Summary of findings for the main comparison. Summary of findings: whole‐body cryotherapy (WBC) compared with control (no WBC or passive rest).

Whole‐body cryotherapy (WBC) compared with control (no WBC or passive rest) for preventing and treating muscle soreness after exercise in adults
Patient or population: physically‐active adults partaking in exercise designed to produce delayed onset muscle soreness (most trial participants were male) Settings: laboratory‐based Intervention: whole‐body cryotherapy (WBC). The timing, format and modality varied. WBC delivered in either in a specialised cryotherapy chamber (temperature ‐110°C) or partial‐body cryotherapy (head and neck not included) in a cryo‐cabin at temperatures of ‐110°C or between 140 to ‐195°C. Exposure: 3 minutes. Timing after exercise ranged from 10 minutes to 24 hours. Repeat exposures, which were every 24 hours in 2 studies, varied from 0 to 5 additional sessions. Comparison: control: no intervention (in chamber but normal temperatures: 15°C and 21°C) or passive rest
Outcomes	Illustrative comparative risks* (95% CI)		Relative effect (95% CI)	No of Participants (studies)	Quality of the evidence (GRADE)	Comments
	Assumed risk	Corresponding risk
	Control (rest or no WBC)	WBC
Muscle soreness: pain at rest (VAS) Follow‐up: 1 hour		The mean difference in muscle soreness in the WBC groups was 0.77 standard deviations lower (1.42 lower to 0.12 lower)	SMD ‐0.77 (‐1.42 to ‐0.12)	20 participants (2 studies)	⊕⊝⊝⊝ very low1	Reported in 2 cross‐over studies only One rule of thumb is that 0.2 represents a small difference, 0.5 a moderate difference and 0.8 a large difference. Based on this 'rule of thumb', this result equates to a moderate to large difference in favour of WBC
Muscle soreness: pain at rest (VAS) Follow‐up: 24 hours		The mean difference in muscle soreness in the WBC groups was 0.57 standard deviations lower (1.48 lower to 0.33 higher)	SMD ‐0.57 ( ‐1.48 to 0.33)	38 participants (3 studies)	⊕⊝⊝⊝ very low2	Reported in one parallel group (which found no difference between the two groups) and two cross‐over studies which found in favour of WBC. Based on the above rule of thumb, this results equates to a moderate difference in favour of WBC but also includes a small to moderate effect in favour of rest or no WBC
Muscle soreness: pain at rest (VAS) Follow‐up: 48 hours		The mean difference in muscle soreness in the WBC groups was 0.58 standard deviations lower (1.37 lower to 0.21 higher)	SMD ‐0.58 (‐1.37 to 0.21)	38 participants (3 studies)	⊕⊝⊝⊝ very low2	Reported in one parallel group (which found no difference between the two groups) and two cross‐over studies which found in favour of WBC. Based on the above rule of thumb, this results equates to a moderate difference in favour of WBC but also includes a small effect in favour of rest or no WBC
Muscle soreness: pain at rest (VAS) Follow‐up: 72 hours		The mean difference in muscle soreness in the WBC groups was 0.65 standard deviations lower (2.54 lower to 1.24 higher)	SMD ‐0.65 (‐2.54 to 1.24)	29 participants (2 studies)	⊕⊝⊝⊝ very low2	Reported in one parallel group (which found no difference between the two groups) and one cross‐over study which found in favour of WBC. There was substantial heterogeneity between the two trials (Chi² = 7.73, df = 1 (P = 0.005); I² = 87%), which brings both pooling and the validity of this result into question
Tiredness (0 [no tiredness] to 100 [maximum tiredness]) Follow‐ups: 1, 24 and 48 hours	The mean tiredness recorded in the study control group at 24 hours was 49.2	The mean tiredness in the WBC group was 13.30 lower (32.17 lower to 5.57 higher)		9 participants (1 study)	⊕⊝⊝⊝ very low1	Reported in one cross‐over study only. The results at 1 and 48 hours showed a similar lack of differences between the two groups, with all 95% CIs crossed the line of no effect
Well‐being (0 [worst well‐being] to 100 [optimal well‐being]) Follow‐ups: 1, 24 and 48 hours	The mean well‐being recorded in the study control group at 24 hours was 65.4	The mean well‐being in the WBC group was 21.7 higher (2.20 to 41.20 higher)		9 participants (1 study)	⊕⊝⊝⊝ very low1	It is possible that the difference in well‐being represented a clinically important difference but the minimal clinically important difference is not known. No differences between groups were observed at 1 and 48 hour follow‐ups; the 95% CIs crossed the line of no effect at both time periods
Adverse events	See comment		See comment		See comment	All studies failed to report active surveillance of predefined adverse events. We found one report of skin burn following WBC in the recent literature. Studies typically exclude people with contradictions to cryotherapy, such as Raynaud’s disease
*The basis for the assumed risk (e.g. the median control group risk across studies) is provided in footnotes. The corresponding risk (and its 95% confidence interval) is based on the assumed risk in the comparison group and the relative effect of the intervention (and its 95% CI). CI: confidence interval; RR: risk ratio; SMD: standardised mean difference
GRADE Working Group grades of evidence High quality: Further research is very unlikely to change our confidence in the estimate of effect. Moderate quality: Further research is likely to have an important impact on our confidence in the estimate of effect and may change the estimate. Low quality: Further research is very likely to have an important impact on our confidence in the estimate of effect and is likely to change the estimate. Very low quality: We are very uncertain about the estimate.

¹The quality of the evidence was downgraded 3 levels for very serious study limitations resulting in a high risk of bias and serious imprecision (very few participants).

²The quality of the evidence was downgraded 3 levels for very serious study limitations resulting in a high risk of bias, serious imprecision (very few participants) and serious inconsistency (substantial heterogeneity).