The validity of the Tractivity motion sensor during walking.

Darren E. R. Warburton, Andrew Jeklin, Shannon S. D. Bredin


Background: Accelerometers have a distinct advantage over pedometers in the capacity to assess accurately and comprehensively physical activity and sedentary behaviours. However, the widespread use of accelerometers has been limited owing to the marked cost difference between sensors. Recent technological advancements have allowed for the development of accelerometers that are more affordable, increasing the potential usage of accelerometers on a population level. The Tractivity motion sensor has recently been developed to monitor distance, steps, and time spent during physical activities. Purpose: To examine the validity of the Tractivity sensor to measure step counts in comparison to direct observation across a range of walking speeds. Methods: Ten participants (5 M; 5 F) were evaluated during four incremental stages of treadmill walking at 2.4, 3.1, 3.5, and 4.1 mph (in randomized order). Each exercise stage lasted 6 min in duration. Step counts were evaluated (in a blinded fashion) via direct observation (video analysis) and the Tractivity sensor. Results: The Tractivity device explained 99.2% of the variance in the actual counts with no evidence of systematic bias across exercise intensity. The average difference between Tractivity device and the criterion method was -3.05 steps (0.44%) across the range of walking speeds, with the majority of step counts being within 10 steps. There was no significant difference between step counts derived by the Tractivity sensor and direct observation. Conclusion: The Tractivity sensor is a valid measure of step counts in comparison to direct observation with less than 0.5% error across a range of walking speeds.


Medicine; Exercise; Physiology; Chronic Disease; Physical Activity; Health Promotion; Exercise Science; Kinesiology, Motion Sensor

Full Text:


Copyright (c)

ISSN: 19206216