Effect of work rate increment on peak oxygen uptake during wheelchair ergometry in men with quadriplegia

Abstract

The purpose of this study was to determine the effect of work rate increment on peak oxygen uptake (VO2 peak) during wheelchair ergometry (WCE) in men with quadriplegia due to cervical spinal cord injuries (CSCI). Twenty-two non-ambulatory subjects (aged 20-38 years) with CSCI were divided into two groups based on wheelchair sports classification (n = 12 for IA group and n = 10 for IB/IC group). Subjects underwent three different, continuous graded exercise tests (spaced at least 1 week apart) on an electronically braked wheelchair ergometer. Following a 3-min warmup, the work rate was increased 2, 4, or 6 W.min-1 for the IA group and 4, 6, or 8 W.min-1 for the IB/IC group. Ventilation and gas exchange were measured breath-by-breath with a computerized system. Repeated-measures ANOVA showed no significant difference among the three protocols for VO2 peak in the IA group (P greater than 0.05). The mean (SD) VO2 peak values (ml.kg-1.min-1) were 9.3 (2.4), 9.4 (3.2), and 8.4 (2.6) for the 2, 4, and 6 W.min-1 protocols, respectively. In contrast, the IB/IC group showed a significant difference among the protocols for VO2 peak (P less than 0.05). The mean (SD) VO2 peak values (ml.kg-1,min-1) were 15.1 (4.0), 14.1 (4.4), and 12.7 (4.0) for the 4, 6, and 8 W.min-1 protocols, respectively. Post hoc analysis revealed a difference between the 4 and 8 W.min-1 protocols. Our results suggest that graded exercise testing of men with quadriplegia due to CSCI, using WCE, should employ work rate increments between 2 and 6 W.min-1 and that work rate increments of 8 W.min-1 or greater will result in an underestimate of VO2 peak.

The Role of Autonomic Function on Sport Performance in Athletes With Spinal Cord Injury

“…The sympathetic nervous system exerts a chronotropic effect in 2 ways: first, by a direct stimulatory effect on the sinoatrial node and ventricular muscle from sympathetic fibers exiting the spinal cord between T1 and T5 (Figure 1); and second, from the stimulatory effect of noradrenaline and adrenaline on β1‐adrenoreceptors. The traditional view of the HR response to exercise in SCI has been that individuals with cervical SCI exhibit a maximum HR between 100 and 120 bpm, whereas those with high‐ and low‐thoracic SCI exhibit a relatively normal maximal HR [20‐29]. The attenuated HR response to maximal exercise in cervical SCI is attributed to a diminished sympathetic activity to the myocardium and a reduction in circulating catecholamines [24,30].…”

Adapted Physical Activity Research: Issues and Recommendations

“…This practice may not be valid in light of the protocol dependency found for certain physiological responses such as maximal oxygen uptake during arm cycle and wheelchair ergometry (Lasko-McCarthey & Davis, 1991aDavis, , 1991b. Therefore more validity, reliability, and optimization studies of test protocols are needed that would help APA professionals answer future and more important questions (e.g., training studies).…”

“…The lack of commercially available testing instruments, developed specifically for persons with disabilities, presents another unique problem to overcome in order to conduct quality research. For example, the exercise physiology literature pertaining to persons with disabilities discusses a variety of home-made ergometric devices such as arm crank ergometers, wheelchair ergometers, and wheelchair treadmills (Glaser, 1985;Golding, Horvat, Beutel-Horvat, & McConnell, 1986;Lasko-McCarthey & Davis, 1991a, 1991b. The lack of commercially manufactured equipment can be attributed to its low market demand.…”

“…Collaboration among specialty areas (e.g., adapted physical activity and biomechanics) will shed light on research questions that the APA professional in the past could not answer alone. For example, specialists in exercise physiology are beginning to work with professionals in adapted physical activity in order to examine the physiological responses and training needs of such diverse special populations as persons with mental retardation (Fernhall & Tymeson, 1988) and spinal cord injuries (Lasko-McCarthey & Davis, 1991a, 1991b. Collaborative research efforts between professionals in adapted physical activity and biomechanics are beginning to help athletes with disabilities determine the most efficient wheelchair racing techniques (Davis, Gehlsen, & Wilkerson, 1990).…”

Peak Heart Rates and Sympathetic Function in Tetraplegic Nonathletes and Athletes

“…After a cervical spinal cord injury (SCI), however, there seems to be an atypical HR response to exercise. In nonathletic individuals with tetraplegia, several studies have documented attenuated peak HR responses to exercise (3,6,12,21,25,27), which have been attributed to the loss of descending input to sympathetic preganglionic neurons. Conversely, there have been a few re ports of elevated exercise HR in elite athletes with tetraplegia (33,36,39).…”