Purpose: The purpose of this study was to compare self-reported exercise to a more objective measurement of exercise (i.e., Tri-Trac Accelerometer) and to assess whether there is a difference in weight loss between individuals who under- and over-report their exercise.
Methods: Fifty overweight females (BMI = 34.0 ± 4.2 kg·m-2) who were participating in a behavioral weight control program were included in this study. Subjects were randomly assigned to a long-bout or a short-bout exercise condition, with both groups instructed to exercise 30 min·day-1 on 5 d·wk-1 for a period of 20 wk. The long-bout group was to exercise in one continuous session (e.g., one 30-min session per day), whereas the short-bout group was to divide the exercise into multiple 10-min sessions (e.g., three 10-min sessions per day). Subjects recorded their exercise in a daily exercise log and wore a Tri-Trac accelerometer for a 1-wk period to validate self-reported exercise bouts.
Results: Results showed that approximately 45% of the women over-reported the amount of exercise that they performed, and this did not differ between the long-bout and short-bout groups. Women who over-reported their exercise had significantly poorer weight loss across the 20-wk program than women who under-reported their exercise (6.3 ± 3.6 kg vs 9.4 ± 5.2 kg).
Conclusions: The results of this study suggest that overweight women who over-report their exercise will have poorer weight loss while enrolled in a behavioral weight loss program compared with others enrolled in the program, and the Tri-Trac Accelerometer may be useful in identifying individuals who inaccurately report the amount of their exercise. The ability to classify individuals as either over- or under-reporters of their exercise may be helpful to weight loss therapists and lead to more successful treatment for obesity.
University of Pittsburgh School of Medicine, Pittsburgh PA 15213
Submitted for publication March 1996.
Accepted for publication June 1997.