Monitoring of Physical Activity in Young Children: How Much Is Enough?

TLDR

Evidence is scarce on the optimal duration and days of accelerometer monitoring needed to reliably assess physical activity in young children. The study monitored 76 children (mean age 5.6 yr) for seven days with Actigraph accelerometers, reporting mean daily activity in counts per minute. Reliability rose with more days and hours up to 10 hr/day, reaching 80 % at seven days of 10 hr/day, with day count outweighing hour count and weekend inclusion having little effect, indicating that a 7‑day, 10‑hr/day period yields the highest reliability and that shorter periods may still be adequate.

Abstract

There is limited evidence on how much and on which days accelerometry monitoring should be performed to obtain a representative measurement of physical activity (PA) in young children. We measured 76 children (40 M and 36 F, mean age 5.6 years ([SD ± 0.4]) on 7 days using Actigraph accelerometers. Mean daily PA was expressed in counts per min (cpm). Reliability increased as the number of days and hours of monitoring increased, but only to 10 hr per day. At 7 days of monitoring for 10 hr per day, reliability was 80% (95% CI [70%, 86%]). The number of days was more important to reliability than the number of hours. The inclusion or exclusion of weekend days made relatively little difference. A monitoring period of 7 days for 10 hr per day produced the highest reliability. Surprisingly short monitoring periods may provide adequate reliability in young children.