by Scott K. Ferguson, Ph.D.
Over the past century, physiologists have paved the road to some of the greatest achievements in climbing history as we have sought to climb increasingly difficult peaks at higher altitudes. Most notably, Griffith Pugh’s seminal work on exercise performance at altitude lead to the development of the open circuit oxygen system which afforded the first ascent of Mt. Everest by Tenzing Norgay and Sir Edmund Hillary in 1953. The rich tradition of science and climbing continues still today as physiologists further our understanding of what drives human performance. Awareness of these advances could help improve your performance in various mountain events, and it is our hope that Uphill Athlete will help share these scientific advances so that your training and performance may benefit.
In this regard, dietary nitrate supplementation has gained considerable interest among scientist and athletes due to recent evidence suggesting that it may elicit beneficial impacts on the determinates of exercise performance, both at sea level and altitude. Many of the experiments have utilized beetroot juice as a convenient source of dietary nitrates and have reported improved tolerance to high intensity exercise as well a reduction in fatigue associated metabolites such as lactate (which is often blamed for the dreaded forearm pump whilst climbing and leg burn during uphill slogs). Here we’ve provided some basics on how nitrate supplementation works and how you could use it to enhance your performance both at your local crag, during your training runs and on your next alpine adventure.
Turning on the faucet of oxygen delivery
At rest and during low intensity exercise, our muscles use primarily oxidative metabolism to create the energy needed for muscle contraction. This type of metabolism utilizes fat and, like it sounds, relies heavily on the availability of oxygen delivered by our blood. The nice thing about oxidative metabolism is that it is sustainable, due to the abundance of energy available from fat, allowing us to continue to exercise at low intensity for long durations. During high intensity exercise, our muscles require an increase in blood flow to meet the increased metabolic demands. Nitric oxide (NO) is a key molecule responsible for elevating blood flow to our muscles. When it is produced it dilates blood vessels, allowing blood to flow at a higher rate (much like turning on a water faucet). Failure to deliver adequate oxygen to our muscles results in a greater reliance on glycolytic metabolism which utilizes carbohydrates and produces lactate and hydrogen ions (acid) at a greater rate, thus sowing the seeds of muscular fatigue. Therefore, sufficient blood flow during exercise is crucial to maximize muscular performance and endurance.
Nitrate supplementation and the Uphill Athlete
We now know that we can elevate the availability of NO simply by increasing the amount of nitrate in our diet. When nitrate (NO3-) is ingested it enters our blood circulation and is then taken up by our salivary glands and secreted into our mouth where it is reduced to nitrite (NO2-) via the bacteria that reside on our tongue. The NO2- is then swallowed and also absorbed into our blood where it is further reduced to NO where it counts, at the muscle. This results in greater skeletal muscle blood flow during exercise, a reduction in blood lactate accumulation, improved muscle force production and ultimately enhanced exercise capacity. In addition, NO3- supplementation also improves the efficiency of mitochondria (the primary energy producers in muscle cells) effectively reducing oxygen demand in the face of improved oxygen delivery; kind of like increasing the gas tank in your car while also improving fuel economy of the engine.
This has big implications for the Uphill Athlete as we consistently utilize a full spectrum of low and high intensity moves in various environments. For those on a technical rock route, NO3- supplementation could afford the extra muscular force needed to stick an exceedingly difficult move and may notice the ability to push through a tough sequence and still have enough stamina to finish a difficult pitch. Alpinists will likely reap the benefits of sustained improvements in muscle efficiency at high altitude where oxygen availability is greatly reduced whilst also allowing them feel more refreshed after a long approach and perhaps lock-off and hang on their ice tools for a bit longer during tough technical ascents.
One thing to keep in mind is that NO3- is the key “active ingredient” in the beetroot juice. There are a plethora of green leafy vegetables that can also provide sufficient amounts of NO3- , so if you don’t like beets there are other options. Here is a short list of easy ways that you can use NO3- supplementation to improve your climbing performance and training efficacy.
- Some of the effects of NO3- supplementation can be elicited within 3 hours of consumption while some may take several days (i.e. 3-6) to develop. This may be because it takes multiple days of increased NO3-/NO2- levels to illicit key protein changes in skeletal muscle and/or the cardiovascular system. Therefore, it may be advisable to give this supplement a try for a couple of weeks.
- Recent studies have found that the maximal effects seem to be elicited 2-3 hours following consumption of ~8-9 mmols of NO3-. This translates to about 100-200 grams (1/2 to 1 cup) of spinach, which is also naturally high in NO3- content. If you fancy giving the beet juice a try you would need ~0.5-1 L to get this amount. There is no added benefit for consuming more than this amount (i.e. more is not better).
- Many physiologists and athletes are now using a concentrated version of the beetroot juice available from James White Drinks Ltd (links to their website below). This concentrated shot packs about 4 mmol of NO3- into 70ml’s of juice (70 ml’s is about as much as one gulp). This is a quick and convenient way for athletes to consume the concentration of NO3- requisite for the physiological benefits. For the mountain athlete this is a super easy way to bring the supplement along on multi-day excursions. For best results consume 2 shots (~8.6 mmol of NO3-).
- While most “pre-workout” supplements recommend that their product be consumed 15-30 minutes prior to exercise, NO3- supplementation does not follow suit. It is imperative that the consume the NO3- at least 2-3 hours prior to the time when you plan to start your ascent. This affords enough time for the NO3- to enter the blood stream, get secreted into the mouth and reduced to NO2- by the bacteria in our mouth. Studies also show that using antibacterial mouthwash completely abolishes any effects of NO3- supplementation so ditch the Listerine.
- The ergogenic effects of dietary of NO3- supplementation seem to be acute and may diminish 8-10 hours following supplementation. This is when plasma levels of NO3-/ NO2- return to baseline levels. Re-dosing once a day during long trips should provide ample boosts to plasma NO3-/ NO2- levels.
Aside from the ergogenic effects of NO3- supplementation I have personally noticed on one occasion that it improved symptoms of acute mountain sickness (AMS) in a fellow climber (at ~12,000 ft). Natives to high altitude naturally have higher levels of NO3-/NO2- than lowlanders and therefore could benefit from some of the beneficial effects highlighted above without the need to supplement with additional NO3-. Thus, NO3- supplementation might be worth giving a try on your next 14er or high altitude training run. Interested in reading more? Check out the list of peer-reviewed articles posted below for a more in-depth dose of science.
As with any intervention, there may be some individuals that notice little change in their performance following dietary nitrate supplementation. The theory as to why some individuals respond better to nitrate than others is related to muscle fiber-type composition. My dissertation work at Kansas State University helped show that dietary nitrate supplementation seems to impact fast- but not slow-twitch muscles during contractions. Both blood flow and contractile force are elevated in fast-twitch muscles following nitrate supplementation with no significant differences seen in their slow-twitch counterparts. The review I wrote with Jones and Poole (see Jones and Ferguson et al. 2016 below) highlights the physiological aspects of this effect and relates the results found in animal research to those observed in human athlete and non-athlete populations. So, athletes with a very high percentage of slow-twitch muscles (e.g. Type I) may not see a significant gain in performance relative to other athlete/non-athlete populations. We also have to remember that the circulating levels of nitrate and nitrite in highly-trained endurance athletes are already substantially higher than untrained individuals such that they may require a higher than usual dose in order to see augmented performance.
About Scott Ferguson
Scott is a Physiologist at the University of Colorado’s Medical Center specializing in exercise performance in hypoxia as well as an avid ice climber and backcountry skier. Twitter: @ScottKFerguson
Links and References
James White Drinks for Beet-it Sport Shot
Bailey, S. J., Winyard, P., Vanhatalo, A., Blackwell, J. R., Dimenna, F. J., Wilkerson, D. P., . . . Jones, A. M. (2009). Dietary nitrate supplementation reduces the O2 cost of low-intensity exercise and enhances tolerance to high-intensity exercise in humans. J Appl Physiol (1985), 107(4), 1144-1155. doi:10.1152/japplphysiol.00722.2009
- Article available at: http://jap.physiology.org/content/107/4/1144.short
Ferguson, S. K., Hirai, D. M., Copp, S. W., Holdsworth, C. T., Allen, J. D., Jones, A. M., . . . Poole, D. C. (2013). Impact of dietary nitrate supplementation via beetroot juice on exercising muscle vascular control in rats. J Physiol, 591(Pt 2), 547-557. doi:10.1113/jphysiol.2012.243121
- Article available at: http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2012.243121/full
Ferguson, S. K., Holdsworth, C. T., Wright, J. L., Fees, A. J., Allen, J. D., Jones, A. M., . . . Poole, D. C. (2015). Microvascular oxygen pressures in muscles comprised of different fiber types: Impact of dietary nitrate supplementation. Nitric Oxide, 48, 38-43. doi:10.1016/j.niox.2014.09.157
- Article available at: http://www.sciencedirect.com/science/article/pii/S1089860314004509
Hernandez, A., Schiffer, T. A., Ivarsson, N., Cheng, A. J., Bruton, J. D., Lundberg, J. O., . . . Westerblad, H. (2012). Dietary nitrate increases tetanic [Ca2+]i and contractile force in mouse fast-twitch muscle. J Physiol, 590(Pt 15), 3575-3583. doi:10.1113/jphysiol.2012.232777
- Article available at: http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2012.232777/abstract
Jones, A. M. (2014). Dietary nitrate supplementation and exercise performance. Sports Med, 44 Suppl 1, S35-45. doi:10.1007/s40279-014-0149-y
- Article available at: http://link.springer.com/article/10.1007/s40279-014-0149-y/fulltext.html
Jones, A. M., Ferguson, S. K., Bailey, S. J., Vanhatalo, A., & Poole, D. C. (2016). Fiber Type-Specific Effects of Dietary Nitrate. Exerc Sport Sci Rev, 44(2), 53-60. doi:10.1249/JES.0000000000000074
- Article available at: http://journals.lww.com/acsm-essr/Abstract/2016/04000/Fiber_Type_Specific_Effects_of_Dietary_Nitrate.2.aspx
Vanhatalo, A., Bailey, S. J., Blackwell, J. R., DiMenna, F. J., Pavey, T. G., Wilkerson, D. P., . . . Jones, A. M. (2010). Acute and chronic effects of dietary nitrate supplementation on blood pressure and the physiological responses to moderate-intensity and incremental exercise. Am J Physiol Regul Integr Comp Physiol, 299(4), R1121-1131. doi:10.1152/ajpregu.00206.2010
- Article available at: http://ajpregu.physiology.org/content/299/4/R1121.long
Vanhatalo, A., Fulford, J., Bailey, S. J., Blackwell, J. R., Winyard, P. G., & Jones, A. M. (2011). Dietary nitrate reduces muscle metabolic perturbation and improves exercise tolerance in hypoxia. J Physiol, 589(Pt 22), 5517-5528. doi:10.1113/jphysiol.2011.216341
- Article available at: http://onlinelibrary.wiley.com/doi/10.1113/jphysiol.2011.216341/full