To determine the effects of repeated hamstring stretching on the muscle activation pattern of the erector spinae during trunk flexion and extension movements.
Hamstring stretching could shorten the erector spinae myoelectric silence period during trunk flexion and extension movements.
Fourteen healthy volunteers performed trunk flexion-extension movements before and after stretching hamstring muscles. Erector spinae EMG activity and hip range of movement were respectively measured with surface electromyography (Muscle Tester ME 6000) and electrogoniometry (Biometrics). Erector spinae offset/onset (expressed as a percentage of the maximum hip flexion value) and erector spinae average EMG during the eccentric and concentric phases were the variables used for the study.
The t-test did not show any significant differences in erector spinae offset and onset before and after stretching (p<0.05). A significant increase on the erector spinae EMG activity during the concentric contraction was observed after the stretching.
Repeated hamstring stretching did not produce any variations on the erector spinae myoelectric silence duration period, although it significantly changed erector spinae EMG activity during trunk extension. This could imply an alteration on the muscular coactivation that is necessary for lumbar spine stability.