Dynamic stability of the human body during unstable pushups

Abstract

Instability training provides the nervous system with a greater challenge than traditional training, and thus can be performed with a reduced external load, potentially reducing the likelihood of injury. Unstable exercises have also been found to elicit higher levels of core muscle activity than their stable counterparts and so may increase joint loading. The degree to which instability challenges the stability of the human body likely relies on the level of instability of the movement, but the influence of experimental instability, and its effect on the level of stability of the human body, has yet to be determined. This study aims to examine how altering the available degrees of freedom of the pushup, as a means of quantifying instability, may affect the dynamic stability of the lumbar spine. The results of this study indicate that adding two available degrees of freedom to the conventional pushup significantly increases kinematic variance of the L1 vertebra through 3-dimensional space. No significant difference in kinematic variability existed between the two conditions of additional available degrees of freedom. These results may help health care professionals improve the individualization of their training programs by taking desired level of instability into account, and adjusting available degrees of freedom accordingly.