Table 1 Summary of results for adiposity indicators organized by study design
No. of participants (No. of studies) | Design | Risk of bias | Inconsistency | Indirectness | Imprecision | Other | Absolute effect | Quality |
|---|---|---|---|---|---|---|---|---|
1060 (4) | Clustered RCT | No serious risk of bias | No serious risk of inconsistency | Very serious risk of indirectnessa | No serious risk of imprecision | None | Overall:  • 4/4 studies reported null findings Additional PA:  • 2/2 studies reported null findings [49, 50] Recess/PE:  • 1/1 studies reported null findings [51] Standing desk:  • 1/1 studies reported null findings [52] | Low |
728 (4) | Non-Randomised Intervention | Serious risk of biasb | No serious risk of inconsistency | Serious risk of indirectnessc | No serious risk of imprecision | None | Overall:  • 2/4 studies reported null findings  • 1/4 studies reported more sedentary behaviour unfavourable for health  • 1/4 studies reported mixed findings   • 1: More sedentary behaviour null and unfavourable for health Active Breaks:  • 1/1 studies reported more sedentary behaviour unfavourable for health [56] Recess/PE:  • 1/1 study reported null findings [53] Standing desk:  • 1/2 studies reported null findings [54]  • 1/2 studies reported mixed findings  • 1: More sedentary behaviour null for BMI, and unfavourable for waist circumference [55] | Very Low |
2330 (3) | Longitudinal | Serious risk of biasd | No serious risk of inconsistency | No serious risk of indirectness | No serious risk of imprecision | None | Homework:  • 1/3 studies reported null findings [57]  • 1/3 studies reported more homework favourable for health [58]  • 1/3 studies reported mixed findingse   • 1: More homework null and unfavourable for health [59]   • 1: Mixed findings included dose response relationships with unfavourable associations for ≥3 h studying, and null for 1–3 h studying for obesity but not overweight [59] | Very Low |
616,995f (21) [38, 41, 46,47,48, 60,61,62,63,64,65,66,67,68,69,70,71,72,73,74,75] | Cross-sectional | Serious risk of biasg | No serious risk of inconsistency | Serious risk of indirectnessf | No serious risk of imprecision | None | Overall:  • 10/21 studies reported null findings  • 4/21 studies reported more sedentary behaviour unfavourable for health  • 7/21 studies reported mixed findings   • 5: More sedentary behaviour null and unfavourable for health   • 2: More sedentary behaviour null and favourable for health Active breaks:  • 1/1 study reported null findings [60] Additional PA:  • 1/1 study reported null findings [60] Homework:  • 5/11 studies reported null findings [61,62,63,64,65]  • 2/11 studies reported more homework unfavourable for health [41, 69]  • 4/11 studies reported mixed findingsh   • 4: More homework null and unfavourable for health [38, 72,73,74] Recess/PE:  • 2/5 studies reported null findings [47, 60]  • 1/5 studies reported more sedentary behaviour unfavourable for health [70]i  • 2/5 studies reported mixed findingsj   • 1: More sedentary behaviour null and favourable for health [46]   • 1: More sedentary behaviour null and unfavourable for health [73] Sedentary time:  • 3/6 studies reported null findings [66,67,68]  • 1/6 studies reported more sedentary time unfavourable for health [71]  • 2/6 studies reported mixed findingsk   • 1: More sedentary time null and favourable for health [75]   • 1: More sedentary time null and unfavourable for health [48] | Very Low |