Effects of wheelchair training on [Vdot]O₂ kinetics in the participants with spinal-cord injury

Abstract

Purpose. We tested the hypothesis that, in eight participants (seven males, one female; 46.5 ± 8.3 years) with spinal-cord injury (complete lesions, T7-L1), the effects of exercise training on pulmonary O₂ uptake ([Vdot]O₂) on- and off- kinetics would appear early in this pilot study.

Methods. The subjects underwent the wheelchair-training program (3 day/w, 30 min/day, and 50% HRreserve), and were evaluated before training (“time 0”, T0), and after 7 (T7), 15 (T15), 30 (T30), and 60 (T60) days of training. Breath-by-breath peak [Vdot]O₂ was determined during the incremental exercise until their exhaustion. At another day following the incremental exercise, the subjects performed three repetitions of a constant exercise at 50% peak [Vdot]O₂ workload so that [Vdot]O₂ could be determined for both on- and off-kinetics.

Results and conclusion. Peak [Vdot]O₂ showed a tendency to increase with training; the increases became significant at T30. The time constants (τ₂) during “phase II” of the [Vdot]O₂ on-kinetics were 62.4 ± 13.0 (s) (T0), 51.2 ± 8.7 (T7), 46.1 ± 7.4 (T15), 45.0 ± 7.2 (T30), and 43.4 ± 6.4 (T60); a significant difference compared to T0 was observed from T7 onward. The same pattern of change as a function of training was described for the [Vdot]O₂ off-kinetics. It is concluded that in SCI participants, the acceleration of [Vdot]O₂ kinetics at the onset of exercise was observed over a short term.

Keywords:

• SCI participant
• oxygen uptake
• kinetics
• time constant
• training