Physical Fitness Assessment Across the Disability Spectrum in Multiple Sclerosis

Background: Appropriate assessment of physical fitness (i.e., aerobic capacity and muscular strength) is necessary to the design and evaluation of exercise training for those with MS. One of the primary limitations in evaluating fitness across the disability spectrum is physical inaccessibility of traditional testing modes (e.g., walking on a treadmill). Traditional tests further lack sensitivity and accuracy in determining maximal physical capacity. This restricts the capacity for well-designed clinical trials of exercise training across the MS disability spectrum.

Objectives: This study compared different methods of measuring cardiorespiratory (arm ergometer vs. recumbent stepper) and muscular (manual muscle testing [MMT] vs. seated dynamometry) fitness across the MS disability spectrum. This study further examined the associations between fitness indices, measured by different testing modes, and clinical, functional, symptomatic, and participatory measures.

Methods: Participants completed two testing sessions separated by 1 week. At each session, participants completed one cardiorespiratory and one muscular fitness test. A clinically-administered EDSS was conducted at the first session. Participants further completed measures of walking speed and endurance, cognition, fatigue, quality of life (QOL), activities of daily living (ADL), and physical activity.

Results: 64 participants completed testing and were grouped as mild (EDSS=1-3.5; n=21), moderate (EDSS=4-6; n=22), and severe (EDSS=6.5-8; n=21). Peak aerobic capacity assessed by recumbent stepping was higher when compared with arm ergometry (p<.001). Peak torque assessed by seated dynamometry was higher when compared with MMT (p<.001). Peak aerobic capacity and peak torque decreased as a function of increasing disability (p<.001). Significant, moderate-to-strong correlations were observed between physical fitness and EDSS score, walking speed and endurance, cognition, fatigue, QOL, and ADL for all aerobic and strength testing modes.

Conclusions: Overall, maximal physical capacity was higher assessed by recumbent stepping and seated dynamometry and decreased as a function of increasing disability. This suggests the prescription of exercise training in MS should be based on more sophisticated testing modes to provide the most appropriate stimulus for training adaptations. There continues to be an important association between physical fitness and other outcomes in MS, regardless of assessment modality.