On Sunday, I will be running the Scotiabank Toronto Waterfront Marathon. Since running season seems to be in full swing for many other runners as well, I thought it was time that I wrote a blog on fuelling during exercise. I have learned a lot in this area through personal experience. My first marathon was the Scotiabank Toronto Waterfront Marathon. I was an undergraduate nutrition student at this time, but didn’t understand the importance of fuelling during exercise. I literally stuffed a couple gummy bears in my pocket to eat during the race. Needless to say, that race didn’t go so well, and I experienced “hitting the wall” for the first time.

water-station Consuming carbohydrates during exercise provides a number of benefits, including sparing body carbohydrates stores, providing an exogenous muscle substrate, preventing low blood sugar and activating reward centers in the central nervous system. However, consuming carbohydrates during exercise is not always necessary. For those participating in exercise lasting less than 45 minutes, no fuel is needed. On the other hand, fuelling during exercise is recommended for the following:

45-75 minutes of sustained high intensity exercise

  • Small amounts of carbohydrate containing beverages, including “mouth rinse” without actually ingesting the carbohydrates
  • Why? Contact of the carbohydrates with mouth and oral cavity stimulates the brain to enhance perception of well-being and increase self-chosen work output

1-2.5 hours of endurance exercise, including stop and start sports

  • 30-60 grams of carbohydrates/hour in the form of either liquids or solids
  • Why? Acts as fuel source for muscles to supplement carbohydrate body stores

>2.5-3 hours of endurance exercise

  • 90 grams of carbohydrates/hour in the form of either liquids or solids
  • Why? Same as above

Athletes should practice to find the fuelling plan that suits their individual preferences and gut comfort. When choosing a product containing carbohydrates to consuming during exercise, it may be beneficial to find one containing a mixture of these carbohydrates: glucose and fructose. There is increased total and consequently, oxidation of carbohydrates when these two carbohydrates are consumed together. Most sports gels and gummies are specially designed with a mixture of glucose and fructose, but you read the ingredients list to be sure.


My water-bottles and gels clearly marked and ready to go for Sunday!

Curious about my fuelling plan for this Sunday? I consume 1 vanilla Cliff Shot gel with Gatorade every 5 km starting at 10km. That’s 6 gels in total, which for my pace works out to be about 52 grams of carbohydrate/hour plus the carbohydrates from the Gatorade that I consume. Please note that just because this works for me, doesn’t mean that it’s the right plan for you. Everyone is different in what they tolerate. The best way to find a plan is by trial and error during practice runs!

Good luck to everyone competing in Scotiabank Toronto Waterfront Marathon and other races this weekend 🙂

Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at: hello@megankuikmanRD.ca


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