Case studies in physiology: Exercise-induced diaphragm fatigue in a paralympic champion rower with spinal cord injury

TILLER, Nicholas, AGGAR, Thomas R., WEST, Christopher R. and ROMER, Lee M. (2017). Case studies in physiology: Exercise-induced diaphragm fatigue in a paralympic champion rower with spinal cord injury. Journal of Applied Physiology.

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Introduction. The aim of this case report was to determine whether maximal upper-body exercise was sufficient to induce diaphragm fatigue in a Paralympic champion adaptive rower with low-lesion spinal cord injury (SCI). Case Presentation. An elite arms-only oarsman (age 28 y, stature 1.89 m, mass 90.4 kg) with motor-complete SCI (T12) performed a 1000 m time-trial on an adapted rowing ergometer. Exercise measurements comprised pulmonary ventilation and gas exchange, diaphragm EMG-derived indices of neural respiratory drive and intrathoracic pressure-derived indices of respiratory mechanics. Diaphragm fatigue was assessed by measuring pre- to post-exercise changes in the twitch transdiaphragmatic pressure (Pdi,tw) response to anterolateral magnetic stimulation of the phrenic nerves. The time-trial (248 ± 25 W, 3.9 min) elicited a peak O2 uptake of 3.46 L·min−1 and a peak pulmonary ventilation of 150 L·min−1 (57% MVV). Breath-to-stroke ratio was 1:1 during the initial 400 m and 2:1 thereafter. The ratio of inspiratory transdiaphragmatic pressure to diaphragm EMG (neuromuscular efficiency) fell from rest to 600 m (16.0 vs. 3.0). Potentiated Pdi,tw was substantially reduced (−33%) at 15-20 min post-exercise, with only partial recovery (−12%) at 30-35 min. Conclusions. This is the first report of exercise-induced diaphragm fatigue in SCI. The decrease in diaphragm neuromuscular efficiency during exercise suggests that the fatigue was partly due to factors independent of ventilation (e.g., posture and locomotion).

Item Type: Article
Research Institute, Centre or Group: Centre for Sport and Exercise Science
Identification Number: 10.1152/japplphysiol.00870.2017
Depositing User: Jill Hazard
Date Deposited: 06 Dec 2017 16:22
Last Modified: 27 Jan 2018 21:02

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