Cardiorespiratory fitness in young and newly diagnosed patients with multiple sclerosis: A cross-sectional study

Cardiorespiratory fitness (CRF) is impaired in patients with multiple sclerosis (MS) regardless of age, but evidence is limited among young and newly diagnosed patients. The aim of the study is to assess CRF using a maximal exercise test on a treadmill and to examine the relationships between CRF, physical activity level, fatigue, depression, and quality of life (QoL) in young patients newly diagnosed with MS.

This cross-sectional study analyzed baseline data from a sample of 43 patients with MS who completed a maximal exercise test on a treadmill, measurement of body composition, and answered the Beck Depression Inventory second edition, modified Fatigue Impact Scale, and 36-item Short Form Survey QoL.

CRF was significantly lower among patients newly diagnosed with MS (aged 20-45 years) compared to normative values (paired Wilcoxon test, p < 0.001). The median absolute differences between normative values and patients' maximal oxygen uptake (VO₂max) was 8.5 ml/kg/min (interquartile range [IQR]: 2.4-13.4 ml/kg/min), and the median relative differences was 28.3 % (IQR: 7.1-53.9 %). VO₂max significantly negatively correlated with fatigue (r_S = -0.37, p = 0.013), but not depression (r_S = -0.01, p = 0.971). Significant positive correlations were found between VO₂max and multiple subscales of QoL, including physical functioning (r_S = 0.50, p = 0.001), social functioning (r_S = 0.41, p = 0.007), pain (r_S = 0.41, p = 0.006), and role limitations due to physical health (r_S = 0.31, p = 0.047).

Young patients with newly diagnosed MS already exhibit substantially reduced CRF compared with normative values. Lower VO₂max is associated with higher fatigue and poorer physical and social aspects of QoL. These findings highlight the need for interventions aimed at improving CRF as an integral component of rehabilitation programs.