What Types of Physical Function Predict Program Adherence? Findings from Enhancefitness Program

Background and Purpose. Health benefits of physical activity is well documented. However, adherence to physical activity is also essential in order to experience the benefits of exercise. Researchers have studied adherence to exercise programs to find the best interventions, but tended to focus on one body part with small sample sizes and used various adherence measurements, and thus, the results widely varied. To find the common predictors of exercise adherence, the purposes of the study were to describe the participants’ demographic characteristics by adherence levels and examine the association between their baseline physical function and adherence using a nationally-representative sample with data on multiple body function parts.

Methods. This is a prospective exploratory study. We used an evidence-based group exercise program, Enhance®Fitness (EF) dataset (N = 36,378). As of 2017, EF was offered in 1,319 sites in 47 states and has served over 79,936 unduplicated participants. The dataset included information on participants’ demographics and body function levels. The levels of physical function were determined by the results of 30-second chair-stand (lower-extremity strength), arm-curl (upper-extremity strength), and 8-foot up-and-go tests (balance and mobility) at baseline. Adherence was calculated as the proportion of attended sessions over offered sessions per participant, and categorized as high (> 67% attendance), moderate (33-66%), and low (<33%) adherence. We used descriptive statistics to describe the participants’ characteristics by adherence levels and multinomial logistic regression to examine the association between participants’ physical function and their adherence to EF.

Results. Participants were aged between 57 and 94 (M = 73.1, SD = 7.6), white (61%), college-educated (69%), married (77%), female (84%) with having at least one chronic disease (66%). Eighty-percent achieved moderate-high adherence (M = 52%, SD = 21%). Overall, older (≥ 85 years), Asian/Pacific Islander male participants with less education achieved the highest adherence level. Regression results showed that the participants with normal to high baseline chair-stand test scores (stronger lower-extremity) were most likely to achieve high adherence (p < .001), those with normal (p = .004) and high (p = .007) arm-curl (stronger upper-extremity) were predictive of moderate adherence, and those with high baseline 8-foot up-and-go test (balance and mobility) were predicted to be a moderate (p = .01) or high adherence level (p = .03). 

Conclusions and Implications. This study described the EF participants’ characteristics with various adherence levels and examined the association between participants’ baseline physical function levels and their adherence to the program. We found that participants with stronger upper- and lower-extremity strength, and better walking balance and mobility are associated with higher adherence. The results underscored the importance of offering classes at various physical function levels while attending the participants’ individual needs. Focusing on participants’ baseline physical function appeared to be a critical key factor to predict participants’ adherence. These findings show implications for tailoring programs to optimize participants’ program adherence and receive the maximum benefits of the exercise program.