Uncategorized

March 15, 2024

Is cold water immersion killing your gainz?

Cold water immersion (a.k.a., “ice baths”) has become a popular method amongst exercise enthusiasts and athletes to enhance recovery after an intense training bout. The strategy involves exposing either the trained limb or the whole body to very cold liquid temperatures. According to proponents, this helps reduce inflammation and muscle soreness, hence improving the ability to recuperate for subsequent training. It should be noted that evidence is conflicting on this matter, with some studies refuting the claim that CWI attenuates post-exercise inflammatory markers and muscle damage; this raises the possibility that any observed recovery benefits may actually be attributed to a placebo effect.

Perhaps more concerning, some studies actually show that consistent use of CWI after resistance training may impair muscular adaptations. Indeed, a recent meta-analysis found that CWI blunts strength gains when the intervention is applied to the trained limbs after training.

But what about muscle hypertrophy? While some research does indicate that it attenuates anabolic processes, acute findings do not necessarily translate into long-term gainz. No study had attempted to meta-analytically quantify how the repeated use of CWI in a resistance training program may influence muscle development.

Until now…

Our recently published meta analysis, led by Lehman College master’s degree student Alec Pinero, provides novel insights into the effects of post-exercise CWI on hypertrophy. Here’s the scoop…

What We Did

We searched the current literature to locate all randomized controlled trials that directly compared changes in measures of muscle growth between resistance training + CWI vs resistance training with either a sham or active/passive recovery in healthy adults. Studies had to last a minimum of 4 weeks and include at least 2 training sessions per week. We then statistically pooled data of all included studies to quantify the effects CWI on muscular adaptations.

What We Found

A total of 8 studies met inclusion criteria. The overall Bayesian meta-analysis indicated a strong likelihood that consistent use of CWI after a resistance training bout diminishes hypertrophic adaptations. The magnitude of difference between conditions was relatively small, but a detrimental effect of CWI was observed across all included studies.

We then performed a series of meta-regressions to determine whether the length of the studies, training status of participants, or the number of training sessions per week may have affected results; however, none of these variables appeared to influence findings.

What are the Practical Implications of Findings

Overall, our results indicate that CWI negatively impacts hypertrophy when consistently employed over time in close proximity to the end of a resistance training session. While the magnitude of the effect appears to be relatively small, it certainly could be considered practically meaningful for those attempting to optimize muscular gainz.

Although the mechanisms by which CWI attenuates hypertrophy remain somewhat unclear, we speculate that vasoconstriction may play a role in the process. Evidence indicates that cold exposure distributes blood to the skin while correspondingly reducing its flow to the musculature. Given that post-exercise nutrient delivery to the muscles is dependent on blood flow, this may blunt muscle protein synthesis—a primary factor in resistance training-induced hypertrophy.

It has been hypothesized that the detrimental effects of CWI on anabolism may be due to its anti-inflammatory effects. This theory is based on evidence that the acute post-exercise inflammatory response plays a role in muscle development; interfering with the process would thus impede hypertrophy. However, a recent meta-analysis found that inflammatory markers linked to hypertrophy were similar between CWI + resistance training vs resistance training alone, thereby calling into question the veracity of this theory.

Ultimately, more research is needed to better understand the mechanisms underlying CWI-induced impairments in muscular adaptations.

Limitations

As with every study, our analysis had several limitations that must be taken into account when attempting to draw practical conclusions.

First and foremost, all included studies administered CWI within 20 minutes after the training bout. It’s therefore uncertain whether waiting several hours or more after exercise to apply CWI may offset some, or perhaps all, of the observed detrimental effects. Although this possibility cannot be ruled out, it should be noted that muscle tissue is sensitized to anabolism for more than 24 hours after intense resistance training. Thus, decreasing circulation to the musculature at any point within this timeframe conceivably could impair the growth process.

Second, the included studies used divergent methods to assess changes in muscle mass. Of note, several studies employed indirect assessments of lean mass (i.e., DXA) or gross measures of limb size (circumferences) as proxies for hypertrophy. These methods are less sensitive in their ability to detect actual changes in muscle size compared to direct measures such as MRI and ultrasound. We thus need more research using direct methods to derive greater confidence in results.

Finally, the vast majority of studies on the topic included young male participants; only 1 of the 8 studies included females none involved adolescents or older adults. We therefore cannot necessarily generalize conclusions to these populations, although I’m hard-pressed to think of a logical rationale why sex or age would influence results on the topic?

Take-Home Conclusions

Our results indicate that you should avoid regular CWI use if your goal is to optimize hypertrophy. Although it’s possible that waiting several hours post-exercise to apply CWI may reduce its negative effects on anabolism, this remains highly speculative. It would seem prudent to avoid cold exposure altogether when training for maximal muscular development.

Alternatively, if optimizing muscular adaptations is not a high priority and you enjoy ice baths, feel free to take the plunge. Our results show that while CWI does blunt hypertrophy, you still can make some gains when employing the strategy. Ultimately, adherence to exercise is paramount and anything that keeps you in the gym is a plus as there are a plethora of health-related benefits to resistance training.

Lastly, the occasional use of CWI should not be an issue regardless of your goals. If you’re really sore after a training session and think that cold exposure may help with recovery then go for it. There is no evidence that its isolated use is detrimental to long-term gainz. Now whether CWI does in fact enhance recovery remains an open question, but even if the placebo effects get you back in the gym refreshed then this could be considered a positive.

If you’d like to delve into the specifics of our paper, I encourage you to peruse the full text. It is open-access and thus free for all to read.

Train hard, train smart.