Effects of post-exercise cold-water immersion on resistance training-induced gains in muscular strength: a meta-analysis

Effects of cold-water immersion on health and wellbeing: A systematic review and meta-analysis

BACKGROUND

Cold-water immersion (CWI) has gained popularity as a health and wellbeing intervention among the general population.

OBJECTIVE

This systematic review and meta-analysis aimed to evaluate the psychological, cognitive, and physiological effects of CWI in healthy adults.

METHODS

Electronic databases were searched for randomized trials involving healthy adults aged ≥ 18 years undergoing acute or long-term CWI exposure via cold shower, ice bath, or plunge with water temperature ≤15°C for at least 30 seconds. Outcomes of interest were sleep, stress, fatigue, energy, skin health, immunity, inflammation, mental wellbeing, depression, anxiety, mood, concentration, and alertness or focus. Meta-analyses were conducted using RevMan software (version 5.4), applying random effects models to calculate standardized mean differences (SMD) between pre- and post-CWI exposure outcomes. Risk of bias was assessed using the PEDro scale.

RESULTS

Eleven studies were included, comprising 3177 total participants and a mean PEDro score of 6.4 (n = 7 moderate quality, n = 4 high quality). CWI interventions were performed in baths (n = 10) or showers (n = 1) at temperatures ranging from 7°C to 15°C and durations ranging from 30 seconds to 2 hours. The meta-analysis revealed significant increases in inflammation immediately (SMD: 1.03, [95% CI: 0.37, 1.68], p <  0.01) and 1 hour post CWI (SMD: 1.26, [95% CI: 0.59, 1.94], p <  0.01), indicating an acute inflammatory response. A significant reduction in stress was observed 12 hours post-CWI (SMD: -1.00, [95% CI: -1.40, -0.61], p <  0.01), however, no significant effects on stress were detected immediately (SMD: -0.09 [95% CI: -0.45, 0.63], p >  0.05), 1 hour (SMD: -0.29 [95% CI: -0.66, 0.08], p >  0.05), 24 hours (SMD: -0.06 [95% CI: -0.50, 0.38], p >  0.05), or 48 hours (SMD: 0.09 [95% CI: -0.28, 0.46], p >  0.05) post-exposure. While meta-analysis showed no significant effects on immune function immediately (SMD: -0.16 [95% CI: -0.82, 0.51], p >  0.05) or 1 hour (SMD: -0.18 [95% CI: -1.09, 0.74], p >  0.05) post-CWI, narrative synthesis suggested longer-term benefits, including a 29% reduction in sickness absence among participants who took cold showers. Improvements were also observed in sleep quality and quality of life, but not mood.

CONCLUSIONS

This systematic review suggests that CWI delivers time-dependent effects on inflammation, stress, immunity, sleep quality, and quality of life, offering potential practical applications for health practitioners considering CWI for stress management and wellbeing support. However, the current evidence base is constrained by few RCTs, small sample sizes, and a lack of diversity in study populations. Future high-quality RCTs are needed to examine the long-term effects of CWI, its impact on diverse health outcomes, and optimal CWI protocols. PROSPERO (ID: CRD42024500591).

Enhancing Post-Training Muscle Recovery and Strength in Paralympic Powerlifting Athletes with Cold-Water Immersion, a Cross-Sectional Study

(1) Background: The recovery method is important and decisive in the training system. This study aimed to assess the effects of various post-training recovery methods on muscle damage and strength indicators in Paralympic powerlifting athletes. (2) Methods: A crossover study was conducted involving eleven male athletes (25.4 ± 3.3 years, 70.3 ± 12.1 kg). Muscle damage was assessed using blood biochemical markers (cytokines IL-6, IL-10, and TNF-α) and isometric force indicators, including the maximum isometric force (MIF), time to MIF, and Rate of Force Development. The following assessments were performed before, immediately after, and at 24 and 48 h after the recovery protocol: (a) passive recovery (RP) or (b) cold-water immersion (CWI). (3) Results: The main results indicated that maximum isometric force (MIF) significantly improved after 48 h of CWI application (p < 0.05; for all comparison). The analysis of biochemical markers did not yield significant differences between the recovery methods at different time points (p > 0.05). For IL-6, there were significant differences between CWI before (2.29 ± 1.08, 95% CI 1.57-3.01) and CWI 2 h later (2 h) (4.59 ± 2.96, 95% CI 2.60-6.57; p = 0.045), and between CWI 15 min later (15 min) (4.14 ± 2.24, 95% CI 2.63-5.64) and CWI 48 h later (48 h) (2.33 ± 1.25, 95% CI 1.49-3.17; p = 0.034). There were differences between CWI 2 h (4.14 ± 2.24, 95% CI 2.63-5.64) and CWI 48 h later (2.33 ± 1.25, 95% CI 1.49-3.17; p = 0.035; F = 9.202; η2p = 0.479; high effect). (4) Conclusions: CWI significantly improved the post-resistance training muscle damage and strength in Paralympic powerlifting athletes.

Effect of CO2 and H2 gas mixture in cold water immersion on recovery after eccentric loading

Background

The findings of previous studies support the efficacy of cold water immersion (CWI) with carbon dioxide (CO2) in enhancing muscle blood flow and maintaining aerobic performance efficiency. We hypothesize that the addition of hydrogen gas (H2), known for its antioxidant properties and role in inflammation regulation, to C-CWI can enhance recovery after eccentric exercise.

Subjects

and Methods: Thirty-four healthy subjects performed a knee-extensor eccentric exercise. They were randomly allocated into four groups: control, CWI, CO2-rich CWI (C-CWI), and CO2 + H2 gas mixture CWI (CH-CWI). In the three CWI groups, all subjects were immersed in the appropriate bath at 20 °C for 20 min immediately after 60 repetitions of eccentric exercise. Before exercise and after 48 h of recovery, the subjects' maximal voluntary isometric contraction torque (MVC-ISO), maximal voluntary concentric (MVC-CON) contraction torque, countermovement jump (CMJ) height, knee flexion range of motion (ROM), muscle soreness, and muscle thickness were measured.

Results

In the CH-CWI group only, the MVC-ISO, CMJ height, and ROM did not decrease significantly post-exercise, whereas all of these decreased in the other three groups. Muscle soreness at palpation, contraction, and stretching significantly increased post-exercise in all groups. Echo intensity and tissue hardness did not increase significantly in the CH-CWI group.

Conclusions

CH-CWI stimulated recovery from impairments in MVC-ISO torque, CMJ height, knee-flexion ROM, tissue hardness, and echo intensity. These findings indicate that CH-CWI can promote recovery after eccentric exercise.