Cardiorespiratory response to different aerobic exercise modalities in people with advanced multiple sclerosis

People with multiple sclerosis (MS) experience physiological deconditioning, notably the loss of cardiorespiratory fitness (CRF). Exercise training is effective for improving CRF in people with mild-to-moderate MS; however, the effect of exercise on CRF in people with advanced MS remains unclear. The objective of this repeated-measures study of acute exercise was to characterize the cardiorespiratory response of people with advanced MS (i.e., wheelchair users) to three aerobic exercise modalities.

Eighteen people with advanced MS (n = 15 female; mean age = 60.7 ± 11.1 years) completed three 15-minute submaximal (prescribed Rating of Perceived Exertion [RPE] = 12-13) exercise bouts using an arm cycle ergometer (ACE), a recumbent stepper (RS), and a functional electrical stimulation (FES) leg cycle. The exercise response was recorded as oxygen consumption (V̇O₂), heart rate (HR), work rate (WR), respiratory exchange ratio (RER), and RPE.

All modalities elicited a cardiorespiratory response that corresponded with moderate-to-vigorous intensity exercise (58-68 %V̇O_2peak; 79-88 %HR_peak), and there was no difference in RPE across modalities (p = 0.317). Mean submaximal V̇O₂ (mL/min, mL/(kg^.min)^-1, and %V̇O_2peak), HR (bpm and %HR_peak), WR (Watts and %WR_peak), and RER were all lower in response to FES cycling compared to ACE (all p ≤ 0.042) and RS (all p ≤ 0.036) exercise. There were no differences between ACE and RS exercise.

The current findings support the potential for improving CRF through aerobic exercise in people with advanced MS. At a matched RPE, FES cycling may provide a less demanding aerobic stimulus.