Fueling Your Engine

It’s Ironman and Half Ironman time 

Gilbert Ayoub July 24, 2018
Everyone has been training for months to be at their best for the big event. Your FTP is up over last season and you feel confident that you will PB. According to the data, you should hold 230 watts on the bike and run a 5: 00-minute pace. Two to three hours into the race you start feeling fatigued and are struggling to stick to the plan. You finish disappointed that you had to slow down and assume that the 15 hours a week of training was not enough.
In previous articles, we talked about developing aerobic capacity through specific training. This takes time but the reward for endurance athletes is the ability to race at lower heart rates and produce the higher power needed to perform. The lower HR make it possible to fuel with lipids (fats) rather than glucose (sugar). Diesel vs high octane. The average 160-pound male athlete starts each day with roughly 40,000 calories of fat and 2000 calories of glucose. At race pace, this athlete can burn 600 to 800 calories per hour. So about 4000 calories needed for a half Ironman and 8000 for a full. You will need a lot of groceries to fuel with high octane, and that's if you can stomach it.
There are many things that combined, will improve your fat burning capacity. Some of them are low-intensity training, selective fasting before and during certain workouts, reducing sugar intake in your diet to name a few. All this can be done haphazardly but I prefer the more calculated approach. I send my athletes for VO2max testing at peakcentremontreal The report that they generate based on gases exhaled during the test gives a good indication of what percentage of sugar over fats are being used at different intensities. This gives us a benchmark to work with in order to try and increase fat burning. It also shows us how many calories the athlete at this time will have to consume during a race to complete it at a given power output.
At race pace this athlete can burn 600 to 800 calories per hour.
For many, it’s shocking to see the impossible amount of glucose that would be required to maintain the race pace that they have prepared for.
Now that we understand that building a bigger engine won’t serve much if we can’t fuel it we can start paying attention to making changes that will reduce glucose dependency.