Changes in Fatigue Are the Same for Trained Men and Women after Resistance Exercise, Purpose To measure changes in fatigue and knee-extensor torque in the 48H after trained men and women completed a full-body resistance exercise session. Methods Eight trained women (mean ± SD; age, 25.6 ± 5.9 years; height, 1.68 ± 0.06 m; mass, 71.0 ± 8.6 kg) and eight trained men (age, 25.5 ± 6.2 years; height, 1.79 ± 0.05 m; mass, 86.4 ± 9.8 kg) performed a full-body resistance exercise session based on real-world athletic practice. Measurements were performed before and after the exercise session, as well as 1H, 24H, and 48H after the session. Fatigue and pain were measured with standardized self-report measures. Maximal isometric contractions with the knee-extensors and superimposed femoral nerve stimulation was performed to examine maximal torque, rate of torque development, voluntary activation, and muscle contractility. Two sets of 10 isokinetic contractions (60°.s-1) with the knee extensors were performed during the protocol with use of near-infrared spectroscopy to assess muscle oxygenation. Electromyograms (EMG) were recorded from two quadriceps muscles during all isometric and isokinetic contractions. Results Fatigue was increased from baseline for both sexes until 48H after training (p<0.001). Maximal torque and evoked twitch amplitudes were similarly reduced after exercise for men and women (p<0.001). Voluntary activation and EMG amplitudes were unchanged after the training session. Muscle oxygenation was 13.3 ± 17.4 % (p=0.005) greater for women during the isokinetic repetitions, and the values were unchanged after the training session. Conclusions This is the first study to show similar changes in the fatigue reported by trained men and women in the 48H after a training session involving full-body resistance exercises. Sex differences in muscle oxygenation during exercise do not influence the reductions in muscle force, activation, or contractility after the training session. Corresponding Author: Jason C. Siegler, j.siegler@westernsydney.edu.au, School of Science and Health, Locked Bag 1797 Penrith South, NSW 2751, AUSTRALIA. Tel: +61 4620 3915 This project did not receive any funding and the authors report no conflicts of interest. The results of the present study do not constitute endorsement by ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 16 July 2019. © 2019 American College of Sports Medicine

Acute Soy Supplementation Improves 20-km Time Trial Performance, Power, and Speed INTRODUCTION Isoflavones, a chemical class of phytoestrogens found in soybeans and soy products, may have biological functions similar to estradiol. After binding with ERβ or perhaps independently of estrogen receptors, isoflavones may augment vascular endothelial relaxation, contributing to improved limb blood flow. PURPOSE To determine if acute fermented soy extract supplementation influences 20-km time trial cycling performance and cardiac hemodynamics compared to a placebo. METHODS Subjects included twenty-five cyclists and triathletes (31 ± 8 y, VO2peak: 55.1 ± 8.4 mL·kg-1·min-1). Each subject completed a VO2peak assessment, familiarization, and two 20-km time trials in randomized order following ingestion of a fermented soy extract supplement or placebo. The fermented soy extract consisted of 30 g powdered supplement in 16 fl. ounces of water. The placebo contained the same quantities of organic cocoa powder and water. Each trial consisted of 60 min of rest, 30 min at 55% Wpeak, and a self-paced 20-km time trial. RESULTS Soy supplementation elicited a faster time to 20km completion (-0.22 ± 0.10 min; -37 s), lower average heart rate (-5 ± 1 bpm), and significantly greater power (7 ± 3 W) and speed (0.42 ± 0.16 km•h-1) during the last 5 km of the time trial compared to placebo. Analysis of the results by relative fitness level (< 57 vs. ≥ 57 mL⋅kg-1⋅min-1) indicated that those with a higher level of fitness reaped the largest performance improvement alongside a reduced heart rate (-5 ± 7 bpm). CONCLUSION Ingestion of a fermented soy extract supplement improved sprint-distance performance through improvements in both power and speed. For those with great aerobic fitness, soy supplementation may help to decrease cardiac demand alongside performance improvement. Address for correspondence: Afton Seeley, MS, Department of Kinesiology and Sport Science, University of Miami, 5202 University Dr. Merrick Bldg Room 315, Coral Gables, FL 33146. Email: ads129@miami.edu The authors disclose that funding was received from BESO Biological Research, Inc. Diamond Bar, CA 91765 to support this investigation. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, or inappropriate data manipulation in any way to intentionally portray anything but those outcomes that were empirically observed. The authors do not have any conflicts of interest to report. The results of the study do not constitute endorsement by the American College of Sports Medicine. Accepted for Publication: 9 July 2019. © 2019 American College of Sports Medicine

Athlete-Opponent Interdependency Alters Pacing and Information-seeking Behavior PURPOSE The influence of interdependency between competitors on pacing decision-making and information-seeking behavior has been explored. This has been done by only altering instructions, and thereby action possibilities, while controlling environment (i.e. competitor behavior) and exercise task. METHODS Twelve participants performed a 4-km time-trial on a Velotron cycle ergometer in a randomized, counterbalanced order alone with no virtual opponent (NO), against a virtual opponent with no restrictions (low athlete-opponent interdependency; OP-IND), or against a virtual opponent who the participant was permitted to overtake only once during the trial (high athlete-opponent interdependency; OP-DEP). Information-seeking behavior was evaluated using an SMI Eye tracker. Differences in pacing, performance and information-seeking behavior were examined using repeated-measures ANOVA (p<0.05). RESULTS Neither mean power output (NO: 298±35W; OP-IND: 297±38W; OP-DEP: 296±37W) nor finishing time (NO: 377.7±17.4sec; OP-IND: 379.3±19.5sec; OP-DEP: 378.5±17.7sec) differed between experimental conditions. However, power output was lower in the first kilometer of OP-DEP compared to the other experimental conditions (NO: 332±59W; OP-IND: 325±62W; OP-DEP: 316±58W; both p<0.05), and participants decided to wait longer before they overtook their opponent (OP-IND: 137±130sec; OP-DEP: 255±107sec; p=0.040). Moreover, total fixation time spent on the avatar of the virtual opponent increased when participants were only allowed to overtake once (OP-IND: 23.3±16.6sec; OP-DEP: 55.8±32.7sec; p=0.002). CONCLUSION A higher interdependency between athlete and opponent altered pacing behavior in terms of in-race adaptations based on opponent’s behavior, and induced an increased attentional focus on the virtual opponent. Thus, in the context of exercise regulation, attentional cues are likely to be used in an adaptive way according to their availability and situational relevance, consistent with a decision-making framework based on the interdependence of perception and action. Corresponding Author: Prof Dr Florentina J Hettinga PhD SFHEA FECSS FACSM, Department of Sport, Exercise & Rehabilitation, Northumbria University, Newcastle Upon Tyne, NE1 8ST, United Kingdom No funding was received for the present study. The authors declare no conflicts of interest. The results of the present study do not constitute endorsement by ACSM. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 15 July 2019 © 2019 American College of Sports Medicine

High-Altitude Acclimatization Improves Recovery from Muscle Fatigue Purpose We investigated the effect of high-altitude acclimatization on peripheral fatigue compared to sea level and acute hypoxia. Methods At sea level (350 m), acute hypoxia (environmental chamber), and chronic hypoxia (5050 m, 5-9 days) (partial pressure of inspired oxygen = 140, 74 and 76 mmHg, respectively), 12 participants (11 in chronic hypoxia) had the quadriceps of their dominant leg fatigued by 3 bouts of 75 intermittent electrically-evoked contractions (12 pulses at 15 Hz, 1.6 s between train onsets, and 15 s between bouts). The initial peak force was ~30% of maximal voluntary force. Recovery was assessed by single trains at 1, 2, and 3 min post-protocol. Tissue oxygenation of rectus femoris was recorded by near-infrared spectroscopy. Results At the end of the fatigue protocol, the impairments of peak force and peak rates of force development and relaxation were greater (all P < 0.05) in acute hypoxia (~51, 53 and 64%, respectively) than sea level (~43, 43 and 52%) and chronic hypoxia (~38, 35 and 48%). Peak force and rate of force development recovered faster (P < 0.05) in chronic hypoxia (pooled data for 1-3 min: ~84 and 74% baseline, respectively) compared to sea level (~73 and 63% baseline) and acute hypoxia (~70 and 55% baseline). Tissue oxygenation did not differ among conditions for fatigue or recovery (P > 0.05). Conclusion Muscle adaptations occurring with chronic hypoxia, independent of other adaptations, positively influence muscle contractility during and after repeated contractions at high altitude. Correspondence: Dr. Chris McNeil, School of Health and Exercise Sciences, Faculty of Health and Social Development, The University of British Columbia – Okanagan Campus, 1147 Research Road, Kelowna, British Columbia, Canada, V1V 1V7. E-mail: chris.mcneil@ubc.ca, Tel.: +1-250-807-9664, Fax: +1-250-807-9865 The authors declare that they have no conflict of interest. The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation and do not constitute endorsement by the American College of Sports Medicine. This work was supported by the Natural Sciences and Engineering Research Council of Canada (DG 435912-2013) and the Canada Foundation for Innovation / British Columbia Knowledge Development Fund (32260). Accepted for Publication: 16 July 2019. © 2019 American College of Sports Medicine

Muscle Glycogen Content during Endurance Training under Low Energy Availability Purpose The present study investigated the effects of 3 consecutive days of endurance training under conditions of low energy availability on the muscle glycogen content, muscle damage markers, endocrine regulation, and endurance capacity in male runners. Methods Seven male long-distance runners [19.9 ± 1.1 years, 175.6 ± 4.7 cm, 61.4 ± 5.3 kg, maximal oxygen uptake (V·O2max): 67.5 ± 4.3 ml/kg/min] completed two trials consisting of 3 consecutive days of endurance training under low energy availability (LEA, 18.9 ± 1.9 kcal/kg FFM/day) or normal energy availability (NEA, 52.9 ± 5.0 kcal/kg FFM/day). The order of the two trials was randomized, with a 2-week interval between trials. The endurance training consisted of 75 min of treadmill running at 70% of V·O2max. Muscle glycogen content, respiratory gas variables, and blood and urine variables were measured in the morning during 3 consecutive days of training (days 1–3) and on the following morning after training (day 4). As an indication of endurance capacity, time to exhaustion at 19.0 ± 0.8 km/h to elicit 90% of V·O2max was evaluated on day 4. Results During the training period, body weight, fat-free mass, and skeletal muscle volume were significantly reduced in LEA (P = 0.02 for body weight and skeletal muscle volume, P = 0.01 for fat-free mass). Additionally, muscle glycogen content was significantly reduced in LEA (~30%, P < 0.001), with significantly lower values than those in NEA (P < 0.001). Time to exhaustion was not significantly different between the two trials (~20 min, P = 0.39). Conclusion Three consecutive days of endurance training under low energy availability decreased muscle glycogen content with lowered body weight. However, endurance capacity was not significantly impaired. Corresponding author: Kazushige Goto, Ph. D. Professor, Graduate school of Sport and Health Science, Ritsumeikan University 1-1-1, Nojihigashi, Kusatsu, Shiga, 525-8577, Japan E-mail: kagoto@fc.ritsumei.ac.jp Phone: +81-77-599-4127 Fax: +81-77-599-4127 The present study was supported by a Grant-in-Aid for Scientific Research from the Japan Society for the Promotion of Science, and research grant from Ritsumeikan University, and the research project of Japan Institute of Sports Sciences for prevention of fatigue and recovery. The authors declare no conflicts of interest. We declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation and do not constitute endorsement by the American College of Sports Medicine. Accepted for Publication: 15 July 2019 © 2019 American College of Sports Medicine

Low-Frequency HIIT Improves Body Composition and Aerobic Capacity in Overweight Men Background The relationship between the frequency of high-intensity interval training (HIIT) and the resultant adaptations is largely unclear. Purpose This study compared the effects of different frequencies of HIIT with those of moderate-intensity continuous training (MICT) on body composition in overweight or obese adults. Methods Fifty-six overweight or obese (BMI: 26.4±2.9) men aged between 18 and 30 years (age: 22.8±3.1) were randomly assigned to the following groups: no-intervention control (CON; n=14), MICT performed thrice weekly (MICT×3/wk; n=9), HIIT performed thrice weekly (HIIT×3/wk; n=14), HIIT performed twice weekly (HIIT×2/wk; n=10), and HIIT performed once weekly (HIIT×1/wk; n=9). Each HIIT session consisted of 12×1-min bouts at 90% heart rate reserve (HRR), interspersed with 11×1-min bouts at 70% HRR. Aerobic capacity, body composition, resting heart rate, vascular function, insulin resistance, and biomarkers of metabolic syndrome risk factor were examined at baseline, after 4 weeks and after 8 weeks of intervention. Results Aerobic capacity and percent fat-free mass significantly increased in all exercise groups compared with those in the CON group (CON vs. all exercise groups: p<0.05), whereas body fat mass and systolic blood pressure significantly decreased after 8 weeks of intervention in all exercise groups compared with those in the CON group (CON vs. all exercise groups: p<0.05). Body fat mass significantly decreased after 4 weeks in all HIIT groups compared with those in the CON group (CON vs. all HIIT groups: p<0.05) but not in the MICT×3/wk group. Conclusion These novel results demonstrated that performing HIIT once weekly, even with a lower weekly volume of exercise, improved cardiorespiratory fitness, body composition, and blood pressure in overweight/obese adults. Low-frequency HIIT might be a feasible and effective strategy for the prescription of an initial exercise program for inactive, overweight or obese young men. Send correspondence and reprint requests to: Parco M. Siu, PhD Division of Kinesiology, School of Public Health, The University of Hong Kong, Pokfulam, Hong Kong, China Phone: (852)2831 5262 Fax: (852)2855 1712 Email: pmsiu@hku.hk This study was supported by the Hong Kong Research Grants Council General Research Fund (Project Number 17103818) and the University of Hong Kong Seed Fund for Basic Research. The authors thank all the volunteer subjects who contributed to this study. CONFLICT OF INTEREST. The authors have no disclosed professional relationships with companies or manufacturers who will benefit from the results of the present study, and the present study does not constitute endorsement by the ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 28 June 2019 © 2019 American College of Sports Medicine

Relative Effort while Walking Is Higher among Women Who Are Obese, and Older Women PURPOSE Individuals who are obese, and older individuals, exhibit gait alterations that may result, in part, from walking with greater effort relative to their maximum strength capacity. The goal of this study was to investigate obesity-related and age-related differences in relative effort during gait. METHODS Four groups of women completed the study, including 10 younger healthy-weight, 10 younger obese, 10 older healthy-weight, and 9 older obese women. The protocol included strength measurements at the hip, knee, and ankle in both flexion and extension, and gait trials under self-selected and constrained (1.5 m/sec gait speed and 0.65 m step length) conditions. Relative effort was calculated as the ratio of joint torques during gait, and strength from a subject-specific model that predicted strength as a function of joint angle. RESULTS Relative effort during self-selected gait was higher among women who were obese in knee extension (p = .028) and ankle plantar flexion (p = .013). Although both joint torques and strength were higher among women who were obese, these increases in relative effort were attributed to greater obesity-related increases in joint torques than strength. Relative effort was also higher among older women in hip flexion (p < .001) and knee extension (p = .008), and attributed to age-related strength loss. Results were generally similar between self-selected and constrained gait, indicating the greater relative effort among women who were obese and older women was not attributed to differences in gait spatiotemporal characteristics. CONCLUSION Women who were obese, as well as older women, walk with greater relative effort. These results may help explain the compromised walking ability among these individuals. Corresponding author: Michael L. Madigan, PhD Grado Department of Industrial and System Engineering, Blacksburg, VA 24061 Phone: (540) 231-3543 Email: mlm@vt.edu This work was supported by award R01OH009880 from the Centers for Disease Control and Prevention (CDC). The contents of this paper are solely the responsibility of the authors, and do not necessarily represent the official views of CDC. CONFLICT OF INTEREST. The authors have no conflicts of interest to report. The results of the present study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. In addition, these results do not constitute endorsement by ACSM. Accepted for Publication: 8 July 2019 © 2019 American College of Sports Medicine

Estimating Sedentary Time from a Hip- and Wrist-worn Accelerometer Purpose Determine the validity of existing methods to estimate sedentary behavior (SB) under free-living conditions using ActiGraph GT3X+ accelerometers (AG). Methods Forty-eight young (18-25 yr) adults wore an AG on the right hip and non-dominant wrist and were video recorded during four 1-hour sessions in free-living settings (home, community, school, exercise). Direct observation videos were coded for postural orientation, activity type (e.g. walking), and METs derived from the Compendium of Physical Activities, which served as the criterion measure of SB (sitting or lying posture, METs < 1.5). Thirteen methods using cut-points from vertical counts/minute (CPM), counts/15-s (CP15s), and vector magnitude counts (vm) (e.g., CPM1853vm), raw acceleration and arm-angle (Sedentary Sphere), Euclidean norm corrected for gravity (ENMO, mg) thresholds, uni- or tri-axial Sojourn hybrid-machine learning models (Soj1x and Soj3x), random forest (RF) and decision tree (TR) models were used to estimate SB minutes from AG data. Method bias, mean absolute percent error (MAPE), and their 95% confidence-intervals were estimated using repeated measures linear mixed models. Results On average, participants spent 34.1 minutes/session in SB. CPM100, CPM150, Soj1x, and Soj3x were the only methods to accurately estimate SB from the hip. Sedentary Sphere and ENMO44.8 over-estimated SB by 3.9 and 6.1 minutes, respectively, while the remaining wrist methods underestimated SB (range: 9.5-2.5 minutes). In general, MAPE was lower using hip methods compared to wrist methods. Conclusion Accurate group-level estimates of SB from a hip-worn AG can be achieved using either simpler count-based approaches (CPM100, CPM150) or machine learning models (Soj1x, Soj3x). Wrist-methods did not provide accurate or precise estimates of SB. Development of large open source free-living calibration datasets may lead to improvements in SB estimates. Address for Correspondence: John R. Sirard Department of Kinesiology University of Massachusetts Amherst 30 Eastman Lane Amherst, MA 01003 Phone: 413-545-7898 Fax: 413-545-2906 Email: jsirard@kin.umass.edu A grant from the National Institutes of Health supported this study (grant number NIH NIDDK 1R01DK110148). None of the authors have financial conflicts of interest with the device manufacturer or distributors. The results of the current study do not constitute endorsement by the ACSM. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 20 June 2019 © 2019 American College of Sports Medicine

Training Load and Energy Expenditure during Military Basic Training Period Purpose To compare training load and energy expenditure during an 8-week military BT period among individuals having different fitness level using objective measurements in an authentic environment. Methods Thirty-four voluntary male conscripts (age 19.1±0.3 years) were divided into three training groups (inactive, moderate, active) by their reported physical activity (PA) level evaluated by the International Physical Activity Questionnaire (IPAQ) prior to military service. Maximal oxygen uptake (VO2max) and heart rate (HR) were determined by maximal treadmill test in the beginning and after 4 and 7 weeks of BT. During BT, HR monitors and accelerometers were used to measure PA and energy expenditure. HR data were used to calculate the training load (TRIMP, training impulse) for each day, week and the whole BT period. Results Training load of BT was comparable to training of competitive athletes at the highest level. The training groups differed (p<0.001-0.05) in terms of VO2max to each other (inactive 36±6, moderate 42±6, active 48±6 ml/kg/min). The conscripts in the inactive group were the most loaded during the study period (TRIMPinactive 12393±2989 vs. TRIMPmoderate 10252±1337, p<0.05 and TRIMPactive 8444±2051, p<0.01). The PA intensity of different military tasks during the BT period were low or moderate (<6MET). Conclusion The remarkable training load during BT period is comparable to the training loads of professional athletes participating three weeks’ cycling competition. The training load in basic training period was, however, primary due to duration of low intensity activities including only some high intensity military activities. In the future, measuring the training load during the military service is recommended in order to customize the physical training for conscripts regarding his/her fitness level as much as possible. Corresponding author: Heidi Jurvelin, Hippiäiskuja 6 c 90420 Oulu, Finland Tel. +358503312468 E-mail: heidi.jurvelin@oulu.fi The study was granted by the Finnish Ministry of Education, Finnish Cultural Foundation, Polar Electro Oy and the Scientific Advisory Board for Defence. Conflict of Interest. Authors declare no conflicts of interest. The results of the present study do not constitute endorsement by ACSM and are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 9 July 2019 © 2019 American College of Sports Medicine

Neuromuscular Function and Blood Flow Occlusion with Dynamic Arm Flexor Contractions Introduction Blood flow restricted or occlusion exercise enhances muscle hypertrophy and strength during resistance training. The acute effects on voluntary and electrically evoked muscle contractile characteristics with impaired blood flow at low and high contraction forces has not been explored. Methods On separate days, nine males completed two different protocols of concentric elbow flexor contractions. A repetitive low-force (~25% of isometric maximum voluntary contraction, MVC) with blood flow occlusion (BFO; 300mmHg) protocol was compared to a high-force (~80% MVC) free blood flow protocol (HF), until range of motion (0-90°) was impaired. Torque, velocity and power were compared to baseline and between protocols. MVC and voluntary activation (VA) were assessed during and following each protocol. Muscle twitch, low (20Hz) and high (50 Hz) tetanus, and compound muscle action potential (Mmax) area were measured at 0, 2, 5, 10, and 20min of recovery. Results Repetitions to failure (FP) were lower for HF (~16) versus BFO (~21), and MVC at FP was reduced more during BFO (~77%) compared to HF (~23%), with no difference in VA (~10% loss) between protocols. At FP, velocities for BFO and HF were similarly reduced by ~63% and ~56%, respectively, however peak power decreased more during BFO (~90%) compared with HF (~67%). Total work for BFO was ~40% lower than for HF. Peak power for HF was recovered by 2mins, whereas BFO required 20mins. Low-frequency fatigue (20Hz/50Hz) was greater following BFO (~70% decrease versus ~29% decrease following HF), while Mmax area was unaffected. Conclusion Concentric elbow flexions at low-force with BFO causes greater impairments in strength and power than HF and therefore may be a replacement for high-force exercise used in chronic training. Corresponding Author: David B. Copithorne, 1151 Richmond Street, London, Ontario, Canada, N6A 3K7. dcopitho@uwo.ca This research was supported by the Natural Sciences and Engineering Research Council (NSERC) as well as Ontario Graduate Scholarships (OGS). DB Copithorne and CL Rice have no conflicts of interest that are directly relevant to the content of this article. The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation and the results of the present study do not constitute endorsement by ACSM. Accepted for Publication: 9 July 2019. © 2019 American College of Sports Medicine