I’ve been reading a lot lately on what is going on biologically when we exercise. This was triggered after choking down some beet juice prior to a ride and then subsequently crushing a couple of climbs that normally left me crying. Maybe it was psychological, maybe not (I don’t care either way) but I figured I’d look into what was going on. I won’t take you completely down the rabbit hole and most everyone has a basic understanding of this, but here is a brief summary of what I found. Prepare your inner geek.
When we begin to exercise and muscles begin to work, your sympathetic nervous system instant messages the nerves in your blood vessels (veins and arteries, aka blood plumbing) and tells them to constrict, which is called vasoconstriction. This message is dispatched through your whole body and restricts blood flow. However, as your muscles work, they release byproducts that cancel out the vasoconstriction message and send a vasodilation message, expanding the blood plumbing that feed them.
What this effectively does is increase the blood flow to where it is immediately needed, the muscles, and decreases the blood flow to lower priority spots like your stomach and intestines. Awesome!
The down side of this decrease in blood flow to the digestive system is why your body is only capable of processing 300-400 calories an hour while exercising. That’s an important number to remember for endurance athletes, because much less than that can leave you bonked, but too much can cause big stomach issues. That’s why longer races have been described as an eating contest on bikes. Get the food wrong, and no amount of fitness can save you. I got a dose of this at Dirty Kanza last year and had to stop and fertilize the Kansas prairie before my abdomen exploded.
Now, where does beet juice fit in? Beet juice contains a high amount of nitrates. These nitrates are converted to nitric oxide by your slobbery saliva (savoring that nasty little shot of dirt flavored beet juice a bit longer in your mouth may increase its benefits). And guess what? Nitric Oxide is a facilitator of vasodilation, helping open up the blood plumbing to your muscles. More blood flow to your muscles means the delivery of more oxygen and fuel and faster flushing of nasty muscle byproduct like lactic acid.
There’s still plenty of studies conflicting on how long the benefits of beet juice last and if taking it multiple times over a few days or once before a race produces different results. One interesting thing I found is that spinach leaves have nearly twice the amount of nitrates per serving as beet juice. Maybe a big ass spinach salad could have similar benefits. I’m guessing the liquid beet juice, being liquid, is broken down by saliva easier than leafy greens.
Now, I’m not going to go into what happens when you go from aerobic to anaerobic exercise and how that affects lactate buildup, mainly because I haven’t read enough corroborating data to form a clear picture. What I do know is that it changes how fuel is metabolized. To help delay that burn, I’ve personally had good success with taking Sport Legs prior to a big ride. It seems to act as a buffer to raise the lactic threshold, or it just dulls the burn of acid build up in the legs. Either way, I feel like I can push harder after taking it. Results may vary. I’ll be digging deeper into that soon.
That’s all for now, hopefully you learned something, as I know I did. The knowledge probably won’t make you any faster, but now you can curse vasoconstriction for the stomach issues you have and drop some knowledge booms when your coworkers ask about the distorted face of horror you make when swishing that red juice around in your mouth. Let me know if you want more info on any of this or if I have something wrong! This is a google education, afterall.