The resulting fully packed training schedule demands a fast recovery between these exercise bouts. Given warmer days now and ahead, I thought it would be interesting to explore the effects of post-exercise cooling on recovery. With the risk of burning my fingers, let me try to shed some light on the most recent findings.
First, it is important to define the exact question I am trying to answer here (will explain later why that is!). So: Does post-exercise cooling of the whole body and/or specific body parts, enhance recovery and thus, improve performance in the next exercise bout?
Let's start with a paper published in PlosOne (Hausswirth et al. Dec 2011). The authors compared recovery after a 10K simulated trail run followed by either whole-body cooling, infrared therapy or passive recovery. Each of the recovery methods was applied 3 times: after 1 hour, after 24 hours and after 48h. Recovery parameters were muscle damage, muscle strength and perceived pain and fatigue. Muscle damage was assessed by measuring an enzyme called creatine kinase (CK) in the blood. CK is an enzyme that you can normally only find in the muscle, but when the muscle cells are damaged by training, the CK flows from the damaged cells into the blood.
Application of either cooling or infrared warmth after 1, 24 and 48h did not result in different CK levels (as compared to passive recovery), but cryotherapy had the greatest effect on limiting the loss of muscle strength and also induced the best results on subjective perception of pain. Ergo, muscle damage was the same, but because subjects felt less pain, they performed better on the strength test.
In this paper, cryotherapy was performed in specially equipped rooms held at extremely low temperatures (-10C, -60C and -110C). This is obviously different from whole-body immersion, let alone topical application of cold (like, an ice-pack). So don't run to your freezer yet!
The attentive reader might have noted that muscle strength is not the same as exercise performance. Important to define when critically evaluating scientific evidence, is the exact nature of the evidence and how that matches with your research question. So, we need some more evidence than muscle strength alone. Especially since muscle damage (i.e. CK levels) seems to be equal after different recovery methods.
A careful search on Pubmed, the online medical journal database, is rather disappointing. Turns out there are not that many studies that actually consider performance. Creatine kinase levels, blood lactate, the level of oxygen in the muscle and blood volume changes might be interesting, but are no guarantee you actually go faster after that ice bath. Coming back to my remark on matching your research question with the scientific evidence - this evidence doesn't answer my question.
I do find some studies that incorporate muscle performance measurements, but I am not sure that any manufacturers of cooling gels or ice packs, are going to like the evidence... An article in The Journal of orthopaedic and sports physical therapy (Stacey et al. Oct 2010) describes sprint performance after either cryotherapy, active recovery or simple rest. Subjects performed 3 x 2-minute sprints, with 20 mins of recovery between each sprint. The subjects reported that their legs felt better after the cryotherapy, but no effect was observed on performance in the sprint after the different methods of recovery.
A paper in the journal Medicine and Science in Sports and Exercise (De Pauw, May 2011) did not find any effect of cooling or active recovery (versus rest) on performance in a 30-min time trial, either.
It must be noted that in both of these studies, the time between the exercise (the one you need to recover from) and the performance measurement, was rather short - 20 minutes to 2 hours. 'Normal' athletes like you and me usually take more time in between trainings and the limited recovery time might make it difficult to pick up small differences between the methods.
Given that the ultimate aim is to improve recovery and thus, long-term training effect, I was interested in a paper I found in the European Journal of Applied Physiology, where cryotherapy was incorporated in a training program (Yamane et al., 2006). Again, the evidence is rather disappointing, if not disturbing. In this study, subjects underwent a 4 or 6 week endurance cycling training program. After each exercise bout, one of their legs was immersed in cold water for 2x20mins, while the other leg did not undergo any treatment. After the training program, the subjects performed a bike test with one leg at the time, thus looking at the increase in endurance capacity of each leg separately. They also measured the diameter of the arteries in the leg. More and wider arteries are a known effect of training, as more blood vessels can transport more blood, thus more oxygen
While both legs were trained equally hard, training effects were greater in the leg that had NOT been cooled. Also, the increase in vessel diameter was larger in the control leg. Thus, the uncooled leg actually had greater training adaptations! Th only problem I can find with this study, is that the training program was not that hard, questionning the extent of actual muscle damage.
This lack of effect of post-exercise cooling might not be as surprising as it seems. To achieve adaptation to training, you need a stimulus. If you take too much of that stimulus away, by extremer recovery methods, you might not get all the benefits of your training. On the other hand it's of course not beneficial either, if you are too sore to train, and you have to skip a training. In the end, the only training that makes you stronger, is the one that you actually do...
A side note: This data applies only to the effects of cryotherapy on training and says nothing about the effect of icing on sports injuries. In addition, it does not apply to the effects of pre-cooling on training in extreme heat.
So. Ice after training? Well, I cannot find scientific evidence that whole-body or muscle-specific cooling has any effect on muscle performance. There are some studies that show improved muscle oxygen levels, or lower blood lactate, but these might actually be detrimental for long-term training adaptations. Subjects reported feeling better after cooling, though. That might be an interesting perspective, given the importance of motivation on training.
What does that mean for you, as an athlete? First of all, it is important that you balance your hard trainings with easy sessions, thus preventing extensive muscle damage and giving your muscles time to recover - and consequently, supercompensate. If you feel you benefit from cooling your muscles after training, you could try turning ending your post-exercise shower with some cold water on your legs. You might feel better, but the physiological effect is probably not as big as you might hope.
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