Abstract:

BACKGROUND: It has been demonstrated that pre-heat stress can elevate the ability of muscle against injury, but the precise mechanism is unclear.
OBJECTIVE: To observe the effect of pre-heat stress on superoxide dismutase activities and malondialdehyde content in rat skeletal muscle after eccentric exercise.
METHODS: Male Wistar rats were randomly divided into control group, eccentric exercise group, heat stress+eccentric exercise group. The temperature of heat stress was 43 ℃ for about 35 minutes. Large load intermittence eccentric exercise was performed at -16° down slope treadmill at 26.8 m/min for 5 minutes, with an interval of 1 minute, totally for 10 groups. Rat gastrocnemius muscle was obtained at 1 hour before exercise, 1, 24 and 48 hours after exercise separately. Rat malondialdehyde content was determined by thiobarbituricacid method. Superoxide dismutase activities were measured by xanthine oxidase method.
RESULTS AND CONCLUSION: Compared with control group, malondialdehyde content was significantly increased in rat gastrocnemius muscle in eccentric exercise group (P < 0.05), and gradually increased over time after exercise. Superoxide dismutase activities were significantly decreased over time after exercise (P < 0.05). Compared with eccentric exercise group, superoxide dismutase activities were significantly increased (P < 0.05), but malondialdehyde content (P < 0.05) was significantly decreased in rat gastrocnemius muscle of heat stress+eccentric exercise group. These indicate that heat stress can enhance superoxide dismutase activities, reduce malondialdehyde content, and protect skeletal muscle from eccentric exercise induced injury.