Moderators and short and long-term effects of a behavioral intervention on sedentary behavior among adults with depressive symptoms: results from a randomized clinical trial

Although physical activity is recognized as an effective strategy for treating depressive symptoms, little is known about its impact on sedentary behavior (SB) when implemented in intervention settings. This study aimed to evaluate the short and long-term effects of a behavioral intervention on different indicators of SB and to identify potential moderators in adults with depressive symptoms. A randomized, controlled, and assessor-blinded clinical trial was conducted with adults exhibiting depressive symptoms. The 16-week intervention included two sessions per week and was designed based on principles of Self-Determination Theory. Theoretical and practical activities were offered with the main objective of increasing participants’ awareness of their lifestyle, especially related to 24-hour movement behaviors. SB was assessed through both accelerometry and validated self-report questionnaires. Generalized estimating equations were used to assess the effects of the intervention. Potential moderators (sex, age, and marital status) of the intervention’s effects were also analyzed. A total of 78 individuals (76.9% women, mean age 37.5 ± 10.2) were equally randomized into control (CG) and intervention (IG) groups. Overall, there was no significant effect on reducing SB. After the intervention, the CG showed an increase in leisure-time SB (p = 0.028) and in mentally passive SB (p = 0.018). Sex moderated the effects for cell phone use (p = 0.087), leisure-time SB (p = 0.042), and mentally passive SB (p = 0.050), with greater increases observed among men. Age also moderated leisure-time SB (p = 0.093), indicating that middle-aged adults spent less time in SB compared to younger adults. Marital status moderated SB measured by accelerometry (p = 0.078), with an increase in weekly SB hours among individuals with a partner. The intervention was not effective in reducing SB, either in the short or long term. Nonetheless, sex, age, and marital status emerged as important factors to consider in the design and evaluation of behavior change strategies. Trial registration Brazilian Registry of Clinical Trials (ReBEC) RBR7466htj, April, 17 2023. Retrospectively registered.