Associations between Total Daily Step Counts and Minutes of "Healthy" Physical Activity David A. Rowe, FACSM, Matthew T. Mahar, Charles D. Kemble, Terrance S. Robinson, Ronald L. Starnes, Thomas D. Raedeke. Activity Promotion Laboratory, Department of Exercise and Sport Science, East Carolina University, Greenville, NC, 27858 Table 1 Intercorrelations between total steps and minutes of MVPA from multiple instruments Methods Abstract Sample Young Middle-Aged Older Middle-Aged/Older Sample size* 51 107 50 57 r(Yamax steps, MVPA) 0.75 0.38 0.79 r(Yamax steps, MVPA Bouts) 0.59 0.36 0.70 r(CSA steps, MVPA) 0.18 0.44 0.76 r(CSA steps, MVPA Bouts) 0.14 0.34 0.60 r(Omron steps, MVPA) 0.84 r(Omron steps, MVPA Bouts) 0.69 r(Omron steps, Omron aerobic mins) 0.68 Design: Secondary analysis of cross-sectional data collected as part of 4 studies conducted in the Activity Promotion Laboratory Multiple measures used to assess minutes MVPA and total daily step counts Data from one 24-hour period of free-living physical activity Participants: Four samples, of Young adults (n = 51) Middle Aged adults (n = 107) Older adults (n = 50) Middle-Aged to Older adults (n = 57) Instruments: Pedometer and accelerometer measures of daily physical activity Omron HJ 700IT pedometers (Young, Middle-Aged to Older samples) Yamax SW-200 pedometers (Young, Middle Aged , Older samples) Actigraph (CSA) AM7164 accelerometers (Young, Middle Aged, Older samples) Total daily steps obtained from all three instruments Mins of MVPA were obtained in three ways: Omron "aerobic steps" mode, which saves steps above 60 steps/min accumulated in bouts of at least 10 min Actigraph counts ≥ 1952 cts/min(3) to assess all minutes of MVPA (MVPA Mins) Actigraph counts ≥ 1952 cts/min occurring in bouts of at least 10 continuous minutes (MVPA MinBouts) Data analysis: Bivariate correlations (Pearson r) were calculated between each measure of total steps and each measure of mins MVPA Total daily step count recommendations for healthy physical activity have recently increased in popularity. Few studies have addressed whether total activity (steps per day) is related to daily minutes of healthy physical activity that would correspond to current health-related recommendations for moderate-to-vigorous intensity physical activity (MVPA) (Pate, 1995). PURPOSE: To examine the relationship between total daily steps and minutes of MVPA, across multiple methods of measurement and multiple populations. METHODS: Pedometer and accelerometer measures of daily physical activity were obtained from samples of young (Y; n = 51), middle aged (MA; n = 107), and older (O; n = 50) adults during their regular physical activity, and from a middle-aged to older adult sample (MAO; n = 57) who were enrolled in an organized walking program. Participants wore Omron pedometers (Y, MAO samples), Yamax pedometers (Y, MA, O samples), and/or Actigraph accelerometers (Y, MA, O samples) for 24 h. Total daily steps were obtained from all three instruments. Minutes of MVPA were obtained in three ways: (a) using the Omron "aerobic steps" mode, which saves steps above 60 steps/min if accumulated in bouts of at least 10 min; (b) from Actigraph counts using the Freedson et al (1998) cut-offs for moderate activity (≥ 1952 cts/min) over all minutes (intermittent MVPA); and (c) from Actigraph counts ≥ 1952 cts/min accumulated in bouts of at least 10 min. RESULTS: The correlations between Omron total steps and Omron-determined minutes of aerobic steps were r = .68 (MAO sample) and r = .71 (Y sample). Correlations between total steps and Actigraph-determined intermittent MVPA minutes ranged from r = .18 (Actigraph steps, Y sample) to r = .84 (Omron steps, Y sample); mean r = .59. For Actigraph-determined MVPA in 10+ min bouts, correlations ranged from r = .14 (Actigraph steps, Y sample) to r = .70 (Yamax steps, O sample); mean r = .46. CONCLUSIONS: Using two different criteria for healthy physical activity, the association between total steps and minutes of MVPA across several samples and measurement methods ranged from very low (2% common variance) to high (70% common variance), with an average 31% common variance between the two forms of expressing "healthy" physical activity behavior. *Sample size was smaller for some correlations due to small amounts of missing data Summary/Conclusions i Summary: Using two different criteria for healthy physical activity (total steps and minutes of MVPA), and multiple instruments (Omron, Actigraph, Yamax), the association between total steps and minutes of MVPA across several samples and measurement methods ranged from very low (2% common variance) to high (70% common variance) Across all methods and samples, there was an average 31% common variance between the two forms of expressing "healthy" physical activity behavior. Conclusions: Instrument selection in physical activity research may influence the results of the study Total daily steps and daily minutes MVPA may not reflect the same behavior, as indicated by the low correlations among some measures Results Bivariate correlations: between Omron total steps and Omron-determined minutes of aerobic steps: r = .68 (Middle-Aged to Older sample) and r = .71 (Young sample) between total steps and Actigraph-determined intermittent MVPA minutes ranged from r = .18 (Actigraph steps, Young sample) to r = .84 (Omron steps, Young sample); mean r = .59 between total steps and Actigraph-determined MVPA in 10+ min bouts, correlations ranged from r = .14 (Actigraph steps, Young sample) to r = .70 (Yamax steps, Older sample); mean r = .46 All correlations are presented in Table 1 Background Activity Promotion Lab Promoting Active Lifestyles Most recommendations for healthy physical activity focus on minutes of moderate to vigorous physical activity, or MVPA(1) Recent increased popularity of total daily step count recommendations for healthy physical activity, e.g., 10,000 steps/day(2) Few studies have investigated the association between daily minutes of MVPA and daily total step counts References Purpose Pate RR, et al. Physical activity and public health: A recommendation from the Centers for Disease Control and Prevention and the American College of Sports Medicine. JAMA. 1995;273(5):402-407. Hatano Y. How Many Steps? 10,000 Steps. Paper presented at symposium on Walking for health: Measurement and research issues and challenges, 2005, October; University of Illinois at Urbana-Champaign. Freedson PS, Melanson E, Sirard J. Calibration of the Computer Science and Applications, Inc. accelerometer. Med Sci Sports Exerc.1998;30:777-81. To examine the relationship between total daily steps and minutes of MVPA, across multiple methods of measurement and multiple populations.