Effect of cadence on locomotor–respiratory coupling during upper-body exercise

Abstract

Introduction

Asynchronous arm-cranking performed at high cadences elicits greater cardiorespiratory responses compared to low cadences. This has been attributed to increased postural demand and locomotor–respiratory coupling (LRC), and yet, this has not been empirically tested. This study aimed to assess the effects of cadence on cardiorespiratory responses and LRC during upper-body exercise.

Methods

Eight recreationally-active men performed arm-cranking exercise at moderate and severe intensities that were separated by 10 min of rest. At each intensity, participants exercised for 4 min at each of three cadences (50, 70, and 90 rev min⁻¹) in a random order, with 4 min rest-periods applied in-between cadences. Exercise measures included LRC via whole- and half-integer ratios, cardiorespiratory function, perceptions of effort (RPE and dyspnoea), and diaphragm EMG using an oesophageal catheter.

Results

The prevalence of LRC during moderate exercise was highest at 70 vs. 50 rev min⁻¹ (27 ± 10 vs. 13 ± 9%, p = 0.000) and during severe exercise at 90 vs. 50 rev min⁻¹ (24 ± 7 vs. 18 ± 5%, p = 0.034), with a shorter inspiratory time and higher mean inspiratory flow (p < 0.05) at higher cadences. During moderate exercise, \( \dot{V}{\text{O}}_{ 2} \) and f _C were higher at 90 rev min⁻¹ (p < 0.05) relative to 70 and 50 rev min⁻¹ ( \( \dot{V}{\text{O}}_{ 2} \) 1.19 ± 0.25 vs. 1.05 ± 0.21 vs. 0.97 ± 0.24 L min⁻¹; f _C 116 ± 11 vs. 101 ± 13 vs. 101 ± 12 b min⁻¹), with concomitantly elevated dyspnoea. There were no discernible cadence-mediated effects on diaphragm EMG.

Conclusion

Participants engage in LRC to a greater extent at moderate-high cadences which, in turn, increase respiratory airflow. Cadence rate should be carefully considered when designing aerobic training programmes involving the upper-limbs.

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