Medicine & Science in Sports & Exercise

Delayed Onset Muscle Soreness and Topical Analgesic Alter Corticospinal Excitability of the Biceps Brachii Introduction The interactive effect of delayed onset muscle soreness (DOMS) and a topical analgesic on corticospinal excitability was investigated. Methods Thirty-two participants completed Experiments A (No DOMS) and B (DOMS). For each experiment participants were randomly assigned to two groups: 1) topical analgesic gel (Topical Analgesic, n=8), or 2) placebo gel (Placebo, n=8) group. Prior to the application of gel (pre-gel), as well as 5, 15, 30, and 45 min post-gel, motor evoked potential (MEP) area, latency, and silent period, as well as cervicomedullary MEP (CMEP) and maximal compound motor unit action potential (Mmax) areas and latencies were measured. In addition, pressure-pain threshold (PPT) was measured pre-DOMS and at the same time points in Experiment B. Results In Experiment A, neither group showed a significant change for any outcome measure. In Experiment B, both groups exhibited a significant decrease in PPT from pre-DOMS to pre-gel. Following the application of topical analgesic, but not placebo, there was a significant increase in PPT at 45 min post-gel, respectively compared to pre-gel and a main effect of time for the silent period to increase compared to pre-gel. Participants with DOMS had reduced MEP and CMEP areas, and increased corticospinal silent periods compared to those who did not have DOMS. Conclusion These findings suggest that DOMS reduced corticospinal excitability and following the administration of menthol-based topical analgesic there was a reduction in pain, which was accompanied by increased corticospinal inhibition. Corresponding author: Duane C. Button School of Human Kinetics and Recreation, Memorial University of Newfoundland, 230 Elizabeth Avenue, St. John's, Newfoundland, Canada, A1C 5S7 Email: dbutton@mun.ca GRANTS: This study was supported by a Memorial University Seed, Bridge, and Multidisciplinary Fund (to D. C. Button). DISCLOSURES: No conflicts of interest, financial or otherwise, are declared by the authors. We declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM. Accepted for publication: 21 May 2019. © 2019 American College of Sports Medicine

Aerobic Training and Green Tea Extract Protect against NMU-induced Prostate Cancer Introduction Aerobic training and green tea extract can be used to reduce the risk of prostate cancer. The goal of this study was to evaluate the effects of eight-week aerobic exercise training and administration of green tea extract on the level of nuclear factor kappa B (NF-kB), cyclooxygenase-2 (COX-2) and p53 tumor suppressor protein (p53) in prostate of rats which were stimulated by N-Methyl-N-nitrosourea (NMU) to induce the prostate cancer. Methods 60 adult male Wistar rats were assigned into six groups including healthy control (HCt), cancer control (CCt), cancer training (CTr: 45 min/day at low-moderate intensity, 5 times/week, 8 weeks), cancer extract (CEx: 1.34 ml of green tea extract, 3 times/week, 8 weeks), cancer training+ cancer extract (CTr+CEx) and sham groups. Rats were sacrificed 48 hours after the last intervention session, and the prostate tissue was isolated to measure the levels of NF-kB, COX-2, and p53. Results The NF- kB level in CCt group was increased significantly compared to the HCt (P=0.02). In the CTr group, NF-kB level was decreased significantly compared to the CCt and CEx groups (P=0.001 and 0.05, respectively). In addition, the levels of P53 protein were reduced in CTr, CEx and CTr+CEx groups compared to CCt group (P=0.001, 0.02 and 0.004, respectively). No significant changes were found in the level of COX-2 between groups. Conclusions These results suggest that a long-term exercise training combined with the intake of green tea extract may reduce levels of NF-kB and p53 in rats with prostate cancer. Given the importance of recognizing complementary therapies in this regard, future studies are warranted. Corresponding author: Marziyeh Saghebjoo; University of Birjand, Avini Blvd, Birjand, South Khorasan, Iran; Mailbox number: 97175/615; E-mail: m_saghebjoo@birjand.ac.ir Iran National Science Foundation (INSF) has financially supported this work with code approval number 96001504. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation, and do not constitute endorsement by ACSM. There are no conflicts of interests. Accepted for publication: 21 May 2019. © 2019 American College of Sports Medicine

High-Intensity Single-Leg Cycling Improves Cardiovascular Disease Risk Factor Profile Introduction Regular exercise can reduce the risk of developing cardiovascular disease through risk factor modification, with high intensity exercise and more recently small muscle mass training providing alternatives to moderate intensity exercise. Methods This study randomly assigned 53 healthy middle-aged adults (age: 62 ± 6 y) to complete 24 sessions (8 wk; 3 d.wk-1) of exercise training, using either high intensity double-leg cycling (n=17; HITDL), high intensity single-leg cycling (n=18; HITSL) or moderate intensity double-leg cycling (n=18; MCTDL). Biomarkers of cardiovascular risk (total cholesterol, triglycerides, HDL-c, LDL-c, apo-B48, glucose), anthropometry measures (body mass, body mass index, waist circumference, waist-to-hip ratio), resting blood pressure and aerobic capacity were assessed pre- and post-intervention. Results Total work completed was greater (p<0.01) in MCTDL (5938 ± 1462 kJ) compared with the HITDL (3462 ± 1063 kJ) and HITSL (4423 ± 1875 kJ). Pre- to post-training differences were observed for waist-to-hip ratio (0.84 ± 0.09 vs 0.83 ± 0.09; p<0.01), resting systolic blood pressure (129 ± 11 mmHg vs 124 ± 12 mmHg; p<0.01), total cholesterol (5.87 ± 1.17 mmol·L-1 vs 5.55 ± 0.98 mmol·L-1; p<0.01) and LDL-c (3.70 ± 1.04 mmol·L-1 vs 3.44 ± 0.84 mmol·L-1; p<0.01), with no differences between conditions. Additionally, aerobic capacity increased following training (22.3 ± 6.4 mL·kg-1·min-1 vs 24.9 ± 7.6 mL·kg-1·min-1; p<0.01), with no differences between conditions. Conclusion These findings suggest that all three modes of exercise can be prescribed to achieve cardiovascular risk reduction in an ageing population. Corresponding author Dr Nicole Gordon Murdoch University 90 South Street Murdoch, Western Australia, 6150, AU Email: N.Gordon@murdoch.edu.au The authors 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 ACSM. No funding was received for this study. The authors declare no conflicts of interest. Accepted for publication: 22 May 2019. © 2019 American College of Sports Medicine

Validity of Cardiorespiratory Fitness Measured with Fitbit Compared to VO2max Purpose Cardiorespiratory fitness (CRF), broadly defined as the body's ability to utilize oxygen, is a well-established prognostic marker of health, but it is not routinely measured. This may be due to the difficulty of acquiring high-quality CRF measures. The purpose of this study was to independently determine the validity of the Fitbit Charge 2's measure of CRF (Fitbit CRF). Methods 65 healthy adults between the ages of 18 and 45 (55% female, 45% male) were recruited to undergo gold standard VO2 max testing and wear a Fitbit Charge 2 continuously for one week during which they were instructed to complete a qualifying outdoor run to derive the Fitbit CRF (units: mL•Kg-1•min-1). This measure was compared with VO2 max measures (units: mL•Kg-1•min-1) epoched at 15 and 60 seconds. Results Bland Altman analyses revealed that Fitbit CRF had a positive bias of 1.59 mL•Kg-1•min-1 compared to laboratory data epoched at 15 seconds and 0.30 mL•Kg-1•min-1 compared to data epoched at 60 seconds (N=60). F statistics (2.09; 0.08) and p-values (0.133; 0.926) from Bradley-Blackwood tests for the concordance of Fitbit CRF with 15 and 60 second laboratory data, respectively, supports the null hypothesis of equal means and variances indicating there is concordance between the two measures. Mean absolute percentage error was less than 10% for each comparison. Conclusions The Fitbit Charge 2 provides an acceptable level of validity when measuring CRF in young, healthy, and fit adults who are able to run. Further research is required to determine if it is a potentially useful tool in clinical practice and epidemiological research to quantify, categorize, and longitudinally track risk for adverse outcomes. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Corresponding Author: Job G. Godino, PhD, 858-822-3749, jgodino@ucsd.edu, 9500 Gilman Drive #0811, La Jolla, CA 92093 The authors acknowledge funding support for the publication of this work from the Mobilize Center, a National Institutes of Health (NIH) Big Data to Knowledge Center of Excellence supported by NIH grant U54 EB020405. The authors have no conflicts of interest to report. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM. Accepted for publication: 3 May 2019. © 2019 American College of Sports Medicine

Supraspinal Control of Recurrent Inhibition during Anisometric Contractions Purpose Increase in recurrent inhibition was observed during eccentric compared with isometric and concentric maximal voluntary contractions but the neural mechanisms involved in this specific control of the Renshaw cell activity are unknown. This study was designed to investigate the supraspinal control of the recurrent inhibition during anisometric contractions of the plantar flexor muscles. Methods To that purpose, the paired Hoffmann-reflex (H-reflex) technique permitted to assess changes in homonymous recurrent pathway by comparing the modulations of test and conditioning H-reflexes (H' and H1 respectively) in the soleus muscle (SOL) during maximal and submaximal isometric, concentric and eccentric contractions. Submaximal contraction intensity was set at 50% of the SOL electromyographic activity recorded during maximal isometric contraction. 14 volunteer subjects participated in an experimental session designed to assess the activity of the recurrent inhibition pathway. Results The results indicate that the amplitude of H1 normalized to the maximal M-Wave were similar (p > 0.05) regardless of the muscle contraction type and intensity. Whatever the contraction intensity, the ratio between H' and H1 amplitudes was significantly decreased (p < 0.05) during eccentric compared with isometric and concentric contractions. Furthermore, this ratio was significantly smaller (p < 0.05) during submaximal compared with maximal contractions whatever the muscle contraction type. Conclusion Together, the current results confirm the supraspinal control of the Renshaw cell activity when muscle contraction intensity is modulated and show that this control remains similar for isometric, concentric and eccentric contractions. Data further suggest that recurrent inhibition pathway may serve as variable gain regulator at motoneuronal level to improve resolution in the control of motor output for the SOL during eccentric contractions. CORRESPONDING AUTHOR: Julien Duclay, University Paul Sabatier, Faculty of sport science, 118 route de Narbonne, F-31062 Toulouse Cedex 9, FRANCE. Mail: julien.duclay@univ-tlse3.fr No funding was received for this work. The authors have no conflicts of interest to declare. The results of the present study do not constitute endorsement by the American College of Sports Medicine. The authors declare that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for publication: 14 May 2019. © 2019 American College of Sports Medicine

Optimal Approach to Load Progressions during Strength Training in Older Adults Progressive resistance training (RT) is one of the most effective interventions for reducing age-related deficits in muscle mass and functional capacity. PURPOSE To compare four approaches to load progressions in RT for older adults to determine if an optimal method exists. METHODS 82 healthy community-dwelling older adults (71.8 + 6.2 y) performed 11 weeks of structured RT (2.5 days/week) in treatment groups differing only by the method used to increase training loads. These included percent 1RM (%1RM): standardized loads based on a percentage of the one repetition maximum (1RM); rating of perceived exertion (RPE): loads increased when perceived difficulty falls below 8/10 on the OMNI RES perceived exertion scale; repetition maximum (RM): loads increased when a target number of repetitions can be completed with a given load; repetitions in reserve (RiR): identical to RM except subjects must always maintain >1 'repetition in reserve', thus avoiding the possibility of training to temporary muscular failure. RESULTS Multiple analyses of covariance indicated no significant between-group differences on any strength (chest press 1RM; leg press 1RM) or functional performance outcome (usual walking speed, maximum walking speed, 8 foot timed up-and-go, gallon jug transfer test, 30 second sit-to-stand). The RPE group found the exercise to be significantly more tolerable and enjoyable than subjects in the RiR, RM, and %1RM groups. CONCLUSION Given the RM, RPE, %1RM, and RiR methods appear equally-effective at improving muscular strength and functional performance in an older population, we conclude that the RPE method is optimal because it is likely to be perceived as the most tolerable and enjoyable, which are two important factors determining older adults' continued participation in RT. Corresponding author: Dr. Andrew N.L. Buskard, Laboratory of Neuromuscular Research and Active Aging, Department of Kinesiology and Sport Sciences, University of Miami, 1507 Levante Avenue, Coral Gables, Florida, 33146, USA, Tel: +1 305 284 3105, Fax: +1 305 284 3003, E-mail: andrewbuskard@miami.edu No outside funding was obtained for this study, but equipment and laboratory support were provided by the University of Miami under the auspices of graduate research support for the first author's PhD in exercise physiology. The authors have no professional relationships with companies or manufacturers who will benefit from the results of the study. The results of this study do not constitute an endorsement by the American College of Sports Medicine (ACSM). The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 8 May 2019 © 2019 American College of Sports Medicine

The Effect of Growth Restriction on Voluntary Physical Activity Engagement in Mice INTRODUCTION The purpose of this study was to determine the effect of growth-restriction on the biological regulation of physical activity. METHODS Using a cross-fostering, protein restricted nutritive model, mice were growth-restricted during either gestation (GUN; N=3 litters) or postnatal life (PUN; N=3 litters). At 21 days of age, all mice pups were weaned and fed a non-restrictive healthy diet for the remainder of the study. At 45 days of age mice were individually housed in cages with free moving running wheels to assess physical activity engagement. At day 70, mice were euthanized, and the nucleus accumbens was analyzed for dopamine receptor 1 expression. Skeletal muscle fiber type and cross-sectional area of the soleus, extensor digitorom longus, and diaphragm were analyzed by immunohistochemistry. The soleus from the other hind leg was evaluated for calsequestrin 1 and annexin A6 expression. RESULTS The PUN female mice (15,365 ±8,844 revolutions·day-1) had a reduction (P=0.0221) in wheel revolutions per day as compared to the GUN (38,667±8648 revolutions·day-1) and CON females (36,421.0± 6,700 revolutions·day-1). PUN female mice also expressed significantly higher Drd1compared (P=0.0247) to the other groups. PUN female soleus had a higher expression of calsequestrin 1, along with more Type IIb fibers (P=0.0398). CONCLUSION Growth-restriction during lactation reduced physical activity in female mice by reducing the central drive to be active and displayed a more fatigable skeletal muscle phenotype. Address for correspondence: David P. Ferguson, 308 W. Circle Dr. Room 27S, East Lansing, MI, 48824, 517-355-4763, Fergu312@msu.edu This project was funded by Michigan State University Department of Kinesiology Start up funds. The authors have no conflicts of interest to report, and the results of this study are not endorsed by the ACSM. The results of this study are also presented clearly and honestly, without inappropriate data manipulation, fabrication, or falsification. Accepted for Publication: 4 May 2019 © 2019 American College of Sports Medicine

The Longitudinal Associations of Fitness and Motor Skills with Academic Achievement PURPOSE This study aimed to examine both independent and dependent longitudinal associations of physical fitness (PF) components with academic achievement. METHODS 954 4th-7th graders (9-15y [Mage=12.5y], 52% girls) from nine schools throughout Finland participated in a two-year follow-up study. Register-based academic achievement scores (grade point average [GPA]) and PF were assessed in the spring of 2013-2015. Aerobic fitness was measured with a maximal 20-m shuttle run test, muscular fitness with curl-up and push-up tests, and motor skills with a 5-leaps test and a throwing-catching combination test. Structural equation modelling was applied to examine the longitudinal associations adjusting for age, gender, pubertal stage, body fat percentage, learning difficulties and mother's education. RESULTS The change in aerobic and muscular fitness were positively associated with the change in GPA (B=0.27, 99% confidence interval CI=0.06-0.48; B=0.36, CI=0.11-0.63, respectively), while the change in motor skills were not associated with the change in GPA. Better motor skills in year 2 predicted better GPA a year later (B=0.06, CI=0.00-0.11; B=0.06, CI=0.01-0.11), while aerobic and muscular fitness did not predict GPA. GPA in year 1 predicted both aerobic (B=0.08, CI=0.01-0.15) and muscular (B=0.08, CI=0.02-0.15) fitness, and motor skills (B=0.08, CI=0.02-0.15) a year later. CONCLUSION The changes in both aerobic and muscular fitness were positively associated with change in academic achievement during adolescence, while the change in motor skills had only borderline significant association. However, better motor skills, although not systematically, independently predicted better academic achievement one year later, while aerobic or muscular fitness did not. Better academic achievement predicted better motor skills, aerobic and muscular fitness. Developmental changes in adolescence may induce parallel and simultaneous changes in academic achievement and PF. This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives License 4.0 (CCBY-NC-ND), where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially without permission from the journal. Corresponding author: Heidi J. Syväoja, LIKES Research Centre for Physical Activity and Health, Jyväskylä, Finland, Rautpohjankatu 8, FI-40700, Finland, tel. +358 (0)400248133, fax +358207629501, heidi.syvaoja@likes.fi This study was funded by the Academy of Finland (grant 273971) and the Finnish Ministry of Education and Culture (OKM/92/626/2013). The authors declare that there are 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: 26 April 2019. © 2019 American College of Sports Medicine

Estimating Tibial Stress throughout the Duration of a Treadmill Run Introduction Stress fractures of the tibia are a problematic injury amongst runners of all levels. Quantifying tibial stress using a modelling approach provides an alternative to invasive assessments that may be used to detect changes in tibial stress during running. This study aimed to assess the repeatability of a tibial stress model and to use this model to quantify changes in tibial stress that occur throughout the course of a 40-minute prolonged treadmill run. Methods Synchronised force and kinematic data were collected during prolonged treadmill running from fourteen recreational male rearfoot runners on two separate occasions. During each session, participants ran at their preferred speed for two consecutive 20-minute runs, separated by a 2-minute pause. The tibia was modelled as a hollow ellipse and bending moments and stresses at the distal 1/3 of the tibia were estimated using beam theory combined with inverse dynamics and musculoskeletal modelling. Results Intraclass correlation coefficients indicated good-to-excellent repeatability for peak stress values between sessions. Peak anterior and posterior stresses increased following 20 minutes of prolonged treadmill running and were 15% and 12% greater respectively after 40 minutes of running compared with the start of the run. Conclusion The hollow elliptical tibial model presented is a repeatable tool that can be utilised to assess within-participant changes in peak tibial stress during running. The increased stresses observed during a prolonged treadmill run may have implications for the development of tibial stress fracture. Corresponding author: Hannah Rice, PhD, Sport and Health Sciences, Richards Building, St Luke's Campus, Heavitree Road, Exeter, EX1 2LU, UK, H.Rice@exeter.ac.uk This research was supported by Brooks Running Company, Seattle, WA, USA. The authors declare no conflicts of interest. The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by ACSM. Accepted for Publication: 8 May 2019 © 2019 American College of Sports Medicine

Myocardial Adaptations to Competitive Swim Training Purpose Swim training is performed in the prone or supine position and obligates water immersion, factors which may augment cardiac volume-loading more than other endurance sports. At present, prospective data defining the cardiac responses to swim training are lacking. We therefore studied myocardial adaptations among competitive swimmers in order to establish a causal relationship between swim training and left ventricular (LV) remodeling. Methods Collegiate swimmers were studied before and after a 90-day period of training intensification. Transthoracic echocardiography was used to examine LV structural and functional adaptations under resting conditions and during an acute LV afterload challenge generated by isometric handgrip testing (IHGT). A sedentary control population was identically studied with IHGT. Results In response to a discrete period of swim training intensification, athletes (n=17, 47% female, 19±0.4 years old) experienced eccentric LV remodeling, characterized by proportionally more chamber dilation than wall thickening, with attendant enhancements of resting LV systolic (LV twist) and diastolic (early and late phase tissue velocities) function. Compared to baseline and controls, athletes post training demonstrated greater systolic twist impairment during IHGT. However, training induced LV dilation coupled with gains in diastolic function offset this acquired systolic susceptibility to acute afterload resulting in relative preservation of stroke volume during IHGT. Conclusion Swim training, a sport characterized by unique cardiac loading conditions, stimulates eccentric LV remodeling with concomitant augmentation of systolic twist and diastolic relaxation. This volume mediated cardiac remodeling appears to result in greater systolic susceptibility to acute afterload challenge. Further work is required to establish how training-induced changes in function translate to human performance and whether these are accompanied by physiologic trade-offs with relevance to common forms of heart disease. Address for correspondence: Aaron Baggish, M.D. Cardiovascular Performance Program Massachusetts General Hospital 55 Fruit Street, Yawkey 5B Boston, MA, 02114 Email: abaggish@partners.org This study was funded in part by a research grant from the American Heart Association FTF2220328 (A.L.B.). The results of this study are presented clearly, honestly and without fabrication, falsification, or inappropriate data manipulation. The results of the present study do not constitute endorsement by the ACSM. CONFLICTS OF INTEREST: The authors have no conflicts of interest to report. Accepted for publication: 22 April 2019. © 2019 American College of Sports Medicine

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