Comparison of two Actigraph models for assessing free-living physical activity in Indian adolescents

J Sports Sci. 2007 Dec;25(14):1607-11. doi: 10.1080/02640410701283841.


This aim of this study was to compare the new Actigraph (GT1M) with the widely used Model 7164. Seven days of free-living physical activity were measured simultaneously using both the Model 7164 and GT1M in 30 Indian adolescents (mean age 15.8 years, s = 0.6). The GT1M was on average 9% lower per epoch than model 7164, thus a correction factor of 0.91 is suggested for comparison between the two monitors. The differences between monitors increased in magnitude with intensity of activity (P < 0.001) but remained randomly distributed (r = 0.01, P = 0.96). No significant difference was observed between monitors for time spent in moderate (P = 0.31) and vigorous (P = 0.34) physical activity when using the same epoch length. The Model 7164 classified less time as sedentary (P < 0.001) and more time as light-intensity activity (P < 0.001) than the GT1M. In conclusion, data from the GT1M can be compared with historical data using average counts per minute with a correction factor, and the two models might be comparable for assessing time spent in moderate to vigorous physical activity in children when using the same epoch length.

Publication types

  • Comparative Study

MeSH terms

  • Acceleration
  • Adolescent
  • Exercise
  • Exercise Test
  • Female
  • Humans
  • India
  • Male
  • Models, Biological
  • Models, Theoretical
  • Monitoring, Ambulatory / instrumentation*
  • Monitoring, Ambulatory / methods
  • Monitoring, Physiologic
  • Motor Activity / physiology*
  • Movement / physiology*