title: Once-weekly muscle endurance and strength training prevents deterioration of muscle oxidative function and attenuates the degree of strength decline during 3-week forearm immobilization.
abstract: OBJECTIVE
  Muscle unloading causes muscle function deterioration, but the extent to which training frequency or volume can be reduced while preserving muscle function during muscle unloading is unknown. We examined the effects of low-volume muscle endurance and strength training on forearm muscle oxidative capacity, endurance, and strength during a 3-week immobilization.
  
  
  METHODS
  Twenty-seven, healthy, male volunteers were divided into four groups: immobilization only (IMM); immobilization with endurance and strength training, once-weekly (IMM + EST1) or twice-weekly (IMM + EST2); and control, without immobilization or training (CNT). Endurance training involved dynamic handgrip exercise, at 30% of maximal voluntary contraction (MVC), until exhaustion (~60 s). Strength training involved intermittent isometric handgrip exercise at 70% MVC (40 s). Muscle oxidative capacity was evaluated after exercise using the phosphocreatine recovery time constant using (31)phosphorus magnetic resonance spectroscopy. Endurance performance was evaluated according to the total work during dynamic handgrip exercise at 30% MVC at 1 Hz until exhaustion.
  
  
  RESULTS
  Muscle oxidative capacity and total work deterioration was restricted to the IMM (P < 0.05) group. MVC decreased in the IMM and IMM + EST1 (P < 0.05) groups. However, the MVC amplitude decrease in the IMM + EST1 group was smaller than that in the IMM (P < 0.05) group. MVC remained unchanged in the other groups.
  
  
  CONCLUSIONS
  During the 3-week immobilization, twice-weekly low-volume muscle endurance and strength training prevented deterioration in muscle strength, oxidative capacity, and endurance performance. Moreover, once-weekly muscle endurance and strength training prevented the deterioration of muscle oxidative capacity and endurance performance, and attenuated the degree of muscle strength decline.
authors.affiliation: Faculty of Sport and Health Science, Ritsumeikan University, 1-1-1 Nojihigashi, Kusatsu, Shiga, 525-8577, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Homma
authors.forename: Takafumi
authors.initials: T
authors.lastname: Hamaoka
authors.forename: Takuya
authors.initials: T
authors.lastname: Osada
authors.forename: Norio
authors.initials: N
authors.lastname: Murase
authors.forename: Ryotaro
authors.initials: R
authors.lastname: Kime
authors.forename: Yuko
authors.initials: Y
authors.lastname: Kurosawa
authors.forename: Shiro
authors.initials: S
authors.lastname: Ichimura
authors.forename: Kazuki
authors.initials: K
authors.lastname: Esaki
authors.forename: Fumiko
authors.initials: F
authors.lastname: Nakamura
authors.forename: Toshihito
authors.initials: T
authors.lastname: Katsumura
mesh_terms: D000328:Adult; D016022:Case-Control Studies; D015444:Exercise; D005542:Forearm / Q000502:physiology*; D006801:Humans; D008297:Male; D009119:Muscle Contraction; D053580:Muscle Strength; D018482:Muscle, Skeletal / Q000378:metabolism / Q000502:physiology*; D010101:Oxygen Consumption; D020127:Recovery of Function; D012149:Restraint, Physical