Updated to include insights and advances in 2023

Cold water immersion therapy is becoming an increasingly popular recovery protocol, and has been proven to improve recovery for subjective measures, but its effects on objective measures are far less apparent.

Recovery is a critical part of training as it is used to minimize the risk of overtraining and injury, whilst promoting physical and psychological readiness. This is particularly important if you partake in intense training or competition periods. Recovery is needed to sustain an optimal state of performance. Understanding the importance of recovery has led to the use and development of many recovery techniques such as massage therapy, foam rolling, electrical stimulation, whole-body vibration, compression garments, hyperbaric oxygen therapy and water immersion therapy (including cold water, warm water, and contrast bathing).

For its ability to improve recovery time and reduce the delayed onset of muscle soreness (DOMS), water immersion therapy has become extremely popular amongst sports scientists. The term water immersion therapy usually refers to all modes of water-based recovery protocols – cold-water immersion, warm-water immersion, and contrast bathing (alternate warm and cold immersion).

It is believed that water immersion therapy can:

·   Reduce oedemas

·   Decrease the perception of pain associated with muscular soreness

·   Decrease the perception of fatigue

·   Alter localised blood flow

·   Alter localised tissue and core temperature

·   Alter heart rate

·   Reduce muscle spasms

·   Reduce tissue inflammation

·   Reduce muscle damage

·   Improve range of motion

However, whilst some research may support some of these effects, others have little (or no evidence) to support these claims.

The Pivot of Recovery in Training

The realm of fitness has recognized recovery as an indispensable element in training regimens, crucial in mitigating the risks of overtraining and injuries, while fostering physical and psychological readiness. This heightened understanding has birthed numerous recovery techniques such as massage therapy, foam rolling, and more notably, water immersion therapy, which encompasses cold water, warm water, and contrast bathing practices.

In 2023, the emphasis is not only on the intensity of workouts but also on the science of recovery, making techniques like cold water immersion therapy a staple in the toolkit of athletes and fitness enthusiasts alike. It promises benefits including reduced oedemas, alleviated muscle spasms, and improved range of motion, although research varies in backing these claims robustly.

What is Cold Water Immersion?

Cold water immersion (CWI), alternatively known as ice baths or cold water therapy, has firmly established itself as a popular recovery modality. The process involves submerging the body into cold water (≤15˚C/59˚F) post-exercise, aiming to enhance the recovery trajectory. In 2023, as individuals seek comprehensive insights into wellness practices, we notice a surge in resources like videos and webinars offering deep-dives into therapies like CWI. For a contemporary understanding of cold water immersion therapy, check out the insightful video below:

Credit to Remote/Frontier Medicine

Does Cold Water Immersion improve recovery?

I bet you've experienced those painful few days after an intense activity! This is called DOMS (Delayed Onset of Muscle Soreness). This is the result of microscopic tears in muscle tissue. Researchers have found that CWI has helped the most with DOMS.

The effectiveness of CWI has also been investigated by measuring several other factors. These include:

Subjective Measures

·   DOMS

·   Ratings of Perceived Exertion (RPE)

Objective Measures

·   Creatine-kinase (CK)

·   Blood lactate-levels

·   Interleukines

·   C-reactive protein (CRP)

In a large quantity of research, CWI has been shown to consistently reduce the effects of DOMS and RPE. In a recent systematic review and meta-analysis, it was concluded that CWI is an effective protocol for reducing the effects of DOMS 24hrs, 48hrs, and 96hrs post-exercise. Moreover, it shows promise in reducing perceived exertion rates post-exercise, although the consensus on its influence on objective measures remains a subject of ongoing research.

How does Cold Water Immersion improve recovery?

Despite being a focal point of research, the precise mechanisms underlying the benefits of CWI remain somewhat elusive. Various theories have been proposed, involving aspects such as vasoconstriction, analgesic effects of cold water, and the role of hydrostatic pressure. With advancements in biotechnology, 2023 sees an intensified effort to decipher these mechanisms using data-driven approaches and sophisticated tools for monitoring physiological responses.

In short, the following theories have been suggested:

·   Vasoconstriction (blood vessel constriction).

·   Analgesic (pain relieving) effect of the cold water.

·   Reducing inflammatory pathways.

·   Placebo effect.

·   Hydrostatic pressure.

Vasoconstriction

One theory suggests that the immersion into cold water causes vasoconstriction, leading to lower localised blood flow. It is thought that the temperature-induced reduction in blood flow around the damaged tissues, caused by strenuous exercise, reduces oedemas and inflammatory activity.

Analgesic effects of the cold water

The second theory notes that the reduction of pain is due to the analgesic effect of the cold water. Whereby the immersion into cold water leads to decreased nerve conduction speeds and excitability, thus reducing nociceptor communication with the sympathetic nervous system.

Reducing inflammatory pathways

Others have suggested that the decrease in the perception of pain is related to reduced inflammatory pathways. This theory is, therefore, a combination of effects, and is often referred to in the research as the primary physiological reason for improved recovery.

Placebo effect

Another theory suggests that the effectiveness of CWI on the reduction of post-exercise pain and fatigue is primarily down to psychological perception (i.e. a placebo effect). This suggests that an individual simply feels more ‘awake’ during and/or after the immersion into the cold water, causing a decrease in their sensitivity to pain.

Hydrostatic pressure

Another theory lies with the effects of hydrostatic pressure on the body during immersion into water. When an individual is immersed into water they are subject to the effects of hydrostatic pressure.

As the pressure gradient increases with depth (i.e. the deeper you go, the more pressure imposed), this hydrostatic pressure causes an inward and upward squeezing action on the body. It is this mechanism that causes the effects of buoyancy. The buoyancy reduces the gravitational load on the body, meaning objects such as the human body weigh less when in water.

Issues with Cold Water Immersion

Availability

While CWI has found a steady fan base, its widespread adoption faces hurdles such as availability and accessibility of suitable facilities, especially for non-professional teams or individuals. As we navigate through 2023, innovative solutions such as portable ice-baths and CWI units are emerging to address these challenges, making the therapy more accessible to a broader audience.

Lack of Knowledge

Furthermore, a comprehensive understanding of the primary mechanisms that fuel CWI’s recovery-enhancing effects could pave the way for improved practical application. Recent trends also indicate a growing inclination towards thermoneutral temperatures, as they potentially offer a more comfortable yet effective alternative to the traditional cold water immersion, fostering better adherence to the therapy.

Duration of immersion

Within the current body of research, there is a substantial variation in the immersion durations, with times ranging from 1-15 minutes (2, 3), and no common agreement in the optimal time being achieved. Interestingly, a 2016 systematic review of the current research has identified that durations of between 11-15 minutes provides the best results for cold water immersion . It has also been recorded that it takes approximately 10-minutes for the movement of interstitial-intravascular fluid to occur, suggesting that immersion should be of at least 10-minutes in order to optimize the effects of recovery.

As of 2023, the optimum duration for cold water immersion remains under debate, though recent systematic reviews still hint at an 11-15 minute window as being particularly effective. This year, we anticipate more refined research to narrow down the best practices, potentially uncovering new insights into the optimal temperature and duration to maximize recovery benefits.

Conclusion

Cold water immersion therapy stands at an exciting juncture in 2023, characterized by renewed interest, evolving protocols, and promising developments in accessibility. Though the optimal protocols are yet to be unanimously agreed upon, the consensus leans towards a positive impact on recovery, with temperatures ranging from cold (≤15˚C/59˚F) to thermoneutral (34-35˚C/93-95˚F) for periods of 11-15 minutes post-exercise. As we forge ahead, the focus will be on fine-tuning these protocols to unlock the full potential of CWI, ushering in a new era of recovery science.

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