Nutrition & Hydration BASICS: During your Run (Part II)
Missed Part I? Read Nutrition & Hydration BASICS: Pre-Run
To run (or do anything at all) we need energy, and our bodies have a few different sources of energy. For higher intensity endeavours such as challenging runs or races our bodies’ preferred source of fast energy is GLYCOGEN (ie. a big sugar molecule) which is broken down into GLUCOSE (tiny bit of sugar) and pumped through the blood stream for use as fast fuel.
The thing is, human bodies don’t have the capacity to store a lot of glycogen, so the supply of glucose can (and will) run out during long runs.
And then…
The dreaded crash & burn, or “bonk.”
At this point our bodies still have sources of energy - we’re breaking down muscle and burning fat for fuel - but these aren’t sources of fast energy. By ingesting carbs during a long run or race, you can prevent that crash, delay the feeling of exhaustion, and get to the finish line strong.
Fast Energy
So how can you choose a mid-run fuel that will give you fast energy? We basically want some carbs that can be digested and transformed into glucose pumping through our arteries ASAP. One helpful tool for identifying these easily digestible carbs is the Glycemic Index & Glycemic Load.
The Glycemic Index ranks carbs based on how fast they can deliver glucose to the blood stream. Bingo. On the Glycemic Index, straight glucose is a 100. So is white bread! Taking it one step further, the Glycemic Load accounts for serving size. Why does that matter? It matters because some carbs can become glucose in the blood stream super fast… but there’s hardly any glucose in a serving size. We runners need enough glucose to make a significant difference, and fast!
Watermelon
Glycemic Index - 70
glycemic load - 2
you would have to eat SO MUCH watermelon mid-run for a significant glucose increase.
Not Just for the Marathon
Oftentimes the mid-run fueling discussion is saved for marathoners or runners who do very long training runs, but in fact a hit of sugar can be also be useful in shorter, higher intensity runs or workouts. Even small doses that of sugar can be beneficial because when the brain even detects sugar in the mouth, it will allow your body to work harder.
The first time I tried mid-run fueling was very memorable! I ate a half a gel during a hard effort “long” run (about 90min) and kept an eye on my watch. I did not physically feel better or increase my effort but my pace dropped significantly! Seeing the splits drop lower and lower was really fun!
FAST FUEL
Some of my personal Favourites for a quick mid-run energy boost.
Start Early & Avoid the Crash
It will be important to start fueling well before you start to feel hungry - as early as 5km or 3miles into your long run or race. You want to keep providing glucose so your body doesn’t completely burn through all it’s stored glycogen. Keep the carbs coming throughout your run so you don’t hit the wall.
This is where trial and error come into play. During hard exercise your body will prioritize pumping blood to your extremities and there will be less blood available to aid digestion. This means that even foods that normally give you no problems could cause GI issues if you eat them during a run. Try taking small bites at more frequent intervals. For example, instead of eating a gel every hour, try eating half a gel every half hour, and make sure to drink water with it.
Test out a variety of fueling options during your training and especially in long runs and take notes on what worked and didn’t. On race day, bring your own snacks that you know from experience will work well for you.
Water and Electrolytes
During a long run or race we want to prevent dehydration. Electrolyte beverages are all the rage right now and brand ambassadors are everywhere on social media promoting a variety of these hydration products. But there is very big range of individual needs when it comes to electrolytes: some people sweat a lot, some sweat only a little. Some people have very salty sweat, and some don’t so it’s important to be intentional to discover what works for you and learning about your body.
If you crave salty snacks after your long runs or workouts, pay attention to that craving. Perhaps you need to add electrolytes during your run instead of drinking plain water. If you don’t really have any salt cravings, you may be getting enough electrolytes through your preferred snacks and plain water. In very hot weather, it’s not a bad idea to weigh yourself before and after your run to determine how much water you’re losing from sweat, because a loss of over 2% body weight in water (via sweating) can be detrimental to performance.
To dial in on your individual needs or for more information of any of these topics, I highly recommend consulting with a registered dietitian, sports nutritionist or qualified health professional.
click to read PART III
Nutrition & Hydration BASICS: Post-Run and Recovery