Are ice baths and cold showers a panacea after exercise?

You've probably already seen images of athletes immersing themselves in ice-cold water after training... Since it was popularized by Wim Hof, known as "Iceman", the practice has become widespread in the fitness world before spreading to other disciplines. And the virtues it is said to have are numerous!

Stéphane Perrey, University of Montpellier and Marc Julia, University of Montpellier

With prophylactic effects on health, stimulation of the central nervous system, improved muscular performance and post-exercise recovery... This strategy of active recovery after physical activity, a fundamental part of all serious training, has become one of the most popular over the last ten years.

Although many athletes, both professional and amateur, use this technique, they are not well informed about its real benefits and effectiveness. If you wince at the idea of plunging into a simple swimming pool, you may be asking yourself more questions... Are ice baths, cold showers, cryotherapy chambers at -80°C (in specialized establishments) really beneficial if you're highly motivated? Or is it just a fashionable trend? Who can benefit?

To answer these questions, it's best to start by looking at how cold affects our bodies...

A myriad of physiological responses

Perhaps the most important physiological adaptation to extreme cold is the narrowing of blood vessels, or "vasoconstriction", which is probably intended to reduce body heat loss. In the short term, ice baths cause a rapid rise in blood pressure, which in turn leads to an increase in heart rate and respiration.

As blood vessels narrow, blood flow to submerged areas slows considerably, in terms of volume. This can be useful in combating the excessive microbleeding and microinflammation induced by certain physical activities involving repeated shocks. If exposure to cold is prolonged, the end of our nerve endings, just beneath our skin, can reduce sensation to the point of numbness.

There is also evidence that swimming in cold water can modulate the production of proinflammatory cytokines, small cellular proteins that activate the body's inflammatory response - which can have an analgesic (pain-reducing) effect.

But beware: an ice bath is not meant to be long, because of the real risk ofhypothermia, with serious consequences.

What are the potential benefits?

Given these physiological changes, why do athletes choose this method after exercise? The most common reason is their belief that it will "heal" sore muscles.

What has been established is that ice baths reduce blood flow to submerged areas, thus reducing oedema (swelling), aided by the hydrostatic pressure effect. And, as we said, cold has an analgesic effect, which is useful in the case of traumatic injury - hence the use of ice packs in the case of local injuries or to relieve post-operative pain. But cold does not heal: the pain will return when the temperature begins to rise. Its use is therefore only punctual and symptomatic.

What about muscle pain after strenuous exercise? Aches and pains? It has been suggested that, due to vasoconstriction of blood vessels, muscle lesions may have a lower inflammatory response, resulting in less muscle soreness.

Over the past 10 years, various studies have shown that cold water immersion can improve the treatment of delayed muscle soreness (24-48h) to some extent. One study of elite rugby players, conducted over three weeks of competition, concluded that there was a reduction in muscle fatigue and a slight decrease in muscle soreness. Separate research also suggested a modest positive effect on muscle soreness perceived by MMA athletes. But there was no improvement in performance.

But... there's also evidence to suggest that cooling isn't necessarily beneficial for post-exercise recovery - the perceived benefits would be due to a placebo effect (when we're convinced it works). Cryotherapy (3-4 min at -85°C), cold water immersion (10 min at 10°C) and a placebo group competed after weight training. The differences were insignificant, and some biological and performance markers even favored the placebo...

A meta-analysis also reported that the proposed beneficial effects of cold water immersion (10°C and 13 min on average) seemed to be based more on subjective markers (perception of pain and feeling of effort difficulty) rather than objective ones (blood markers).

To summarize, cold water immersion, mainly due to its ability to decrease tissue temperature and blood flow, can reduce muscle soreness and edema, but its effects on muscle recovery and performance are much debated. The beneficial effects on post-exercise recovery appear to be context-specific, and several factors such as body composition, gender, type of physical effort performed and training status need to be taken into account.

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Muscle friend or foe?

Recent data has shown that post-exercise cooling can be detrimental when the aim is to build muscle mass (hypertrophy).

One study indicates that acute exposure to cold reduces the anabolism of skeletal muscle proteins (enabling muscle growth) while increasing their catabolism (leading to degradation). This has no effect on muscle strength.

Another study examined the effects of active recovery and ice baths on adaptations to strength training. After 12 weeks, ice baths reduced muscle growth... and strength gains! The acute (negative) effects of cold water immersion thus appear over the longer term, perhaps as a result of a reduction in circulating testosterone in the blood.

If gaining muscle mass and strength is an objective (as part of a training plan, at a distance from competitions), cold water immersion should be avoided as a post-exercise recovery strategy.

So... taking ice baths?

Potentially costly and time-consuming, ice baths (10-15°C for 11-15 min) are not a panacea... They can help reduce delayed muscular pain, but the same applies to active recovery, such as walking - which is cheaper and much easier to do!

While in the short term, we can note a faster recovery of strength production capacities, reduced inflammation and soreness, over a longer period of time, immersion in cold water would have no effect, positive or negative, on physiological adaptations.

Above all, cold water is not suitable for people following a bodybuilding program - bodybuilders or weightlifters who want to build muscle mass and strength... But at the same time, they may find it advantageous to enjoy the benefits of an ice bath after a very intense workout or competition.

How you use the bath will depend on your sport and your goals!

If you don't need to put on a lot of muscle, you can use it. This applies to many athletes, as well as combat sports. And even if strength and muscle mass are important, weigh up the pros and cons... For example, in a competition over two consecutive days, with sessions several times a day, the benefits of faster recovery will outweigh any attenuation of muscle growth.

And you don't need to take an ice bath after light exercise: your muscles won't have accumulated enough damage to justify its use.

Especially if you suffer from high blood pressure or cardiovascular disease, an ice bath may be too much of a shock for you and your heart! Medical advice is required. As always, it's important to know your body, the goals you're aiming for and the effect of the techniques you use.

Stéphane Perrey, University Professor in Exercise Physiology / Integrative Neuroscience, Director of the Research EuroMov Digital Health in Motion Unit, University of Montpellier and Marc Julia, Sports Physician, STAPS Associate Researcher, University of Montpellier

This article is republished from The Conversation under a Creative Commons license. Read theoriginal article.