Background: In spite of frequent recommendations on physical activity, women's participation in physical activity is a matter of concern, highlighting the use of modern methods to increase their physical activity. In this regard, the theory of self-determination (SDT) has offered a new horizon to researchers. Method: A randomized controlled trial of a SDT based intervention in the physical activity was conducted for Iranian women, 2017 to 2018. All 114 eligible ones entered the study. Interventions: The 8-hour SDT-based intervention sessions were used for intervention group and the control group participated in a routine educational intervention. The two groups were evaluated for SDT constructs, behavioral regulation in exercise activity (BreQ-2) and physical activity (pedometer) at baseline and three months later. Results: The participants had an average age of 36.2 ± 0.46 years and a mean weight of 69.8 ± 1.2 kg, with 82.6% married, 46.7% holding academic degrees, and 23.9% employed. The rate of women’s physical activity was 4524 ± 214 steps per day and their mean BMI was 27.6 ± 0.46. The results indicated significant effects of SDT-based interventions on physical activity and behavioral regulation of the participants in the intervention group. Discussion: Despite the effects of SDT-based interventions on behavioral regulation changes, the complexity, proximity, and interrelation of motivational levels and their relationships with the SDT theory constructs are all the challenges faced by health systems in replacing innovative methods rather than traditional ways to realize health behaviors.
