Pilot testing of a mindfulness- and acceptance-based intervention for increasing cardiorespiratory fitness in sedentary adults: A feasibility study

• Feasibility of an ACT-based group treatment for increasing physical activity.
• Participants showed high levels of adherence to the interval walking intervention.
• Participants showed increases in cardiorespiratory fitness.
• Participants showed significant changes in exercise related experiential avoidance.

ObjectiveVigorous physical activity (PA) has been promoted for improving cardiorespiratory fitness (CRF). However, therapeutic techniques designed to engage participants in vigorous PA have fallen short; one reason for this may be the unpleasant physical sensations associated with vigorous exercise (e.g., temporary shortness of breath and mild muscle soreness). Mindfulness and acceptance-based therapies such as Acceptance and Commitment Therapy (ACT) may be helpful at improving adherence to vigorous PA levels. In this open clinical trial, we sought to demonstrate the feasibility and acceptability of a mindfulness- and acceptance-based intervention for increasing CRF in sedentary adults and to generate initial outcomes data.DesignParticipants (N=24) engaged in a 10-week fitness walking program while attending regular group sessions based on ACT.Main outcome measures and resultsThe feasibility and acceptability of the intervention were demonstrated through high levels of walking adherence (89.30%) and group session attendance (85.50%). A large significant decrease in total 1-mile walk test time [t(18)=4.61, p=.0002, d=.64] and a moderate significant increase in estimated VO2max [t(18)=−4.05, p=.0007, d=−.43] were observed. Analyses indicated a large significant increase in exercise-related experiential acceptance [t(18)=−9.19, p<.0001, d=−2.09].ConclusionThis study demonstrates the feasibility and acceptability of an ACT-based intervention for supporting participation in vigorous PA in sedentary individuals.