Field validation of the Tritrac-R3D Activity Monitor for the assessment of physical activity in older children
Holowachuk, Darryl Ray
The purpose of this research project was to assess the convergent validity of the Tritrac-R3D Activity Monitor (Tritrac) as a field measure for assessing physical activity in children over a one week period. The Tritrac is a motion sensor that integrates acceleration in three dimensions to provide an objective measure of physical activity. Forty-four (20 males and 24 females) from grades four through eight were examined to evaluate the convergent validity of the Tritrac against a Caltrac motion sensor, the Physical Activity Questionnaire for Older Children (PAQ-C; Crocker, Bailey, Faulkner, Kowalski, & McGrath, 1997), and the Physical Activity Recall interview (PAR; Sallis et al., 1985). Participants wore the Tritrac and Caltrac motion sensors for seven days that did not contain any special school events. Upon retrieval of the motion sensors, participants completed the PAQ-C and were individually interviewed by trained assistants with the PAR interview. As expected, the Tritrac was highly correlated with the Caltrac (r = 0.80). The Tritrac was not, however, significantly related to the PAQ-C (r = 0.22), the PAR Total score (sum total of hours that participants engaged in moderate, hard, or very hard activity; r = 0.15) and the PAR Daily Average (activity score converted to METs; r = 0.16). Issues of compliance and practicality were also considered when assessing the validity of the Tritrac. Approximately 43% of the participants reported not wearing the Tritrac during active periods because of discomfort, interference with activity, and officials/coaches instructions. Results of the study seriously question the use of the Tritrac as a valid means of quantifying children's physical activity for extended periods of time.