cold water immersion

Research Update: Can Cold Water Immersion Improve Recovery?

Cold water immersion (CWI) therapy has been reported to offer distinct health benefits, with numerous health influencers, fitness sites, and medical studies offering confirmation of its benefits. However, we wanted to look at the science behind CWI therapy to help determine how effective it can be in improving performance. Are there benefits? Let’s take a look below, as we cover the research and ask, can cold water immersion improve recovery and aid in performance development?

What is Cold Water Immersion

CWI therapy is the practice of using water that’s around 59°F (15°C) to treat health conditions or stimulate health benefits. It’s also known as cold hydrotherapy. Hydrotherapy is one of the basic methods of treatment widely used in the system of natural medicine, which is also called water therapy, aquatic therapy, pool therapy, and balneotherapy.

Reported Benefits of CWI

Scanning both popular and research literature, there are several reported CWI benefits. These include:

  • Reduce swelling
  • Reduce painful sensations in association with muscle pain
  • Reduce the feeling of fatigue
  • Regulate localized blood flow
  • Regulate localized tissue and internal temperature
  • Regulate heart rate
  • Reduce muscle spasms
  • Reduce inflammation
  • Reduce muscle damage
  • Improve range of motion

Research Findings of CWI

In reviewing the research on CWI, CoreTek focused on the following three questions:

  1. Does CWI research suggest it provides benefits in recovery? (any signs it works?)
  2. Does any CWI research suggest it provides benefits in excess of other recovery means? (does it have anything special that other techniques cannot provide?)
  3. Are the requirements of any effective CWI therapy within the capability of the traditional athletes? (if it does work, can the average person implement the therapy?)

Our review of research found multiple journals with recent, or relatively recent, studies that assess CWI, either on its own, or as part of a larger review of hydrotherapy effectiveness.

Does CWI Provide Recovery Benefits

According to a study of evidence-based effects of hydrotherapy published in the North American Journal of Medical Sciences, cold exposure to a small surface area produced compensatory vasodilatation in the deeper vascular system resulting in increased blood flow to the tissues underlying the site of the exposure. The same study found that immersion at 14°C increased the metabolic rate by 350 %, heart rate by 5 %, systolic blood pressure by 7 %, and diastolic pressure by 8 %. Additionally, plasma noradrenaline increased by 530 % and dopamine concentrations by 250 %. Repeated CWI was associated with a reduced frequency in infections, increased peak expiratory flow, lymphocyte counts, and expression of gamma-interferon. Lastly, the study noted that CWI < 15°C, which is one of the most popular methods used after exercise, significantly lowered ratings of fatigue and potentially improved ratings of physical recovery immediately after immersion with a reduction in delayed onset muscle soreness at 24, 48, 72, and 96-hour follow-ups.

A more recent study in the Journal of Physiology that compared the effect of CWI and active recovery on inflammatory and cellular stress responses in skeletal muscle suggested that CWI is no more effective than active recovery for minimizing the inflammatory and stress responses in muscle after resistance training. In this study, participants were provided CWI five minutes after the training session or an active recovery consisting of low intensity using a stationary bike. Blood and tissue samples were taken 30 minutes, and 1, 2, 24, and 48 hours after exercise, and were compared to pre-exercise samples. The authors concluded that current findings do not suggest CWI mitigates the stress-related signals that stimulate the cellular movement of HSPs (Heat shock proteins are a large family of molecular chaperones that are well-known for their roles in protein maturation) after exercise. One interesting aspect of the study, noted by the authors, was muscle soreness. The authors noted that a reduction in muscle soreness after intense exercise may be the most consistent effect of CWI, and that this aspect was not part of the study.

A final study we will offer is from the international journal Research in Sports Medicine. This focuses on the effects of CWI with a higher CO2 concentration (CCWI) on aerobic cycling work efficiency. The authors concluded that a reduction in heart rate following immersion was the largest at CCWI compared to the other conditions. They concluded that CCWI is an effective intervention for maintaining repeated cycling work efficiency, which might be associated with reduced blood lactate levels and heart rate.

With these studies, and other studies we considered, our view is that CWI can provide a benefit to performance training recovery – however, you should be fully aware that the effect of CWI treatments on exercise performance and recovery are distinct, and influenced by many factors including the duration, timing, magnitude, individual responses, and nature of the activity. As with training programs, there is no universal standard for therapies – what can work for one person’s physiology, may not work for another.

Does CWI Offer Unique Recovery Benefits

So if we have answered if cold water therapy can improve recovery, what are its unique benefits? Well, none – if you follow the research.

Many studies have looked at CWIs effects on weight loss, immune system improvement, body fat composition, recovery times, etc. While studies have shown that CWI can possibly impact these areas, many of the same studies identified that other recovery techniques or recovery methods produce comparable results. What we keep coming back to is the way a recovery program makes the individual feel, and in that regard, the perception of CWI, or reaction to how one physically feels as a result, may be the primary indicator of its success. In that, many studies have directly linked preference to an activity to one’s perception of its success. If CWI is a preferred recovery method, then the psychological aspect of that preference also needs to be considered.

How to Administer CWI

Using CWI therapy methods is not difficult. However, as exposure to cold can have varying reactions on each physiology, we recommend you attempt gradual exposure to cold water, before taking a (literal) plunge. Below are four basic ways to conduct CWI:

  • Gradual Shower: Work up from warm, and get colder. We recommend waiting a few minutes at each temperture change, and gradually drop the temperature.
  • Cold Shower: Just start at cold, and keep it there. You will likley find this helpful, and easiest to endure if you just finished an intense workout where your body temperature and metabolism are both elevated.
  • Ice Bath Immersion: Add ice to water until the temperature is between 10°C and 15°C, and stay submerged for only 10 to 15 minutes.
  • Short Cold Water Swim: First, follow all safety protocols for swimming. Second, be very careful in this technique, as whereas in the other techniques you can rapidly remove yourself from the cold if there are issues, swimming in cold water is not something you can easily get out of if you have have temperatue issues. A buddy system is helpful in this one.

Most important in administering CWI is to listen to your body – and if you have any health concerns – check with a physician before attempting any of these. We do not encourage you to ever start a new fitness, recovery, or nutrition program without first researching how it affects your own unique condition.


So, can cold water immersion therapy improve recovery? Generally speaking, yes. However, the research suggests its level of effectiveness, when compared to other recovery therapies is not incredibly unique. The biggest item we noted in our review of the research is how it altered the research participants’ perception of recovery. That is, it clearly improves the perception of how the body feels. We suspect that is linked to the chemical stimuli triggered by the CWI effect, notably in dopamine levels. But to offer a final caveat, there are certain medical conditions in which CWI can offer direct benefits, as several studies indicated – however, as those benefits pertained to medical conditions and not exercise recovery, we excluded those from our commentary and assessment.

As with all areas of your health, if CWI is of interest, we recommend you seek professional guidance on how best to implement new techniques into your performance training efforts. Only by working with a specialist who can answer your unique questions, and adjusts a training, nutrition, or recovery program to your unique needs will you see the most benefit.

– Train Hard!

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negative effects of excess weight

Research Update: Can Exercise Counter the Negative Effects of Excess Weight?

You’ve probably already noticed in several news organizations the publication of research findings in the European Journal of Preventive Cardiology that assessed the claim that a high cardiorespiratory fitness (CRF) might mitigate the detrimental effects of excess body weight on cardiometabolic health, termed the ‘fat but fit’ paradox. Can CRF negate the negative effects of excess weight? Let’s find out…

We’re going to skip to the end of the story for you:

According to study author Dr. Alejandro Lucia of the European University, Madrid, Spain, “Exercise does not seem to compensate for the negative effects of excess weight. This finding was also observed overall in both men and women when they were analysed separately.”

…refute the notion that a physically active lifestyle can completely negate the deleterious effects of overweight/obesity…

Joint association of physical activity and body mass index with cardiovascular risk: a nationwide population-based cross-sectional study

Study highlights

The specific study notes, “…the present findings, which are based on data from insured active workers across Spain, represent one of the largest studies to date (n = 527 662) and refute the notion that a physically active lifestyle can completely negate the deleterious effects of overweight/obesity.”

Want more data, then try “…a study conducted in 2196 participants reported that although PA was associated with a lower CVD risk within each BMI category during a 30-year follow-up, individuals with overweight or obesity presented with an increased CVD risk regardless of their PA levels…”

Or let this one sink in, “… in line with our findings, a systematic review concluded that an excess BMI is associated with increased CVD risk irrespective of PA levels.” Put another way, physical activity (PA) levels for those with a high BMI, did not alleviate cardiovascular disease (CVD) risks.

We’re not selectively pulling from this study. It shows PA is a good thing for any BMI level, but the study does not find that PA negates BMI or excess weight affects on health or CVD risks.

How did we get here?

The key point to notice is the researchers wanted to use science to test the “fat but fit” claim that has grown in recent years. What has driven this claim in several areas of modern culture is the conflation between a healthy body image and a healthy body. One is emotional, the other physiological. Too many supposed health and lifestyle outlets have been amplifying the belief that all that matters is that you are happy with who you are, and any level of activity is sufficient for health. First, we’re going to stay away from that argument here – there’s too much to unpack. Second, this study shreds that from the physiological aspect.

Third, if you have weight to lose, you have weight to lose. It’s not criticism, it’s about health.

A performance-focused solution

Building your lifestyle program around performance is a solid method to combat the negative effects of excess weight. Below are three tips, each from our performance triad, on how you can tackle your BMI, if needed.

Nutrition: Get serious about what you eat. No really, get f*ing serious about what you eat. Do not go nuts, do not go to extremes. But performance management of your BMI means you own your results. Performance diets are not guesswork, either – you need to spend some time with a pencil and calculator. Knowing your daily caloric and macronutrient needs to reach and sustain your performance means taking the time to run the numbers. Want more nutrition advice, then check out our article on Performance Diet Tips.

Fitness: Solve your time issues by using short duration, micro-HIIT sessions. These have shown the potential to be more beneficial than traditional exercise routines that rely on steady-state. Sound new? Their not – a 2016 study showed that one minute of intense training within a 10 minute period yielded the same results as a 50-minute steady-state trained group over a 12-week period. See our full Fitness Tip on Micro-HIIT.

Rest: As much as you exercise, and feed your body, a notable portion of your ability to manage weight comes from your rest cycle. Check out a good overview at The Healthy on how sleep helps burn fat. For now, here are some quick tips to help ensure you get proper rest: stick to a regular time for bed, it will keep your body on a schedule, do not over-sleep on the weekends, or off days, as this too will impact your body’s ability to manage its rests cycles, be careful with naps; they are fine, but too many, too long, or at the wrong time, and you can mess up your body’s sleep cycle, and during the day, get as much exposure to light as possible; this not only helps the body develop vitamin D, but also helps tell it to be awake. You can see more from us on rest here.

– Train Hard!

negative effects of excess weight

Achieving Your Target Weight – Doing the Math

Achieving your target weight goal should not be the difficult challenge so many encounter; however, so many seem to have a hard time keeping on a path to reach it…sound familiar?

Many people struggle to stay on track to hitting their weight goals, and the solution may be as simple as dusting off a calculator, doing some math, and keeping track.

First, we’re going to assume that you have all the other parts dialed in – workout routine is built to get your results and you are eating a macronutrient balanced diet. What we are going to work on here, for you, is the science of weight control for achieving your target weight.

Let’s start with losing weight

Dropping weight for most means lowering body fat composition. In numbers 3,500 calories is a pound of body fat. To lose a pound, per week, you need to create a deficit of 3,500 calories. You can get there through burning calories (exercise), diet (eat less), or both.

Easy – maybe. So why do so many start this path, see beginning results, and then nothing? Answer is easy (hint, but keep it a secret…it’s the math)

What is the math of weight management

Everyone has a basic daily caloric intake need – officially known as your Total Daily Energy Expenditure (TDEE). 

This is the amount of calories you need on a daily basis to maintain your body weight. There are two formulas (using the MIFFLIN ST. JEOR EQUATION):

Men: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) + 5
Women: 10 x weight (kg) + 6.25 x height (cm) – 5 x age (y) – 161

Basic Activity Factor

1.2: If you are sedentary (little or no exercise) = BMR x 1.2
1.375: If you are lightly active (light exercise/sports 1-3 days/week) = BMR x 1.375
1.55: If you are moderately active (moderate exercise/sports 3-5 days/week) = BMR x 1.55
1.725: If you are very active (hard exercise/sports 6-7 days a week) = BMR x 1.725
1.9: If you are extra active (very hard exercise/sports & physical job or 2x training) = BMR x 1.9

TDEE Example

Let’s meet Alex. Alex weighs 108 kg, 180 cm tall, 36 years old, and does light sport 3 days a week. Following this:

((10 x 108) + (6.25 x 180) – (5 x 36) + 5) x 1.375 = 2791 calories

Per week, Alex needs 19,537 to maintain his weight of 108 kg.

Now to lose a pound (.45 kg), Alex needs to reduce his caloric intake to 16,037 per week. And so he does, and the weight starts coming off, until it doesn’t. What happened?

This is where you are now going to understand how to avoid this pitfall. As the weight comes down, the math changes.

Let’s assume Alex is now 103 kg:

((10 x 103) + (6.25 x 180) – (5 x 36) + 5) x 1.375 = 2723 calories, or, 19,061 calories per week.

If Alex still has his diet adjusted to 16,037 calories per week, his deficit is only 3,024. A lot, but not enough to get off a pound. And as his weight drops, this will continue to be an issue.

And this is the mistake so many make in trying to achieve their target weight – keeping up the simple math behind the numbers.

So how do you avoid this? Simple – we recommend that for every 5 kg of weight loss, you do the math – work out your new TDEE.

If you are not seeing great results, and think your program is not working – it likely is for the most part, but it needs updating.

If you want to put away the calculator, you can head here, for a free online TDEE tool.

But you want to gain weight

Adding high-quality protein to your diet is essential for building muscle. Based on current research, your should consume 0.8g of protein for each kg of body weight as part of your TDEE. Let’s be clear – 0.8g per kg, just to maintain weight.

Research suggests that to support muscle development, one should increase protein intake to 1.5-2.0g per kg of body weight. For example, in a 90 kg individual, that would equate to 135-180 grams of protein per day. We strongly recommend your protein intake come from natural food sources; seek guidance from a registered dietician if you want to assess the affects of supplementation on your specific body.

In the end

This is why fitness programs, the good ones, will cycle through different elements every 3-6 weeks (depending on the program). It is because your body adjusts to a diet and workout. The same effort and calories that worked when you started a routine are not the ones that are going to get you across the finish line. Achieving your target weight means taking the time to monitor your progress, and make adjustments.

– Train Hard!

Vitamin D Benefits: Science or Hype?

First, what is Vitamin D exactly?

Vitamin D is required for the regulation of the minerals, calcium, and phosphorus found in the body. And in addition to calcium, it is an important aspect of maintaining proper bone structure.

Natural sunlight exposure is the easiest and most reliable way for most people to get vitamin D. Normal exposure of the hands, face, arms, and legs to sunlight 2-3 times a week for 10-30 minutes is sufficient time to produce enough vitamin D. The necessary exposure time varies with age, skin type, season, time of day, and other factors. During periods of sunlight, vitamin D is stored in your body fat and then released when sunlight is gone.

Vitamin D’s ability to help build strong bones by increasing the body’s absorption of calcium and phosphorous is long known. However, recent years have seen it associated as a defense against cancer, heart disease, diabetes, mood swings, and depression. But current studies are now altering our understanding of this vitamin, and while not diminishing its importance to our body’s health, may be challenging some decades-old hype.

In 2014, in a study funded by the National Institutes of Health, researchers recruited and studied the vitamin D effects in over 25,000 healthy U.S. adults over 50 for an average of almost 5 1/2 years. The study concluded that vitamin D supplements did not lower the risk of cancer, stroke, or heart attack.

And in early 2019, researchers published an analysis of prior studies on the link between vitamin D supplements, cancer risk, and survival. The analysis found no link between supplementation and reduced cancer risk; however, studies suggested that taking vitamin D supplements may lower the risk of dying from cancer by 13%. The study did not determine if the potential vitamin D supplement effect actually caused the body’s own immune system to improve and fight cancer, or if the supplement was directly responsible. In contrast to these possible positive results, a recently published Vitamin D and Omega-3 Trial (VITAL) noted that in a large study of more than 25,000 participants that those taking a vitamin D supplement did not lower rates of heart attack, stroke, or cancer. However, among people who later developed cancer, those who took vitamin D supplements for at least two years had a 25% lower chance of dying from their cancer compared with those who received a placebo.

Possible Assistance in Weight Loss

There is limited evidence vitamin D levels may affect one’s ability to lose weight.

In a 2009 study in the British Journal of Nutrition, some participants taking daily calcium and vitamin D supplement were able to lose more weight than subjects taking a placebo supplement.

Possible Evidence that Vitamin D Supplementation Could Reduce Respiratory Inflammation Risks

An April 2020 article in the periodical Nutrients, suggests vitamin D can reduce risk of infections.

According to the article’s researchers, vitamin D supports mechanisms that can lower viral replication rates and reduce concentrations of pro-inflammatory cytokines that produce lung inflammation that typically leads to pneumonia, as well as boosting concentrations of anti-inflammatory cytokines. Again, there are mixed results on this too, as several observational studies and clinical trials did not observe any effect from vitamin D in reducing the risk of influenza.

Foods highest in vitamin D on wooden background.

Natural Sources of Vitamin D

Foods that provide vitamin D include:

  • Fatty fish, like tuna, mackerel, and salmon
  • Foods fortified with vitamin D, like some dairy products, orange juice, soy milk, and cereals
  • Beef liver
  • Cheese
  • Egg yolks


Vitamin D Supplements

While research is ongoing, there are benefits from taking vitamin D supplements to promote bone health; however, large amounts of vitamin D are not required to get the benefit.  Notably, a 2010 study published in JAMA showed that intake of very high doses of vitamin D in older women was associated with more falls and fractures.

But too much vitamin D (or any supplment) can create risks. Taking a supplement that contains too much vitamin D can be toxic in rare cases. It can lead to hypercalcemia, a condition in which too much calcium builds up in the blood, potentially forming deposits in the arteries or soft tissues. It may also predispose women to painful kidney stones.

Vitamin D2 and D3

The most important forms of Vitamin D for the human body are D3 and (to a lesser extent) D2. If you select to take vitamin D supplements, choose a quality supplement and eating some foods fortified with D3.

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