Biomechanical responses to repeated stretches in human hamstring muscle in vivo

Am J Sports Med. 1996 Sep-Oct;24(5):622-8. doi: 10.1177/036354659602400510.


To examine stiffness, energy, and passive torque in the dynamic and static phases of a stretch maneuver in the human hamstring muscle in vivo we used a test-retest protocol and a repeated stretches protocol. Resistance to stretch was defined as passive torque (in newton-meters) offered by the hamstring muscle group during passive knee extension as measured using an isokinetic dynamometer with a modified thigh pad. In 13 uninjured subjects, the knee was passively extended to a predetermined final position (0.0875 rad/ sec, dynamic phase) where it remained stationary for 90 seconds (static phase). The test-retest protocol included two tests administered 1 hour apart. On a separate occasion, five consecutive static stretches were administered separated by 30 seconds and followed by a sixth stretch 1 hour later. For the test-retest phase, stiffness and energy in the dynamic phase and passive torque in the static phase did not differ and yielded correlations of r = 0.91 to 0.99. During the static phase, passive torque declined in both tests (P < 0.0001). For the repeated stretches, decreases were observed for energy (P < 0.01) and stiffness (P < 0.05) in the dynamic phase and for passive torque (P < 0.0001) in the static phase. However, the decline in the variables returned to baseline within 1 hour. The data show that the method employed is a useful tool for measuring biomechanical variables during a stretch maneuver. This may provide a more detailed method to examine skeletal muscle flexibility.

MeSH terms

  • Adult
  • Analysis of Variance
  • Area Under Curve
  • Biomechanical Phenomena
  • Follow-Up Studies
  • Humans
  • Kinetics
  • Knee Joint / physiology
  • Leg / physiology*
  • Male
  • Muscle Contraction / physiology*
  • Muscle, Skeletal / physiology*
  • Pliability
  • Range of Motion, Articular
  • Signal Processing, Computer-Assisted
  • Stress, Mechanical
  • Torque