| Stretching routines are typically integrated into exercise programs to improve flexibility and performance. Static stretching has been promoted as the safest and best method of stretching whereas the very different ballistic method of stretching has been virtually abandoned due to its associated risk of injury. The purpose of the current investigation was to examine the biomechanics and muscle activity associated with static and ballistic stretching of the hamstring muscles in order to compare the assets and liabilities of each technique. In a randomized cross-over design, 16 men and 13 women (22.5 +/- 4.5 yrs) participated in both static (STA) and ballistic (BAL) conditions. Each condition required the subject to perform a pre-maximum stretch, a series of three 30-second static or ballistic stretches, and a post-maximum stretch. Electromyography (EMG) of the gluteus maximus, hamstrings, gastrocnemius, and rectus femoris muscles as well as joint kinematics were measured during all procedures. Data regarding maximum stretch distance and hip angle were recorded. Measurements of perceived soreness were made before and after the stretching exercise as well as at 24, 48 and 72 hours after stretching. A two-way repeated measures ANOVA was used for statistical analysis of perceived soreness, maximum stretched distance, and hip angle and t-tests were used for analysis of muscle activity. Significance was determined at the p < 0.05 level. Stretching exercise significantly increased maximum distance stretched and hip flexion (p < 0.05), however there was no difference between the stretching techniques. No significant effects for muscle activity or soreness were found between the static and ballistic conditions. In conclusion, static and ballistic stretching influence range of motion, hip angle, muscle activity, and soreness similarly and, thus, contraindications towards ballistic stretching may be unwarranted. Future research should investigate whether differences exist in the kinematics and muscle activity patterns of the actual static and ballistic stretching maneuvers. |
