No effect of arm-crank exercise on diaphragmatic fatigue or ventilatory constraint in Paralympic athletes with cervical spinal cord injury

• Published in: Journal of applied physiology (1985) Vol. 109; no. 2; pp. 358 - 366
• Main Authors: Taylor, Bryan J., West, Christopher R., Romer, Lee M.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD American Physiological Society 01.08.2010
• Subjects: Adult; Arm; Athletes; Athletes with disabilities; Biological and medical sciences; Cervical Vertebrae - injuries; Diaphragm - innervation; Diaphragm - physiopathology; Disabled Persons; Electric Stimulation; Exercise; Fatigue; Female; Football; Fundamental and applied biological sciences. Psychology; Humans; Magnetics; Male; Muscle Contraction; Muscle Fatigue; Muscle Strength; Muscle, Skeletal - physiopathology; Neuromuscular diseases; Neurons; Oxygen Consumption; Oxygen uptake; Paraplegia - physiopathology; Phrenic Nerve - physiopathology; Physical Endurance; Pulmonary Ventilation; Respiration; Respiratory Function Tests; Respiratory Mechanics; Spinal cord injuries; Spinal Cord Injuries - physiopathology; Time Factors; Wheelchairs; Physical exercise; Human; upper body exercise; Tetraplegia; Nervous system diseases; Neuromuscular diseases; Motor system disorder; Constraint; quadriplegia; Fatigue; Athlete; Respiratory system; respiratory muscles; neuromuscular disorder; Vertebrata; Striated muscle disease; Mammalia; Respiratory muscle; Spinal cord trauma; Central nervous system disease; respiratory mechanics; Neurological disorder; Spinal cord disease; Arm
• ISSN: 8750-7587; 1522-1601; 1522-1601
• DOI: 10.1152/japplphysiol.00227.2010

Cervical spinal cord injury (CSCI) results in a decrease in the capacity of the lungs and chest wall for pressure, volume, and airflow generation. We asked whether such impairments might increase the potential for exercise-induced diaphragmatic fatigue and mechanical ventilatory constraint in this population. Seven Paralympic wheelchair rugby players (mean ± SD peak oxygen uptake = 16.9 ± 4.9 ml·kg −1 ·min −1 ) with traumatic CSCI (C 5 –C 7 ) performed arm-crank exercise to the limit of tolerance at 90% of their predetermined peak work rate. Diaphragm function was assessed before and 15 and 30 min after exercise by measuring the twitch transdiaphragmatic pressure (P di,tw ) response to bilateral anterolateral magnetic stimulation of the phrenic nerves. Ventilatory constraint was assessed by measuring the tidal flow volume responses to exercise in relation to the maximal flow volume envelope. P di,tw was not different from baseline at any time after exercise (unpotentiated P di,tw = 19.3 ± 5.6 cmH 2 O at baseline, 19.8 ± 5.0 cmH 2 O at 15 min after exercise, and 19.4 ± 5.7 cmH 2 O at 30 min after exercise; P = 0.16). During exercise, there was a sudden, sustained rise in operating lung volumes and an eightfold increase in the work of breathing. However, only two subjects showed expiratory flow limitation, and there was substantial capacity to increase both flow and volume (<50% of maximal breathing reserve). In conclusion, highly trained athletes with CSCI do not develop exercise-induced diaphragmatic fatigue and rarely reach mechanical ventilatory constraint.