Mark Blog
Friday, February 07, 2014

Need for calories 20-minutes into a workout

Posted 12:34 AM, February 07 2014

Need for calories 20-minutes into a workout

Mark, there was just one more question that I had but didn’t ask. I hope you could give me some quick advice.

Sometimes when I am on a training run….after about 15-20min, I feel really really sluggish and weak….to the point where my whole body feels like shutting down and I feel dizzy. After eating about 4-5 sugar gummy snake lollies, I make a full recovery 10 minutes later and am able to run again and with strength. Do you think I have a blood sugar level problem or have I not eaten enough or not eaten properly in the hours prior to my training run?

RESPONSE

I am glad you asked this question. This is a first! No one has asked me this question. But I know exactly what you are talking about. Often when I go for a workout after about 15-20 minutes I can feel like I am ready to completely bonk, like my blood sugar is dropping and I just want to stop or eat or take a nap. I have thoughts on it, but I am not an expert on blood sugar issues, so take my words as such. 
 
Of course what you are feeling could be a result of something that is a bigger issue with blood sugar such a hypoglycemia or diabetes. So check that out.
 
However, there can be something else going on that is unique to trained athletes, which you are one of. Often when you start out in training if the actual pace and training need is not extreme, your body will not respond with the normal physiological responses that a "normal" person would have happen, like the release of stored fat and carbohydrate to help you sustain your physical effort.. Your body will not read it as a stress need and will do nothing. So what happens? You do not release fatty acids for energy. You do not release stored carbs for energy, and after 15-20 minutes you feel like you are going to collapse. 
 
Human beings elicit certain physiological responses based on what their baseline experience of need is. So for example, if someone is a couch potato and does no training, if they go out and run for 15-20 minutes, every fiber in their body is going to respond with huge survival tactics. They will shut off fat burning. They will turn on carbohydrate burning. They will perceive the experience as a need to flee danger. They will feel totally alive from the experience and release all stored fuel to help them out. 
 
But let's look at you. You are a well trained athlete. You have completed Ironman distance races. A 15-20 minute run can be so below the radar of needing a physiological response that your body basically doesn't get the trigger to go into exercise mode. Your blood has a certain amount of glucose circulating in it to take care of basic needs (brain function, heart beating, breathing, keeping your body warm). That is not a huge amount of energy requirement.
 
Upping stored energy release only happens when your body gets the wakeup call that says you are in action mode.  As a trained athlete, in the first 15-20 minutes of a run, because you are so used to significantly higher energy demands, your body does nothing to kick in the release of stored fuel. Suddenly, you feel dizzy, like you are out of gas, like you need to eat. An untrained athlete will never experience this 20-minutes into a workout. A very trained athlete may experience this frequently. 
 
I have found there are two solutions to this problem. One is to just continue on through the session. Usually after about 25-minutes your body gets the idea that you are exercising and that you are requiring some fuel. It then starts to do what is needed and releases stored fat stores and carb stores.
 
Another solution is to do as you have said and eat some high glycemic sugar to get the energy engine firing. Both work. One is not better than the other. I personally like keeping my body in as low of a stressed state as possible. So eating the gummies is a better solution than waiting until you physiology finally realizes that you are doing a training session. 
 
I hope that helps. Thanks for asking!
Mark


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