In general, pedometers are not accurate when used for activities that do not involve footfalls (e.g., weight–lifting, biking, household activities) (Basset 20002, Beighle 20013). Even for ambulatory activities, pedometers have been found to be inaccurate at both counting steps and in assessing distance walked (Basset 2000). In most cases, pedometers (at the higher end) can be accurate at counting steps, although they are much less accurate at predicting energy expenditure, even during walking, with error rates of +/– 30% (Crouter 2003)4.
A pedometer can be used as a coaching or self–monitoring tool (Crouter 2003) to help people set goals (Basset 2000). As a result, pedometers are reasonable tools for helping individuals increase their physical activity levels. The main drawback to pedometers is that they do not measure the intensity, duration or frequency of physical activity (Beighle 2001). Other draw–backs of the pedometer are its inability to store information over extended periods of time and to evaluate patterns of physical activity within or across days. Another drawback of the pedometer is that it is designed specifically to capture lower body movement, i.e. walking behaviors; therefore it does not capture activities such as swimming, cycling, or activities that incorporate upper body movement.
Unlike a physical activity questionnaire, the pedometer does not rely on participant recall therefore reducing the possibility of bias. In addition, pedometers have the ability to capture intermittent or continuous activity participation throughout the assessment period of interest. Since they are relatively low cost, they are being used in a variety of funded clinical trials as both an assessment tool and an intervention tool.
The pedometer appears to be accurate in healthy individuals who walk at a normal gait speed and who are not obese (Shepherd, 1999)5. Pedometers tend to be less accurate in patients who are extremely obese, primarily because it is worn on the waist and it needs to be perpendicular to the ground in order to accurately count steps. In patients with substantial central obesity this can be difficult to achieve. In addition, the pedometer is less accurate at slower gait speeds and/or in individuals with irregular or unsteady gaits.
Furthermore it has been shown to provide a valid measure for estimation of distance walked when compared with a calibrated measuring wheel (r=0.98) (Bassett, 2000). The pedometer has also been validated against indirect calorimetry (Nelson, 1998)6. The concurrent validity of the pedometer in assessing physical activity in free-living individuals provided significant correlations between the steps/day and the activity counts from the Tritrac and CSA accelerometers, r=0.84 to r=0.93 (Leenders, 2000)7.