Eight minutes and 40 seconds and you’re done! You’ve just completed your workout for the day and still have 20 minutes remaining on your half-hour lunch break. Plenty of time to take a few minutes to find out a little more about exactly what you accomplished with that CAR.O.L intense ride.
CAR.O.L and muscle glycogen depletion
Recall from our last blog that we highlighted the importance of ATP regeneration to support repeated muscle contraction and that muscle glycogen serves as an immediate substrate source for rapid ATP regeneration during high-intensity exercise. The real magic of CAR.O.L takes place with those two 20-second sprints and what happens during the recovery timeframe between workouts. Research has consistently found with this frequency and duration of sprints that muscle glycogen stores are depleted 20 to 30 percent in the quadriceps. Even more fascinating is that the maximal rate of glycogen breakdown is also achieved with this frequency/duration combination of sprints. Simply put, more sprints and/or longer sprints do not elicit a greater rate of glycogen breakdown. This is one reason why you don’t have to exercise a long time with CAR.O.L to get optimal benefits!
What it means?
The rapid muscle glycogen depletion that occurs during a CAR.O.L intense ride sets in motion two important metabolic events that persist into recovery:
Activation of signaling pathways: Along with glycogen depletion comes the release of a glycogen-bound enzyme called AMPK. The activation of AMPK turns on an important signaling cascade that will eventually lead to more mitochondria. More on that next time!
Activation of transporter proteins: Following CAR.O.L sprints muscle glycogen stores need to be replenished. Glycogen synthesis requires bringing glucose from the blood stream into the muscle cell via a transporter protein known as GLUT-4. Increased GLUT-4 transporter protein activity persists for up to 24 to 48 hours post-exercise. This metabolic event has tremendous implications for those trying to manage their blood sugar levels.
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