Agreement Between 5 Measures Of Light, Moderate, And Vigorous Levels Of Habitual Physical Activity

Abstract

A wide variety of objective and subjective instruments exist to monitor levels of habitual physical activity, however, there is insufficient standardization of the cutpoints used to categorize levels of light, moderate, and vigorous physical activity (PA). PURPOSE To examine the agreement between 5 different measures of light, moderate and vigorous levels of PA. METHODS Over 7 consecutive days 49 Chinese volunteers (30 male) aged between 15 and 55 years (M ± SD = 28.6 ± 9.0 years) recorded a daily PA-log and wore a heart rate monitor (HRM) together with a 1-D and 3-D accelerometer: on day 8, each participant completed the IPAQ (short form). Intensity cut-points for each measure were based on published research (Pollock et al., 1998; Freedson et al., 1998; Nichols et al., 1999; Craig et al., 2003). RESULTS The total week's time (minutes) spent in vigorous activity was significantly higher for IPAQ (126) than the PA-log (84), HRM (48), 1-D (29) and 3-D (26). For moderate activity, the IPAQ (931) and PA-log (953) significantly exceeded the 1-D (302) and 3-D (311) accelerometers, and the HRM (173). Time recorded in low activity was significantly higher from the HRM (1730) than the PA-log (976), IPAQ (785), 1-D (471) and 3-D (426) accelerometers; the PA-log was also significantly higher than the 1-D and 3-D accelerometers. Correlations between instruments were generally weak, centering around 0.38 for vigorous, 0.17 for moderate, and 0.19 for light intensity. CONCLUSIONS Either the participants over-reported their levels of vigorous activity in the subjective PA-log and IPAQ, or the objective cut-points are too stringent. Similar conclusions are applicable to moderate activity, with the HR threshold appearing too stringent. However, during low intensity activity the HR threshold was too lenient. These results and the overall weak correlations between instruments across all levels of exercise expose the dangers of relying on only one method to monitor different levels of habitual PA.