Accelerometer-Based Physical Activity Assessment During Intermittent Conditions: Effect of Epoch Length on Energy...

Area of Science:

• Exercise Physiology
• Biomedical Engineering
• Wearable Technology

Background:

• Accelerometer-based physical activity (PA) assessment is widely used.
• Epoch length is a critical parameter influencing data accuracy.
• Current consensus often favors shorter epochs for PA assessment.

Purpose of the Study:

• To investigate the impact of varying epoch lengths (1-60 seconds) on energy expenditure (EE) and moderate-to-vigorous physical activity (MVPA) estimates.
• To compare accelerometer-derived estimates with criterion measures (indirect calorimetry) under different exercise conditions.
• To determine optimal epoch lengths for accurate PA and EE assessment.

Main Methods:

• Ten active students performed treadmill exercises (running/walking, continuous/intermittent).
• Accelerometers recorded PA data, analyzed with epoch lengths of 1, 10, 30, and 60 seconds.
• Indirect calorimetry served as the criterion measure for energy expenditure.

Main Results:

• For intermittent running, 30- and 60-second epochs yielded EE and MVPA estimates comparable to indirect calorimetry.
• Shorter epochs (1, 10 seconds) showed significant differences during intermittent running.
• No significant differences in EE estimates were found during walking conditions, irrespective of epoch length or PA pattern.

Conclusions:

• Longer epoch lengths (30-60 seconds) are optimal for accurately estimating EE and MVPA during intermittent running.
• This contrasts with the prevailing view favoring shorter epochs.
• Researchers should select epoch lengths based on study objectives, considering PA (external load) vs. EE (internal load) estimation.