What effect does a six week static stretching programme have on the muscles of the lower leg?
It is widely accepted that stretching can increase range of motion around a joint. There is very little literature however to support the theory that this increase in motion comes from the target muscle increasing in length.
This study took 49 volunteers and separated them into a stretch group or a control. Following a six week stretching programme the length of the medial gastrocnemius (calf muscle) and the Achillies tendon were measured by ultrasound. Although there had been an increase in range of motion at the ankle of the stretch group, the muscle and tendon length remained the same.
So what can explain the increase in motion?
The authors suggest that the increase comes from the subjects being able to tolerate more stretching. As the stretch is repeated, the nervous system reduces the signalling to the brain that the situation is potentially damaging. In other words, you just get accustomed to it.
In my experience this results in muscle weakness as a muscle that is repeatedly stretched loses it’s ability to contract effectively. Again this is a nervous system response.
Whilst range of motion will increase following a stretching programme, ultimately stability will decrease. In the long term this is may be detrimental to the health of your joints.