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 minimise 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.
What is Cold Water Immersion?
Cold water immersion (CWI), otherwise known as ice-baths, plunges pools and cold water therapy is a recovery process involving the immersion of the body into cold water (≤15˚C/59˚F) immediately after exercise in an attempt to enhance the recovery process. Check our the video below for a good overview of cold water immersion therapy:
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:
- Ratings of Perceived Exertion (RPE)
- Creatine-kinase (CK)
- Blood lactate-levels
- 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 was also shown to reduce the symptoms of RPE 24hrs post-exercise!
Whilst numerous research supports the use of CWI for reducing the effects of subjective measures post-exercise (i.e. DOMS and RPE), its effects on objective measures are far less apparent.
How does Cold Water Immersion improve recovery?
Despite there being an abundance of research on CWI, the primary mechanisms for its ability to improve recovery are still not fully understood. However, 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.
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.
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.
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
A common problem with CWI is the accessibility and/or transportability of ice-baths. Official ice-baths are often expensive pieces of equipment which require an abundance space for usage, which can be difficult for non-professional teams due to lack of funds and available space. This had led to the improvisation of other resources as replacements, such as wheelie bins and paddling pools.
Lack of Knowledge
Understanding the primary mechanisms responsible for the recovery enhancing effects of CWI would lead to improved practical application. Using thermoneutral temperatures would increase involvement/compliance in water immersion therapy as many athletes often avoid CWI due to discomfort and/or a dislike of the recovery method.
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.
Whilst cold water immersion is commonly used in practical environments, still very little is known about the best protocols to use in order to optimize recovery. There is also still disagreement on the optimal temperature to induce maximal recovery effects, in addition to ever-increasing knowledge of thermoneutral water temperatures – which may appear more effective than cold water. In summary, vertical full-body immersion into cold (≤15˚C/59˚F) to thermoneutral temperatures 34-35˚C (93-95˚F) for 11-15 minutes post-exercise appears to have a positive effect upon recovery.