Comparison of intervention and control school PE classes

A comparison of Intervention and Control PE classes was made using the system of observing fitness instruction time (SOFIT) [16]. This involved a group of trained observers recording the duration of PA of randomly selected children, teacher’s behaviour, and lesson context of PE lessons. Student PA during PE lessons was classified into minutes spent lying down, sitting, standing, walking and very active. SOFIT activities classified as walking and very active were combined to give an estimate of MVPA. Lesson context and teacher behaviour was categorised into time spent in management, general knowledge, physical fitness knowledge, fitness activity, skill practice and game play. In accordance with recommendations from a previous study [17], interval-by-interval intra-observer agreements in excess of 85 % were achieved on pre-recorded lessons prior to the collection of data in LOOK study schools. Six observers, five who were not otherwise involved in the study, completed all SOFIT observations over the four-year period. Observation times were arranged in advance with both Intervention and Control teachers.

To assess the number of PE lessons conducted per week, students were asked the following question: How many times per week do you usually do PE? (0 = never, 1 = once, 2 = twice, 3 = 3 times, 4 = 4 or more times per week). This question was part of a wider health questionnaire which referred to the current school year (grade 6, age 12 years). From these responses the average number of PE lessons conducted per week in Control and Interventions schools was calculated.