Validity of pedometers for measuring exercise adherence in heart failure patients

Background: Measuring adherence to exercise is important to clinicians and researchers because inadequate adherence can adversely affect the effectiveness of an exercise program and cloud the relationship between exercise and clinical outcomes. Hence, assessment strategies for adherence to exercise, as with assessment strategies for other Outcomes, must have demonstrated validity if they are to be employed with confidence. We conducted this study to determine the validity of pedometers as a measure of exercise adherence to a home-based walking program in heart failure patients. Methods and Results: Exercise adherence was measured using pedometers in 38 patients (74% men) age 54.1 +/- 11.7 years who participated in a 12-month home-based walking program. A comparison of functional status as measured by the 6-minute walk distance and peak oxygen uptake (VO2 max) at 6 months into the exercise training program was made between 2 groups of participants who were thought to represent adherers and nonadherers: participants who demonstrated >= 10% change in pedometer scores (n = 20) and those who showed no change in pedometer scores (n = 18) from baseline to 6 months. Patients who showed improvements in their pedometer scores over 6 months had better functional status at 6 months (6-minute walk distance 1718 +/- 46 versus 1012 +/- 25 meters, F = 5.699, P =.022 VO2 max 17 +/- 0.7 versus 10 +/- 0.5 units, F = 7.162, P =.011) when compared with patients whose pedometers reflected minimal change in distance walked (ie, <= 10%). Conclusion: Pedometers are inexpensive and readily available to both clinicians and researchers. The results of this study Suggest that they may be a valid indicator of exercise adherence in heart failure patients who participate in a home-based walking program.