Hot Water (Not Cold) Immersions More Effective For Recovery

Picture from Racold.com

With the Paris Olympics around the corner, many of my patients have been asking me about recovery, ice immersions and the Singapore women's swimming Olympic selection fiasco (no, I am not discussing that).  

A patient I saw yesterday mentioned that an ice immersion recovery center just opened near his home and he was hoping it will help his sore muscles.

Picture from Business Insider by Alexandre Simoes 

I told him that evidence shows that ice baths/ immersions does not help  recovery. In fact cold water immersion after hard exercise suppressed signaling pathways associated with recovery. This suppression lasted several days. In addition, ice bathing reduced the body's muscles uptake of dietary proteins, which is important for growth and cell maintenance. Grgic (2022) showed that cold water immersion reduced exercise related strength gains while (Pinero et al, 2024) showed that ice bathing immediately after weight training inhibited muscle growth.

On the contrary, hot water immersion (below) improved recovery follwing exercise induced muscle damage (Sautillet et al, 2024).

Picture from Newsmeter

Following exercise induced muscle damage, Sautillet and colleagues (2024) put 30 active males through one of the following recovery interventions : cold water immersion (11 degrees Celcius), hot water immersion (41 deg Celsius) and control group of warm-bath (36 deg Celcius).

Quadriceps maximum strength and explosive strength were measured pre, 24 and 48 hours post exercise. Pressure pain threshold (PPT), or was also measured to quantify the recovery from muscle soreness

Here are the results. 48 hours post exercise, quadriceps maximal strength returned to baseline values after both cold and hot water immersions. However, explosive strength levels and PPT (muscle tenderness) returned to baseline levels post 48 hours only after hot water immersion.

In addition, surface electromyography (electrodes) signals from the vastus lateralis (outer quadriceps) was significantly increased following cold water immersion. Meaning more muscle fatigue. Or as patients like to say, their muscles are 'very tight'.

The authors concluded that a single session of hot water immersion (rather than cold water immersion) improved the rate of explosive strength followed exercise induced damage. When explosive power is a key performance requirement, hot water immersion should be preferred over cold.

*Note that the cold bath temperature used in this study (Santillet et al, 2024) was 11 degrees Celcius. Wim Hof (the Dutch iceman), others on Tik Tok, other social media and purveyors of commercial health and wellness have different protocols.

For those who are keen the temperature of the hot bath was 41 degrees Celsius for a duration of 15-30 minutes.

References

Grgic J. (2023). Effects Of post-exercise Cold-water Immersion On Resistance Training-Induced Gains In Muscular Strength: A Meta-analysis. Eur J Sp Sci. 23(3): 372-308. DOI: 10.1080/17461391.2022.2033851.

Pinero A, Burke R, Augustin F et al (2024). Throwing Cold Water On Muscle Growth: A Systematic Review With Meta-analysis Of The Effects Of Postexercise Cold Water Immersion On Resistance Training-induced Hypertrophy. Eur J Sp Sci. 24: 177-189. DOI: 10.1002/ejsc.12074

Sautillet B, Bourdillon N, Millet GP et al (2024). Hot Bt Not Cold Water Immersion Mitigates The Decline In Rate Of Force Development Following Exercise-Induced Muscle Damage. Med Sci Sp Ex. DOI: 10.1249/MSS.0000000000003513