Effect of cadence on respiratory response during unloaded cycling in healthy individuals

Abstract

PurposeThe aim of the study was to establish the respiratory response to unloaded cycling at different cadences.MethodsEleven healthy participants performed a maximal graded exercise test on a cycle ergometer to assess aerobic fitness (maximal oxygen consumption: 46.27 ± 5.41 ml • min<sup>–1</sup> • kg<sup>–1</sup>) and eight 10-min unloaded pedaling (0 W) bouts at a constant cadence (from 40 to 110 rpm). Respiratory data were measured continuously during each effort and then averaged over 30 s. Blood samples were collected before and 2 min after each effort to monitor changes in acid–base balance.ResultsThe efforts were performed at an intensity of 16.5–37.5% VO<sub>2peak</sub>. Respiratory response was not differentiated in cadences of 40, 50, 60 rpm. From 70 rpm, an increase in cadence was significantly associated with increased minute ventilation (<i>F</i> = 168.11, <i>p</i> < 0.000) and oxygen consumption (<i>F</i> = 214.86 <i>p</i> < 0.000) and, from 80 rpm, respiratory frequency (<i>F</i> = 16.06, <i>p</i> < 0.001) and tidal volume (<i>F</i> = 54.67, <i>p</i> < 0.000). No significant changes in acid-base balance were observed as a result of difference cadences.ConclusionsUnloaded cycling at a cadence of 70 rpm or above has a significant effect on respiratory function and may be associated with the involvement of large muscle ergoreceptors (mechanoreceptors) stimulated by the frequency of muscle contractions.