Hello Mirtha, Fueling for high intensity burst of energy is not different for fueling for a 10, 20, 30 or even 60 minute event. The reason for this is that during high intensity bursts the muscles take in fuel faster than they do at low intensity but, as soon as the burst of power output is over, the rate of muscle fueling drops exponentially so that, over the course of an hour, the total amount of fuel consumed by a muscle doing high intensity bursts versus endurance activity is within 50% of each other. Secondly, whether doing sprints or endurance work, muscle can burn 1000 Cal per hour but only absorb 1/4 to 1/3 that rate in fuel. That means muscle depletes its fuel reserves when doing intensive sprints or endurance work no matter how well we fuel the body. FOR THESE REASONS, the goal during both sprints and endurance work is to keep blood sugar stable so that fuel availability is always at its maximum i.e. whenever muscle decides to absorb more fuel, that fuel is there. We can't perfectly time when we consume sugars and when they get to muscle during a competition because digestion and transport rate of fuel between swalling and the calories arriving at the muscle depends on a person's recent nutrition history, fitness level, hydration status, current training intensity, and sympathetic nervous system hormone response (anxiety/anticipatory adrenalin, training respons/cortisol). The only consistent way to allow muscle to decide when and how much it will allow itself to be fueled is to simply keep blood sugar topped off (maintain steady fueling) without ever going low (not consuming enough or consuming too much, which swings blood sugar high then low because of the insulin response). Also, a blood sugar swing drops free fatty acid availability because insulin tells fat cells to absorb sugar and make fat, instead of secreting fat to be burned in muscle fueling. I am well aware of the athlete's tendancy to think that fueling for high-intensity versus endurance training should be different because the training is so different, but the fact is that in neither case can we force muscle to absorb all the fuel it is expending and therefore must focus on keeping our bloodstream topped off so that muscle can decide for itself what it will do. In other words, we need to set the stage for the body to take care of itself, because we can't force in more fuel than our bloodstream or muscle will allow. In the end, the difference in how we fuel for strength and endurance activity is based on logistics and experience. For example, during heavy weight lifting, I can't eat any solid food and just consume dilute maltodextrin in water. During a long run (over an hour) I can eat 1/4 peanut butter sandwiches because my digestion is better. Some endurance athletes can't handle solid food at all even in a 3 or 4 hour event or even during the 3 hours before a competition, whereas others can eat a regular breakfast an hour before intensive efforts. This is where individual variation comes in. I think the best middle-of-the-road approach for fueling during competition day is to have a blended food shake (the nonfat milk, banana, peanut butter and uncooked oats recipe that is on the downloads page of my web site) to sip on between competitions and very dilute maltodextrin in water for the 20 minute before each actual competitive event. After each competition is over IMMEDIATELY get calories and water into your body, keep the calories coming in slowly and steadily until the next competition that day, in the 20-30 minutes before the competition use just malto in water (no blended food), and then let your body go to work during the event and repeat. Immediate refueling with malto/water, blended food calories while waiting for next event, malto/water slowly 20 min before next event, run event, repeat. If you have 3 hours or more between events you could eat some solid food; something you feel comfortable with that will not give you gastrointestinal upset at a time when nervousness in competition is adding to the physical stress of the activity. If you only have one high-intensity event, you can "spike" your blood sugar by "power-fueling" right before (5 or 10 minutes at the most) the event, but if your timing is off at all you will significantly reduce your performance; I think of this as a gamble more than a reasonable approach to high-intensity performance.
Hi Clyde, Thanks for sharing your knowledge with us - it really makes such a difference. My questions regard sprints. I am a swimmer and sometimes we have to do workouts comprised primarily of sprints. Do we change our power drink accordingly - add more sugar, for example? Also, during a swim meet, which is largely warm-up, wait, go like heck for a couple of seconds or minutes, stop again - you get the picture. Does the power drink need to be tweaked for meets? How do we get the "burst" needed for such events?
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