Clinical use of objective measures of physical activity

Abstract

With measurement of physical activity becoming more common in clinical practice, it is imperative that healthcare professionals become more knowledgeable about the different methods available to objectively measure physical activity behaviour. Objective measures do not rely on information provided by the patient, but instead measure and record the biomechanical or physiological consequences of performing physical activity, often in real time. As such, objective measures are not subject to the reporting bias or recall problems associated with self-report methods. The purpose of this article was to provide an overview of the different methods used to objectively measure physical activity in clinical practice. The review was delimited to heart rate monitoring, accelerometers and pedometers since their small size, low participant burden and relatively low cost make these objective measures appropriate for use in clinical practice settings. For each measure, strengths and weakness were discussed; and whenever possible, literature-based examples of implementation were provided.

Letter to the Editor: Do Activity Levels Increase After Total Hip and Knee Arthroplasty?

“…We agree that accelerometry is generally preferred when whole-body physical activity is the focus of interest, but in knee and hip arthroplasty, walking activity expressed in the number of gait cycles is an important issue. In this case, researchgrade pedometers are considered an appropriate tool, and they provide valuable information [4,7]. Therefore, we are not convinced that the differences in the activityrelated outcomes of our study and the findings of Harding et al can be explained by the measurement protocols, which are both based on a 7-day assessment period.…”

The importance of physical activity

“…Objective measures of physical activity do not rely on information provided by the patient, but instead register biomechanical and/or physiological consequences of performing physical activity [43]. We will focus on accelerometers and pedometers as their small size, low participant burden and relatively low cost make these objective tools suitable for use in clinical practice.…”

“…These additional signals might improve the estimates of activity intensity, especially during activities that are known to be difficult to assess with pedometers and accelerometers. Activities such as cycling, lifting or carrying objects, and the increased energy cost associated with walking an incline or walking up stairs fall into this category [43].…”

“…Accelerometry-based motion sensors have become one of the most commonly used methods for assessing physical activity [24,43]. These devices are commonly worn on the hip, wrist or back and typically sample the acceleration of the body along three axes (tri-axial accelerometers).…”

“…A pedometer is an electronic or electromechanical device worn on the waist or hip that counts each step a person takes by detecting the acceleration of the body's centre of mass during the gait cycle [43]. Steps are registered when the acceleration signal exceeds a critical threshold.…”