Effect of jaw clenching on balance recovery: Dynamic stability and lower extremity joint kinematics after forward loss of balance

Postural control is crucial for most tasks of daily living, delineating postural orientation
and balance, with its main goal of fall prevention. Nevertheless, falls are common events,
and have been associated with deficits in muscle strength and dynamic postural stability.
Recent studies reported on improvements in rate of force development and static
postural control evoked by jaw clenching activities, potentially induced by facilitation
of human motor system excitability. However, there are no studies describing the
effects on dynamic stability. The present study, therefore, aimed to investigate the
effects of submaximum jaw clenching on recovery behavior from forward loss of
balance. Participants were 12 healthy young adults, who were instructed to recover
balance from a simulated forward fall by taking a single step while either biting at a
submaximum force or keeping the mandible at rest. Bite forces were measured by
means of hydrostatic splints, whereas a 3D motion capture system was used to analyze
spatiotemporal parameters and joint angles, respectively. Additionally, dynamic stability
was quantified by the extrapolated CoM concept, designed to determine postural
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stability in dynamic situations. Paired t-tests revealed that submaximum biting did not
significantly influence recovery behavior with respect to any variable under investigation.
Therefore, reductions in postural sway evoked by submaximum biting are obviously not
transferable to balance recovery as it was assessed in the present study. It is suggested
that these contradictions are the result of different motor demands associated with
the abovementioned tasks. Furthermore, floor effects and the sample size might be
discussed as potential reasons for the absence of significances. Notwithstanding this,
the present study also revealed that bite forces under both conditions significantly
increased from subjects’ release to touchdown of the recovery limb. Clenching the jaw,
hence, seems to be part of a common physiological repertoire used to improve motor
performance.