Hiruma, E., Umimura, M., & Katamoto, S. Effects of repeated maximum endurance strength exercise on muscle damage and repair in collegiate females. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 748.

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This study determined the relationships among muscle damage, recovery, and adaptation following repeated bouts of daily muscle-endurance exercise for three or seven consecutive days. Females (N = 40) were assigned to groups experiencing one day of exercising (N = 9), three days of exercising (N = 9), or seven days of exercising (N = 12). This study examined creatine kinase activity, dorsiflexed ankle-joint angle, scale of perceived pain during rest, maximum circumference of calf muscle, isometric muscle strength on the lower leg, and long jumping off one leg before and after daily exercising for the three- or seven-day periods. In the exercise period, Ss performed a maximum calf-raise at one movement per two seconds for as long as possible. Ss counted daily walking steps by using a walking step-counter.

Ss walked 7000 to 8000 steps per day. After the initial exercise, creatine kinase significantly increased and the peak creatine kinase was on Day 4 in the three groups. Recovery times in the three- and seven-day groups were longer than that of the one-day group. Perceived pain during rest in the three groups were significantly elevated from Day 1. Peak perceived pain in the one-, three-, and seven-day groups were on Days 2, 3, and 4, respectively. The long-jump off one leg decreased significantly in the three groups. The long jump and perceived pain in the three groups returned to the baseline in three days after the peak perceived pain. Range of motion of the dorsiflexed ankle in each group significantly decreased during each exercise period and these values did not fully return by the termination of the study.

Implication. Muscle adaptation can be achieved by continuous muscle endurance exercise for three or seven days. However, the flexibility of muscle takes considerable time beyond the length of this investigation.

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