Assessing and tailoring predictive equations of VO₂max for women with multiple sclerosis with mild to moderate disability

Background: Established equations to predict peak oxygen uptake (VO₂max) in healthy subjects are not directly applicable to patient populations, including people with multiple sclerosis (PwMS). PwMS, who commonly exhibit impaired cardiorespiratory and neuromuscular function, often require tailored predictive models. This study aimed at (1) testing the validity, reliability, and accuracy of four widely used formulae, developed in healthy populations, to estimate VO₂max in mildly to moderately disabled women with MS, and (2) develop adjusted formulae tailored on MS features.

Methods: Fifty-one mildly to moderately disabled women (mean age 46, median EDSS 3.5) with relapsing-remitting multiple sclerosis (RRMS) underwent incremental cardiopulmonary exercise testing (CPET) using cycle ergometry. Gas exchanges were analyzed by open-circuit spirometry. Four commonly employed predictive equations (ACSM, Storer's, Uth's, and Myers') were tested for reliability and accuracy against measured VO₂max. Regressions were performed to identify significant VO₂max predictors and to introduce adjustments to develop gender-specific equations aimed at estimating cardiorespiratory fitness with varying degrees of exercise involvement.

Results: ACSM and Storer's equations underestimated VO₂max (-6.09 %, Z = -3.22, p = 0.001; and -21.74 %, Z = -5.02, p < 0.001, respectively) whereas Uth's and Myers' equations overestimated it (+20.19 %, Z = -5.92, p < 0.001; and +19.31 %, Z = -6.19, p < 0.001, respectively). Regressions for adjusted equations revealed work rate/bodyweight (WR/BW) (β = 0.867, p < 0.001) for ACSM adjusted; age (β = -0.275, p = 0.004), BW (β = -0.658, p < 0.001) and peak Watts (β = 0.485, p < 0.001) for Storer's adjusted; heart rate ratio (β = 0.512, p < 0.001) for Uth's adjusted, and age (β = -0.492, p < 0.001), BW (β = -0.483, p < 0.001) and EDSS (β = -0.211, p = 0.046) for Myers' adjusted as predictors of VO₂max.

Conclusions: VO₂max can be validly estimated in women with MS using established formulae, provided that specific adjustments are introduced to account for their signature functional impairments. The models proposed in this study enable reliable assessment of cardiorespiratory fitness with protocols at different levels of exercise involvement, making them practical for clinical and everyday use. This approach supports a translationally driven bench-to-bedside perspective, allowing for patient VO₂max assessment in virtually all settings.