Does Technique Suffer on a Low-Carb Diet?

We tend to think of the effect of carbohydrates on energy levels, but what about the nervous system? A new study suggests carb consumption might affect performance in highly technical sports.

We’ve heard a lot about the role of carbohydrates in sports nutrition lately. There has been much ado regarding the waning importance of carbohydrates in a post-workout golden ratio with protein, the use of carbs as an ergogenic for sustained efforts shorter than an hour in length, and even how little is needed between workouts when doing two-a-days. This may be due in part to the growing interest in paleo diets, and more importantly the questions they raise regarding how voluminous dietary carbohydrate sources really were in a historical setting. If we didn’t need so much in the past, perhaps we don’t need so much now.

The evidence to support a reduction in carbohydrate intake for athletes has been pretty substantial. But one area that has been poorly studied is the influence of carbohydrates on the technical demands of sport. In a recent study in the Journal of the International Society of Sports Nutrition, researchers wanted to find out if carbs affect technical components of gymnastics.

This may seem like a strange thing to study. Carbs are for energy, but it seems if we have enough fat to fuel most of our efforts, we are safe to reduce carbs. Looking at it from the perspective of providing energy for your muscles, it is true we can have great athletic success with low-carbohydrate diets. But it seems less likely that carbs would affect technique on the surface, especially when we don’t need much to fuel our muscles.

Looking at our blood we arrive at the reason why carbs can affect technique. We have blood sugar – a pretty consistent level of blood sugar, in fact. The purpose of consistent blood sugar isn’t actually for our muscles – they have their own store of carbs called glycogen – but actually for our nerves. Unlike our muscles, our nerves don’t store carbohydrates, so they need a constant supply. When we exercise, our muscles begin to draw from our blood sugar, potentially leaving less for our nerves, and voila, technique might suffer.

To study this phenomenon, researchers examined young female gymnasts during a balance beam workout. Some of them drank a carb drink and some of them didn’t. Some of them were already fatigued before getting on the balance beam and some weren’t. Considering what the researchers believed might happen – that those without carbs would take a header off the beam more often – it seems like a cruel test, but I suppose that makes it easier for study.

Sure enough, the girls who went carbless and were fatigued ahead of time fell off the beam over twice as much as those who were fatigued ahead of time but drank a twenty percent carb solution.

Now let’s consider what this means for non-gymnasts. Anyone engaged in a technical sport, such as a combat sport, can benefit from this knowledge. When a highly technical demand is coupled with fatigue, our technique fails. This may be obvious on a high beam like in this study, but in other sports the effect might be more subtle, although no less important.

I’ve been a proponent of diet plans like the paleo diet for athletes, but for those engaged in sports with a highly technical component, both avoiding fatigue and consuming carbs while working on technique is probably beneficial. If your technique were to succeed more than twice as often, think of what that means for your training. Under a paleo diet guideline, this means eating a banana or something similar while you train.


1. Helena Batatinha, et. al., “Carbohydrate use and reduction in number of balance beam falls: implications for mental and physical fatigue,” Journal of the International Society of Sports Nutrition 2013, 10:32.

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