Journal of Applied Physiology, Vol 72, Issue 4 1375-1379, Copyright © 1992 by American Physiological Society
Locomotor-respiratory coupling during wheelchair propulsion
M. L. MacDonald, R. L. Kirby, S. T. Nugent and D. A. MacLeod
Department of Medicine, Dalhousie University, Halifax, Nova Scotia, Canada.
Visceral movement due to impact loading is believed to play a role in the
locomotor-respiratory coupling (LRC) that has been detected in a number of
mammalian species. In the bird and bat species in which LRC has been
described, the effect of the wing muscles on the timing of respiration
appears to be a dominant influence. To test the hypothesis that LRC occurs
in humans propelling wheelchairs (where there is no impact loading and the
arms are used for locomotion), we studied 10 wheelchair athletes on a
motorized treadmill at three speeds. Each subject's data were analyzed by
spectral analysis (based on the fast Fourier transform), which detected
apparent LRC (rates within 1% of a single-digit integer ratio) in 12 (40%)
of the 30 test settings. However, a control analysis, in which each
subject's arm-thrust rates were compared with another subject's breathing
rates, revealed apparent (but false) coupling in 8 (27%), not significantly
less often (using the chi 2 test). These findings appear to refute the
hypothesis that LRC occurs during wheelchair propulsion. These data are
consistent with the theory that the visceral piston is important to LRC and
suggest that rhythmic arm movements are insufficient to induce the
phenomenon in this setting.
