When it comes to performance enhancement for a runner, does training with low glycogen levels actually make a difference? Training with very little carbohydrate fuel in your legs can be a very hard thing do. Especially if you are a person that is use to having carbohydrates as a fuel source for running. If you are carb depleted it may lead to constant fatigue and consistently training at slower speeds along with the possibility of injury. So why do it? Training on a low carb diet and the depletion of glycogen in the muscle actually leads to major physiological adjustments within the body and leads to improvements with performance.
When we look at the molecular adaptations that are made, anytime there is a deficiency in the body, the body will adapt and compensate to decrease the risk of future deficiencies. Just as the human body adapts to any new stimulus in the body. It protects itself to make sure the next time a deficiency arises, that it can adjust and compensate for it.
For example, an experience runner that is trying to increase there VO2max must train at an intensity above what there body can currently handle. A level of intensity where the body struggles to meet the requirements of the work out will produce a much stronger stimulus than training the body at an intensity it can easily handle and adapt to. Training at an intensity that forces the body to adapt so next time the work out is performed the body can handle it. Since the body is training at an intensity above its current VO2max, the circulatory, nervous, and muscular systems think they are deficient and create adaptations that increase VO2max.
Same holds true for training with low glycogen levels. If the body is not use to training in a glycogen depleted state, adaptions need to be made so the body can handle the work out intensity and is forced to adapt to the new stimulus.
What adaptations are made training with low glycogen levels? There was a study done by a group of Danish researchers to test the glycogen deficiency theory. They recruited 7 healthy young men that averaged the age of 26, and performed a 10 week study that involved doing exercise in a glycogen depleted state and a high glycogen state. They discovered the following after the 10 weeks of training...
-When the glycogen depleted legs was restocked with glycogen and performed against the legs in a high glycogen state in a work out, the previously glycogen depleted legs performed much better than the legs that were always trained in a high glycogen state. In fact the time to exhaustion was twice as long for the previously glycogen depleted legs compared with the high glycogen legs and the total work performed was much greater. This is due to hormonal changes that take place in the body in a glycogen depleted state.
What are the hormonal and molecular change that take place?
-When training in a glycogen depleted state, plasma epinephrine and norepinephrine levels are significantly higher. These hormones are potent boosters of nervous system activity and can also increase the force which muscle produce when they contract.
-On the molecular level, differences in very important aerobic enzymes (hydroxyacyl CoA dehydrogenase HAD and citrate synthase CS) increased significantly in the glycogen depleted training state. As a result of the increased aerobic enzymes in the body, oxygen can be processed at a higher rate, fuel can be provided to the muscle cells at a greater speed, and endurance at quality intensities may improve significantly.
-Along with the molecular changes, the number and percent area of type II-X (fast twitch) fibers decreased significantly in the high glycogen state legs but not in the glycogen depleted legs. The body had to rely on the fast twitch fibers to complete the work out when glycogen depleted. In return this preserved the fast twitch fibers in the glycogen depleted training legs.
How can you supplement this into your own training? What I would recommend is starting to supplement a couple workouts each week in a glycogen depleted state. Depending on your current carb intake (nutrition) and current training plan, this can vary from person to person.
For example, if you are a person that has a high carb meal or uses carb supplements prior to training, try a run with out the added carb. This may come down to reducing carbs in your overall nutrition to enhance your performance and overall body composition too.
Feel free to email me with any questions and post any additional comments!!
Happy Performance Enhanced Running :)
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