Accelerometers can estimate the intensity, frequency, and duration of physical activity
in healthy adults. Although thresholds to distinguish varying levels of activity intensity using the
Actigraph wGT3X-B have been established for the general population, their accuracy for Huntington’s
disease (HD) is unknown. We aimed to define and cross-validate accelerometer cut-points for different
walking speeds in adults with mild to moderate HD. A cross-sectional, multicentre, case-control,
observational study was conducted with a convenience sample of 13 symptomatic ambulatory HD
participants. The accelerometer was placed around the right hip, and a heart monitor was fitted
around the chest to monitor heart rate variability. Participants walked on a treadmill at three speeds
with light, moderate and vigorous intensities. Correlation and receiver operation curve analyses were
performed between the accelerometer magnitude vector with relative oxygen and heart rate. Optimal
cut-points for walking speeds of 3.2 km/h were ≤2852; 5.2 km/h: >2852 to ≤4117, and in increments
until their maximum velocity: >4117. Our results support the application of the disease-specific
cut-points for quantifying physical activity in patients with mild to moderate HD and promoting
healthy lifestyle interventions.
