Coupling of motor oscillators – What really happens when you chew gum and walk?

Highlights • The impact of chewing on walking dynamics was examined. • The walking rate of young and older adults was driven by their chewing frequency. • Older adults walked at a slower velocity compared to young adults. • No difference in chewing rates were seen between young and older adults. Abstract Chewing and walking are two oscillatory behaviors performed on an everyday basis. The current study examined the impact chewing at different speeds (i.e. fast, slow, preferred) had on walking performance for fifteen young healthy adults (23.2 + 4.2 years) and fifteen healthy older participants (66.5 + 3.2 years). Chewing rates were attained from surface EMG activity recorded from the masseter muscle. For gait, accelerometers mounted on the lower trunk and lower leg were used to determine the timing of individual steps. In addition, a pressure sensitive walkway was also used to collect gait metrics (i.e., gait velocity, step length, step time). Our results demonstrated a strong link between chewing and walking for all participants, with increases or decreases in a person's chewing rate leading to similar changes in their stepping rate (and hence walking speed). One explanation for this coupling is that the neural drive related to chewing entrains the muscles involved in the basic gait action of stepping. The coupling of stepping with chewing rates for all individuals was observed despite the older adults tending to walk slower overall. However, there were no age-related differences in chewing rates, suggesting that despite the general slowing of motor function seen with increasing age, mastication itself does not appear to be similarly affected. [ABSTRACT FROM AUTHOR]