I’ve seen circus acts, like the video below, where some contortionist demonstrates flexibility to the point that its probably more agonizing to the audience than it is to the contortionist. I’m not very flexible, though not for lack of effort; I’ve had my share of yoga, dynamic and static stretching, and all sorts of regimes geared for increased ROM (range of motion).
Turns out, there’s good evidence the block is entirely in my head. In 1996 researchers from the University of Copenhagen published in the Journal of Physiology some telling findings on how human skeletal muscle flexibility is altered by stretching and flexibility training.
Resistance to stretch was measured as torque (in N m) offered by the hamstring muscle group during passive knee extension while electromyographic (EMG) activity, knee joint angle and velocity were continuously monitored during a standardized stretch [sic] manoeuvre. Seven healthy subjects were tested before and after a 3 week training period using two separate protocols.
Protocol 1 consisted of a slow stretch at 0.087 rad s-1 to a predetermined angle followed by a 90 s holding phase. Subjects were brought to the same angle before and after the training period. Protocol 2 was a similar stretch, but continued to the point of pain.
They used 2 methods: one to evaluate the physical resistance to the stretch and another to gauge the subjects’ threshold to pain during stretching.
Before and after the 3 week training regime, physical resistance to stretch measured both in terms of torque, stiffness, and EMG activity did not change significantly. In contrast, how far the subjects could stretch before experiencing pain did increase after the training regime.
The findings suggests flexibility (or lack thereof) is at least in part mental. Increasing flexibility with training doesn’t actually alter body structure; instead it just acclimates the mind to a higher threshold of pain.
Useful to know for athletes.