Pre-WOD Nitro Boost

Fruits and vegetables improve WOD performance by optimizing blood flow to muscle.
By Rob Wildman, PhD., RD,

It goes without saying that muscle uses a lot of oxygen, which must be continuously delivered by the blood, during intense WODs. At the same time, muscle produces a relative amount of carbon dioxide and heat, both of which must be carried away by the blood. Based on the importance of delivery and removal efforts, optimal blood flow to and from hardworking muscle is critical during a workout. Our hearts are tireless warriors, ratcheting up their beat cadence and vigor to pump more than quadruple the blood during strenuous workouts. However, can we say that delivery of blood to muscle is truly maximized by the heart’s amazing efforts? Or is there more that we can do on the nutrition side? For instance, are there foods or supplements we can consume before we train and/or as part of our general diet to optimize circulation to muscle during a WOD? Absolutely, and in this article we will explore nutritional factors that can support maximal circulation during and after a WOD and that can be built into your diet or supplement regimen preworkout.

Getting the Ol’ Juices Flowing

Nutrients and oxygen continuously circulate throughout our bodies’ thousands of miles of blood vessels. During periods when we are simply hanging out, skeletal muscle might receive 15 to 20 percent of the five or so liters of blood being pumped by the heart each minute. However, during a WOD, the demands made by muscle result in it receiving as much as 80 percent of the heart’s ramped-up output. That’s large volumes of blood surging through muscle, delivering oxygen and nutrients while picking up carbon dioxide and heat to be released by the lungs and skin, respectively. While the diameter of larger arteries carrying blood from the heart to muscle remain generally constant, smaller arteries and arterioles can expand to increase blood flow to hardworking muscle downstream, based largely on oxygen needs. Another molecule, nitric oxide, is one of the factors that can help expand the diameter of smaller blood vessels, thereby increasing blood flow, making it an important factor during intense exercise.

Arginine, Nitrates, Nitrites and Nitric Oxide

Arginine is an amino acid that can be converted to nitric oxide in muscle blood vessels. The principal enzyme involved is nitric oxide synthase in the walls of smaller blood vessels, and it makes sense that if you can increase the availability of arginine or increase the activity of NOS, blood flow would be maximized. While arginine has dominated the nitric-oxide supplement marketplace for the past decade, researchers have recognized its limitations, including rapid breakdown and higher gram amounts necessary to have a shot at any impact. Meanwhile, over the past decade, researchers also have been investigating the potential of natural nitrates and nitrites from fruits and vegetables to be more efficient and effective than arginine in supporting circulation to muscle. What’s more, it seems that nitrates and nitrites also may increase the efficiency of oxygen use, meaning that someone could use less oxygen to perform the same exercise. 

Nitro Plants: Performance and Beyond

Nitrates are simple nitrogen- and oxygen-endowed molecules, once considered to be byproducts or even potentially hazardous. However, today we understand that naturally occurring nitrates can be converted to nitric oxide and serve to support blood flow during exercise and healthier blood pressure during the rest of the day. Among the best sources of nitrates are several fruits and vegetables, including dark-green leafy vegetables, turnips, rhubarb, pomegranate, spinach, endive, fennel, celery, carrots, lettuce, cabbage, cucumber, broccoli, tomato and beet juice.

Supplemental forms of high-nitrate and nitrite fruits and vegetables are available, but you need to look for ingredients that have specific levels. At this time, there are no hard recommendations for nitrate intake to help maximize performance. However, much of the research does target intake levels of at least 300 milligrams of nitrates from plant sources or supplements.

So when it comes to maximizing blood delivery to muscle for optimal WOD performance and benefit, perhaps ol’ Mother Nature can lend a hand — or a fruit, if you will. θ

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