Effectiveness of a Self-Determination Theory (SDT) Based Intervention on ‎Physical Activity, Quality of Life, and Happiness: A Protocol for a Randomized ‎Clinical Trial ‎

Mohammadreza Ghaneapur , Hassan Eftekhar* , Ali Montazeri , Gholamreza Garmarudi , ‎Mahdi Yaseri , Arefeh Rezaei Ahvanoei


Background of the study: Despite the important role of physical activity in maximizing ‎health during the life span, impaired mobility is the main cause of diseases such as breast ‎cancer, diabetes and a significant proportion of the burden of ischemic heart diseases. This ‎paper will describe the protocol for a randomized clinical trial of an SDT-based (self-‎determination theory) physical activity motivational intervention for women aged 30-45 ‎years. To this end, an SDT-based intervention aims at promoting physical activity, quality ‎of life and happiness of women.‎ Methodology: A randomized controlled trial parallel design will be used to ‎evaluate the effectiveness of SDT-based intervention on physical activity, quality ‎of life, and happiness. Ninety two women aged 30-45 years (non-pregnant, Body ‎Mass Index ≤35 (kg/m2) and without a medical ban to do physical activity) will be ‎randomly allocated into the self-determination (intervention) and control group. ‎The primary outcome will be the physical activity and motivation for physical ‎activity and secondary outcomes will be the quality of life and happiness. Physical ‎activity will be evaluated using 7-day accelerometer. Moreover, participants will ‎complete MPAM-r, BREQ-2, EQ-5D-5L, SF-36 and OHI questionnaires. The ‎change in the mean score of the determinants at baseline, 1 and 3 months after ‎intervention will be compared between the two groups (5% alpha error and 80% ‎power).‎ Discussion: This study will be conducted to assess the effectiveness of an SDT- based ‎intervention developed for 30-45 years old women. If successful, the intervention would ‎help women with the necessary knowledge and skills to enable them to make healthier ‎choices for themselves. Moreover, women living in urban areas with similar economic and ‎social conditions would be able to benefit from the current research`s experiences.‎