Medicine & Science in Sports & Exercise

Prediction of Planetary Mission Task Performance for Long-Duration Spaceflight Introduction This study aimed to determine values and ranges for key aerobic fitness variables that can individually map the level of success for planetary mission tasks performance for long-duration spaceflight. With the goal to develop a predictor-testing model that can be performed with in-flight equipment. Methods We studied a group of 45 men and women who completed a series of mission critical tasks; a surface traverse task and a hill climb task. Participants performed each mission task at a low and moderate intensity designed to elicit specific metabolic responses similar to what is expected for ambulation in Lunar and Martian gravities, respectively. Aerobic fitness was characterized via cycling and rowing V[Combining Dot Above]O2peak, ventilatory threshold (VT), and critical power. Logistic regression and receiver operating characteristic (ROC) curve analysis were used to determine the cutoff thresholds for each aerobic fitness parameter that accurately predicted task performance. Results The participants of this study were characterized by a range of cycling V[Combining Dot Above]O2peaks from 15.5 to 54.1 ml kg−1 min−1. A V[Combining Dot Above]O2peak optimal cutoff values of X and Y ml kg−1 min−1 were identified for the low and moderate intensity surface traverse task respectively. For the low and moderate intensity hill climb test the optimal V[Combining Dot Above]O2peak cutoff values were X and Y ml kg−1 min−1, respectively. VT and critical power also showed high sensitivity and specificity for identifying individuals who could not complete the mission tasks. Conclusion In summary, we identified aerobic fitness thresholds below which task performance was impaired for both low and moderate intensity mission critical tasks. Specifically, cycling V[Combining Dot Above]O2peak, VT, and rowing CP could each be used to predict task failure. Address for correspondence Carl J. Ade, Ph.D. Kansas State University Manhattan, KS 66506 E-mail: cade@ksu.edu The results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation, and statement that results of the present study do not constitute endorsement by ACSM. This study was supported by a National Aeronautics and Space Administration (NASA) research grant awarded to C.J Ade and T. J. Barstow. CONFLICT OF INTERESTS. None Submitted for publication August 2018. Accepted for publication February 2019. © 2019 American College of Sports Medicine

Independent Influence of Spinal Cord Injury Level on Thermoregulation during Exercise Purpose Establish the true influence of spinal cord injury (SCI) level on core temperature and sweating during exercise in the heat independently of biophysical factors. Methods 31 trained males (8 tetraplegic (TP; C5-C8), 7 high paraplegic (HP; T1-T5), 8 low paraplegic (LP; T6-L1) and 8 able-bodied (AB)) performed 3×10-min of arm ergometry with 3-min rest at a metabolic heat production of: a) 4.0 W/kg (AB vs. TP), or b) 6.0 W/kg (AB vs. HP vs. LP), in 35°C, 50% relative humidity (RH). Esophageal (Tes) and local skin temperatures, and local sweat rate (LSR) on the forehead and upper-back were measured throughout. Results Change in Tes was greatest in TP (1.86±0.32°C vs. 0.29±0.07°C, p<0.001), and greater in HP compared to LP and AB, reaching 1.20±0.50°C, 0.66±0.23°C and 0.53±0.12°C, respectively (p<0.001). Approximately half of the variability in end-trial ΔTes was described by SCI level in paraplegics (adjusted R2=0.490; p=0.005). Esophageal temperature onset thresholds of sweating at the forehead and upper-back were similar among HP, LP and AB, while no sweating was observed in TP. Thermosensitivity (ΔTes vs. ΔLSR) was also similar, except for LP demonstrating lower thermosensitivity than AB at the upper-back (0.78±0.26 mg·cm-2·min-1 vs. 1.59±0.89 mg·cm-2·min-1, p=0.039). Change in skin temperature was greatest in denervated regions, most notably at the calf in all SCI groups (TP: 2.07±0.93°C, HP: 2.73±0.68°C, LP: 2.92±1.48°C). Conclusion This study is the first to show the relationship between ΔTes and SCI level in athletes with paraplegia after removing variability arising from differences in metabolic heat production and mass. Individual variability in ΔTes is further reduced among athletes with tetraplegia due to minimal evaporative heat loss secondary to an absence of sweating. Address for correspondence: Dr. Ollie Jay PhD Thermal Ergonomics Laboratory, Faculty of Health Sciences, University of Sydney, NSW 2141. Australia e-mail: ollie.jay@sydney.edu.au This study was supported by a Collaborative Research Network for Advancing Exercise and Sport Science grant from Bond University, and a High Performance Sport Research Fund grant from Australian Institute of Sport. The authors would like to thank the athletes who volunteered their time, and the National Sporting Organisations that supported their involvement. In addition, to Nikola Srnic for his assistance with the data collection, Dr Yorgi Mavros for performing the DXA scans, and the University of Sydney Thermal Ergonomics Laboratory staff and students for technical support during data collection. The results of the present study do not constitute endorsement by ACSM and the authors declare no conflict of interest. The results of the study are presented honestly, and without fabrication, falsification, or inappropriate data manipulation. Submitted for publication November 2018. Accepted for publication February 2019. © 2019 American College of Sports Medicine

Testosterone and Resistance Training Improve Muscle Quality in Spinal Cord Injury Purpose Spinal cord injury (SCI) negatively impacts muscle quality and testosterone levels. Resistance training (RT) has been shown to increase muscle cross-sectional area (CSA) following SCI, while testosterone replacement therapy (TRT) has been shown to improve muscle quality in other populations. The purpose of this pilot study was to examine if the combined effects of these interventions, TRT+RT, may maximize the beneficial effects on muscle quality after SCI. Methods Twenty-two SCI subjects randomized into either a TRT+RT (n = 11) or TRT (n = 11) intervention for 16 weeks. Muscle quality measured by peak torque at speeds of 0, 60, 90, and 180°·sec-1 (PT-0°, PT-60°, PT-90°, PT-180°), knee extensor CSA (KE-CSA), specific tension (ST), and contractile speed (rise time [RTi], and half-time to relaxation [½TiR]) was assessed for each limb at baseline and post-intervention using 2x2 mixed models. Results Following 16-weeks subjects in the TRT+RT group increased PT-0° (48.4%, P = 0.017), KE-CSA (30.8%, P < 0.0001), and RTi (17.7%, P = 0.012); with no significant changes observed in the TRT group. Regardless of the intervention, changes to PT-60° (28.4% P = 0.020), PT-90° (26.1%, P = 0.055), and PT-180° (20.6% P = 0.09) for each group were similar. Conclusion The addition of mechanical stress via RT to TRT maximizes improvements to muscle quality following complete SCI when compared to TRT administered alone. Our evidence shows that this intervention increases muscle size and strength, while also improving muscle contractile properties. CORRESPONDING AUTHOR: Ashraf S. Gorgey, MPT, PhD, FACSM, FACRM, Hunter Holmes McGuire VA Medical Center, Spinal Cord Injury & Disorders Service, 1201 Broad Rock Blvd, Richmond, VA 23249, USA, Phone: (804) 675-5000 ext. 3386, Email: ashraf.gorgey@va.gov This work was supported by funding from the United States Department of Veteran Affairs: VA-RRD CDA2 (B7867-W). We, the authors, affirm that we have no financial interests or involvement with any commercial organization that has a direct financial interest in any matter included in this manuscript. Our study design, collection, analysis, and reporting of results were not influenced by our funding source. The results of the present study do not constitute endorsement by the ACSM. The results of the present study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for Publication: 1 March 2019 © 2019 American College of Sports Medicine

Fat Oxidation Rates in Professional Soccer Players Purpose Large inter-individual variation exists in maximal fat oxidation rates (MFO) and the exercise intensity at which it occurs (FATMAX). However, there is no data describing the shape of the fat oxidation curve or, if individual differences exist when tested on separate occasions. Furthermore, there is limited data on fat metabolism in professional team sport athletes. Therefore, the aim of this study was to test-retest the concavity (shape) and intercept (height) of fat oxidation curves within a group of professional soccer players. Method On two occasions 16 professional male soccer players completed a graded exercise test in a fasted state (≥5 h). Rates of fat oxidation were determined using indirect calorimetry. Maximal oxygen uptake (VO2max) was measured to calculate FATMAX (%VO2max). The shape of the fat oxidation curves were modelled on an individual basis using third degree polynomial. Test-by-test differences, in the shape and vertical shift of the fat oxidation curves, were established to assess within-individual variability. Results Average absolute MFO was 0.69 ± 0.15 g[BULLET OPERATOR]min-1 (range 0.45 – 0.99g[BULLET OPERATOR]min-1). On a group level, no significant differences were found in MFO between the two tests. No differences were found (p>0.05) in the shape of the fat oxidation curves in 13/16 players (Test1 vs. Test2). There were also no differences (p>0.05) in the vertical shift of the fat oxidation curves in 10 players. Conclusion In general, the shape of the fat oxidation curve does not change within an individual however the vertical shift is more susceptible to change, which may be due to training status and body composition. Understanding a player's metabolism may be of value to practitioners working within sport, with regards to personalising nutrition strategies. Address for Correspondence: Rebecca K. Randell, Gatorade Sports Science Institute, PepsiCo Global R&D, Beaumont Park, 4 Leycroft Road, LEICESTER, LE4 1ET, United Kingdom. Email: rebecca.randell@pepsico.com The results of this study are presented clearly, honestly and without fabrication or inappropriate data manipulation and statement that results of the present study do not constitute endorsement by ACSM. R.R, J.C, I.R are employees of The Gatorade Sports Science Institute (GSSI), a division of PepsiCo, Inc. MA.L and J.Y are employees of FC Barcelona. The views expressed in this article are those of the authors and do not necessarily reflect the position or policy of PepsiCo, Inc. Financial support for this study was provided by the Gatorade Sports Science Institute, a division of PepsiCo, Inc. Accepted for publication: 26 February 2019. © 2019 American College of Sports Medicine

Shared Neuromuscular Performance Traits in Military Personnel with Prior Concussion Concussions are common in military personnel and may result in increased risk of musculoskeletal injury. One plausible explanation for this risk could be that neuromotor deficiencies enhance injury risk following concussion through altered muscular activation/contraction timing. Purpose To compare military personnel with at least one concussion during the past 1 month to 2 years (CONCUSSED) to military branch-, age- and Special Operations Forces group- matched controls (CONTROL) on physiological, musculoskeletal and biomechanical performance. Methods A total of 48 (24 CONCUSSED, 24 CONTROL) male Air Force and Naval Special Warfare Operators aged 19-34 years participated in the study. Participants self-reported demographics/injury history and completed the following assessments: 1) physiological- body composition, anaerobic power and capacity, aerobic capacity and lactate threshold; 2) musculoskeletal- lower extremity isokinetic strength testing, including time to peak torque; and 3) biomechanical- single-leg jump and landing task, including landing kinematics of the hip, knee and ankle. A machine learning decision tree algorithm (C5.0) and one-way ANOVA were used to compare the two groups on these outcomes. Results Despite non-significant differences using ANOVA, the C5.0 algorithm revealed CONCUSSED demonstrated quicker time to peak knee flexion angle during the single-leg landing task (<=0.170 secs; CONCUSSED: n=22 vs. CONTROL: n=14), longer time to peak torque in knee extension isokinetic strength testing (>500 msecs; CONCUSSED: n=18 vs. CONTROL: n=4) and larger knee flexion angle at initial contact (>7.7°; CONCUSSED: n=18 vs. CONTROL: n=2). Conclusion The findings supported the hypothesis that CONCUSSED military personnel would demonstrate altered neuromuscular control in landing strategies and muscular activation. Future research should assess prospectively neuromuscular changes following concussion and determine if these changes increase risk of subsequent musculoskeletal injuries. Corresponding Author: Shawn R. Eagle, 3860 S. Water St, Pittsburgh, PA 15203. (p): 412-246-0460. (e): seagle@pitt.edu The results of this study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The results of this study do not constitute endorsement by ACSM. The authors have no conflicts of interest to report. This study was funded by Air Force Special Operations Command (#FA8650-12-2-6271) and Office of Naval Research (#N00014-11-1-0929). Opinions, interpretations, conclusions, and recommendations are those of the authors and not necessarily endorsed by the Department of Defense, US Navy, US Air Force or Naval Special Warfare. Accepted for publication: 28 February 2019. © 2019 American College of Sports Medicine

Compositional Influence of Movement Behaviours on Bone Health during Ageing Introduction and Purpose Physical activity (PA) is considered the best non-pharmacological treatment for the decrease in bone mass (BM) produced during ageing. Therefore, it is essential to assess how the time spent in PA is distributed in order to control further changes. This work examines the relationship between movement behaviours and BM during ageing, using compositional data analysis. Methods We studied 227 older people aged 65 to 94 (102 men and 125 women) divided by sex and bone status, over a period of 4 years. Time spent in sedentary behaviour (SB), light PA (LPA) and moderate-to-vigorous PA (MVPA), was assessed using accelerometry. BM was determined by dual-energy X-ray absorptiometry. Results The changes in MVPA was positively associated with the rate of BM decay at spine and leg in the whole sample and men's subgroup (p≤0.05). In women, the rate of BM decay at spine and Ward's triangle were negatively associated with SB changes and BM decay at femoral neck and Ward's was positively associated with LPA (p≤0.05). Conclusion Increasing MVPA related to other movement behaviours produces improvements in the rate of bone change in older men; while to increase LPA and maintain MVPA would be the best approach to enhance bone mass in older women. Corresponding Author: Ignacio Ara, PhD, GENUD Toledo Research Group; University of Castilla-La Mancha, Avda Carlos III s/n; 45071 Toledo, Spain. Phone: +34 925 268 800 Ext 5543. Email: ignacio.ara@uclm.es Equal contribution (Francisco J. García-García and Ignacio Ara) This work was supported by the Biomedical Research Networking Centre on Frailty and Healthy Ageing (CIBERFES) and FEDER funds from the European Union (CB16/10/00477) and (CB16/10/00456). It was further funded by grants from the Government of Castilla-La Mancha (PI2010/020; Institute of Health Sciences, Ministry of Health of Castilla-La Mancha, 03031-00), Spanish Government (Spanish Ministry of Economy, "Ministry of Economy and Competitiveness," The Carlos III Institute of Health, PI10/ 01532, PI031558, PI11/01068), and by European Grants (Seventh Framework Programme: FRAILOMIC). IRG and AM received a PhD grant from the University of Castilla-La Mancha "Pre-doctoral contracts for the training of research staff in the framework of its own programme of I+D+I, cofinanced by the European Social Fund" (2014/10340 and 2015/4062, respectively). The authors report no conflict of interest and they affirm 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 the American College of Sports Medicine. Accepted for publication: 14 February 2019. © 2019 American College of Sports Medicine

Persistent Impairment in Cardiopulmonary Fitness following Breast Cancer Chemotherapy Purpose Anthracycline chemotherapy (AC) is associated with acute reductions in cardiopulmonary fitness (VO2peak). We sought to determine whether changes in VO2peak and cardiac function persisted at 12-months post-AC completion, and whether changes in cardiac function explain the heightened long-term heart failure risk. Methods Women with breast cancer scheduled for AC (n=28) who participated in a non-randomized trial of exercise training (ET; n=14) or usual care (UC; n=14) during AC completed a follow-up evaluation 12-months post-AC completion (16-months from baseline). At baseline, 4-months, and 16-months, participants underwent a resting echocardiogram (left ventricular ejection fraction, LVEF; global longitudinal strain, GLS), a blood sample (troponin; b-type natriuretic peptide), a cardiopulmonary exercise test, and cardiac MRI measures of stroke volume (SV), heart rate (HR) and cardiac output (Qc) at rest, and during intense exercise. Results Seventeen women (UC: n=8; ET: n=9) completed evaluation at baseline, 4-months and 16-months. At 4-months, AC was associated with 18% and 6% reductions in VO2peak in the UC and ET groups respectively, that persisted at 16-months (UC: -16%; ET: -7%), and was not attenuated by ET (interaction, P=0.10). Exercise Qc was lower at 16-months compared to baseline and 4-months (P<0.001), which was due to a blunted augmentation of SV during exercise (P=0.032; a 14% reduction in peak SV), with no changes in HR response. There was a small reduction in resting LVEF (baseline to 4-months) and GLS (between 4-months and 16-months), and an increase in troponin (baseline to 4-months), but only exercise Qc was associated with VO2peak (R2=0.47, P<0.01). Conclusion Marked reductions in VO2peak persisted 12-months following anthracycline-based chemotherapy, which was associated with impaired exercise cardiac function. Clinical Trial Registration: ACTRN12616001602415 Address for correspondence: Associate Professor André La Gerche, Head, Clinical Research Domain, Baker Heart and Diabetes Institute, 75 Commercial Rd, Melbourne 3004, VIC, Australia. Phone: +61 38532 1143. Fax: +61 38532 1899. E-mail: Andre.LaGerche@baker.edu.au This project was supported by a project grant from the Jack Brockhoff Foundation, Australia (JBF 4039). Andre La Gerche is supported by a Career Development Fellowship from the National Health and Medical Research Council (NHMRC 1089039) and a Future Leaders Fellowship from the National Heart Foundation (NHF 100409) of Australia. Stephen Foulkes is supported by an Australian Government Research Training Program Scholarship (RTP 4635089552). Professor Haykowsky is funded, in part, by the Moritz Chair in Geriatrics in the College of Nursing and Health Innovation at the University of Texas at Arlington. The authors have no conflict 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 February 2019. © 2019 American College of Sports Medicine

High-Intensity Aerobic Exercise Acutely Increases Brain-derived Neurotrophic Factor Aerobic exercise (AEx) exerts antidepressant effects, although the neurobiological mechanisms underlying such effects are not well understood. Reduced brain-derived neurotrophic factor (BDNF) and elevated cortisol have been implicated in the pathophysiology of depression and appear to normalize with antidepressant treatment. Thus BDNF and cortisol may serve as biological targets for developing AEx as an antidepressant treatment. Purpose This study examined the effects of AEx, of different intensities, on serum BDNF and cortisol in individuals with and without depression. Methods Thirteen participants with depression (10 female; age = 27.2 ± 6.9; Montgomery-Äsberg Depression Rating Scale (MADRS) = 21.7 ± 4.7) and thirteen control participants (10 female; age 27.2 ± 7.2; MADRS = 0.5 ± 0.9) participated. Experimental visits consisted of 15 minutes of low intensity cycling (LO) at 35% heart rate reserve (HRR), high intensity cycling (HI) at 70% HRR, or sitting (CON). During each visit, blood samples were obtained at baseline, immediately post-exercise (IP), and then every fifteen minutes post-exercise for one hour (15P, 30P, 45P, 60P). Group, condition, and time differences in BDNF and cortisol were assessed. Results There were no group differences in cortisol and BDNF. Secondary analysis revealed that BDNF increased in an intensity-dependent nature at IP and cortisol was significantly elevated at 15P following HI. Changes in BDNF and cortisol showed significant linear relationships with changes in HR. Conclusion HI AEx can elicit acute, transient increases in BDNF and cortisol in young, healthy, and physically active, non-depressed and mild-moderately depressed individuals. This work suggests AEx has potential to significantly impact central nervous system function and the magnitude of such impact may be directly driven by exercise intensity. Corresponding author: Ryan E. Ross, 77 President St., MSC 700, Charleston, SC 29425. (p) 843-792-3477. (e) rossre@musc.edu This project was supported by funding from the National Institute of General Medical Sciences under grant number P20-GM109040 and by MUSC's Clinical and Translational Science Award grant UL1 TR001450 from the National Center for Advancing Translational Sciences (NCATS). Conflict of Interest. The authors have no conflicts to report. The results of this study do not constitute endorsement by the American College of Sports Medicine. The results are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. Accepted for publication: 24 February 2019. © 2019 American College of Sports Medicine

Effects of Exercise on Stress-induced Attenuation of Vaccination Responses in Mice Studies suggest that exercise can improve vaccination responses in humans. Chronic stress can lead to immunosuppression, and there may be a role for exercise in augmenting immune responses. Purpose To investigate the effects of acute eccentric exercise (ECC) and voluntary wheel exercise training (VWR) on antibody and cell-mediated immune responses to vaccination in chronically stressed mice. We hypothesized that both ECC and VWR would attenuate chronic stress-induced reductions in vaccination responses. Methods Mice were randomized into four groups: Control (CON), Stress (S)-ECC, S-VWR, and S-Sedentary (SED). Stressed groups received chronic restraint stress for 6 h/day, 5 days/wk for three weeks. After the first week of stress, S-ECC were exercised at 17m/min speed at -20% grade for 45 minutes on a treadmill and then intramuscularly injected with 100μg of ovalbumin and 200μg of alum adjuvant. All other groups were also vaccinated at this time. Stress-VWR mice voluntarily ran on a wheel for the entire experiment. Plasma was collected prior to, and at one, two and four weeks post-vaccination. ELISA was performed to analyze anti-OVA IgG and IgM antibodies. After three weeks of chronic stress, all mice were injected with OVA into the ear to determine the delayed-type hypersensitivity (DTH). Results We found that chronic restraint stress significantly reduced body weight and caused adrenal hypertrophy. We also found both S-ECC and S-VWR groups had significantly elevated anti-OVA IgG (p < 0.05) while no significant differences between the two exercise groups. Neither S-ECC nor S-VWR altered anti-OVA IgM or DTH responses compared to S-SED group. Conclusion Acute eccentric exercise and voluntary exercise training alleviated the chronic stress-induced anti-OVA IgG reductions in vaccination responses. Corresponding Author: Jeffrey A. Woods, 1008B Khan Annex/Huff Hall, 1204 S. 6th Street, Champaign, IL 61820. woods1@illinois.edu. (217) 244-8815 The authors state that the results of the study are presented clearly, honestly, and without fabrication, falsification, or inappropriate data manipulation. The authors report no conflict of interest. The results of the present study do not constitute endorsement by ACSM. Accepted for publication: 25 February 2019. © 2019 American College of Sports Medicine

High-Intensity Interval Training Improves Left Ventricular Contractile Function Introduction Improved myocardial contractility is a critical circulatory adaptation to exercise training. However, the types of exercise that enhance left ventricular (LV) contractile and diastolic functions have not yet been established. This study investigated how high-intensity interval (HIIT) and moderate-intensity continuous training (MICT) influence LV mechanics during exercise. Methods Fifty-four healthy sedentary males were randomized to engage in either HIIT (3-minute intervals at 40% and 80% of VO2max, n=18) or MICT (sustained 60% of VO2max, n=18) for 30 minutes/day, 5 days/week for 6 weeks or to a control group (CTL, n=18) that did not engage in exercise intervention. LV mechanics during semi-upright bicycle exercise tests were measured by two-dimensional speckle-tracking echocardiography. Results Before the interventions, acute bicycle exercise increased (i) peak basal/apical radial and circumferential and peak longitudinal strains and strain rates (SRs), (ii) peak basal/apical rotations and torsion, and (iii) peak systolic twisting and early diastolic untwisting velocities in the LV. After the interventions, the HIIT group exhibited greater LV mass and diastolic internal diameter as well as higher E/A ratio and early diastolic propagation velocity than the MICT group. Despite decreased peak apical rotation and torsion, HIIT enhanced peak apical radial strain and SR as well as shortened the time to reach peak untwisting velocity in the LV during exercise. However, the LV mechanics during exercise were unchanged in the CTL group. Conclusion HIIT but not MICT induces eccentric myocardial hypertrophy. Moreover, HIIT effectively improves the LV mechanics during exercise by increasing contractile and diastolic functions. Correspondence to: Professor, Jong-Shyan Wang Graduate Institute of Rehabilitation Science Chang Gung University 259 Wen-Hwa 1st Road, Kwei-Shan, Tao-Yuan, 333, Taiwan. E-mail: s5492@mail.cgu.edu.tw This work was supported by the National Science Council of Taiwan (grant number NSC 100-2314-B-182-004-MY3), Chang Gung Medical Research Program (grant number CMRPD1A0131), and Healthy Aging Research Center, Chang Gung University (grant number EMRPD1A0841). 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. No conflicts of interest, financial or otherwise, are declared by the authors. Submitted for publication January 2018. Accepted for publication February 2019. © 2019 American College of Sports Medicine