Prevention of disuse muscular weakness by restriction of blood flow.
OBJECTIVE
The aim of the present study was to compare the effects of periodic restriction of blood flow to lower extremities with those of isometric exercise on disuse muscular atrophy and weakness induced by immobilization and unloading.


METHODS
The left ankle of each of 15 healthy males was immobilized for 2 wk using cast, and subjects were instructed to walk using crutches with non-weight bearing during this period. Subjects were divided into three groups: a restriction of blood flow (RBF) group (application of external compressive force of 200 mm Hg for 5 min followed by 3 min of rest, repeated five times in a single session, two sessions per day for 14 d); an isometric training (IMT) group (20 "exercises" of 5-s isometric contraction of the knee extensor, flexor, and ankle plantar flexor muscles followed by rest, twice a day, daily for 2 wk); and a control (CON) group (no intervention). We measured changes in muscle strength, thigh/leg circumferences, and serum growth hormone levels.


RESULTS
Immobilization/unloading resulted in significant decreases in muscle strength of knee extensor and flexor muscles (P < 0.01 and < 0.05, respectively) and thigh and leg circumferences (P < 0.05, each) in the CON group, and significant decreases in muscle strength of the knee flexor muscles, ankle plantar flexor muscles, and leg circumference (P < 0.05) in the IMT group. RBF protected against these changes in muscle strength and thigh/leg circumference (P < 0.01 and < 0.05, respectively). No changes in serum growth hormone levels were noted.


CONCLUSIONS
Our results indicate that repetitive restriction of blood flow to the lower extremity prevents disuse muscular weakness.
Kubota
Atsushi
A
Department of Sports Medicine, Graduate School of Medicine, Juntendo University, Tokyo, Japan. akubota@med.juntendo.ac.jp
Sakuraba
Keishoku
K
Sawaki
Keisuke
K
Sumide
Takahiro
T
Tamura
Yoshifumi
Y
D000328:Adult; D000843:Ankle Joint; D005081:Exercise Therapy; D013006:Growth Hormone; D006801:Humans; D007103:Immobilization; D035002:Lower Extremity / Q000502:physiology; D008297:Male; D018908:Muscle Weakness; D018482:Muscle, Skeletal / Q000098:blood supply*; D020966:Muscular Disorders, Atrophic / Q000517:prevention & control*; D011312:Pressure
D013006:Growth Hormone