fueling during exercise

We see intake guidelines for during endurance exercise everywhere. In magazine articles, on the labels of products, and these are just that, guidelines. Nutrition is a challenging topic, and the high variability between each and every individual makes it extremely difficult to provide recommendations that will be suited to everyone. But you do have to start somewhere, and the recommendations that have come from the latest research are definitely a good starting point. This article’s goal is not to focus on any specific strategies or guidelines, rather it is intended to encourage the reader to think more strategically about how much fuel they require during a particular workout.

So, let’s start by taking a look at what academia suggests for carbohydrate intake during endurance exercise. This fantastic article, by Asker Jeukendrup, recommends varying amounts of carbohydrate depending upon the duration of activity, and also some other factors like intensity. As an example, based on this article, for 2-3 hours of exercise at a medium-high intensity one should consider taking on around 60g of carbohydrates per hour. Now, this may need to be adjusted based on the individual, but this is out of the scope of this article. So, for now, let’s delve a little deeper into the 60g per hour recommendation.

60g of carbohydrates per hour is a substantial amount of food, it’s the equivalent of about 2-3 gels, or about 2 energy bars. If we take an example of a 2-3 hour group cycling ride, using these guidelines at face value, you should eat a total of about 4-6 energy bars. But let’s take this a step further using the same group cycling ride and ask some questions. On this group ride are there any rest stops, re-group points, descents, and/or coffee stops? What we are trying to get at here is that one needs to be cautious when determining the duration and intensity of an activity. What someone considers to be 3 hours of intense cycling may well begin to look more like 1 hour, once you factor in stops, drafting, and descending. This example obviously applies more to cyclists, as opposed to say runners, but this way of thinking can really benefit anyone who partakes in physical activity.

You can certainly gauge duration and intensity yourself, by feel. Be more conscious of how much you are drafting, how long you stopped at a re-group point, how much climbing vs. descending you performed. Then apply this to the nutrition guidelines. If for your regular 2 hour group ride you have two re-group points where you stop for 10 mins each and there is a substantial amount of time you spend descending, you may not necessarily need 60g per hour. Experiment, and over time you will find out what works for you.

But there are some quantitative data you can look at also to help you determine the intensity of your activities. Activity tracking applications, like Strava, sometimes provide a data point for the amount of time you were actually moving during a bike or run. From this you can calculate “move ratio”. Simply divide the “moving time” by the “total activity time”, the closer the number is to 1 the more time you spent actually moving. For example, if your moving time is 90 mins and your total activity time is 120 mins, your move ratio is 0.75 meaning you spent 75% of the time moving. Cyclists can take this one step further with a data point called “pedal ratio”. The calculation is the same as for move ratio but instead of using moving time you use “time pedaling” as the numerator, this gives an excellent idea of how much time you were actually riding your bike vs. resting, drafting, and descending.

Again, this article’s goal wasn’t to try and provide specific strict recommendations, but rather just make one think differently about how to fuel during endurance exercise based upon the duration and intensity of the activity. Finding the right balance is definitely challenging, experimentation is key, training the gut takes time, but the reward is worth it.

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