New Findings Classically, the stimulation of thin fibre skeletal muscle afferents via the application of post exercise circulatory occlusion (PECO) at rest, fails to generate ventilatory responses. We used a novel experimental protocol to examine whether the involvement of these metabosensitive afferents in ventilatory control can only be revealed during exercise, when other potentially synergistic inputs that increase central respiratory drive are activated. We found that PECO of one leg, augmented the ventilatory and heart rate responses to single legged exercise of the contralateral leg, suggesting that metaboreceptive muscle afferents contribute to the control of the exercise hyperpnoea. Inhibition of thin fibre skeletal muscle afferent neurotransmission attenuates ventilatory and cardiovascular responses to exercise. However, stimulation of muscle metaboreceptive afferents at rest, via post exercise circulatory occlusion (PECO), classically fails to generate increases in ventilation (VE) or heart rate (HR). It is possible that the involvement of muscle afferent feedback in ventilatory control can only be revealed during exercise, when other potentially synergistic inputs that increase central respiratory drive are activated. Therefore, we assessed the cardiorespiratory responses to single-legged cycling exercise with/without PECO of the contralateral leg. 13 healthy participants performed left-legged cycling exercise (40W or 60W) followed by either: 1) No PECO (Con trial) or 2) PECO (PECO trial) of the left leg for 3 min. During this 3-min period, right-legged cycling exercise was performed at the same workload as the preceding left-legged exercise (40W or 60W). During 60W right-legged cycling, ventilation relative to baseline (DeltaVE) was significantly higher in the PECO trial vs. Con trial (22.9 ± 2 vs. 18.7 ± 1.8 l/min; P < 0.05), but there was no difference between the trials performed at 40W. DeltaHR was significantly higher during right-legged cycling in the PECO trial vs. Con trial in 40W (41.2 ± 4 vs. 34.1 ± 3.1 b/min; P < 0.05) and 60W trials (49.7 ± 2.7 vs. 43.4 ± 3.7 b min-1+; P < 0.05). There were no differences in VO2, VCO2 and ratings of perceived exertion between trials. These findings suggest that stimulation of muscle metaboreceptive afferents can drive increases in ventilation and heart rate during dynamic exercise.
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