Modification of stretch tolerance in a stooping position.

Abstract

A stooping (slump) position is believed to add tension to the nerve tissue complex. This study was designed to determine whether this position would have an effect on the stretch tolerance in a passive knee extension. Thirteen healthy individuals were tested. The knee extension was stopped by the subjects at "onset of pain". Joint range of motion and passive resistance to the extension were recorded in four test situations: upright sitting and stooping position, with the ankle joint in either the neutral or maximal dorsi-flexed position. A significant decrease in range of motion was seen when shifting from upright to stooping position: Delta angle -2.4 degrees (P<0.01). According to this, the passive tissue tension was accepted at significantly lower values in stooping position: Delta torque -1.2 N m (P<0.01). Testing with maximal dorsi-flexion of the ankle showed more pronounced changes: Delta angle -3.4 degrees (P<0.001); Delta torque -2.3 N m (P<0.001), but the effect of foot position was not significant. Knee joint range of motion was acutely diminished in a stooping position. Thus, stretch tolerance was affected by manipulation of structures, which were not directly mechanically related to this joint. An influence from the nerve tissue complex must be considered to be a factor when describing the mechanisms behind altered stretch tolerance.