How vitamin D affects performance and recovery for running, OCR, and endurance sports
Thomas Solomon, PhD.
Updated onReading time approx 7 minutes (1400 words).
What you’ll learn:
Vitamin D’s main job is to regulate calcium metabolism and bone health.
If you rarely eat foods that contain vitamin D or you do not get regular daylight exposure across the year, you are at higher risk of vitamin D deficiency and a supplement might be advised by your doctor.
If you have vitamin D deficiency and/or you are an older adult (around 50 years or older) who also does strength training, daily vitamin D supplementation is likely to help restore and increase muscle strength.
If your vitamin D levels are already healthy, taking extra vitamin D is very unlikely to boost your performance or speed up your recovery.
Curious about the how and why? Scroll down for the details, the nuances, and the nerdy bits.
The information I provide is not medical advice. Vitamin D can have side effects and might interact with other drugs, nutrients, and medical conditions (see here). If you are unsure, always consult your doctor to ensure that a specific supplement is safe for you to use.
What is vitamin D?
Vitamin D is a fat-soluble vitamin that helps your body control calcium, phosphate, and magnesium metabolism. This matters because these minerals are crucial for bone growth, bone strength, and muscle function (read about that here). When vitamin D is too low for too long, such as in vitamin D deficiency, bones do not form or repair properly. In children, severe deficiency can cause rickets, where bones grow poorly and become deformed. In adults, deficiency can lead to osteomalacia (soft bones and weak muscles) and osteoporosis (thin, fragile bones that fracture more easily).
Your body can get vitamin D from 2 main places. First, your skin can make vitamin D when it is exposed to sunlight, especially UV-B radiation. In that case, skin cells produce a compound called cholecalciferol (vitamin D3). Second, you can get vitamin D from food. Good sources include egg yolks, liver, oily fish such as salmon, mackerel, and sardines, and cod liver oil. Some foods, like certain breakfast cereals and some milk, are “fortified” with extra vitamin D3.
Now for the slightly geeky part — because vitamin D metabolism is kinda complex. When vitamin D3 is made in your skin or eaten in food, it travels in your blood to your liver. There, your liver adds a small chemical group (a hydroxyl group, —OH) to make a prohormone called calcifediol, also known as 25-hydroxyvitamin D or 25(OH)D. This is the form that doctors usually measure in a blood test. Calcifediol then travels to your kidneys, where another hydroxyl group is added to produce the active hormone form of vitamin D, called calcitriol (1,25(OH)2D). Calcitriol is released into your blood, binds to vitamin D receptors in many tissues, and switches genes on and off to produce its effects. Some immune cells can also make calcitriol, where it helps support innate immunity.
Phew! Still with me?
The prevalence of vitamin D deficiency has been widely studied. Because many people spend a lot of time indoors, live at higher latitudes, cover their skin, or have low dietary intakes, deficiency is actually pretty common. Roughly 20% of adults in Australia, 68% across 5 South-East Asian countries, about 40% in the USA, 34% in Scotland, and 18% across Africa have vitamin D deficiency. These estimates vary a lot between seasons and between studies, but the basic message is that low vitamin D is not rare.
Because deficiency is common, vitamin D is often prescribed as a dietary supplement to bring blood levels of cholecalciferol (vitamin D3) back into the healthy range. Vitamin D supplements are also easy to buy over the counter, which is both convenient and slightly risky. Vitamin D is fat-soluble, so your body can store it, and very high long-term doses can be toxic. For example, data from the 2013–2014 NHANES (National Health and Nutrition Examination Survey) showed that 18% of American adults took more than 1,000 IU of supplemental vitamin D each day, which is more than double the US Recommended Dietary Allowance (RDA)Recommended Dietary Allowance refers to the level of daily intake for a specific nutrient that meets the nutritional requirements of nearly all people without health conditions. This value for specific nutrients can vary by age, sex, and pregnancy status. RDA values are calculated from Estimated Average Requirement (EAR) data.. About 3% took more than 4,000 IU per day, which exceeds the Tolerable Upper Intake Level (UL)Tolerable Upper Intake Level (UL) is the highest level of daily intake for a specific nutrient that is unlikely to cause harm in almost all people without health conditions. UL values should NOT be used as a recommended level of intake. and increases the risk of adverse effects. Back in 1999–2000, only 0.3% and 0.1% of adults exceeded 1,000 or 4,000 IU per day, so high-dose supplementation has increased a lot.
Vitamin D has many roles in the body and is essential for maintaining health. Systematic reviewsA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. and meta-analysesA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment. have examined how blood levels of the vitamin D prohormone, calcifediol (25(OH)D), relate to health outcomes. Low 25(OH)D is associated with higher risk of dying from any cause and from cardiovascular causes (see here & here), and with a higher risk of severe infections such as sepsis, cardiovascular disease, type 2 diabetes (see here & here), gestational diabetes, and dementia. But these are associations. They do not prove that low vitamin D causes these problems or that taking vitamin D will fix them. Thankfully, researchers have also looked at what happens when people actually supplement with vitamin D.
In the general population, vitamin D supplementation does not reduce the risk of death from any cause (all-cause mortality) (see here, here, & here). It also does not reduce the risk of cardiovascular disease or major cardiovascular events such as heart attack, stroke, or cardiovascular death. However, vitamin D supplementation might reduce the risk of dying from cancer (cancer-related mortality), might reduce all-cause mortality in older adults (see here), might reduce progression to type 2 diabetes in people with prediabetes (see here, here, & here), and might help improve blood sugar control in people with type 2 diabetes (see here & here).
NOTE: At this time, there is no meta-analysisA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment. examining the effect of vitamin D supplementation on cognitive decline in dementia or Alzheimer’s disease.
To summarise that wall of text: vitamin D deficiency is linked with higher disease risk, and supplementation may reduce the risk for some conditions. Importantly, several meta-analysesA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment. found that the benefits of vitamin D supplementation were largest in people who were deficient at baseline (blood 25(OH)D below about 30 ng/mL). In other words, supplements mostly help when they correct a deficiency — they put you back into a healthy range rather than turning you into a superhero.
Vitamin D has therefore become a very popular dietary supplement. For some people it is genuinely needed, such as those with low daily sunlight exposure, low intake of vitamin D–containing foods, or problems with vitamin D metabolism. Since 2020, Public Health England (the health authority in the famously cloudy UK) has recommended that people who do not get enough vitamin D from food should take a vitamin D supplement in autumn and winter — which, let’s be honest, can feel like a normal day in the life of a Brit. That said, the optimal dose from supplements and the ideal intake from diet are still uncertain (see here).
Certain groups have a higher risk of vitamin D deficiency — for example, children and adolescents aged 1 to 18 years, adults aged 75 years and older, pregnant women, and people with intestinal disorders (see here). If you suspect you are deficient, the sensible step is to ask your doctor for a blood test to measure 25(OH)D (25-hydroxyvitamin D). A blood level below about 30 ng/mL is commonly taken as deficiency, and your doctor may then recommend a vitamin D supplement and dose based on your results.
NOTE: You might see a vitamin D blood test described in several ways — a 25-OH vitamin D test, cholecalciferol (vitamin D3) test, ergocalciferol (vitamin D2) test, calcidiol test, vitamin D2 test, or vitamin D3 test. These labels refer to different forms in the vitamin D pathway, but the most common clinical test measures 25(OH)D.
Vitamin D receptors and vitamin D–related metabolites have been found in skeletal muscle. Because vitamin D helps regulate calcium, and calcium is essential for muscle contraction, it is reasonable to think that vitamin D might influence muscle function. A 2013 systematic reviewA systematic review answers a specific research question by systematically collating all known experimental evidence, which is collected according to pre-specified eligibility criteria. A systematic review helps inform decisions, guidelines, and policy. showed that blood 25(OH)D (that is, calcifediol) is associated with muscle strength. Because deficiency is common, it is tempting to think that vitamin D supplements might boost performance. Supplement companies have certainly noticed this and now regularly market vitamin D as a “recovery” or “performance” aid for athletes. So, the important question is…
What is the scientific evidence on vitamin D’s impact on athletic performance?
Please note that this summary focusses on exercise performance/recovery, not disease risk, prevention, or treatment. To go deep on the effects of vitamin D on general health, please check out examine.com/supplements/vitamin-d. I consider Examine a carefully-researched and trusted resource. (For full disclosure, I’ve worked as a researcher and medical writer for Examine since October 2022, but do not receive royalties/bonuses for these referrals.)
The “true” dietary requirement for vitamin D is not known, but the Adequate Intake (AI)Adequate Intake is the level of daily intake for a specific nutrient that may ensure nutritional adequacy in most people without health conditions when there is insufficient evidence to develop an Estimated Average Requirement (EAR) and, therefore, a Recommended Dietary Allowance (RDA) cannot be calculated. for adults, based on population data, is 15 micrograms (μg) per day (about 600 IU per day) from vitamin D in the form of ergocalciferol (vitamin D2) or cholecalciferol (vitamin D3). Vitamin D is generally safe to consume, but there is a Tolerable Upper Intake Level (UL)Tolerable Upper Intake Level (UL) is the highest level of daily intake for a specific nutrient that is unlikely to cause harm in almost all people without health conditions. UL values should NOT be used as a recommended level of intake. of 100 micrograms per day (about 4,000 IU per day). Source: Dietary Reference Values for the EU.
For dietary reference values (DRVs) in Europe, consult efsa.europa.eu/drvs/index.htm. Or click here to view all DRVs for vitamins, minerals, and fatty acids (DHA, EPA, and ALA). And, to search for the vitamin/mineral content of specific foods, consult fdc.nal.usda.gov/fdc-app.html.
In postmenopausal women, daily vitamin D supplementation of about 800 to 1,000 IU vitamin D3 (cholecalciferol) without added exercise does not improve common functional tests (like the “timed up-and-go” test). However, it can produce small gains in hand-grip strength, which is often used as a simple marker of whole-body muscle strength. These benefits seem strongest in women older than 60 years, in women who are not also taking calcium supplements, and in women who are vitamin D deficient at the start (blood 25(OH)D below about 30 ng/mL).
In older adults (around 50 years and older), daily vitamin D supplementation of about 800 to 1,000 IU vitamin D3 without exercise does not meaningfully improve muscle strength, functional performance (for example, timed up-and-go), or lean body mass (a rough marker of muscle mass).
But…
In older adults who take vitamin D daily and also do regular strength training, muscle strength can improve more than with strength training alone. This is promising, but more large, high-quality studies are still needed before we can be fully confident.
In younger adults (roughly 18 to 50 years old), daily vitamin D supplementation has trivial effects on muscle strength and no clear effect on muscle mass or muscle power. Benefits are greater in people who start out deficient (blood 25(OH)D below about 30 ng/mL). Again, more high-quality research is needed here.
In adults of all ages, daily vitamin D supplementation has a moderate effect sizeA standardised measure of the magnitude of an effect of an intervention. Unlike p-values, effect sizes show the size of the effect and how meaningful it might be. Common effect size measures include standardised mean difference (SMD), Cohen’s d, Hedges’ g, eta-squared, and correlation coefficients. for reducing the rise in blood creatine kinase after exercise-induced muscle damage. That means vitamin D can blunt some of the biochemical signs of muscle damage. However, it does not seem to prevent the temporary loss of muscle strength after that damage. More recent work also suggests that daily vitamin D doses of at least 2,000 IU for at least 1 week can help reduce markers of post-exercise muscle damage and inflammation (see Rojano-Ortega et al. 2023). Still, we need more high-quality randomised trials to be sure.
In athletes, daily vitamin D supplementation combined with regular training does not consistently improve performance. Some studies report small benefits for lower-limb strength but not upper-limb strength; some suggest benefits in athletes who mainly train indoors. But the studies differ a lot in design, dose, participant type, baseline vitamin D status, and sunlight exposure. This “between-study variability” (or heterogeneityHeterogeneity shows how much the results in different studies in a meta-analysis vary from each other. It is measured as the percentage of variation (the I2 value). A rule of thumb: if I2 is roughly 25%, that indicates low heterogeneity (good), 50% is moderate, and 75% indicates high heterogeneity (bad). High heterogeneity means there’s more variability in effects between studies and, therefore, a less precise overall effect estimate.) makes it hard to draw firm conclusions, and more good-quality research is needed, especially comparing deficient and non-deficient athletes in different climates and latitudes (and, therefore, different exposures to UV light).
If you choose to use vitamin D, a reasonable dose is:
Around 15 micrograms (μg) or about 600 international units (IU) of cholecalciferol (vitamin D3) per day. Note: this is based on commonly used and effective doses in research, not on a personalised prescription.
This daily dose is roughly similar to about 30 minutes of direct sun exposure on bare skin, depending on your skin tone, clothing, time of day, and latitude.
Supplement labels might list vitamin D in micrograms (μg) or in International Units (IU). One microgram of vitamin D equals 40 IU. So, 15 μg per day is the same as 600 IU per day, and the Tolerable Upper Intake Level (UL)Tolerable Upper Intake Level (UL) is the highest level of daily intake for a specific nutrient that is unlikely to cause harm in almost all people without health conditions. UL values should NOT be used as a recommended level of intake. of 100 μg per day is the same as 4,000 IU per day.
Taking more doesn’t necessarily mean a bigger effect and dietary supplements like vitamin D are intended as a supplement to, not a replacement for, real food.
Can vitamin D enhance athletic performance?
Vitamin D is unlikely to improve your recovery or your performance if your vitamin D status is already in the healthy range.
In older adults, taking vitamin D daily alongside regular strength training is likely to increase muscle strength more than strength training alone.
In people who are vitamin D deficient (blood 25(OH)D below about 30 ng/mL), vitamin D supplementation combined with strength training is also likely to increase muscle strength more than strength training alone. However, realistically this probably reflects a return to normal muscle function after correcting the deficiency, rather than a bonus “super-strength” effect.
The effect sizesAn effect size is a standardized measure of the magnitude of an effect of an intervention. Unlike p-values, effect sizes show how large the effect is and indicate how meaningful it might be. Common effect size measures include standardised mean difference (SMD), Cohen’s d, Hedges’ g, eta-squared, and correlation coefficients. are small for benefits to muscle strength, and the effects appear to be similar between males and females, although further research is needed in females because they are underrepresented among studies in this field.
Keep in mind: there is moderate-to-high heterogeneityHeterogeneity shows how much the results in different studies in a meta-analysis vary from each other. It is measured as the percentage of variation (the I2 value). A rule of thumb: if I2 is roughly 25%, that indicates low heterogeneity (good), 50% is moderate, and 75% indicates high heterogeneity (bad). High heterogeneity means there’s more variability in effects between studies and, therefore, a less precise overall effect estimate. (variability) in study designs and effect sizes between studies, the studies are generally small, and there is a moderate risk of biasRisk of bias in a meta-analysis refers to the potential for systematic errors in the studies included in the analysis. Such errors can lead to misleading/invalid results, and unreliable conclusions. This can arise because of issues with the way participants are selected (randomisation), how data is collected and analysed, and how the results are reported. and possible publication biasPublication bias in meta-analysis occurs when studies with significant results are more likely to be published than those with non-significant findings, leading to distorted conclusions. This bias can inflate effect sizes and misrepresent the true effectiveness of interventions, making it crucial to identify and correct for it in research.. So, the overall certainty of evidenceCertainty of evidence tells us how confident we are that the results reflect the true effect. It’s based on factors like study design, risk of bias, consistency, directness, and precision. Low certainty means more doubt and less confidence, and that future studies could easily change the conclusions. High certainty means that the current evidence is so strong and consistent that future studies are unlikely to change conclusions. is lowA low quality of evidence means that, in general, studies in this field have several limitations. This could be due to inconsistency in effects between studies, a large range of effect sizes between studies, and/or a high risk of bias (caused by inappropriate controls, a small number of studies, small numbers of participants, poor/absent randomisation processes, missing data, inappropriate methods/statistics). When the quality of evidence is low, there is more doubt and less confidence in the overall effect of an intervention, and new studies could easily change overall conclusions. The most effective way to enhance the quality of evidence is for scientists to conduct large, well-controlled, high-quality randomised controlled trials.. Therefore, additional high-quality randomised controlled trialsThe “gold standard” approach for determining whether a treatment has a causal effect on an outcome of interest. In such a study, a sample of people representing the population of interest is randomised to receive the treatment or a no-treatment placebo (control), and the outcome of interest is measured before and after exposure to the treatment and control. are needed to increase the certainty (confidence) in the overall effect sizes reported in meta-analysesA meta-analysis quantifies the overall effect size of a treatment by compiling effect sizes from all known studies of that treatment..
If you suspect you have vitamin D deficiency because you get little direct sunlight or rarely eat vitamin D–containing foods (for example, egg yolks, liver, oily fish, cod liver oil, or fortified foods like some breakfast cereals and milk), speak with your doctor. They can arrange a blood test and help you decide whether a supplement is needed, and at what dose. Self-diagnosing and “megadosing” supplements is not a good idea. As with any dietary supplement, taking more does not equal a bigger effect, and a dietary supplement is intended as a supplement to, not a replacement for, real food — learn how to establish a healthy eating pattern at veohtu.com/healthyeatingpattern.
To minimise the risk of consuming a supplement that contains prohibited substances, only choose products that have been independently tested (e.g., Informed Sport). And, remember: Supplements do not make athletes and do not replace training; they're just the icing on a very well-baked cake. Before reaching for pills and potions, optimise your training load and dial in your sleep, nutrition, and rest.
How to use this: If you are an endurance athlete, think of vitamin D as a “fix a deficiency” tool, not a performance booster. If you live at a higher latitude, train mostly indoors, cover most of your skin, or belong to a higher-risk group, ask your doctor about a 25(OH)D blood test. If you are deficient, follow their advice on dose (often around 600 IU per day, but tailored to you), keep your intake below the upper limit unless medically supervised, and pair it with sensible strength training — especially if you are 50 years or older. If your vitamin D level is already healthy, you can safely skip performance-focused vitamin D megadoses and put your energy into the big rocks: smart training, adequate fueling, recovery, and sleep.
Strengthen the fight for clean sport
Remember: You are the only person responsible for what goes in your body! Ignorance is not an excuse! Stay educated. Be informed.
Consult WADA’s prohibited list, cross-check your meds against the Global DRO drug reference list, and only choose supplements that have been tested by an independent body (e.g., Informed Sport or LabDoor).
Information you can trust. All content on Veohtu is meticulously researched and written by Thomas Solomon, PhD. He does not sell supplements, recovery products, or ad space, and he has no sponsorships, brand affiliations, or ambassador roles. Everything you read reflects his independent views, shaped solely by peer-reviewed scientific evidence — and that will never change.
Full list of meta-analyses examining vitamin D for performance.
Here are the meta-analyses I've summarised above:
Effects of vitamin D supplementation on maximal strength and power in athletes: a systematic review and meta-analysis of randomized controlled trials. Sist et al. (2023) Front Nutr
Effects of vitamin D supplementation on muscle function and recovery after exercise-induced muscle damage: A systematic review. Rojano-Ortega et al. (2023) J Hum Nutr Diet
Vitamin D Supplementation Improves Handgrip Strength in Postmenopausal Women: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. Jia-Li Zhang, Christina Chui-Wa Poon, Man-Sau Wong, Wen-Xiong Li, Yi-Xun Guo, Yan Zhang. Front Endocrinol (2022)
Effect of vitamin D monotherapy on indices of sarcopenia in community-dwelling older adults: a systematic review and meta-analysis. Konstantinos Prokopidis, Panagiotis Giannos, Konstantinos Katsikas Triantafyllidis, Konstantinos S Kechagias, Jakub Mesinovic, Oliver C Witard, David Scott. J Cachexia Sarcopenia Muscle (2022)
Effects of Vitamin D in Post-Exercise Muscle Recovery. A Systematic Review and Meta-Analysis. Hugo J Bello, Alberto Caballero-García, Daniel Pérez-Valdecantos, Enrique Roche, David C Noriega, Alfredo Córdova-Martínez. Nutrients (2021)
The Optimal Strategy of Vitamin D for Sarcopenia: A Network Meta-Analysis of Randomized Controlled Trials. Shih-Hao Cheng, Kee-Hsin Chen, Chiehfeng Chen, Woei-Chyn Chu, Yi-No Kang. Nutrients (2021)
The effects of vitamin D supplementation on muscle strength and mobility in postmenopausal women: a systematic review and meta-analysis of randomised controlled trials. M Abshirini, H Mozaffari, H Kord-Varkaneh, M Omidian, M C Kruger. J Hum Nutr Diet (2020)
Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis. Lin Zhang, Minghui Quan, Zhen-Bo Cao. PLoS One (2019)
The effect of combined resistance exercise training and vitamin D3 supplementation on musculoskeletal health and function in older adults: a systematic review and meta-analysis. Antoniak AE, Greig CA. BMJ Open (2017)
Vitamin D supplementation and its influence on muscle strength and mobility in community-dwelling older persons: a systematic review and meta-analysis. H Rosendahl-Riise, U Spielau, A H Ranhoff, O A Gudbrandsen, J Dierkes. J Hum Nutr Diet (2017) — This article has a correction at ncbi.nlm.nih.gov/pmc/articles/PMC6885933/.
Effects of Vitamin D Supplementation on Serum 25-Hydroxyvitamin D Concentrations and Physical Performance in Athletes: A Systematic Review and Meta-analysis of Randomized Controlled Trials. Forough Farrokhyar, Gayathri Sivakumar, Katey Savage, Alex Koziarz, Sahab Jamshidi, Olufemi R Ayeni, Devin Peterson, Mohit Bhandari. Sports Med (2017)
Effects of Vitamin D Supplementation on Muscle Strength in Athletes: A Systematic Review. Chien-Ming Chiang, Ahmed Ismaeel, Rachel B Griffis, Suzy Weems. J Strength Cond Res (2017)
A Systematic Review of the Role of Vitamin D on Neuromuscular Remodelling Following Exercise and Injury. Minshull C, Biant LC, Ralston SH, Gleeson N. Calcif Tissue Int (2016)
Effects of vitamin D supplementation on upper and lower body muscle strength levels in healthy individuals. A systematic review with meta-analysis. Peter B Tomlinson, Corey Joseph, Manuela Angioi. J Sci Med Sport (2015)
The effects of vitamin D on skeletal muscle strength, muscle mass, and muscle power: a systematic review and meta-analysis of randomized controlled trials. Charlotte Beaudart, Fanny Buckinx, Véronique Rabenda, Sophie Gillain, Etienne Cavalier, Justine Slomian, Jean Petermans, Jean-Yves Reginster, Olivier Bruyère. J Clin Endocrinol Metab (2014)
Effect of vitamin D supplementation on muscle strength, gait and balance in older adults: a systematic review and meta-analysis. Muir SW, Montero-Odasso M. J Am Geriatr Soc (2011)
Effect of vitamin D supplementation on muscle strength: a systematic review and meta-analysis. K A Stockton, K Mengersen, J D Paratz, D Kandiah, K L Bennell. Osteoporos Int (2011)
Vitamin D-related changes in physical performance: a systematic review. C Annweiler, A M Schott, G Berrut, B Fantino, O Beauchet. Journal (2009)
Vitamin D and cognitive performance in adults: a systematic review. C Annweiler, G Allali, P Allain, S Bridenbaugh, A-M Schott, R W Kressig, O Beauchet. Eur J Neurol (2009)
Effects of vitamin D supplementation on strength, physical performance, and falls in older persons: a systematic review. Nancy K. Latham, Craig S. Anderson, Ian R. Reid. J Am Geriatr Soc (2003)
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Who is Thomas Solomon?
My knowledge has been honed following 20+ years of running, cycling, hiking, cross-country skiing, lifting, and climbing, 15+ years of academic research at world-leading universities and hospitals, and 10+ years advising and coaching in athletic performance and lifestyle change.
I have a BSc in Biochemistry, a PhD in Exercise Science, and over 90 peer-reviewed publications in medical journals.
I'm also an ACSM-certified Exercise Physiologist (ACSM-EP), an ACSM-certified Personal Trainer (ACSM-CPT), a VDOT-certified Distance Running Coach, and a UKVRN Registered Nutritionist (RNutr).
Since 2002, I’ve conducted biomedical research in exercise and nutrition and have taught and led university courses in exercise physiology, nutrition, biochemistry, and molecular medicine.
And, with my personal experience of competing on the track (800m to 10,000m), the road (5 k to marathon), on the trails, and in the mountains, by foot, bicycle, cross-country ski, and during obstacle course races (OCR), I deeply understand what it's like to train and compete — I've been there, done it, and gotten sweat, mud, and tears on my t-shirt.
Disclaimer: I occasionally mention brands and products, but it is important to know that I don't sell recovery products, supplements, or ad space, and I'm not affiliated with / sponsored by / an ambassador for / receiving advertisement royalties from any brands. I have conducted biomedical research for which I’ve received research money from publicly-funded national research councils and medical charities, and also from private companies, including Novo Nordisk Foundation, AstraZeneca, Amylin, the A.P. Møller Foundation, and the Augustinus Foundation. I’ve also consulted for Boost Treadmills and Gu Energy on R&D grant applications, and I provide research and scientific writing services for Examine.com. Some of my articles contain links to information provided by Examine.com but I do not receive any royalties or bonuses from those links. Importantly, none of the companies described above have had any control over the research design, data analysis, or publication outcomes of my work. I research and write my content using state-of-the-art, consensus, peer reviewed, and published scientific evidence combined with my empirical evidence observed in practice and feedback from athletes. My advice is, and always will be, based on my own views and opinions shaped by the scientific evidence available. The information I provide is not medical advice. Before making any changes to your habits of daily living based on any information I provide, always ensure it is safe for you to do so and consult your doctor if you are unsure.