Validation of a New Counter for Direct Observation of Physical Activity in Parks

Purpose: This study aims to examine the reliability of a 12-button counter to simultaneously assess physical activity (PA) by age and gender subgroups in park settings. Methods: A total of 1,160 pairs of observations were conducted in 481 target areas of 19 neighborhood parks in the great Los Angeles, California, area between June 2013 and March 2014. Interrater reliability was assessed by Pearson's correlation, intra-class correlation (ICC), and agreement probability in metabolic equivalents (METs). Cosine similarity was used to check the resemblance of distributions among age and gender categories. Pictures taken in a total of 112 target areas at the beginning of the observations were used as a second reliability check. Results: Interrater reliability was high for the total METs and METs in all age and gender categories (between 0.82 and 0.97), except for male seniors (correlations and ICC between 0.64 and 0.77, agreement probability 0.85 to 0.86). Reliability was higher for total METs than for METs spent in moderate-to-vigorous PA. Correlation and ICC between observers' measurement and picture-based counts are also high (between 0.79 and 0.94). Conclusion: Trained observers can reliably use the 12-button counter to accurately assess PA distribution and disparities by age and gender.