Exercise fuel: Is that a banana in your pocket or are you increasing your performance?

Jan 16 2013 Published by under Physiology/Pharmacology

As a distance runner, I see a lot of nutritional advice. As we get more serious about running, more serious about decreasing our times, increasing our distance, and other measures of "performance", we start haunting forums and websites, places that refer to food as "fuel". You hear a lot about "pre-race fuel", "post-race fuel", "post-workout fuel". Is it better to have an apple with peanut butter 1 hour before running? Or a bowl of oatmeal two hours before? It's better to "fuel" with pasta the night before a half marathon, but what about a 10k? When you're running for more than an hour, when should the "race fuel" come out? What kind? When do you switch from water to Gatorade and in what amounts? Should we never eat cheese? These are the kinds of questions that can make runners spend hours comparing notes, and that's not even getting into the actual workouts and races themselves! We all want to do our best, and we all want to feel our best doing it, to recover quickly, and to do it again.

When you talk a lot about different types of "fuel", you hear a lot about certain ones in particular. Peanut butter gets a lot of praise, high protein, tasty, and you don't have to eat a lot of it. For extreme conditions, honey will get you there. Oatmeal is a universal favorite. And then there's the banana. I sometimes think that endurance athletes must account for 90% of all banana sales in the US. No matter where you are, at the end of every race, 5k, or ultra-marathon, there will ALWAYS be bananas. Huge piles of them on the post-race tables, and racers snarfing them down.

Me, I've always felt a certain amount of banana conflict. In my daily life, I really hate them. I hate the flavor, I REALLY hate the texture. And the gross little strings just make me gag. The first thing that turns me off a food is telling me it's got banana in it. But after a long run, or a race…I'll snarf those bananas just like everyone else. After morning workouts I'll be there choking down a banana with my breakfast, grimacing all the while. Heck, after a while I ever started to crave them! During a long race, you really do start to visualize that banana at the end.

But why do I do it? I still hate them. I still choke them down and try desperately to get the taste out of my mouth afterward.

But I'm a runner, and I have always, always been told that bananas are a freaking wonder fruit. They've got carbohydrates, they've got potassium, they've got fiber. They've got the sugar to keep you on your feet and the potassium to stop your muscle cramps. They are THE thing that every athlete should eat.

I have always, always been told this. But after a while, I started hunting around. Where is the proof?! After all, we SEE all that nutritional advice…but most of it is anecdotal at best. What's truth and what's not? And where lies the banana?


Nieman et al. "Bananas as an energy source during exercise: a metabolomics approach" PLoS ONE, 2012.

The authors of this study wanted to see how bananas compared to a carbohydrate beverage (6% carbohydrate, the concentration of Gatorade), in cyclists doing a time trial. Exercise is a stressor (though not necessarily a bad one), and during hard exercise you will see changes in these like cytokines and innate immune measures, showing that the physical stress produces a bodily challenge. You can counter this effect somewhat by taking in about 60 g of carbohydrate per hour during intense exercise. And if you've ever run a half marathon without gels or gatorade, and then switched over…believe me, you notice the difference.

The authors wanted to see how bananas matched up against the carbohydrate beverage alone. They took 14 trained cyclists, matched for dietary intake and training, and had them complete two different time trials. For one time trial, they ate 60g of carbohydrate per hour. For the other, they ate an equivalent amount of banana. They then looked at measures of cytokines, blood glucose, and performance.

What they showed was that exercise induced inflammation happened no matter what, with increases in cytokines like TNF-alpha, IL-6 and IL-10. The athletes showed no difference in performance, blood glucose, or pretty much anything else. So it appears that bananas as as good as straight carbs when it comes to this kind of exercise, according to these measures.

The only difference they came up with was a difference in blood levels of dopamine, where bananas significantly elevated dopamine and carbohydrate alone did not. This is probably because bananas actually contain dopamine. But the circulating dopamine here did not do anything to change blood pressure or cardiac performance, and was probably just a tracer of the banana in question (dopamine does not cross the blood brain barrier unless it is in precursor form as L-DOPA, so you wouldn't see any rewarding effects of bananas here).

So it looks like bananas and carbs might be equal in this case, but it still raises some questions. While they did look at performance, which is a definite positive, I wonder how the athletes felt. Did they feel better with the banana or the carbohydrate? Not only that, I do feel they are missing a control group. While they didn't see many differences between the banana and the carbohydrate groups, what happens if there is NOTHING there? Are both of these better than nothing? Their previous experiments confirm that the carbohydrates are better than nothing, but it would be nice to see the control group repeated here to see how the banana condition compares.

And of course there are other questions as well: most people don't eat bananas WHILE exercising, how do they affect recovery as compared to carbs alone, or to nothing, or to other types of food? But it meantime, it looks like when it comes to bananas vs carbs, I may not have to choke down my daily banana after all!!

Nieman DC, Gillitt ND, Henson DA, Sha W, Shanely RA, Knab AM, Cialdella-Kam L, & Jin F (2012). Bananas as an energy source during exercise: a metabolomics approach. PloS one, 7 (5) PMID: 22616015

15 responses so far

  • dr24hours says:

    My own anecdotal evidence: I have experienced no difference in energy or cramping between post-run banana based smoothies and post-run nothing (n~=50 for each group)

    I seem to have my best runs when I have granola about 30 minutes prior.

  • Jennifer says:

    I am a huge fan of chocolate milk. Not only is there evidence to support it for workout recovery, but you replace several minerals (calcium, phosphorus, magnesium, sodium, etc) in addition to potassium which improve electrolyte balance. It also tastes fabulous, but I'll call that part anecdotal.

  • Peter Copping says:

    As an ex fruit vendor may I suggest RIPE bananas rather then the pretty yellow ones in the picture.

    Most fruit nowadays unless you pluck it yourself is unripe.

    • Thomas Ghoat says:

      I second this opinion.

      I loathe unripe ones, but that's all they sell in the American grocery store. Let them sit on the counter until little brown spots appear on this skin and they're ridiculously good.

      (Must admit that I laugh at the "cheap bananas" have been "reduced for quick sale". Those are the best ones! And cheaper!

      An even more delicious treat (almost too delicious to believe) is dehydrated banana. I don't mean banana chips, which are deep fried, but whole bananas (or sometimes halves) that have been fully dried in a food dehydrator (takes 24+ hours). They are so good you'll be tempted to eat 20 dried bananas in a sitting (and regret it once it turns you into a methane-machine).

    • Scicurious says:

      Sorry, but I really HAVE tried. I infinitely prefer unripe, as the overripe = squishy and gross. Unripe is at least less gross, though can be extra chalky which is also gross. The strings are always vile.

      Also Thomas I did try dehydrated actually...it's just...the flavor. I just can't. 🙁 Choke 'em down because I feel I should but I really do loathe them.

  • You note, "The only difference they came up with was a difference in blood levels of dopamine, where bananas significantly elevated dopamine and carbohydrate alone did not. This is probably because bananas actually contain dopamine." Clearly, then, an important reason to eat bananas during exercise is the bananas enjoy it.

  • Craig says:

    From my own research, potassium is mostly consumed during high intensity bursts, like accelerating up sharp inclines, and has little impact on cramping or the kind of continuous steady rate output of a cycling time trial. I've found that if I find myself flat when trying to accelerate, that's probably potassium deficiency. Potassium literally keeps your neurons as well as other cells on fire, while dopamine keeps you in control and focused when I pass you up said inline.

    "By regulating the flow of potassium ions into the cell, potassium channels control when neurons fire – electrically discharge and release a chemical messenger that signals neighboring neurons in a circuit. This flow is regulated, in part, by activity of the chemical messenger dopamine, the main target of antipsychotic medications used to treat schizophrenia."

    Sore losers might be helped with a banana.

    Fructose also plays a part in powering garbage collection after cell inflammation, a /ripe/ banana is likely to help here. That and a chocolate (magnesium rich) milkshake, which is apparently the most satisfying drink to have after exercise, and may be even better in an orange mug.

    • Scicurious says:

      Unfortunately, as I stated in the post, the dopamine in bananas cannot cross the blood brain barrier and so cannot affect your mood. Otherwise I'd totally eat more bananas.

  • dfgdfgd says:

    If you hate bananas try eating them at a different ripeness. For instance, i hate, hate over ripe bananas, they are horrid. But if you get them before they are fully ripe, verging on slightly green they are awesome. Green bananas aren't good either, but not as bad as the fully ripe ones.

    There seems to be a very short window(a couple days) when bananas are truly an awesome fruit.

  • WhizBang says:

    Chocolate milk seems to be the latest craze. As much potassium as a banana plus some fluid and calcium.

    • Thomas Ghoat says:

      Someone posted this on Reddit years ago. It's a simple recipe that was titled "Recovery Chocolate Milk". He didn't like all the chemicals in the store-bought kind.

      1 gallon Whole milk (3904 grams)
      1 cup Dutch Process cocoa powder (110 grams)
      1.5 cups granulated sugar (300 grams)
      1/2 teaspoon salt
      2 teaspoons vanilla extract

      Add cocoa powder, sugar, salt, and 1 cup water to a large pot (big enough to hold a gallon+ of milk) and stir to mix. Bring mixture to boil, whisking rapidly. Add milk and thoroughly mix. Bring milk to boil, then immediately remove from heat (keep a close watch, as boiled milk will rapidly overflow your pot). Add vanilla and stir. Cool chocolate milk to room temperature. Store in refrigerator or freeze.

  • Nathaniel says:

    I am training for my second half-marathon (after an 18 month break from completing my first...but that's another story) and swear by eating bananas during my long run. I am running between 6-10 miles at the moment and notice a "kick" after consumption. I tend to eat 1/3 banana at 3, 6, and 9 mile markers, slowly chew it until it becomes mushy and wash it down with water. Can't complain, but haven't tried any alternative "fuel" either. Suggestions?

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