Speaker 1: 0:00

Welcome to Bodyholic with Dee. I'm your host, dee, and today the discussion delves into a topic that sparked considerable debate in the fitness and athletic communities Cold water immersion, often simply referred to as CWI or ice baths. The question is basically are these practices a miraculous recovery tool or could they potentially impede progress? The aim today is to cut through the anecdotal claims and provide clarity based on robust scientific evidence Before diving into the research. A brief and very important note If these evidence-based discussions prove helpful, please won't you consider subscribing to the podcast. It supports the effort to bring more research-backed insights directly to you, to the listener, thank you. Okay, welcome to Bodyholic with Dee. No fads, just facts. I'm Dee and I'm here to help you ditch the noise and build a life you love. Let's go. Oh, but wait. I'm not a doctor, so use your common sense. Now let's dive in.

Speaker 1: 1:21

So the focus for this episode centers on the work of Dr Brad Schoenfeld, a highly respected figure in exercise science. Just to give you a little bit of an understanding, dr Schoenfeld is a professor of exercise science at Lehman College, recognized for his extensive research and his seminal textbooks Science and Development of Muscle Hypertrophy. His expertise specifically lies in understanding how various exercise variables influence muscle growth and body composition, making him uniquely qualified to investigate the effects of cold water immersion. So today we're going to explore two critical scientific papers. First, a meta-analysis led by Dr Schoenfeld that examines CWI's impact on muscle growth. Then the discussion will shift to a very recent study that investigates CWI's effects on acute neuromuscular recovery and subsequent day performance. The objective is to provide a clear and comprehensive understanding of what the current science indicates.

Speaker 1: 2:39

So let's get into Brad Schoenfeld's meta-analysis on hypertrophy. To begin, it is very, very important to understand the significance of a meta-analysis. This is not merely a single study. It represents a powerful research methodology that systematically combines and analyzes data from multiple independent studies that address the same topic. It functions basically as a study of studies, if you will, pulling data to provide a more robust and statistically powerful answer than any single investigation could actually achieve on its own. This approach helps to identify overarching trends and minimize the influence of individual study limitations. So in complex fields such as exercise science, where individual studies might present conflicting results or involve a super small sample size, a meta-analysis offers a clearer, more comprehensive view of the accumulated evidence. So, dr Schoenfeld, excuse me accumulated evidence. So Dr Schoenfeld, excuse me and his collaborators undertook this meta analysis with a specific research question to systematically review existing literature and synthesize data on the effects of post-exercise cooling, particularly cold water immersion. On the effects of post-exercise cooling, particularly cold water immersion, when combined with resistance training, on gains in muscle hypertrophy.

Speaker 1: 4:35

The impetus behind this investigation is crucial. While CWI is widely adopted by practitioners for recovery, often cited for its ability to reduce muscle soreness, mitigate perceived fatigue and accelerate recovery time, a critical distinction must be drawn between acute subjective recovery and long-term physiological adaptations. So prior research had already suggested that CWI following resistance training might diminish gains in absolute strength and muscular power. There was also evidence indicating that CWI could attenuate increases in muscle sizes, even in cohorts where strength was not adversely affected. Where strength was not adversely affected, these observations highlighted a really significant gap in the scientific literature concerning CWI's specific impact on muscle hypertrophy. As explicitly stated in the research material this is going to be a quote no known meta-analysis has been conducted on the effect of post-exercise cold application on RT-induced muscle hypertrophy. This gap in the literature should be considered, given the evidence showing differential effects of CWI on strength versus hypertrophy.

Speaker 1: 6:04

Now, regarding Dr Schoenfeld's meta-analysis, it's important to understand its foundational contribution. This paper meticulously outlined the rationale and the specific research question it aimed to address how post-exercise cooling, particularly cold water immersion, impacts muscle hypertrophy when combined with resistance training. Right, we've already said that. So our discussion of this work will therefore center on the crucial intent behind this conduction, the precise question it sought to answer and the compelling mechanistic considerations that drove the investigation. This meta-analysis provided a vital framework for understanding the potential effects of cold water immersion on muscle growth. A comprehensive review of its full results is actually going to be beyond the scope of today's episode, but the bottom line is what we're here for. So the paper's introduction you can access it.

Speaker 1: 7:19

It delineates several mechanistic reasons why cold water immersion might exert detrimental effects on long-term skeletal muscle growth. These mechanisms are centered on CWI's acute influence on the cellular processes that are fundamental for muscle repair and growth. Specifically, cwi has been reported to acutely diminish the activity of several key molecular pathways, and I want us to get into it. The first is mTOR-C1 signaling. This is a pathway that is a pivotal regulator for cell growth, including muscle protein synthesis. Attenuating this signal could directly impede the muscle building process. There's also the ribosome biogenesis, so ribosomes are the cellular machinery that are responsible for translating genetic information into proteins. A reduction in their formation would directly decrease the muscle's capacity to synthesize new tissue. Then there's muscle protein synthesis MPS. This is the fundamental biological process by which muscle cells create new proteins, a process that is essential for both post-exercise repair and for increasing muscle size. Also, satellite cell activity. Satellite cells are adult stem cells that are located on muscle fibers that are crucial for muscle repair, regeneration and, ultimately, hypertrophy, and suppressing their activity could limit long-term muscle growth.

Speaker 1: 9:00

The past research really indicates everything that I just mentioned. This provides a strong biological basis for the concerns regarding CWI's impact on muscle adaptation. The concerns raised this is all in the introduction of Schoenfeld's meta-analysis. It highlights a fundamental tension in exercise science the distinction between acute recovery and chronic adaptation. So while CWI has demonstrated benefits for immediate recovery, such as reducing soreness and perceived fatigue and improving short-term recovery time, the literature suggests it may have negative implications for long-term physiological changes like strength and muscle size. This indicates that the utility of CWI is not universal, but rather dependent on the specific training objective. So, guys, for athletes and coaches, this means a strategic consideration of primary training goals. This is essential If the overarching objective is to maximize muscle growth over extended periods, cwi might be counterproductive due to its interference with the anabolic signaling pathways. Conversely, if the immediate goal is a rapid turnaround for multiple competitions within a short timeframe, the acute subjective benefits might be prioritized over the potential long-term blunting of hypertrophy.

Speaker 1: 10:45

And let's take it a step further the detailed mechanistic explanations provided in this meta-analysis. It really offers a deeper understanding of the potential negative effects. It is not simply an observation that CWI might hinder hypertrophy. The paper really gets into, points to a specific cellular and molecular mechanism and the attenuation of, like I mentioned, the mTOR C1, the muscle protein synthesis, the satellite cell activity, and these pathways are directly responsible for driving muscle protein synthesis and growth. So if CWI interferes with these acute post-exercise signaling events, it provides a compelling biological rationale for why long-term hypertrophy could be compromised. This really elevates the discussion beyond just that mere observation and perceived feedback. It underscores that feeling recovered okay is not always the same as optimal recovery, and the sensation, the reduced soreness, might actually hinder the biological processes and the synthesis. So this is a really crucial point for athletes who might prioritize immediate comfort over long-term gains, emphasizing the necessity of an evidence-based approach to recovery rather than just solely relying on perception.

Speaker 1: 12:34

Now here's the biggie. So the latest and why we are here today, it's while Dr Schoenfeld's meta-analysis focuses on long-term muscle growth, a very recent study published in 2025 from New York University shifts the focus to the immediate aftermath of exercise. So this newer paper investigates how cold water immersion impacts acute muscular recovery and next day exercise performance following high intensity interval exercise. This area of research is super critical for athletes who require repeated high level performance within short timeframes. The study's abstract you can access it easily as well clearly states the primary finding Cold water immersion does not enhance recovery and performance after high intensity interval dorsiflexion exercise.

Speaker 1: 13:37

The methodology of the study warrants a closer look to understand these findings. The research involved 12 healthy young, recreationally active individuals 10 males, 2 females, with an average age of 23.3 years. So, although the sample size is relatively small, the use of the randomized crossover design is a robust methodological choice. So in this design, each participant serves as their own control, experiencing both the cold water immersion and room temperature that's the control conditions. This approach significantly minimizes individual variability and strengthens the internal validity of the findings. So what happened was the participants went through high-intensity interval exercise protocol, which involved six sets of 30-second all-out isokinetic concentric contractions of the ankle, dorsiflexor and plantar flexor muscles. This specific protocol was selected because it's known to induce significant skeletal muscle fatigue, including a phenomenon that's known as prolonged low-frequency forced depression, plffd a particular type of fatigue affecting muscle contraction, and immediately it followed the HIE.

Speaker 1: 15:17

The lower leg was randomized to one of two recovery interventions. One was the cold water immersion 10 minutes of complete immersion in 10 degrees Celsius water with crushed ice. This temperature and duration were chosen, actually based on common protocols found in existing literature and room temperature 10 minutes of seated rest at room temperature serving as the control condition. Neuromuscular function was evaluated periodically over a 24-hour period. Assessments included measures such as maximal voluntary contraction, mvc torque, which indicates maximal strength, and voluntary activation, which assesses the brain's ability to activate the muscle. Responses to electrical stimulant at different frequencies were also measured, as these help to assess different aspects of muscle fatigue.

Speaker 1: 16:23

Intramuscular temperature was continuously monitored throughout the recovery period. Importantly, a second identical high-intensity interval exercise bout was performed 24 hours later to assess next day performance and fatigue resistance. This is a very impressive study, if I may say so. So the study concluded that 10 minutes of CWI at 10 degrees Celsius does not enhance post-exercise recovery or next day exercise performance following the high intensity interval exercise. While this headline finding is significant, a deeper dive into the specific metrics reveal a more nuanced picture and I want us to actually get into that. So the detailed results reveal a complex picture of neuromuscular recovery, indicating that cold water immersions effects are not a simple yes or no. So Wallace study's overall conclusion is that CWI and this is a quote does not enhance recovery. End quote.

Speaker 1: 17:34

The specific data points show differential impacts. For instance, cwi delayed the recovery of 50 Hertz torque, which is related to maximal force production, but simultaneously accelerated the recovery of the 10 to 50 Hertz ratio, a specific marker for reversing prolonged low frequency force depression. This demonstrates, in other words, that CWI has specific differential influences on various aspects of neuromuscular function. The faster recovery of the 10 to 50 hertz ratio with CWI suggests a targeted benefit in addressing a particular type of fatigue, even if other aspects, such as absolute high-frequency force production, are transiently impaired. This complexity highlights that recovery I'm doing air quotes is not a single monolithic process, but rather comprises multiple physiological pathways that can be affected distinctly. So for athletes, understanding which specific aspect of fatigue is most critical for your sport is key to deciding if CWI is appropriate.

Speaker 1: 19:04

A blanket recommendation for or against CWI is just insufficient. So a particularly crucial finding from this study is the distinction between acute effects and next day performance. So, despite the observed acute neuromuscular differences, such as the delayed 50 Hertz torque recovery with CWI, the study found no significant impact on performance during a repeat high intensity interval exercise bout 24 hours later. This suggests that for recovery periods extending beyond a few hours, the acute physiological changes induced by CWI might not translate into a meaningful performance decrement or benefit. The body appears to normalize or adapt over a longer period, mitigating the acute effects. This finding holds significant and practical implications for athletes and coaches guys. So if that's you, it's important.

Speaker 1: 20:18

If an athlete has 24 hours or more between training sessions or competitions, the nuanced acute effects of CWI on specific neuromuscular markers might be less relevant for their overall performance on the next, on the subsequent day, in such scenarios, the focus might shift to other recovery modalities or long-term adaptation goals. However, for sports with very short turnaround times, such as multiple events in a single day or brief rest periods between sets or intervals, these acute effects could still be important. This reinforces the concept of context-dependent efficacy. Finally, it's important to consider the specificity of these findings, utilized a relatively small sample of 12 participants 10 males, 2 females I mentioned that earlier and a very specific, isolated exercise protocol focusing on ankle, dorsiflexor and plantarflexor high-intensity interval exercises. So, while the randomized crossover design does strengthen the internal validity, the generalizability of these findings to a broader population, such as elite athletes, different muscle groups or other exercise modalities like full body resistance training or endurance exercise is limited. So the physiological responses to cold water immersion can vary significantly depending on the type, intensity and duration of the preceding exercise, as well as the specific muscles involved and the overall physiological stress. This is a standard scientific caution that should be clearly communicated. So, while valuable, this study represents one piece of a much larger puzzle. It underscores the need for more diverse research across different athletic contexts and populations to really fully understand the comprehensive effects of CWI. One you me cannot definitively conclude that CWI behaves the same way for a marathon runner as it does for a weightlifter based solely on this particular study. I want to just take a moment to connect the science.

Speaker 1: 23:02

Hypertrophy versus recovery, the trade-off hypothesis. Synthesizing the insights from these two distinct yet related areas of research leads to a crucial central dilemma. Dr Schoenfeld's meta-analysis was initiated due to the concern that CWI might blunt long-term muscle growth by interfering with critical molecular signaling pathways like muscle protein synthesis and like mTOR C1. And the latest study, on the other hand, really focused on acute neuromuscular recovery and next day performance, finding that CWI had mixed acute effects on specific neuromuscular markers, some positive, some negative, but no overall benefit for next day performance. This juxtaposition suggests a critical trade-off hypothesis. Cold water immersion might offer perceived benefits in terms of reducing soreness and subjective fatigue, and even specific acute neuromuscular advantages come at the expense of optimal long-term adaptations like muscle hypertrophy, particularly due to CWI's documented impact on cellular signaling critical for growth. This potential trade-off is a central message for anyone considering CWI.

Speaker 1: 24:37

The utility of CWI is not universal. It is highly dependent on specific training goals and timelines. This is perhaps the most important practical takeaway from the current body of evidence. And when I say current, it is now the end of May 2025, right. I don't know what's going to happen in a year from now. The end of May 2025, right. I don't know what's going to happen in a year from now. When might CWI be considered and when should caution be exercised when it should be considered? I guess rapid turnaround for performance For athletes needing to perform multiple times within a very short window, such as heats in competition or back-to-back gains, or and when where subjective recovery or specific aspects of neuromuscular function are paramount.

Speaker 1: 25:36

Cwi might be considered for its acute effects on perceived fatigue or specific fatigue markers. The latest study suggests it does not hinder next day performance. For a 24-hour recovery window, which can be reassuring for athletes in such scenarios, pain or soreness management for immediate relief of muscle soreness and perceived fatigue, cwi has been found to be effective. This remains a subjective benefit that many athletes value. That's great. It's subjective, though, when CWI might be less beneficial or counterproductive.

Speaker 1: 26:23

Maximizing muscle hypertrophy If the primary goal is to maximize muscle growth from resistance training, the potential blunting of anabolic signaling pathways MPS, mtorc1, satellite cell activities by CWI, it suggests it could be counterproductive. In this scenario we would think about prioritizing strategies that enhance these pathways, such as optimal nutrition, adequate rest and progressive overload. Probably these are much more appropriate than CWI. Strength or power gain similar to hypertrophy if the focus is on long-term strength and power development, cwi's potential to blunt these gains should be a significant consideration. Ultimately, there is no one-size-fits-all answer in recovery. Athletes and coaches must carefully weigh immediate recovery needs against long-term adaptation goals. Understanding the underlying science empowers more informed strategic decisions rather than simply following trends or just anecdotal evidence, which we experience a lot in social media.

Speaker 1: 27:45

The conclusion is it's not one size meets all. Just to recap, dr Schoenfeld's meta-analysis highlighted a critical gap. That's what's going on in the research concerning CWI's effect on muscle hypertrophy. It also pointed to compelling mechanistic reasons, specifically the attenuation of muscle protein synthesis and TORC1 signaling, ribosome biogenesis and satellite cell activity. Why CWI might be detrimental to long-term muscle growth? Because it blunts all that. And this underscores that, while CWI may offer acute relief, its impact on the fundamental biological processes of muscle adaptation warrants caution for those prioritizing gains in muscle size.

Speaker 1: 28:42

Second, the very latest study found that cold water immersion does not enhance overall acute neuromuscular recovery or next day performance after high intensity interval exercise. While it presents mixed acute effects on specific neuromuscular markers for example delaying 50 Hertz torque recovery but accelerating 10 to 50 Hertz ratio recovery these specific acute changes did not translate to significant impact on overall exercise capacity during a repeat bout 24 hours later. This indicates that for recovery periods extending beyond a few hours, the acute physiological changes induced by CWI might not significantly influence subsequent performance. The overarching conclusion in that case is that from the current scientific landscape, there is a trade-off. Cold water immersion might assist with subjective recovery and specific acute fatigue markers, but it could potentially hinder long-term adaptation, like muscle hypertrophy, particularly when applied immediately post-resistance training. Therefore, the recovery strategy should always always align with primary training goals. If muscle growth is paramount, it would be prudent to consider avoiding cold water immersion immediately after resistance training. If rapid acute recovery for repeated performance is key and long-term hypertrophy is not the primary objective, cwi might have a role, but its benefit for next day performance appear limited, based on this latest research.

Speaker 1: 30:43

The world of fitness and recovery is continuously evolving. Staying informed with the latest scientific research enables individuals to make smarter, more effective choices for their training and overall health. Harder, more effective choices for their training and overall health. So we need to always question and we need to always seek evidence and remember that what works for one goal might completely not work for another. Okay, thank you so much for listening and for joining me on this journey, and I hope you enjoyed the episode, and if so, then definitely sharing is caring. And don't forget to also five-star the episode so more people can get to it and I will see you next week. Hey, thanks so much for tuning in and if this hit home, please share it with your crew. Likes, comments, shares. Show your loved ones you care.