05) for any group. Changes in RER, but not RMR, occurred with HIIT (mean change; [95% CI]: − 0.04; [− 0.07, − 0.02]) and EAA (− 0.03; [− 0.06, − 0.01]) after 8 weeks. Cardiorespiratory fitness increased following 8 weeks of HIIT (+ 5.1 ml/kg/min [3.3,6.8]) and HIIT + EAA (+ 4.1 ml/kg/min [1.0,6.4]). Changes with HIIT + EAA were not significantly different from HIIT. There were no changes in cardiometabolic markers (p > 0.05) and no sex interaction (p > 0.05). HIIT is efficacious for promoting positive changes in cardiorespiratory fitness and resting substrate metabolism in adults considered overweight/obese. Addition of EAA did not significantly enhance HIIT-induced adaptations. ClinicalTrials.gov ID#NCT04080102.

Amino acid intake prior to exercise has been shown to extend incremental exercise time to exhaustion (TTE). Acute benefits to performance may be due to delayed central fatigue, but effects on intermittent exercise have not been investigated. PURPOSE: To explore the effects of pre-workout essential amino acid (EAA) supplementation on high-intensity interval training (HIIT) in untrained men and women. METHODS: Thirty-eight sedentary, overweight and obese adults (50% female; 36.5 ± 6.1 yrs; 35.4 ± 6.7% body fat) completed a single HIIT session (6 × [1 min @ 90% VO2max: 1 min rest]) on an electronically braked cycle ergometer. Nineteen participants consumed 3.6 g of EAA 30 minutes prior to the HIIT session. Heart rate (HR) and rating of perceived exertion (RPE) were recorded after each set. On the sixth set, participants rode to volitional fatigue and TTE (s) was recorded. Difference in TTE was evaluated by independent sample t-test; differences in HR and RPE were evaluated by separate repeated measure ANOVAs (2 × 5), in the full group and in men and women separately. RESULTS: There was no difference in TTE between groups (mean difference (Δ): 2.2 ± 17.5 s; p = 0.9). HR and RPE increased with each set (p < 0.001), but were not significantly different between groups (p > 0.05). Results were similar when men and women were evaluated separately, but in women, there was a trend toward a lower RPE with EAA as the HIIT session progressed (Δ: 0.8, 0.7, 1.2, 1.6, 1.7, 1.2) despite no differences in HR (p > 0.05). CONCLUSIONS: Pre-workout EAA supplementation did not extend TTE or impact HR and RPE throughout a single HIIT session. There was a trend toward reduced perceived exertion in later stages of a HIIT session in overweight and obese women, but further research is needed to confirm these results. Future studies are needed to understand specific mechanisms in women and evaluate if this trend persists over a greater number of HIIT sets and sessions, in addition to implications for chronic training adaptation. FUNDING: This study was supported by a Doctoral Student Grant from the National Strength and Conditioning Association Foundation.

The purpose of this study was to characterize physical activity (PA), sedentary time (ST), and body composition across collegiate years. 143 participants (Age: 19.7±1.2yrs) were measured using a modified four compartment model and the Long International Physical Activity Questionnaire. Two-way ANOVAs and Pearson Correlations were utilized. For males, PA and ST were significant across class year. Vigorous PA and ST were significantly correlated to %body fat (p=0.001 and p=0.036, respectively) and fat mass (p=0.002 and p=0.023, respectively) suggesting vigorous PA and reduced ST may be associated with improved body composition. Males expressed differences in PA and ST across class year while females were stable.

AbstractUnderstanding the effects of acute feeding on body composition and metabolic measures is essential to the translational component and practical application of measurement and clinical use. To investigate the influence of acute feeding on the validity of dual-energy X-ray absorptiometry (DXA), a four-compartment model (4C) and indirect calorimetry metabolic outcomes, thirty-nine healthy young adults (n 19 females; age: 21·8 (sd 3·1) years, weight; 71·5 (sd 10·0) kg) participated in a randomised cross-over study. Subjects were provided one of four randomised meals on separate occasions (high carbohydrate, high protein, ad libitum or fasted baseline) prior to body composition and metabolic assessments. Regardless of macronutrient content, acute feeding increased DXA percent body fat (%fat) for the total sample and females (average constant error (CE):–0·30 %; total error (TE): 2·34 %), although not significant (P = 0·062); the error in males was minimal (CE: 0·11 %; TE: 0·86 %). DXA fat mass (CE: 0·26 kg; TE: 0·75 kg) and lean mass (LM) (CE: 0·83 kg; TE: 1·23 kg) were not altered beyond measurement error for the total sample. 4C %fat was significantly impacted from all acute feedings (avg CE: 0·46 %; TE: 3·7 %). 4C fat mass (CE: 0·71 kg; TE: 3·38 kg) and fat-free mass (CE: 0·55 kg; TE: 3·05 kg) exceeded measurement error for the total sample. RMR was increased for each feeding condition (TE: 1666·9 kJ/d; 398 kcal/d). Standard pre-testing fasting guidelines may be important when evaluating DXA and 4C %fat, whereas additional DXA variables (fat mass and LM) may not be significantly impacted by an acute meal. Measuring body composition via DXA under less stringent pre-testing guidelines may be valid and increase feasibility of testing in clinical settings.