Submitted on August 3, 2007
Accepted on December 23, 2007
Breathing frequency changes at the onset of stepping in human infants
J Adam Noah1, Carol A Boliek2, Tania Lam1, and Jaynie F Yang3*
1 Physical Therapy, University of Alberta, Edmonton, Canada
2 Speech Language Pathology and Audiology, University of Alberta, Edmonton, Canada
3 Department of Physical Therapy, University of Alberta, Edmonton, Canada
* To whom correspondence should be addressed. E-mail: jaynie.yang{at}ualberta.ca.
Breathing frequency increases at the onset of movement in a wide rage of mammals including adult humans. Moreover, the magnitude of increase in the rate of breathing appears related to the rate of the rhythmic movement. We determined whether human infants show the same type of response when supported to step on a treadmill. Twenty infants (aged 9.7±1.2 months) participated in trials consisting of sitting, stepping on the treadmill, followed by sitting again. Breathing frequency was recorded with a thermocouple, positioned under one naris and taped to a soother which the infant held in his/her mouth. A video camera, electrogoniometers, and force platforms under the treadmill belts recorded stepping movements. We found that the rate of breathing changed at the beginning of stepping. Most surprisingly, we found that when infants stepped at a frequency slower than their breathing frequency in sitting, the breathing frequency decreased. Average breathing frequency during stepping was positively correlated with stepping frequency. There was no evidence of entrainment between stepping and breathing. In conclusion, the rapid change in breathing frequency at the beginning of movement is functional in infants. The direction and magnitude of change in breathing is associated with the leg movements.
