Validity of the Polar M200 to measure sedentary time in free living conditions

Abstract

Objectives The aim of the present study is to evaluate the validity of a CWAT, the Polar M200, for measuring posture-related outcomes and step count in free-living conditions in comparison with the gold standard, the AP3.

Participants An observational design was used. Eighteen healthy adults (men: n=12; women: n=6) with a mean age of 29.50±2.55 years old met all inclusion criteria.

Measurements The subjects simultaneously wore the Polar M200 and AP3 for three consecutive days to measure ST (lying-sitting time; LST) and secondarily other posture-related outcomes (standing time, StT; moving time, MT) and step count (SC).

Results The Polar M200 underestimated LST and MT by respectively 2.5% (27.4min) and 86.4% (59.5min) while it overestimated StT and SC by respectively 23.3% (38.1min) and 41.4% (3468.77steps). Correlation coefficients indicate a good to strong correlation (p<0.001) between the Polar M200 and the AP3. A random error was observed for all outcome parameters, which precludes correction.

Conclusion The Polar M200 is not recommended to measure ST for research purposes. However, it can be used in daily life to monitor and reduce sedentary behavior.