Testing for inter-group contamination in a controlled longitudinal study of added physical education.

ABSTRACT

OBJECTIVE: This case report examines whether there was any cross-contamination between students enrolled in classes that received additional physical education, and their siblings who were enrolled in preceding and succeeding class-cohorts. EXPERIMENTAL DESIGN: A controlled longitudinal study extending over 6 years of primary school. SETTING: An urban and a rural primary school in Québec. PARTICIPANTS: 546 primary students, comprising approximately equal numbers of boys and girls from the urban and the rural school. INTERVENTION Entire class-cohorts were given and hour of additional physical education ach day throughout their primary schooling, with immediately preceding and succeeding class-cohorts serving as controls. MEASURES: The measured data included standing height, body mass, maximal oxygen intake (direct treadmill test) and PWC170. RESULTS: We found no evidence of cross-contamination between siblings in experimental and control class-cohorts. CONCLUSION: Although a theoretical possibility, cross-contamination between students in preceding and succeeding class-cohorts does not seem an important source of error in primary school students, presumably because such children prefer to play with friends from their immediate age cohort.