Ardoy 2011.

Study characteristics
Methods	Study design: cluster‐RCT
Participants	School inclusion criteria: — School exclusion criteria: — Student inclusion criteria: age 12 to 14, enrolled in first year of secondary school Student exclusion criteria: partial injury or illness or chronic disease that prevented involvement in PE classes Setting: school Age group: adolescents Gender distribution: females and males Country/Countries where trial was performed: Spain
Interventions	Intervention 1: experimental group 1 doubled the academic load stipulated for this subject (4 sessions/week). Experimental group 1 was taught in the same sessions as the control group, doubling the volume of booster sessions with the same objectives, content, and methods. For practical matters and questions of viability, extra sessions were carried out during the afternoon, under the same conditions, and in the same facilities as the usual sessions (held during the morning). Sessions were carried out in accordance with the established curriculum, with approval of the educational institution and the parents Intervention 2: experimental group 2 also received 4 sessions/week in which there was special emphasis on increasing the intensity of sessions. Experimental group 2 objectives and content were the same, but with high intensity across all sessions. For practical matters and questions of viability, extra sessions were carried out during the afternoon, under the same conditions, and in the same facilities as the usual sessions (held during the morning). Sessions were carried out in accordance with the established curriculum, with approval of the educational institution and the parents Comparator: control group received 2 sessions of PE/week as established by regulations currently in force in Spain. For all groups, content included the same teaching units (subjects) and sessions on physical fitness and health, games and sports, personal driving qualities, movement, and environmental activities. This intervention was designed to adhere closely to characteristics and context of educational content to obtain results of great application and transfer to national education policies Duration of intervention: 16 weeks Duration of follow‐up: 16 weeks Number of schools: 1  Theoretical framework: social cognitive theory, information‐motivation behavioural skills model, control theory, theory of planned behaviour
Outcomes	BMI Fitness
Study registration	NCT01098968 (retrospectively registered)
Publication details	Language of publication: Spanish Funding: non‐commercial funding (governmental organisation) Publication status: peer‐reviewed journal
Stated aim for study	"The purpose of the present study is to examine the effect on physical fitness and body composition of: a) doubling the number of sessions of PE/week; b) doubling the number of sessions of PE/week plus increasing their intensity; and c) increasing the intensity of the sessions, while maintaining the same number/week"
Notes
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Comment: not described
Allocation concealment (selection bias)	Unclear risk	Comment: not described
Blinding of participants and personnel (performance bias) All outcomes	High risk	Comment: students could not be blinded
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Comment: randomisation was blinded for those who performed the outcome assessment
Incomplete outcome data (attrition bias) Anthropometrics, Fitness	Low risk	Comment: minimal missing data and very few dropouts in each group
Selective reporting (reporting bias)	Low risk	Comment: all outcomes specified in protocol paper reported on
Cluster RCT ‐ Recruitment bias	Unclear risk	Comment: unclear when baseline data were collected
Cluster RCT ‐ Baseline imbalance	Low risk	Comment: secondary analysis adjusted for age
Cluster RCT ‐ Loss of clusters	Low risk	Comment: no clusters lost
Cluster RCT ‐ Incorrect analysis	High risk	Comment: clustering within classes not accounted for in analysis.