Exploring the Interrelationships Between Physical Function, Functional Exercise Capacity, and Exercise Self-Efficacy in Persons Living with HIV

While physical activity can mitigate the metabolic effects of HIV disease and HIV medications, many HIV-infected persons report low levels of physical activity. Purpose: To determine if there were differences between the subjective and objective assessments of physical activity while controlling for sociodemographic, anthropometric, and clinical characteristics. Setting/sample: A total of 810 participants across eight sites located in three countries. Measures: Subjective instruments were the two subscales of Self-efficacy for Exercise Behaviors Scale: Making Time for Exercise and Resisting Relapse and Patient-Reported Outcomes Measurement Information System, which measured physical function. The objective measure of functional exercise capacity was the 6-minute Walk Test. Analysis: Both univariate and multivariant analyses were used. Results: Physical function was significantly associated with Making Time for Exercise (beta = 1.76, p = .039) but not with Resisting Relapse (beta = 1.16, p = .168). Age (beta = -1.88, p = .001), being employed (beta = 16.19, p < .001) and race (beta s = 13.84-31.98, p < .001), hip-waist ratio (beta = -2.18, p < .001), and comorbidities (beta = 7.31, p < .001) were significant predictors of physical functioning. The model predicting physical function accounted for a large amount of variance (adjusted R-2 = .938). The patterns of results predicting functional exercise capacity were similar. Making Time for Exercise self-efficacy scores significantly predicted functional exercise capacity (beta = 0.14, p = .029), and Resisting Relapse scores again did not (beta = -0.10, p = .120). Among the covariates, age (beta = -0.16, p < .001), gender (beta = -0.43, p < .001), education (beta = 0.08, p = .026), and hip-waist ratio (beta = 0.09, p = .034) were significant. This model did not account for much of the overall variance in the data (adjusted R-2 = .081). We found a modest significant relationship between physical function and functional exercise capacity (r = 0.27). Conclusions: Making Time for Exercise Self-efficacy was more significant than Resisting Relapse for both physical function and functional exercise capacity. Interventions to promote achievement of physical activity need to use multiple measurement strategies.