School-related sedentary behaviours and indicators of health and well-being among children and youth: a systematic review

Table 4 Summary of results for musculoskeletal growth indicators organized by study design

No. of participants (No. of studies)	Design	Risk of bias	Inconsistency	Indirectness	Imprecision	Other	Absolute effect	Quality
236 (1) [51]	Clustered RCT	Serious risk of bias^a	No serious risk of inconsistency	No serious risk of indirectness	Serious risk of imprecision^b	None	Recess/PE: • 1/1 study reported null findings [51]	Low
228 (1) [53]	Non-Randomised Intervention	Serious risk of bias^c	No serious risk of inconsistency	Very serious risk of indirectness^d	Serious risk of imprecision^e	None	Recess/PE: • 1/1 studies reported null findings [53]	Very Low
1586 (1) [69]	Cross-sectional	Serious risk of bias^f	No serious risk of inconsistency	No serious risk of indirectness	Serious risk of imprecision^g	None	Homework: • 1/1 studies reported mixed findings • 1: Null for boys and more homework favourable for girls health [69]	Very Low

Mean age at baseline ranged from 7.7 years to 11.5 years. Study designs included clustered RCT and non-randomised intervention with up to 7 years follow-up, and cross-sectional. Musculoskeletal growth was assessed objectively with height, weight, and fat-free mass (i.e., bioelectrical impedance, and skinfold thickness)
^a Groups were randomised to intervention and control within the same schools
^b Only one study, but not a small sample size
^c Intervention effects not reported, only differences in mean follow-up values
^d Study did not report school-related sedentary exposure
^e Only one study, but not a small sample size
^f Study did not demonstrate psychometric testing for subjective exposure measure
^g Only one study, but large sample size

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