Entrained Breathing and Oxygen Consumption During Treadmill Walking

Entrainment of the breathing rhythm to that of the rhythm of limb movement during exercise has been shown to decrease oxygen consumption for cycling at a moderate workload. This study examined the effect of entrainment on oxygen consumption during treadmill walking at two workloads. For each workload, 8 subjects performed two exercise protocols consisting of walking on a treadmill for 8 min. For the first protocol they received no instructions, but for the second protocol they were instructed to coordinate one breath per auditory cue which was provided during the last 4 min of exercise. The auditory cue was transmitted as a click via headphones. It was derived from a foot switch and was designed to synchronize breathing to the walking pace at a respiratory frequency close to that observed in the first protocol. Entrainment and oxygen consumption were compared between the protocols for the last 4-min segments for each workload. These comparisons showed that the presence of the auditory cue significantly increased entrainment from 29 to 74%, but oxygen consumption was not significantly changed.