Who benefits from a single-arm online intervention to improve physical activity? A longitudinal pilot study

Abstract

Treatment effects may vary in terms of participants’ psychological prerequisites such as their levels of self-efficacy, planning, or action control. In the context of a three-country research collaboration, findings from a pilot study on physical activity are reported. A single-arm online intervention was conducted to improve participants’ physical activity and nutrition in Italy, Spain, and Greece (N=473; 63% women), including a follow-up assessment of n=87. Age ranged from 18 to 65 years (M=42.4,SD=10.4). Activity was assessed by the General Practice Physical Activity Questionnaire (GPPAQ) at two points in time. The question was which motivational characteristics (in terms of self-efficacy, coping planning, or action control) were associated with possible changes in activity levels. Preliminary quantitative analyses yielded a significant overall increase in the GPPAQ indicator for men and women. Moreover, there were interactions between time and all three motivational characteristics on changes in GPPAQ (p<.01). Those with lower levels of self-efficacy, planning, or action control were found to have steeper slopes than those with higher levels. This was also replicated when collapsing all psychosocial variables (8 items) into two latent classes indicating low or high motivation. Follow-up assessment is still ongoing. The intervention produced overall improvements in physical activity but self-efficacy, planning, and action control operated as moderators, indicating that those with lower motivational and self-regulatory prerequisites were able to gain more from the online treatment. Individual differences in participants’ readiness for change need to be taken into account to gauge who would benefit most from a given treatment.