Duration of maintained hamstring flexibility after cessation of an acute static stretching protocol.
OBJECTIVE
Increased muscle flexibility from static stretching is supported by the literature, but limited research has assessed the duration of maintained flexibility gains in knee joint range of motion after same-day static hamstring stretching. The purpose of our study was to determine the duration of hamstring flexibility gains, as measured by an active knee-extension test, after cessation of an acute static stretching protocol.


METHODS
All subjects performed 6 active warm-up knee extensions, with the last repetition serving as the baseline comparison measurement. After warm-up, the experimental group performed 4 30-second static stretches separated by 15-second rests.


METHODS
Thirty male subjects (age = 19.8 +/- 5.1 years, ht = 179.4 +/- 18.7 cm, wt = 78.5 +/- 26.9 kg) with limited hamstring flexibility of the right lower extremity were randomly assigned to control and experimental groups.


METHODS
Postexercise active knee-extension measurements for both groups were recorded at 1, 3, 6, 9, 15, and 30 minutes.


RESULTS
Tukey post hoc analysis indicated significant improvement of knee-extension range of motion in the experimental group that lasted 3 minutes after cessation of the static stretching protocol. Subsequent measurements after 3 minutes were not statistically different from baseline. A dependent t test revealed a significant increase in knee-extension range of motion when comparing the first to the sixth active warm-up repetition.


CONCLUSIONS
Our results suggest that 4 consecutive 30-second static stretches enhanced hamstring flexibility (as determined by increased knee-extension range of motion), but this effect lasted only 3 minutes after cessation of the stretching protocol. Future research should examine the effect of other stretching techniques in maintaining same-day flexibility gains.
Sports Medicine/Athletic Training Research Laboratory, University of Virginia, Charlottesville, VA.
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Depino
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Webright
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Arnold