title: Effect of a prior bout of preconditioning exercise on muscle damage from downhill walking.
abstract: This study investigated whether reduced-duration downhill walking (DW) would confer a protective effect against muscle damage induced by a subsequent bout of longer duration DW performed 1 week or 4 weeks later. Healthy young adults were allocated to a control or one of the preconditioning exercise (PRE-1wk or PRE-4wk) groups (10 men and 4 women per group). PRE-1wk and PRE-4wk groups performed 20-min DW (-28% slope, 5 km/h, 10% body mass added to a backpack) 1 week and 4 weeks before 40-min DW, respectively, and the control group performed 40-min DW only. Maximal voluntary contraction (MVC) knee extension torque, plasma creatine kinase (CK) activity, and muscle soreness (100-mm visual analog scale) were measured before, immediately after, and 24, 48, and 72 h after DW, and the changes in these variables were compared among groups. The control group showed symptoms of muscle damage (e.g., prolonged decrease in MVC: -14% ± 10% at 48 h post-DW) after 40-min DW. Changes in all variables after 40-min DW of PRE-1wk and PRE-4wk groups were 54%-61% smaller (P < 0.05) than the control group, without significant differences between PRE-1wk and PRE-4wk groups for MVC and plasma CK activity. Importantly, changes after the preconditioning exercise (20-min DW) were 67%-69% smaller (P < 0.05) than those after the 40-min DW of the control group. These findings suggest that 20-min DW resulting in minor muscle damage conferred a protective effect against subsequent 40-min DW, and its effect could last for more than 4 weeks.
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, 1 Shiromizu, Kanoya, Kagoshima 891-2393, Japan., Japan Society for the Promotion of Science, Kouji, Tokyo 102-0088, Japan., School of Exercise and Health Sciences, Centre for Exercise and Sports Science Research, Edith Cowan University, Joondalup, WA 6027, Australia.
authors.forename: Sumiaki
authors.initials: S
authors.lastname: Maeo
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Ochi
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Yamamoto
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Kanehisa
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nosaka
mesh_terms: D001696:Biomechanical Phenomena; D003402:Creatine Kinase; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006801:Humans; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000473:pathology*; D009135:Muscular Diseases / Q000209:etiology / Q000517:prevention & control*; D010146:Pain; D005082:Physical Exertion / Q000502:physiology; D013997:Time Factors; D016138:Walking / Q000502:physiology*; D055815:Young Adult
chemical_list: D003402:Creatine Kinase
keywords: activité de la créatine kinase; creatine kinase activity; douleur musculaire; eccentric exercise; effet de protection; exercice pliométrique; extenseurs du genou; force musculaire maximale; hiking; knee extensors; maximum strength; muscle soreness; protective effect; randonnée d’aventure; randonnée pédestre; trekking