Improvement of muscle flexibility

Forty-seven male subjects were randomly assigned to 4 different groups. Three groups of 10 subjects trained three times a week with a modified contract-relax (CR) method for improving muscle flexibility. Seventeen subjects trained during the same time with a traditional ballistic stretch (BS) method. After 30 days (14 training sessions) the latter group switched over to the CR method. The results showed that the CR method was significantly better than the BS method for improving muscle flexibility in the four different, bilateral muscle groups studied. After the initial 30 days the three groups of 10 subjects trained one, three, and five times a week, respectively, for another 30 days. The results showed that once a week was enough to maintain improved flexibility, while three and five times a week increased it further. The former BS group improved muscle flexibility between the 30th and 60th day, as expected from the results of the initial 30 days with the three CR groups, when training with the CR method three times a week.