What Happens to Our Bodies After We Exercise & How to Boost the Health Benefits

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How to Boost the Benefits of Exercise

We all know exercise is beneficial to our health. Then why is it that ultramarathon runners may generate so many free radicals during a race that they can damage the DNA of a significant percentage of their cells? Researchers have looked at the exercise-induced increase in free radical production as a paradox: why would an apparently healthy act—exercise—lead to detrimental effects through damage to various molecules and tissues? This arises out of somewhat of a misunderstanding: exercise in and of itself is not necessarily the healthy act—it’s the recovery after exercise that is so healthy, the whole “that-which-doesn’t-kill-us-makes-us-stronger” notion. For example, exercise training has been shown to enhance antioxidant defenses by increasing the activities of our antioxidant enzymes. So, during the race ultra-marathoners may be taking hits to their DNA, but a week later they can experience great benefits, as shown in my video, Enhanced Athletic Recovery Without Undermining Adaptation.

In a recent study, researchers from Oregon State University looked at the level of DNA damage in athletes. Six days after a race, athletes didn’t just go back to the baseline level of DNA damage, but had significantly less, presumably because they had revved up their antioxidant defenses. So, maybe exercise-induced oxidative damage is beneficial, similar to vaccination. By freaking out the body a little, we might induce a response that’s favorable in the long run.

This concept, that low levels of a damaging entity can up-regulate protective mechanisms, is known as hormesis. For example, herbicides kill plants, but in tiny doses may actually boost plant growth, presumably by stressing the plant into rallying its resources to successfully fight back.

Wait a second, though. Could eating anti-inflammatory and anti-oxidant rich plant foods undermine this adaptation response? We know that berries may reduce inflammatory muscle damage (See Reducing Muscle Soreness with Berries), and greens may reduce free radical DNA damage (See Preventing Exercise Induced Oxidative Stress with Watercress). Dark chocolate and tomato juice appear to have similar effects. How it works is that flavonoid phytonutrients in fruits, vegetables, and beans seem to inhibit the activity of xanthine oxidase, considered the main contributor of free radicals during exercise. And the carbs in plant foods may also decrease stress hormone levels.

So in 1999, a theoretical concern was raised. Maybe all that free radical stress from exercise is a good thing, and increased consumption of some antioxidant nutrients might interfere with these necessary adaptive processes. If we decrease free radical tissue damage, maybe we won’t get that increase in activity of those antioxidant enzymes.

A group of researchers who performed a study on tart cherry juice and recovery following a marathon responded to this antioxidant concern by suggesting that, although it is likely that muscle damage, inflammation, and oxidative stress are important factors in the adaptation process, minimizing these factors may improve recovery so we can train more and perform better. So, there are theories on both sides, but what happens when we actually put it to the test?

While antioxidant or anti-inflammatory supplements may prevent these adaptive events, researchers found that blackcurrant extract – although packed with antioxidant and anti-inflammatory properties – actually boosted the health benefits of regular exercise.

If we take antioxidant pills—vitamin C and vitamin E supplements— we can also reduce the stress levels induced by exercise, but in doing so we block that boost in antioxidant enzyme activity caused by exercise. Now maybe we don’t need that boost if we don’t have as much damage, but vitamin C supplements seem to impair physical performance in the first place. With plant foods, though, we appear to get the best of both worlds.

For example, lemon verbena, an antioxidant-rich herbal tea, protects against oxidative damage and decreases the signs of muscular damage and inflammation, without blocking the cellular adaptation to exercise. In a recent study, researchers showed that lemon verbena does not affect the increase of the antioxidant enzyme response promoted by exercise. On the contrary: antioxidant enzyme activity was even higher in the lemon verbena group. In my video, Enhanced Athletic Recovery Without Undermining Adaptation, you can see the level of antioxidant enzyme activity before and after 21 days of intense running exercises in the control group. With all that free radical damage, the body started cranking up its antioxidant defenses. But give a dark green leafy tea, and not only do we put a kabosh on the damage due to all the phytonutrients and antioxidants, but we still get the boost in defenses—in fact, in this case, the boost was even greater.

Find out more on enhancing athletic recovery in this three-part video series:

1. Reducing Muscle Fatigue with Citrus
2. Reducing Muscle Soreness with Berries
3. Preventing Exercise-Induced Oxidative Stress With Watercress

Then there’s my 15-video series on using nitrate-rich vegetables to boost athletic performance starting with Doping With Beet Juice and ending with So Should We Drink Beet Juice or Not?

-Michael Greger, M.D.

PS: If you haven’t yet, you can subscribe to my videos for free by clicking here and watch my full 2012 – 2015 presentations Uprooting the Leading Causes of Death, More than an Apple a Day, From Table to Able, and Food as Medicine.


Michael Greger M.D., FACLM

Michael Greger, M.D. FACLM, is a physician, New York Times bestselling author, and internationally recognized professional speaker on a number of important public health issues. Dr. Greger has lectured at the Conference on World Affairs, the National Institutes of Health, and the International Bird Flu Summit, testified before Congress, appeared on The Dr. Oz Show and The Colbert Report, and was invited as an expert witness in defense of Oprah Winfrey at the infamous "meat defamation" trial.

12 responses to “How to Boost the Benefits of Exercise

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  1. I’m curious if this might be more a question of dose than source. So far as I know, the studies which have shown a negative effect from vitamin C supplementation have all used 1000 mg, or well above the RDA. You’d be hard pressed to eat anywhere near that, of course, but if you did, might the results be the same? I think it’s possible, at least, considering studies with 100-200 mg of supplemental vitamin C haven’t shown any detrimental effects. As ever, too much is as bad as too little. The dose makes both the poison and medicine.

  2. Probably my favorite series of subjects on the website. Demonstrates the absolute perfection of using natural foods as they are, and sticking with whole food plants.

  3. A recent study at, I believe the University of TX, suggested that aerobic exercise improves health by increasing autophagy. I’m guessing this might be a prime factor in helping to clean up the damaged dna. Adding the phytonutrients I would suppose reduces the damage to begin with.

    It’s much easier to run my 6 miles when I know what good it’s doing me. Just had my watermelon so gotta do my run.

  4. I found this article confusing. So, do we take the dark green leafy tea right after exercising? What type of tea? I appreciate all the background, but would love a succinct course of action provided at the end that I can skip to when some of the material is beyond my brain capacity or I’m short on time. Thank you!

  5. I have found that just being a vegan made recovery from exercise much better. Then when I adopted the raw ’til 4 diet, my recovery went through the roof! I am 55 and I am so amazed at the things my body will now tolerate in terms of being able to do new activities and not suffer the stiff muscles the next day. I have not gone to a gym and done any body building mind you, but I have done plenty of other stuff. I love it!

  6. On a related topic I heard about this concept of metabolic efficiency recently for endurance athletes like marathons and beyond. The idea was to encourage the use of fat as fuel rather than glycogen so that glycogen stores would last longer during running/cycling, reducing the need for topping up with so much “sugar” during the exercise. The argument was don’t carbohydrate load pre-race. Carbohydrate produces a spike in sugar in blood, brings insulin, which stops fat burning. Go for protein first like yoghurt and fruit for 2 hours before a big event rather than a bowl of porridge. It was also stated that after a couple of weeks of eating like this you could have an 80% increase in fat burning as opposed to glycogen burning and long slow runs provided the other 20% potential improvement. I was interested in this topic as a way of improving my performance, reducing tiredness in later stages of say a marathon, but this talk was predicated on eating animal products. I am a vegan so essentially live on complex carbohydrates fruit and veggies (and as we know there is plenty of protein). I wondered what Dr Greger thought of this metabolic efficiency idea in terms of fat burning and if there has been work done on it in relation to vegans?

  7. Yes, I agree that many of the videos are great, but I am left with not knowing exactly what I should or should not do based on the studies. Please give us clear directions.. ex. “so when you exercise, make sure you do abc and def to minimize the oxidative stress”. thank you.

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