Number of days required for reliably estimating physical activity and sedentary behaviour from accelerometer data in older adults

ABSTRACT

The purpose of the study was to examine the minimum number of monitoring days for reliably estimating physical activity (PA) and sedentary behaviour (SB) from accelerometer data in older adults. Forty-two older adults from a local senior centre participated in this study. Participants wore an ActiGraph wGT3X-BT on the right hip for 7 consecutive days. Accelerometer data were downloaded to a computer and converted to activity count data in 60s epochs. Time spent in SB and different PA intensity categories were estimated with commonly used activity count cut-points. Participants with at least 7 valid days of monitoring (≥10 h^.day⁻¹) were included in the analysis. Intraclass correlation coefficients (ICC) were calculated for determining single-day monitoring reliability. The Spearman-Brown prophecy formula was used to estimate the minimum number of monitoring days required for achieving an ICC of 0.80. Single-day ICC values for time spent in SB and PA intensity categories ranged from 0.45 to 0.61. Minimum number of monitoring days required for achieving an ICC of 0.80 ranged from 2.5 to 4.9 days. In this study, a minimum of 5 consecutive days of monitoring was required for reliably estimating SB and PA from accelerometer data in older adults.

KEYWORDS:

• Physical activity assessment
• sedentary behaviour
• accelerometry
• older adults

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Jeffer Eidi Sasaki was supported by CAPES (Coordenação de Aperfeiçoamento de Pessoal de Ensino Superior) through the “Programa Nacional de Pós-Doutorado – CAPES” (PNPD/CAPES) from the Brazilian Ministry of Education.