To investigate the physical strain of walking and its relationship with daily activity
time in individuals with neuromuscular diseases (NMD).
Data were collected from multiple research projects at the Department of Rehabilitation
Medicine at the Amsterdam UMC, location AMC.
Thirty-one adults with post-polio syndrome (N = 11), Charcot-Marie-Tooth disease (N = 12)
and other slowly progressive NMD (N = 8) participated (age: 59.9 ± 14.3).
Steady state oxygen consumption during comfortable 6-minute walking (VO2walk), peak
oxygen uptake (VO2peak) during maximal cycle ergometry, and heart rate and step count
during 7 consecutive days were assessed.
Main Outcome Measures
Physical strain was defined as the ratio of VO2walk and VO2peak (in %). Daily activity
time was expressed as average daily step count and time spent in moderate (40-60%
heart rate reserve) to vigorous (>60% heart rate reserve) physical activity (MVPA).
Regression analyses assessed the relationships between physical strain, VO2walk, and
VO2peak with daily activity time.
Participants walked 8262 ± 3403 steps and physical strain during walking was 64% ±
15%. Physical strain was inversely related to step count (r2=.26, p=0.004), while
VO2peak was positively related to step count (r2=.20, p=0.013) and inversely related
to MVPA (r2=.14, p= 0.040). The other relations were not significantly correlated.
Physical strain of walking is high in patients with slowly progressive NMD compared
to able-bodied individuals (27% ± 6%) , approximating vigorous exercise intensities.
People with a higher physical strain take less steps daily. People with lower VO2peak
take less steps daily, while spending more time in MVPA. The small proportions of
explained variance indicate that more factors play a role in daily activity.