Low-volume muscular endurance and strength training during 3-week forearm immobilization was effective in preventing functional deterioration.
OBJECTIVE
The purpose of this study was to determine whether endurance and strength hand grip exercises during 3-week upper limb immobilization preserve muscle oxidative capacity, endurance performance and strength.


METHODS
Ten healthy adult men underwent non-dominant forearm immobilization by plaster cast for 21 days. Five healthy adult subjects were designated as the immobilization (IMM) group and five were designated as the immobilization + training (IMM+TRN) group. Grip strength, forearm circumference, dynamic handgrip endurance and muscle oxygenation response were measured before and after the 21 day immobilization period. Using near-infrared spectroscopy (NIRS), muscle oxygen consumption recovery (VO2mus) was recorded after a submaximal exercise and the recovery time constant (TcVO2mus) was calculated. Reactive hyperemic oxygenation recovery was evaluated after 5 minutes ischemia. Two training programs were performed by the IMM+TRN group twice a week. One exercise involved a handgrip exercise at 30% maximum voluntary contraction (MVC) at a rate of 1 repetition per 1 second until exhaustion (about 60 seconds). The other involved a handgrip exercise at 70% MVC for 2 seconds with a 2 second rest interval, repeated 10 times (40 seconds).


RESULTS
There was a significant group-by-time interaction between the IMM and IMM+TRN groups in the TcVO2mus (p = 0.032, F = 6.711). A significant group-by-time interaction was observed between the IMM and IMM+TRN groups in the MVC (p = 0.001, F = 30.415) and in grip endurance (p = 0.014, F = 9.791). No significant group-by-time interaction was seen in forearm circumference and reactive hyperemic oxygenation response either in IMM or IMM+TRN group.


CONCLUSIONS
The training programs during immobilization period used in this experiment were effective in preventing a decline in muscle oxidative function, endurance and strength.
Matsumura
Mika
M
Department of Sports Medicine for Health Promotion, Tokyo Medical University, 6-1-1 Shinjuku, Shinjuku-ku, Tokyo, Japan. mikamori0719@yahoo.co.jp
Ueda
Chihoko
C
Shiroishi
Kiyoshi
K
Esaki
Kazuki
K
Ohmori
Fumiko
F
Yamaguchi
Kuniko
K
Ichimura
Shiro
S
Kurosawa
Yuko
Y
Kime
Ryotaro
R
Osada
Takuya
T
Murase
Norio
N
Katsumura
Toshihito
T
Hoshika
Akinori
A
Hamaoka
Takafumi
T