REPRODUCIBILITY AND VALIDITY OF AN EPIDEMIOLOGIC QUESTIONNAIRE TO ASSESS PAST YEAR PHYSICAL-ACTIVITY IN ADOLESCENTS

The reproducibility and validity of a past year physical activity ques tionnaire was determined in a sample of 100 adolescents aged 15-18 yea rs, randomly selected from a population-based cohort. Subjects complet ed four 7-day recalls of activity approximately 3 months apart. The av erage of the four 7-day recalls of activity was utilized as the ''gold standard'' against which the past year questionnaire was compared to evaluate validity. The questionnaire was also validated against object ive measures, such as physical fitness and body mass index. Interschol astic team rosters were utilized to directly validate the reporting of specific activities. One-month and one-year test-retest reproducibili ty of the questionnaire were determined. For different measures of act ivity, the Spearman correlations between the questionnaire and the ave rage of the 7-day recalls ranged from 0.55 to 0.67 in males and 0.73 t o 0.83 in females, all significant at p < 0.01. In general, although t here was no association between the past year activity questionnaire r esults and objective measures, there was a significant, albeit weak as sociation between the physical activity questionnaire and time to comp lete a 1-mile (1.61-km) run (r = -0.47) in females. Subjects reported participating in specific interscholastic sports with an accuracy of 1 00%, 86%, and 95% for the fall, winter, and spring sports, respectivel y. Test-retest reproducibility was higher over one month (r = 0.79) th an over one year (r = 0.66). These data provide evidence that the ques tionnaire yields a reasonable estimate of past year or ''habitual'' ph ysical activity in adolescents.