Abstract
[Purpose] This study investigated the acute effects of ballistic stretching (BS) on the muscle and tendon of the gastrocnemius medialis muscle (GCM). [Subjects] Twenty male individuals participated in this study. [Methods] BS consisted of stretching the gastrocnemius by indirectly moving the non-dominant ankle joints from plantar flexion to maximum dorsiflexion using the dominant knee active flex/extension at a rate of one bounce per second for a total duration of three minutes. Movement of the myotendinous junction (MTJ) of GCM was measured before and after the stretching exercise using ultrasonography. The difference between the MTJ position in a quiet standing position before and after the stretching exercises was used to determine the muscle elongation. The tendon elongation was calculated using the estimated muscle tendon unit and the muscle elongation. [Results] The ankle dorsiflexion angle significantly increased after BS. The differences of muscle elongation and tendon elongation were not significant between before and after BS. [Conclusion] The BS method of this study did not produce structural change in the tendon. A stronger muscle contraction may be necessary to increase tendinous extensibility.
