Table 1

Categories of research evidence used for this report, adapted from the American College of Sports Medicine criteria62 (applied in box 1)

(A) Randomised, controlled trials (overwhelming data)Provides a consistent pattern of findings with substantial studies
(B) Randomised, controlled trials (limited data) and high-quality observational dataFew randomised trials exist which are small in size, and results are inconsistent or observation studies supported by evidence of causality from acute or experimental studies
(C) Non-randomised trials, observational studiesOutcomes are from uncontrolled, non-randomised, and/or observational studies
(D) Panel consensus judgementPanel’s expert opinion when the evidence is insufficient to place it in categories A–C