Table 1 GRADE analyses.

Outcomes	Certainty assessment					Number of participants and studies	Certainty of evidence (GRADE)
Outcomes	Risk of bias	Inconsistency	Indirectness	Imprecision	Risk of publication bias	Number of participants and studies	Certainty of evidence (GRADE)
Body composition (body mass index) follow-up: range 12 to 22 weeks	Serious^a	Serious^b	Not serious	Serious^c	Not serious	369 (4 studies)	⊕◯◯◯VERY LOW
Body composition (body fat percentage) follow-up: range 6 to 36 weeks	Serious^a	Serious^b	Not serious	Serious^c	Not serious	341 (8 studies)	⊕◯◯◯VERY LOW
Body composition (lean mass) follow-up: range 12 to 36 weeks	Serious^a	Not serious	Not serious	Serious^c	Not serious	149 (4 studies)	⊕⊕◯◯LOW
Muscular strength follow-up: range 4 to 36 weeks	Serious^a	Not serious	Not serious	Not serious	Not serious	865 (15 studies)	⊕⊕⊕◯MODERATE
Cardiorespiratory fitness follow-up: range 4 to 12 weeks	Serious^a	Not serious	Not serious	Serious^c	Serious^d	493 (6 studies)	⊕⊕◯◯LOW
Flexibility follow-up: range 6 to 12 weeks	Serious^a	Not serious	Not serious	Serious^c	Not serious	276 (4 studies)	⊕⊕◯◯LOW

GRADE Working Group grades of evidence High certainty: we are very confident that the true effect lies close to that of the estimate of the effect. Moderate certainty: we are moderately confident in the effect estimate: the true effect is likely to be close to the estimate of the effect, but there is a possibility that it is substantially different. Low certainty: our confidence in the effect estimate is limited: the true effect may be substantially different from the estimate of the effect. Very low certainty: we have very little confidence in the effect estimate, the true effect is likely to be substantially different from the estimate of the effect.
GRADE Grading of Recommendations Assessment, Development and Evaluation.
^aDowngraded by one level due to high or some concerns risk of bias.
^bDowngraded by one level due to the substantial heterogeneity (I² ≥ 50%).
^cDowngraded by one level, as < 400 participants were available for a comparison or there was an unclear direction of the effects. Downgraded by two levels in case of imprecision based on both assessed points.
^dDowngraded by one level due to the significant of Egger’s test (p < 0.05).

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