Chelsea Fitness Training Centre

To Ice or Not to Ice?

To Ice or Not to Ice?

The following article by author and very well respected professor (and more importantly accomplished athlete) Lon Kilgore, appeared in the 11/29/18 edition of the CrossFit journal. This is a VERY important topic for our coaches and athletes so we have reproduced the article here.  If you subscribe to the CrossFit journal, which I HIGHLY recommend you do as it is a measly $40 per year for an amazing amount of information, the link for it is . ENJOY!

The use of ice in association with exercise is quite controversial.

Using ice—applied locally or via submersion of the body in an ice bath—to augment recovery is both recommended and condemned: Some athletes and coaches swear by it while others suggest that it is a waste of time. The science surrounding its use is informative but equivocal.

Because experience and science are not strong enough to make a blanket statement, let’s consider some details.

Swelling and Numbing

Cryotherapy, cold therapy, icing and similar treatments with different names have been around for longer than most people can remember and at least as long as photographic and motion-picture technology.

Icing is often attributed to Friedrich Esmarch, considered the father of modern first aid for his development of the triangular bandage, hemostasis by constriction (tourniquet) and airway-management procedure, as well as his use of ice. He was known in his academic and medical communities as Fiete Isbüddel, translated as Friedrich Ice Pack. Cold application in medicine likely goes back much further than the 1800s, as previously recorded accounts document the use of snow and ice as pre-amputation anesthesia, but Esmarch formalized it during his time as director of surgery at the University of Kiel between 1854 and 1898.

Historically, cold has been applied to injuries. In the old black-and-white movies from the early 1900s, the medium was stereotypically a piece of steak taken from an icebox and placed on a black eye. The intent was to keep the swelling down. Slowed swelling was beneficial for boxing, in which vision loss could follow a punch due to subsequent closure of the eye as a result of accumulation of inflammatory fluid. In this context, cold application—anecdotally—works and is still used to this day.


After General Electric’s launch of refrigerators in the 1920s, the use of ice and frozen devices such as a metal enswell became viable. (The enswell remains common in the boxing world today.) In 1959, the manufacture of chemical cold packs (U.S. patent 2,898,744) made cryotherapy available anywhere.

Does scientific evidence provide any support for the use of ice in this context? Yes.

A 1980 paper by William McMaster and Sharon Liddle demonstrated that one hour of cold application—wherein tissue temperature was reduced to 30 C—following a crush-type injury reduced swelling in rabbits up to 24 hours post-injury (6). These researchers, however, provided cautionary data, as repeated one-hour-on, one-hour-off application for three cycles of cooling was not as effective as a single hour of application, nor was reducing tissue temperature to 20 C.

A problem here is that this is an animal model, and generalization to humans must be done cautiously. Quality human-subject research is mixed and frequently biased by researcher or the subject’s prior experience with use of ice after injury. Chris Bleakley and co-researchers noted this in their systematic review of existing research on the use of ice as an intervention following soft-tissue injury (1). After lengthy consideration of available research the authors wrote:

“Cryotherapy is a versatile modality and may be used in the immediate and rehabilitative phases of injury management.”

Beyond the immediate slowing of the inflammatory swelling process, ice used during a boxing bout mildly numbed the injured tissues, allowing the boxer to pay more attention to the fight at hand and less to the injury.

Numbing an injury to mask pain might keep you in the game today but at the risk of exacerbating the problem tomorrow.

Ice application in the case of injury during competition has long been a go-to strategy to keep athletes in the game. As a teen, this author broke his thumb on his opening snatch at the 1976 Junior Olympic Nationals. A physician in attendance brought over a bucket of ice in which the injured hand was kept submerged between attempts for the duration of the competition (then it was off to the ER for treatment).

Speaking from experience, the numbing effect was the key to remaining in the competition. It really hurt at first, but about two minutes into submersion the pain mildly abated and the prickly numbness to both cold and fracture kicked in.

Does ice really numb tissue and reduce perceived pain? Yes.

Although the original uses of cryotherapy for pain reduction were driven by anecdotal reports and experience, a very simple experiment involving needles and humans demonstrated that cold application to the skin can significantly reduce perceived pain (5). After the skin was cooled, needle penetration was rated as a 1 on the McGill 10-point pain scale—wherein 0 represents an absence of pain and 10 is excruciating—as opposed to a placebo non-cooling treatment, which generated a pain rating of 3.


It appears that ice applied following injury can keep an athlete in the game, so these singular and short-term uses of cold application to delay swelling and produce numbness can be appropriate. The unknown aspect—and the issue of concern—is the severity of injury. Athletes and coaches must use reason to ensure that staying in the game does no more harm than the original injury. This is a legitimate concern in every situation in which ice-induced numbness and abatement of inflammatory swelling are employed. The incident described above permanently reduced the range of motion of this author’s thumb by about 10 degrees.

Cold is effective for immediate swelling and pain reduction but does little for long-term recovery.


In virtually every NCAA or pro-sports athletic-training room you will find the antithesis to hot tubs, something akin to ice packs on steroids: ice baths.

The idea is that if athletes submerse themselves in ice baths, they will recover faster and be ready for the next training session sooner, or they will be more completely recovered. Data suggests that ice therapy is the second-most-common service provided in an athletic training room (4).

Historically, jumping into a pool of cold water—really cold water—is common practice. It has existed in the weightlifting world for at least 50 years. In higher-end spas, gyms and recreational facilities, a cold pool is generally located in proximity to saunas.

The concept presented to the author at a 1974 junior national training camp was that a sauna or hot tub increases circulatory flow rate. When one moves from a sauna to cold submersion, one experiences profound vasoconstriction (8). This constriction supposedly drives the blood from arteries into veins for more rapid filtration through the liver and kidneys. More rapid filtration was sold to us as faster recovery and metabolic movement from catabolism to anabolism.

"No one ever cooled anything down and sped it up except making fucking ice."

-Greg Glassman

The concept sounded like science, so 15-year-old me believed it. When a national coach, a weightlifting legend and a world-record holder were teaching us, we listened. I hated this process when we did it at camp. But following my instructors’ advice, I also practiced the recommended home version: After training, take a shower as hot as tolerable followed immediately by a cold-water shower. Did it work? Unknown. I did not have a baseline metric or an outcome metric for comparison.

We have evolved away from using the heat portion of contrast baths for athletes in competition and training. Adding heat load to the already-heated human post-exercise can be a cause for concern (hyperthermic injury), so it’s more common to see hot and sweaty athletes instructed to jump into big tubs of cold water to reap a recovery benefit.

So what does the scientific literature say?


If you are trying to cool down a hyperthermic athlete to avoid heat injury, ice application is well supported, as evidenced by an early review of research (2). But for actual promotion of physiological recovery, the evidence in favor of its use is weak to absent and somewhat strong in opposition to it.

In a systematic research review of the effects of cold-water immersion on delayed-onset muscle soreness, markers of muscle damage (creatine kinase and C-reactive protein) and lactate clearance (3), it was noted that while most reviewed studies showed muscle soreness was reduced at 24, 48 and 96 hours after icing, the blood-chemical measures generally accepted as markers of recovery were unaffected.

So in terms of making the trainee more comfortable in the days after a training session, cold immersion seems to be effective, but the actual short-term biochemical responses to the training load appear unaffected—neither promoted nor hindered. Icing does seem to have application in reducing muscle soreness in the short term. That perception of decreased pain might be construed as recovery.

But we need to consider the long term. Exercise is a lifestyle, not a one-off trip to the park interspersed between days, weeks, months or years of sedentarism. Adaptation toward fitness takes time and effort. So even though ice appears to be beneficial for immediate reduction of swelling and pain relief—and it appears to be beneficial over a period of days after training to ease delayed-onset pain—this does not mean cryotherapy does not affect recovery processes and fitness adaptation over time. It might.

"The mechanism of this disruption has been attributed to cold-induced negative effects on the inflammatory processes that protect us, heal us and adapt our bodies to stress."

-Lon Kilgore

Experimentation by Llion Roberts et al. (7) showed that routine icing blunted satellite-cell and protein-synthetic processes, thereby reducing muscle-mass gains after 12 weeks of strength training. The mechanism of this disruption has been attributed to cold-induced negative effects on the inflammatory processes that protect us, heal us and adapt our bodies to stress.


But that is only one study, and we have a problem when it comes to making decisions regarding this subject. Substantial data exists, but it is frequently disconnected and conflicting. Maria Urso’s 2013 review, “Role of Inflammation in Skeletal Muscle, Connective Tissue, and Exertional Injuries: To Block or Not to Block?” asked a perfect question. The answer, however, is elusive, as the author noted in her conclusions:

“The scientific community is faced with great diversity in treatment options and conflicting results. To date, there is no clear message with regards to the effect and mode of action of anti-inflammatory interventions and how they can best promote muscle healing and functional recovery.”

Humans are homeothermic, maintaining a body temperature of 37 C for a reason. Temperature is a tremendously important factor for life, as it has a profound influence on biochemical reactions. Reduction in body temperature slows most physiological processes, changes how our cellular proteins interact with each other, reduces how flexible our cell membranes are, and changes the density and viscosity of water in the cells—water being the substrate in which so many biological reactions occur. These are just a few of the potential physiochemical outcomes of cold temperatures. So while many people may follow the trendy marketing and recommend ice baths for recovery, others definitively do not.

“Ice baths: All you have to do to go there is abandon one of the most important and basic principles in all of physics. And that is that cold slows reactions down. No one ever cooled anything down and sped it up except making fucking ice,” said CrossFit Founder Greg Glassman in a 2017 episode of the CrossFit Podcast.

Ice baths might make athletes more comfortable immediately after training, but some research indicates that routine icing can negatively affect recovery and muscle-building. (Ágúst Sigurjónsson/CrossFit Journal)

Use Discretion

Trainees, athletes and coaches often focus on the micro before they have attended to the macro.

Before considering the use of ice for recovery—or any recovery aid—match training load to recovery rate, which changes over time and in response to individual circumstances. Pay attention to the basics and support training with things such as adequate sleep and better eating habits.

Collect data and watch the athlete or yourself for trends indicative of waning performance or the appearance of nagging injuries and adjust loading accordingly. Keep records of those observations for comparison over time. Part of being an effective trainer or athlete is operating in a way in which everything we do in our quest for fitness is measurable, observable and repeatable.

When we coach the basics well and the trainee executes the basics well within a well-designed program of training, the need for extraneous recovery aids is eliminated or at least minimized, especially for the average gym-goer. If we decide to use ice, we should use it judiciously and have a clear purpose in mind for its use: preventing heat injury, staying in the game, or managing swelling and alleviating pain in the short term.

Beyond the short term, the continued and chronic application of cold is of questionable value, and is a risky endeavor for those who want to adapt to training and become fitter faster.


Bleakley C et al. The use of ice in the treatment of acute soft-tissue injury: a systematic review of randomized controlled trials. American Journal of Sports Medicine 32: 251–261, 2004.

Costrini A. Emergency treatment of exertional heatstroke and comparison of whole body cooling techniques. Medicine and Science in Sports and Exercise 22(1): 15-18, 1990.

Hohenauer E et al. The effect of post-exercise cryotherapy on recovery characteristics: a systematic review and meta-analysis. Plos One 10: 2015. Available here.

Lam KC et al. Athletic training services during daily patient encounters: A report from the athletic training practice-based research network. Journal of Athletic Training 51(6): 435-441, 2016.


Mace SE. Prospective, randomized, double-blind controlled trial comparing vapocoolant spray vs placebo spray in adults undergoing venipuncture. American Journal of Emergency Medicine 34(5): 798-804, 2016.

McMaster WC and Liddle S. Cryotherapy influence on posttraumatic limb edema. Clinical Orthopaedics and Related Research 150:283-287, 1980.

Roberts LA et al. Post-exercise cold water immersion attenuates acute anabolic signalling and long-term adaptations in muscle to strength training. Journal of Physiology 593(18): 4285–4301, 2015.

Tipton MJ. The initial responses to cold-water immersion in man. Clinical Science 77: 581-588, 1989.

Urso ML. Anti-inflammatory interventions and skeletal muscle injury: benefit or detriment? Journal of Applied Physiology 115: 920-928, 2013.


About the Author: Professor Lon Kilgore is a longtime contributor to the CrossFit Journal and the fitness industry in general. He might be best known for his work with Mark Rippetoe as concept originator, co-author, illustrator, and book designer for “Starting Strength” and “Practical Programming” (first and second editions). He also co-created the Basic Barbell Training and Exercise Science specialty seminars offered through CrossFit in the mid-2000s. After a 20-year professorial career in higher academia, he currently creates and delivers vocational-education courses through the Kilgore Academy and works as a writer and illustrator.

Schedule a Fitness Consultation