February 2018 Running Challenge

7lenny7 wrote: »

@kgirlhart I think it's worth refueling if you race for 90 minutes or more.

Key points

• You likely have enough glycogen in your body for at least 90 minutes of hard running
• It takes about 30 minutes for the calories you ingest to be available to your muscles
• Most people can only digest 200 to 240 calories per hour. Taking in more that than can have detrimental effects.

Based on that,

• first refuel should be about 60 minutes after start of the race
• last refuel should be about 45 minutes before the end of the race
• Take no more than 200 calories per hour unless through training runs you've found you can take in more.
• If you can run a 90 minute half, you probably don't need to refuel. You may not even need it for a longer run, but it won't hurt.

This only applies to a half. For a full, I'd start taking in calories about 15 minutes before the race. Since you can't digest as many carbs as your body is using through glycogen, you want to start that refueling process immediately to try to keep topped off as long as you can. For a half, you're not running long enough to warrant immediate refueling

Lenny is suggesting to be very conservative in refueling for HM's but aggressive in refueling in full marathons; and I agree in his assessment. The biggest thing here is the amount of glycogen your body can store and the rate at which you will exhaust it. For things like HM's (depending on how long it takes you to complete the HM) refueling may not be necessary. You would be better off to just use up your body's stores or take very little fuel. That's because when you take in fuel, your body now has to devote your blood supply in digesting and absorbing it. The same blood supply that competes to send nutrients and oxygen to your working muscles (and brain) and forces your heart to work harder.

However, in a full marathon, most people do not have enough stored glycogen in their body to make it the full distance of 26.2 miles (or more). So refueling is a must and learning the optimum strategy for refueling becomes part of your marathon training.

Also, the faster you run at a pace above lactate threshold the more your body depends on glycogen (stored sugar or carbs) which is limited in supply. The slower you run (below lactate threshold pace), the better you can make use of your body's fat reserves (much larger in supply). It may seem counter intuitive but sometimes running slower will yield more energy throughout your entire race or training run because you are conserving your precious stored sugar supply.

Plain and simple, force your body to operate at an anaerobic level, you force your body to burn sugar only. Slow down to an aerobic pace, your body can burn both fat and sugar.


https://www.runtastic.com/blog/en/how-to-burn-fat-while-running/
http://siimland.com/difference-between-burning-sugar-and-fat/