title: Age and activity status affect muscle reoxygenation time after maximal cycling exercise.
abstract: OBJECTIVE
  The purpose of this study was to determine the interaction of age and habitual physical activity on recovery time of muscle oxygenation following maximal cycling exercise (CycEXmax).
  
  
  METHODS
  Twelve sedentary middle-aged (50+/-6), 13 sedentary elderly (66+/-3), 13 active middle-aged (53+/-5), and 20 active elderly (67+/-5) women participated in this study. We evaluated the peak pulmonary oxygen uptake (VO2peak) during CycEXmax and the half-recovery time of muscle oxygenation (T1/2reoxy time) using near-infrared spectroscopy at the vastus lateralis (VL) during the recovery phase after CycEXmax.
  
  
  RESULTS
  T1/2reoxy time was significantly greater in the elderly subjects than in the middle-aged subjects in both sedentary (P<0.05) and active groups (P<0.01). T1/2reoxy time of the active group was lower (P<0.01) than that of the sedentary group regardless of age. Age was significantly correlated to T1/2reoxy time in both sedentary and active groups (in both sedentary and active groups: P<0.01). The slope of T1/2reoxy time against age in the sedentary group was significantly greater (VL: P<0.05) than that of the active group. VO2peak showed significant inverse correlation with T1/2reoxy time at the VL in both sedentary and active groups. The slope of VO2peak against T1/2reoxy time showed no significant differences between middle-aged and elderly subjects.
  
  
  CONCLUSIONS
  The results of this study suggest that T1/2reoxy time was prolonged with aging, regardless of habitual physical activity levels. However, habitual physical activity may prevent the age-related prolongation in T1/2reoxy time after CycEXmax. VO2peak appears to be one of the major factors determining T1/2reoxy time, not age.
authors.affiliation: Department of Liberal Arts, Faculty of Science and Technology, Tokyo University of Science, Chiba, Japan. shiro@rs.noda.tus.ac.jp
authors.forename: Shiro
authors.initials: S
authors.lastname: Ichimura
authors.forename: Norio
authors.initials: N
authors.lastname: Murase
authors.forename: Takuya
authors.initials: T
authors.lastname: Osada
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Kime
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Homma
authors.forename: Chihoko
authors.initials: C
authors.lastname: Ueda
authors.forename: Takeshi
authors.initials: T
authors.lastname: Nagasawa
authors.forename: Mayuko
authors.initials: M
authors.lastname: Motobe
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hamaoka
authors.forename: Toshihito
authors.initials: T
authors.lastname: Katsumura
mesh_terms: D000368:Aged; D001642:Bicycling / Q000502:physiology*; D003430:Cross-Sectional Studies; D005080:Exercise Test; D005260:Female; D006801:Humans; D007564:Japan; D008875:Middle Aged; D008991:Monitoring, Physiologic / Q000379:methods; D018482:Muscle, Skeletal / Q000502:physiology*; D010101:Oxygen Consumption / Q000502:physiology*; D019265:Spectroscopy, Near-Infrared