This systematic review and network meta-analysis adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines. The protocol was officially registered with the International Prospective Register of Systematic Reviews (PROSPERO), registration ID: CRD42024602359.

A comprehensive, computerized search was executed across multiple databases such as CNKI, PubMed, Cochrane Library, Web of Science, and Embase. The objective was to collate randomized controlled trials (RCTs) examining the impact of CWI on recovery after acute EIMD. The search covered the period from January 2000 to September 2024. Developed based on the PICOS framework, the strategy included: (P) Population—healthy individuals; (I) Intervention—CWI; (C) Comparison—control and passive recovery groups without intervention; (O) Outcomes—CK, DOMS, and jump performance (including counter-movement jump or squat jump); (S) Study design—RCTs. The search utilized a blend of subject headings and free-text terms. Additionally, references of all included studies were scrutinized to unearth further pertinent literature. Search terms deployed included various combinations and synonyms of CWI, muscle fatigue, EIMD, and study design descriptors.

(1) Only studies employing a RCT design were selected.

(1) Research not limited to a singular CWI intervention (e.g., studies combining CWI with compression garments, active recovery, or nutritional supplements).

Two researchers independently screened the literature, extracted data, and cross-verified their findings. In cases of disagreement, a third party was consulted for assistance. Missing data were supplemented by contacting the authors whenever possible. Literature screening began with reading titles and abstracts; after excluding obviously irrelevant studies, full texts were reviewed to determine final inclusion. Data extraction primarily included: first author, country, year of publication, intervention subjects (sample size for each group, gender, age, occupation), intervention measures (CWI protocol, testing time after intervention), and outcome indicators.

Risk of bias was assessed by two researchers using the Cochrane Handbook’s tool for RCTs. The assessment criteria included: allocation sequence generation, allocation concealment, blinding of participants and personnel, blinding of outcome assessment, completeness of outcome data, absence of reporting bias, and other potential biases.

Based on the temperature and duration differences in the CWI intervention protocols from the included literature, this study identified the following six criteria for grouping:

SD-LT-CWI: Short-duration low-temperature cold water immersion (<10 min, 5°C–10°C).

MD-LT-CWI: Medium-duration low-temperature cold water immersion (10–15 min, 5°C–10°C).

LD-LT-CWI: Long-duration low-temperature cold water immersion (>15 min, 5°C–10°C).

MD-MT-CWI: Medium-duration medium-temperature cold water immersion (10–15 min, 11°C–15°C).

MD-HT-CWI: Medium-duration high-temperature cold water immersion (10–15 min, 16°C–20°C).

LD-HT-CWI: Long-duration high-temperature cold water immersion (>15 min, 16°C–20°C).

To minimize the impact of baseline differences, this study utilized the change values of mean and standard deviation before and after the intervention for effect size synthesis. The calculation method for standard deviation changes was based on the formula provided in the Cochrane Handbook (6th edition) (Higgins and Collaboration, 2019). Following the PRISMA guidelines for network meta-analysis (Hutton et al., 2015), a random-effects model was employed within a frequentist framework to combine effect sizes and calculate the 95% confidence intervals (CIs) using Stata 16.0 software (Salanti, 2012). This approach was used to assess the effects of various CWI intervention protocols on CK, DOMS, and JUMP. Due to the inconsistency in measurement units for outcome indicators, standardized mean difference (SMD) was used as the effect size for synthesis. A network evidence plot was generated to describe the relationships between different exercise interventions, where the lines connecting nodes represent direct comparisons between interventions, with line thickness proportional to the number of studies and node size proportional to sample size. The inconsistency factor and its 95% CI were calculated to evaluate the consistency of each closed loop (Chaimani et al., 2013). An inconsistency model was employed to test for inconsistency; when P > 0.05, a consistency model was used for analysis. The surface under the cumulative ranking curve (SUCRA) was utilized to rank and compare the effects of different types of interventions. SUCRA values range from 0% to 100%, with 100% indicating the best intervention effect and 0 indicating the worst. A funnel plot was created to assess the presence of publication bias or small sample effects.

The search strategy yielded 1,299 potentially relevant articles across several databases: CNKI (5), PubMed (170), Embase (142), Cochrane Library (631), and Web of Science (351). The elimination of 540 duplicates was followed by the exclusion of 431 articles after screening titles and abstracts. Subsequent full-text reviews led to the exclusion of an additional 260 articles, with data extraction being unfeasible for 13 articles. Ultimately, 55 RCTs were selected for inclusion in this analysis (Figure 1).

A total of 55 randomized controlled trials were included, comprising 1,139 participants. The intervention protocols for the experimental group included MD-LT-CWI, MD-MT-CWI, LD-LT-CWI, SD-LT-CWI, MD-HT-CWI, and LD-HT-CWI. The included studies were predominantly published in the last 10 years, with 42 studies reporting DOMS as an outcome measure, 36 studies reporting JUMP, and 30 studies reporting CK. Detailed information is presented in (Table 1).

Figure 2A presents an overview of the risk of bias across the included studies. All incorporated studies utilized random allocation methods; 47 studies provided details on allocation concealment methods such as sealed container use or computer-generated random sequences. However, many studies lacked clarity regarding the blinding of implementers and participants, thus elevating the potential for bias since blinding during the interventions proved challenging. Blinding of outcome assessors was confirmed in 45 studies, mitigating detection bias. Regarding data integrity, 48 studies showed a low risk of bias, with complete data reported in 35. The other studies adequately justified any participant withdrawals or follow-up losses, utilizing robust methods for handling incomplete data. A low likelihood of reporting bias was observed, with 49 studies analyzing and presenting results as pre-specified in their protocols. Nonetheless, 16 studies faced additional bias risks related to insufficient exercise intervention details or small sample sizes (Supplementary Figure S2B).

In this network meta-analysis, MD-MT-CWI (10–15 min, 11°C–15°C) demonstrated the best efficacy in alleviating delayed onset muscle soreness (DOMS). DOMS is a delayed pain resulting from micro-damage to muscle tissue following intense exercise, typically occurring 24–72 h post-exercise (Hill et al., 2014; Vieira et al., 2016). This pain is closely related to factors such as mechanical damage to muscle fibers, local inflammatory responses, edema around the muscles, and activation of pain receptors (Afonso et al., 2021). The inflammatory response following exercise can lead to local swelling and the release of inflammatory mediators (such as prostaglandins and interleukins), which further exacerbate pain and discomfort. (Ascensão et al., 2011).

Cold water immersion, particularly MD-MT-CWI (10–15 min, 11°C–15°C), can alleviate DOMS through several primary mechanisms. First, cold water induces vasoconstriction, reducing local blood flow and thus decreasing the accumulation and release of inflammatory mediators, significantly inhibiting the initial local inflammatory response (Ihsan et al., 2016). Second, cold water lowers tissue temperature, slowing local metabolism and reducing edema and interstitial fluid accumulation, which alleviates tissue pressure and stimulation of pain receptors (Hohenauer et al., 2015).

Compared to low-temperature CWI (5°C–10°C), medium-temperature CWI (11°C–15°C, 10–15 min) may offer a better balance between cooling effect and comfort. While low-temperature CWI is effective in reducing muscle inflammation and pain, prolonged exposure to excessively low temperatures can lead to discomfort, muscle tightness, or even vasoconstriction, potentially hindering optimal recovery (Wilcock et al., 2006; Crystal et al., 2013; Yeargin et al., 2024; Versey et al., 2013). In contrast, medium-temperature CWI (11°C–15°C) provides sufficient cooling to mitigate muscle soreness and inflammation without the discomfort associated with colder temperatures (Machado et al., 2016; Machado et al., 2017). Several studies (Machado et al., 2016; Machado et al., 2017) suggest that moderate temperatures can be more comfortable for longer immersion durations, which may reduce stress responses and improve adherence to recovery protocols. Furthermore, medium temperatures might enhance blood flow by avoiding excessive vasoconstriction, thus promoting more effective muscle repair and reducing delayed onset muscle soreness (DOMS). While further research is needed to validate these mechanisms, medium-temperature CWI appears to be a more practical approach in clinical settings for alleviating DOMS while maintaining patient comfort.

The results indicate that MD-LT-CWI (10–15 min, 5°C–10°C) was the most effective in enhancing jump performance. This finding is significant, especially for athletes needing rapid recovery of functional performance. Jump performance reflects a combination of neuromuscular function and strength, and cold water immersion can promote recovery through various mechanisms (Bailey et al., 2007).

First, cold water lowers local muscle temperature, slowing nerve conduction and muscle metabolic rates, allowing for effective recovery in a short time while alleviating soreness and fatigue caused by muscle damage, which is crucial for athletes needing to regain jump capacity quickly (Rowsell et al., 2011). Second, cold water immersion helps reduce muscle fatigue accumulation, promotes blood return, and aids in clearing metabolic waste such as lactic acid, thereby accelerating energy supply recovery and micro-damage repair, which mitigates fatigue (Leeder et al., 2012). Additionally, the vasodilation that occurs after cold water immersion enhances blood flow in the recovery phase, increasing the supply of oxygen and nutrients to support muscle regeneration and repair. This process helps accelerate the recovery of muscle function and aids in the restoration of neuromuscular function (Leeder et al., 2012).

It is critical to acknowledge that while MD-LT-CWI significantly boosts jump performance, overly low temperatures may induce muscle stiffness and discomfort (Machado et al., 2017; Wilcock et al., 2006; Crystal et al., 2013; Yeargin et al., 2024; Versey et al., 2013) if applied for extended periods. Therefore, it is advisable to tailor the timing and temperature of immersion to the specific needs of the athlete to optimize recovery benefits without imposing additional physiological strain.

Creatine kinase (CK) is a key biomarker for muscle damage, with elevated levels typically associated with damage to muscle cell membranes and leakage of muscle fibers (Choo et al., 2022; Rowsell et al., 2009). This meta-analysis found that both MD-LT-CWI (10–15 min, 5°C–10°C) and MD-MT-CWI (10–15 min, 11°C–15°C) significantly reduced CK levels post-exercise, indicating that cold water immersion effectively mitigates muscle damage.

The mechanisms by which cold water immersion lowers CK levels primarily involve reducing the extent of muscle damage and accelerating the repair process (White et al., 2014). Cold immersion lowers local temperatures, decreasing the permeability of muscle cell membranes and thus curtailing CK leakage into the bloodstream (White and Wells, 2013), helping to preserve cellular structural integrity and minimize further membrane damage (Ingram et al., 2009). Additionally, it diminishes inflammatory responses and local edema, creating an optimal environment for muscle regeneration (Ascensão et al., 2011). Enhanced vasodilation following cold immersion increases nutrient and oxygen supply to muscles, accelerating the repair process and the reestablishment of normal physiological functions (Ascensão et al., 2011). Moreover, intense exercise triggers oxidative stress, boosting free radical production that exacerbates muscle damage. CWI mitigates these effects by reducing tissue metabolic rates, curtailing free radical production, and enhancing antioxidant activity (Malta et al., 2021), crucial for decreasing CK release.

In this study, both MD-LT-CWI (10–15 min, 5°C–10°C) and MD-MT-CWI (10–15 min, 11°C–15°C) exhibited consistent effects in lowering CK levels. However, MD-MT-CWI (10–15 min, 11°C–15°C) provides greater comfort, potentially making it more suitable for the practical needs of most athletes. Considering practical circumstances, selecting an appropriate cold water immersion protocol can help alleviate muscle damage while providing a more comfortable recovery experience.

Despite efforts to reduce heterogeneity across the included primary studies, unavoidable factors such as participant age and geographical differences remained. Specifically, geographical differences refer to variations in studies conducted across different countries and regions, where factors such as climate, culture, and local exercise habits may influence the effectiveness of cold water immersion (CWI). These differences could result in variations in study design, participant selection, and intervention implementation, potentially impacting the generalizability of the findings.

Notably, the analysis revealed limited gender diversity within the sample populations: only one study exclusively used female participants, five studies did not specify the gender of participants, and the remaining studies involved only male participants. As a result, the outcomes of this review may primarily reflect the effects of six different CWI doses on muscle recovery among males.