APPLICATION OF THE INTRINSIC MOTIVATION INVENTORY IN U.S. ARMY BASIC TRAINING:

The Intrinsic Motivation Inventory (IMI) was developed to assess participants' intrinsic motivation with respect to physical activity in laboratory settings (Ryan, J Pers Soc Psych, 43: 450–61, 1982). Previous studies have shown this questionnaire has a very stable factor structure; the modification of individual questions, the use of 3 questions per subscale, and the exclusion of whole subscales has not shown adverse effects on its reliability. PURPOSE This study applied the IMI in an epidemiologic field investigation of exercise motivation in U.S. Army basic trainees. METHODS Six subscales (interest/enjoyment, competence, effort/importance, value/usefulness, pressure/tension, and choice) were measured using 3 questions each, for a total of 18 questions. All questions were slightly modified for this basic training environment and assessed for face validity. A pilot study (n=58) was conducted to test reliability prior to its administration in the test population (n=2,580). RESULTS Analysis of pilot study data showed that all 6 subscales had adequate test-retest reliability (Spearman rank coefficients=0.65–0.87). Four subscales had high internal consistency (Cronbach's alpha > 0.6), while 2 subscales (pressure/tension and choice) were not reliable (Cronbach's alpha < 0.4). In the test population, internal consistency of the interest/enjoyment, competence, and effort/importance subscales remained high (Cronbach's alpha > 0.6). A factor analysis using the individual questions from these subscales confirmed the presence of three components (Eigenvalues > 1.00, 72% of variance explained), with factor loadings reflective of the 3 subscales. CONCLUSION A modified IMI reliably measured three key components of exercise motivation (interest/enjoyment, competence, and effort/importance) in an Army basic training environment. Future studies of Army trainees might use this questionnaire to assess the contribution of exercise motivation to physical performance, injury risk, or other outcomes.