title: Effect of intensive interval training during unloading on muscle deoxygenation kinetics.
abstract: The present study investigated the effects of intensive interval training during 20-day of unloading on local muscle oxygenation kinetics evaluated by near infrared spectroscopy technique (NIRS). Eleven adult men completed 20-day unloading and were divided into two groups; the control (CON) group and training (TR) group. The TR group engaged in exercise training sessions that consisted of one-legged submaximal cycle exercise using the unloaded leg at 60 approximately 80% of VO(2peak) with intermittent rest periods, 25 min/day every other day. All subjects performed isometric knee extension exercise at 50% of their maximum voluntary contraction force before and after unloading. NIRS Delta[deoxy-Hb/Mb] signal was recorded from m. vastus lateralis and was fitted to an exponential equation in order to determine the kinetics parameters. The time constant (tau) of the % Delta[deoxy-Hb/Mb] was unchanged in the TR group, while it significantly increased in the CON group after unloading (pre, 5.0+/-1.0; post, 7.4+/-1.0 s). It is concluded that 20-day unloading increased the tau, suggesting deterioration of capacity for oxidative phosphorylation and oxygen utilization in a skeletal muscle. Additionally, the preservation of tau in the TR group suggested that intensive interval training could have an impact on the maintenance of muscle oxidative metabolism during unloading.
authors.affiliation: Graduate School of Education, Kanazawa University, Kanazawa-city, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Furuichi
authors.forename: K
authors.initials: K
authors.lastname: Masuda
authors.forename: H
authors.initials: H
authors.lastname: Takakura
authors.forename: N
authors.initials: N
authors.lastname: Hotta
authors.forename: K
authors.initials: K
authors.lastname: Ishida
authors.forename: K
authors.initials: K
authors.lastname: Katayama
authors.forename: S
authors.initials: S
authors.lastname: Iwase
authors.forename: H
authors.initials: H
authors.lastname: Akima
mesh_terms: D000328:Adult; D001642:Bicycling / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate; D006801:Humans; D007537:Isometric Contraction; D007700:Kinetics; D008297:Male; D018482:Muscle, Skeletal / Q000378:metabolism* / Q000502:physiology; D010085:Oxidative Phosphorylation; D010101:Oxygen Consumption / Q000502:physiology*; D010807:Physical Endurance / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared; D013848:Thigh / Q000502:physiology