EFFECT OF REDUCED MUSCLE TEMPERATURE ON ECCENTRIC EXERCISE-INDUCED MUSCLE DAMAGE 1120

Eccentric muscle actions produce a greater increase in muscle temperature compared with concentric actions. It has been suggested that higher muscle temperature generated during eccentric actions is a factor of eccentric exercise-induced muscle damage. If so, then reducing muscle temperature during eccentric exercise should reduce muscle damage. Therefore the purpose of this study was to investigate the effect of icing prior to eccentric exercise on eccentric exercise-induced muscle damage. Eight female students(18.6±0.7 yrs) who were not participating in any resistance training program performed about of 12 maximal eccentric actions of the elbow flexors with each arm. One arm performed the exercise after being applied ice (0°C) for 10 min over the elbow flexors (treatment), and the other arm preformed the same exercise without any treatment (control). The two conditions were separated by 2-4 weeks and presented in balanced order. The icing reduced muscle temperature (assessed by a deep body temperature monitor) about 10 °C. Muscle temperature was still 5-8 °C lower when the eccentric exercise started, and muscle temperature of the treatment arm was 2-3 °C lower right after the exercise comparing to the control arm. Isometric force (IF), range of motion, muscle soreness, circumference of the elbow flexors, plasma creatine kinase activity (CK), and B-mode ultrasound pictures of the elbow flexors were measured before and for 5 days after exercise. All measures changed significantly (p<0.05) after exercise, however the changes were not significantly different between the treatment and the control. For example, IF decreased from 104.8±5.4 to 56.5±4.2 N at 1 day after exercise for the treatment and 103.5±4.4 N to 58.3±5.3 N, respectively, for the control. Peak CK for the treatment and control was 2,982±1,400 IU/L and 3,308±1,417 IU/L, respectively. From these results, it is unlikely that higher muscle temperature generated during eccentric exercise is a primary cause of larger development of muscle damage in eccentric exercise. It is also important to note that reduced muscle temperature does not appear to increase muscle damage susceptibility by increasing the stiffness of muscle or connective tissue.