It is unknown whether respiratory motor output is constrained during exhaustive exercise in healthy adults. We hypothesised that neural inhibition did occur; to test this hypothesis we measured diaphragm EMG from a maximal inspiratory capacity maneuver (EMG(di)-IC) at rest and during exercise. EMG(di)-IC was measured before and after the amplitude of the diaphragm EMG entered a plateau phase in eleven healthy adults undertaking exercise at 60% and 80% of maximal workload achieved from incremental exercise. The mean EMG(di)-IC at rest was 65 ± 16% of the maximum that could be obtained from a battery of inspiratory tasks. Before and after the plateau phase of diaphragm EMG, EMG(di)-IC was 68 ± 13% and 72 ± 12% (p > 0.05) during 60% of the maximum workload, and was 70 ± 13% and 78 ± 13% (p > 0.05) during 80% of the maximum workload achieved on an incremental test. A further sub-study in which 5 participants exercised at 90% of the maximum workload also showed that EMG(di)-IC was not diminished during exercise. Our data show that exercise condition does not reduce the magnitude of EMG(di)-IC. This argues against neural inhibition as feature of submaximal exercise in healthy adults.
Keywords: Diaphragm; Diaphragmatic electromyography; Exercise testing; Inspiratory capacity.
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