Influence of epoch length on measurement of light physical activity in the elderly: A technical analysis
Journal of Human Sport and Exercise
Aims: To clarify how epoch lengths of accelerometers affect measurement of physical activity in elderly people. Methods: The data was based on 70 elderly people (72.6 ± 5.4 years) living in Japan between 2017 and 2018. Furthermore, we used data obtained from triaxial accelerometers that the subjects wore for more than 10 hours every day for 7 days. We evaluated light physical activity (2.9 Mets or less) and further grouped it into sedentary behaviour (SB, 1.5 Mets or less) and Light Intensity
... d Light Intensity Physical Activity (LIPA, between 1.6 and 2.9 Mets). We also compared 10-second epoch lengths (ELs) to 60-second ELs (%) by Bayesian estimation. Results: In 2017 and 2018, SB at 10-second ELs was longer than at 60-second ELs (55.5 vs. 50.4% in 2017; 55.7 vs. 48.9% in 2018); however, LIPA at 10-second ELs was shorter than at 60-second ELs (35.0 vs. 42.3% in 2017; 35.0 vs. 44.5% in 2018). The Bayesian factor varied between 3.0x10 12 and 3.2x10 24 . The robustness of the Bayesian factor was confirmed by the robustness check. Furthermore, effect sizes were between |1.68| and |3.00|. Conclusion: ELs of the accelerometer may affect measurement of physical activity in elderly people. Thus, SB at 10-second ELs may be longer than at 60-second ELs and may be the reverse for LIPA.