title: Vitamin D2 supplementation amplifies eccentric exercise-induced muscle damage in NASCAR pit crew athletes.
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.
authors.affiliation: Human Performance Laboratory, Appalachian State University, North Carolina Research Campus, Kannapolis, NC 28081, USA. niemandc@appstate.edu.
authors.forename: David C
authors.initials: DC
authors.lastname: Nieman
authors.forename: Nicholas D
authors.initials: ND
authors.lastname: Gillitt
authors.forename: R Andrew
authors.initials: RA
authors.lastname: Shanely
authors.forename: Dustin
authors.initials: D
authors.lastname: Dew
authors.forename: Mary Pat
authors.initials: MP
authors.lastname: Meaney
authors.forename: Beibei
authors.initials: B
authors.lastname: Luo
mesh_terms: D000328:Adult; D000363:Agaricales / Q000737:chemistry; D056352:Athletes; D001334:Automobile Driving; D003402:Creatine Kinase / Q000097:blood; D019587:Dietary Supplements; D004311:Double-Blind Method; D004872:Ergocalciferols / Q000008:administration & dosage* / Q000097:blood; D015444:Exercise / Q000502:physiology*; D006801:Humans; D045022:Lactate Dehydrogenases / Q000097:blood; D009119:Muscle Contraction / Q000187:drug effects; D018482:Muscle, Skeletal / Q000502:physiology*; D063806:Myalgia / Q000503:physiopathology; D009211:Myoglobin / Q000097:blood; D013177:Sports
chemical_list: D004872:Ergocalciferols; D009211:Myoglobin; D045022:Lactate Dehydrogenases; D003402:Creatine Kinase