Abstract:

BACKGROUND: Environment and sports can cause great changes in muscle fibers.
OBJECTIVE: To observe rat gastrocnemius myosin and actin expression and muscle tension changes under normoxic and hypoxic training conditions.
METHODS: SD rats were randomly divided into a normoxic control (20% oxygen, without any treatments), normoxic training 2, 4 and 6 weeks groups, hypoxic training 2, 4, and 6 weeks groups, and a hypoxic control group (12.7% oxygen, without training).
RESULTS AND CONCLUSION: No matter under normoxic or hypoxic environment, rat gastrocnemius mass and gastrocnemius muscle fiber crossection area were significantly increased after exercise training (P < 0.05, P < 0.01). After 6 weeks of exercise training, the maximum tension of gastrocnemius muscle in isometric contraction was significantly increased (P < 0.01). After exercise training, total MHC and α-actin expression in rat gastrocnemius muscle was gradually increased with the prolongation of training time and the increase was greater in the hypoxic training groups than in the normoxic training groups. Results demonstrated that hypoxic training can effectively promote gastrocnemius myosin and actin expression and increase muscle tension, and strengthen type Ⅰmuscle fiber, and that the longer the training time, the better the efficacy, suggesting that hypoxic training is an effective method of exercise training.