greens for performance

Based on a study of over 2,000 adolescents, higher fruit and vegetable consumption was found to be positively associated with muscle power in teens, but that’s not who really needs it. What about the consumption of fruit and vegetables and risk of becoming weak in the elderly? Well, higher fruit and vegetable consumption was associated with stronger elders as well, “in a dose-response manner”—meaning more fruits and veggies was correlated with less weakness and more energy. But these were observational studies, which can’t alone prove cause and effect.

What Happens When You Put Food To The Test?

According to a study published in the journal Nutrients, there was no positive impact when runners ingested chia-seed oil. But, according to The Journal of Sports Medicine and Physical Fitness, an effect was found for “spinach supplementation on exercise-induced oxidative stress.” And, by spinach supplementation, they meant they just gave guys some fresh raw spinach leaves—one gram per kilo. So, like a quarter of a bunch a day for two weeks, and then they had them run a half-marathon. They found that “chronic daily oral supplementation of spinach”—uh, meaning like eating a salad—"has alleviating effects on known markers of oxidative stress and muscle damage.''

What happens when you run a half-marathon without spinach? A big spike in oxidative stress. Blood malondialdehyde levels (one of the markers of oxidative stress) stay up hours or even days later. In the spinach-eating group, the before and after blood work looks pretty similar. But, put the body under pressure, and then you can really see the spinach effect! With dark leafy greens on board, our bodies are better able to deal with the stress of physical activity.

If you look at the resulting muscle damage, as measured by creatine kinase (CK) leakage from your muscles (an enzyme that should be in your muscles, not leaking out into your blood), the participants started out with baseline CK at about 100 U/L and were at double that level after the half-marathon, 200 U/L just two hours later. But it’s the next day where they really felt it—that delayed onset muscle soreness with CK levels reaching 600 U/L before coming back down. That’s without spinach, though. On spinach, you get a similar immediate post-race bump, but it’s that next day where spinach really shines with levels back down in the 200’s. There is no next day CK spike. So, for a competitive athlete, that quicker recovery may get you back training harder sooner. The researchers who published this article attribute this to “the anti-inflammatory effects of spinach.”

Recovery & Soreness

A study in 2016 found potentially similar protective benefits in black currant juice. After some hardcore weight training, muscle damage indicators go up and stay up. Whereas the same lifting regime and then drinking berries, the muscle damage indicators went up but came right back down. This study was just measures of a biomarker of muscle soreness though. What about actual soreness?

A study published in the journal Nutrients looked at that. If you look at the effects of tart cherry juice on recovery following prolonged, intermittent sprints in soccer players, you see the same kind of reduction in biomarkers of inflammation. But, more importantly, less resulting muscle soreness.

The group drinking tart cherry juice reported half the soreness as the control group. Interestingly, they also measured maximum voluntary isometric contractions of the leg muscles, which understandably take a hit in the days after an intense workout, but not in the cherry group. They concluded that participants who supplemented with a tart cherry concentrate were able to maintain greater functional performance. But, that was testing how high the participant could vertically jump, not if they played soccer any better.

However, a study published in the journal Applied Physiology, Nutrition, and Metabolism did just this. This study on purple grape juice showed “an ergogenic effect in recreational runners by promoting increased time-to-exhaustion,” where you ramp people up on a treadmill and see how long they can go before collapsing. After a month of drinking a grape Kool-Aid type placebo control drink. There was no real change in performance, but a whopping 15% improvement in the real grape juice group, who hung on for another 12 minutes.

How Do I Get These Benefits?

These studies used juice so that the researchers could make a matched placebo control drink. You can buy fresh Concord grapes, fresh tart cherries, frozen, or water-packed in a can. That way you skip all of the added sugar that is common in prepared juice drinks, and you get all of the added benefits of fiber in the whole fruit form. I mix frozen cherries with oatmeal, cocoa, and mint leaves for a chocolate-covered-cherry type sensation. According to the proven benefits, you may want to try that for a few days before workouts.


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About The Author

Dr. Greger is a physician, New York Times bestselling author, internationally recognized speaker on nutrition, food safety, and public health issues, and founder of NutitiornFacts.org. Dr. Greger is a founding member and Fellow of the American College of Lifestyle Medicine and specializes in clinical nutrition. He is a graduate of the Cornell University School of Agriculture and Tufts University School of Medicine. Both his latest books, How Not to Die and the How Not to Die Cookbook, became instant New York Times Best Sellers and all of his book proceeds are donated to charity.