Increasing exercise improves cardiovascular health, decreases cancer risk, decreases diabetes risk, and improves overall quality of life, while decreasing all-cause morbidity and mortality. Improving the effectiveness of exercise programs by fostering long-term adherence may be an important step toward improving health. The components of Motivational Interviewing have previously been used successfully to initiate behavior change in cases of alcohol and substance abuse, chronic diseases, and smoking. However, the application of a motivational enhancement-type intervention to increasing participation and maintenance in exercise interventions has not been established. The present study examined the effects of motivational enhancement on long-term adherence to aerobic exercise as compared to a standard program consisting of behavioral prompts. The participants were drawn from a large-scale, NIH-sponsored exercise intervention. A total of 237 participants were randomized into groups receiving one of two treatments. One group received five motivational enhancement prompts designed to increase motivation and commitment to walking. The other group received five standard behavioral prompts. Both were delivered in a series of bi-weekly telephone calls that occurred six to nine months after the participants' initial start of the exercise program. The primary hypothesis was that treatment with Motivational Enhancement would result in greater adherence to exercise prescription than a standard behavioral prompt as measured by the seven-day Physical Activity Recall, participant walking logs, and telephone interviews
There were three key findings. The primary hypothesis received partial support. The Physical Activity Recall and the walking logs indicated that physical activity in the Motivational Enhancement condition and Standard Behavioral Prompt condition were equivalent at months 9 and 12. However, analysis of the telephone interview data indicated that during the intervention period there was a greater increase in the percentage of walks completed by the group that received Motivational Enhancement vs. the group that received the Standard Behavioral prompt. In addition, there is evidence that the Motivational Enhancement group showed greater change in Exercise Self-Efficacy and in their Stage of Change than the standard Behavioral Prompt group. Collectively, these findings suggest partial support for the hypothesis that a Motivational Enhancement intervention delivered via telephone could enhance the maintenance of exercise
