The purpose of this study was to investigate the impact of a 12-week strength training intervention implemented within a mastery motivational climate on specific performance parameters in sedentary individuals. A repeated measures design was used in the study. Participants underwent performance tests, which included squat jump, depth jump, and sitand-reach test. A total of 29 sedentary participants (age = 21.79±1.08) were randomly assigned to the experimental (EG; n= 14) and control (CG; n= 15) groups. In EG, the perceived motivational climate during the intervention program was manipulated. The Task and Ego Orientation in Sport Questionnaire (TEOSQ) was utilized to examine the extent to which participants were influenced by the manipulated motivational climate. In the EG, significant statistical differences were noted in the pre-test and post-test values for total scores and task orientation scores on the TEOSQ (p= 0.001, d= 0.979; p= 0.002, d= 1.087, respectively). Conversely, no significant statistical differences were observed in the CG (p < 0.05). No significant interaction effects were founded between groups and over time for the natural logarithmic-transformed squat jump height (p= 0.590, η2= 0.011), natural logarithmictransformed depth jump height (p= 0.810, η2= 0.002), ground contact time in depth jump (p= 0.506, η2= 0.017), reactive strength index (p= 0.324, η2= 0.036), and sit-and-reach test (p= 0.144, η2= 0.077). The findings are deliberated within the framework of pertinent literature.
Keywords: Exercise Motivation, Strength Training, Reactive Strength Index, Exercise and Sports Psychology.