title: Muscular adaptations to short-term low-frequency downhill walking training.
abstract: This study examined muscular adaptations of knee extensors following short-term low-frequency downhill walking training. 22 young males (training group: TG, n=12; control group: CG, n=10) participated. TG conducted 40-min downhill treadmill walking (load: 10% of body mass, gradient: 28%, velocity: 5 km/h) 1 session/week for 4 weeks. Before and after the intervention, muscle thickness of knee extensors and maximal knee extension torques in eccentric (- 120, - 60, - 30°/s), isometric (0°/s), and concentric (30, 60, 120, 240°/s) conditions were measured. For TG, muscle damage markers were also measured before and up to 72 h following each session. After the intervention, CG did not show any changes in all variables. TG had significant increases in maximal knee extension torques at all angular velocities, with higher relative gains in eccentric torques (+ 24% on average) than isometric (+ 13%) and concentric (+ 12% on average) torques. No changes were found in the muscle thickness. Although considerable muscle damage was observed after the first training session in TG, the magnitudes of changes in all markers following the second to fourth sessions were minimal. These results indicate that even with relatively short-term and low-frequency, downhill walking training can increase the strength capacity of knee extensors, especially in eccentric strength.
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Maeo
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Sports and Life Science, National Institute of Fitness and Sports in Kanoya, Kagoshima, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Kanehisa
mesh_terms: D000222:Adaptation, Physiological; D000328:Adult; D003402:Creatine Kinase / Q000097:blood; D006801:Humans; D007717:Knee / Q000502:physiology*; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength / Q000502:physiology*; D018482:Muscle, Skeletal / Q000033:anatomy & histology / Q000293:injuries / Q000502:physiology*; D063806:Myalgia / Q000503:physiopathology; D010806:Physical Education and Training; D016138:Walking / Q000502:physiology*; D055815:Young Adult
chemical_list: D003402:Creatine Kinase