Effect of coupling the breathing- and cycling rhythms on oxygen uptake during bicycle ergometry

The influence of the degree of coupling between the breathing and cycling rhythms (K) on oxygen uptake (Vo2) was examined in 30 volunteers. They cycled on an ergometer with a load equal to 50% of their work capacity 170 in two experimental runs with spontaneous breathing rhythm, and in a further two runs with acoustically triggered breathing. K was continuously ascertained. Vo2 and other respiratory parameters were measured by an automatic "breath-by-breath analysis" system. In 16 subjects, Vo2-differences between runs were correlated with the differences in K. In the majority of these subjects (12), Vo2 decreased significantly with increasing K. In 14 subjects, Vo2-and K-variations within individual runs were analyzed. Phases with higher K were regularly accompanied by a decrease in Vo2. It is concluded that coupling the breathing and cycling rhythms reduces Vo2 for a given moderate work load, although the magnitude of the Vo2-reduction varies considerably between individuals.