THE EFFECTS OF STRETCHING ON SERIES ELASTIC MUSCLE STIFFNESS AND PASSIVE RANGE OF MOTION

  • S.N. Stanley
  • P.J. McNair

Abstract

Sports people participating in activities involving running and jumping are vulnerable to Achilles tendon injuries. These injuries occur from either acute trauma or develop more slowly over a longer period of time. "Warm up" exercises are often advocated for the prevention and treatment of muscle and tendon injuries. These exercises usually include aerobic and stretching exercises, however, at this time the effect of these "warm up" regimes is largely anecdotal. Therefore the purpose of this investigation was to determine the effect of stretching and jogging on the series elastic muscle stiffness of the Soleus/Achilles tendon complex and on the range of motion of the ankle joint. Twenty subjects with no history of musculoskeletal pathology participated in this study, and were required for four testing sessions. In the first session maximum voluntary contraction (MVC) was assessed so that subsequent stiffness testing would be at 30% of their MVC. In the second session subjects were randomly assigned to one of a stretching, jogging, or stretching and jogging combined protocol. During the third and forth sessions the subjects completed the remaining protocols. The stretching protocol was five 30 second static stretches with 30 seconds rest between stretches, while the aerobic exercise protocol had the subjects jogging on a treadmill for 10 minutes at 60% of maximum-age-predicted heart rate. A damped oscillation technique was used to measure the series elastic stiffness of the Soleus/Achilles tendon complex. Range of motion was assessed using weights and a pulley system to move the ankle joint through its range passively. EMG of soleus was monitored to ensure muscle activity was minimal. The results for stiffness showed that running was significantly (pd.05) more effective than stretching for decreasing series elastic muscle stiffness. In contrast, the results for range of motion showed that a combination of running and stretching were significantly (peO.05) better than either running or stretching separately for increasing joint range of motion. These data have implications for the sports participant. It may be best to prepare for activities with extreme ranges of motion by combining an aerobic warmup with stretching. Those involved in movements not reaching the limits of joint motion may be best served by an aerobic warmup only.
Section
Coaching and Sports Activities