Equivalence of accelerometer data for walking and running: Treadmill versus on land

Abstract

The aim of this study was to compare equivalence and agreement of physical activity output data collected by a Research Tri-axial accelerometer (R3T) during walking and running on a treadmill versus on land. Fifty healthy volunteers, 35 males (age 21.9 +/- 1.8 years) and 15 females (age 21.6 +/- 0.7 years), underwent a series of tests on a treadmill and on land with the order of testing administered randomly. Each participant walked for 10 min at 4 km x h(-1) and 6 km x h(-1), and ran at 8 km x h(-1) and 10 km x h(-1), with the same accelerometer. Analysis of output data was assessed by two statistical tests: the equivalence test and Bland and Altman method. Mean differences for walking were 41.2 +/- 129.8 counts per minute and -68.8 +/- 173.15 counts per minute at 4 km . h(-1) and km x h(-1), respectively. Mean differences for running were 19.1 +/- 253.20 counts per minute and 38.9 +/- 270.2 counts per minute at 8 km x h(-1) and 10 km x h(-1), respectively. The physical activity output data from the treadmill were higher by an average of 3.5% than the data collected on land. The differences obtained between the treadmill and on land were small and non-significant. The equivalence test showed that output data from the treadmill versus on land were equivalent (P < 0.05). The Bland and Altman method showed good agreement between the counts obtained on the treadmill and on land (P < 0.05). In conclusion, physical activity output data were similar as measured by the RT3 accelerometer on a treadmill and on land. The findings suggest that the RT3 may be used in a laboratory and extrapolated to data obtained on land.

Construct validity of RT3 accelerometer: A comparison of level-ground and treadmill walking at self-selected speeds

“…A similar research study recently reported that RT3 accelerometer data from level-ground and treadmill walking was equivalent [33]. Despite this similarity, important differences also exist in these two studies.…”

“…Our results found no differences in treadmill-derived RT3 accelerometer output from participants' preferred walking speeds over the two testing points and also demonstrated that RT3 accelerometer output equally distinguished between participants' normal and brisk walking speeds on both surfaces. Although Vanhelst et al found equivalence at specified speeds on a single occasion [33], they have not addressed treadmill and level-ground walking at participants' preferred walking speeds and whether their measures are stable over time. Similarly, we have not addressed equivalence and will require further research to determine this factor under both normal and brisk walking conditions on these two surfaces.…”

“…The current study assessed for differences in RT3 accelerometer data at participants' self-determined normal and brisk speeds over two separate days. In contrast, Vanhelst et al used tests of equivalence to compare walking and running conditions at specified speeds of 4 km/h, 6 km/h, 8 km/h, and 10 km/h on a single occasion [33]. Our results found no differences in treadmill-derived RT3 accelerometer output from participants' preferred walking speeds over the two testing points and also demonstrated that RT3 accelerometer output equally distinguished between participants' normal and brisk walking speeds on both surfaces.…”

“…However, not only does uniaxial output differ from that of a vector-summated triaxial accelerometer, but output differences also exist from the same accelerometer when comparing surfaces that have been linked to testing speed, epoch length, and step frequency [17]. A recent cross-sectional study found equivalence and agreement between RT3 accelerometer output at preset speeds on the treadmill and on level ground [33]. As clinical and research studies employ repeat measures to assess for change in participant's self-selected walking speeds, research is required to determine whether treadmill activities change over time in a manner similar to walking on level ground at participants' preferred walking speeds.…”

Estimating cut points: A simple method for new wearables

“…Although a common tool used in performance and clinic laboratories, previous studies [13,14] have found activity count data obtained from accelerometers on treadmills may not be identical to activity data obtained on ground. Therefore the results of this investigation may differ slightly to freeliving conditions.…”