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Vitamin D2 Supplementation Amplifies Eccentric Exercise-Induced Muscle Damage in NASCAR Pit Crew Athletes
Human Performance Laboratory, Appalachian State University, North Carolina Research Campus, Kannapolis, NC 28081, USA
Dole Nutrition Research Laboratory, North Carolina Research Campus, Kannapolis, NC 28081, USA
Key Laboratory of Exercise and Health Sciences of Ministry of Education, Shanghai University of Sport, Shanghai 200438, China
* Author to whom correspondence should be addressed.
Received: 18 October 2013; in revised form: 4 December 2013 / Accepted: 17 December 2013 / Published: 20 December 2013
Abstract: This study determined if 6-weeks vitamin D2 supplementation (vitD2, 3800 IU/day) had an influence on muscle function, eccentric exercise-induced muscle damage (EIMD), and delayed onset of muscle soreness (DOMS) in National Association for Stock Car Auto Racing (NASCAR) NASCAR pit crew athletes. Subjects were randomized to vitD2 (n = 13) and placebo (n = 15), and ingested supplements (double-blind) for six weeks. Blood samples were collected and muscle function tests conducted pre- and post-study (leg-back and hand grip dynamometer strength tests, body weight bench press to exhaustion, vertical jump, 30-s Wingate test). Post-study, subjects engaged in 90 min eccentric-based exercise, with blood samples and DOMS ratings obtained immediately after and 1- and 2-days post-exercise. Six weeks vitD2 increased serum 25(OH)D2 456% and decreased 25(OH)D3 21% versus placebo (p < 0.001, p = 0.036, respectively), with no influence on muscle function test scores. The post-study eccentric exercise bout induced EIMD and DOMS, with higher muscle damage biomarkers measured in vitD2 compared to placebo (myoglobin 252%, 122% increase, respectively, p = 0.001; creatine phosphokinase 24 h post-exercise, 169%, 32%, p < 0.001), with no differences for DOMS. In summary, 6-weeks vitD2 (3800 IU/day) significantly increased 25(OH)D2 and decreased 25(OH)D3, had no effect on muscle function tests, and amplified muscle damage markers in NASCAR pit crew athletes following eccentric exercise.
Keywords: delayed onset of muscle soreness (DOMS); myoglobin; creatine phosphokinase; muscle function testing; eccentric exercise; LC-MS/MS
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Nieman, D.C.; Gillitt, N.D.; Shanely, R.A.; Dew, D.; Meaney, M.P.; Luo, B. Vitamin D2 Supplementation Amplifies Eccentric Exercise-Induced Muscle Damage in NASCAR Pit Crew Athletes. Nutrients 2014, 6, 63-75.
Nieman DC, Gillitt ND, Shanely RA, Dew D, Meaney MP, Luo B. Vitamin D2 Supplementation Amplifies Eccentric Exercise-Induced Muscle Damage in NASCAR Pit Crew Athletes. Nutrients. 2014; 6(1):63-75.
Nieman, David C.; Gillitt, Nicholas D.; Shanely, R. A.; Dew, Dustin; Meaney, Mary P.; Luo, Beibei. 2014. "Vitamin D2 Supplementation Amplifies Eccentric Exercise-Induced Muscle Damage in NASCAR Pit Crew Athletes." Nutrients 6, no. 1: 63-75.