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CAROL Bike and muscle glycogen: the facts

CAROL Bike's short maximum-intensity sprint workouts are the most efficient way to deplete glycogen and improve your aerobic capacity—but how do they work?

03 Jul 2022


What is muscle glycogen?

Glycogen is a stored form of carbohydrate found in skeletal muscle—that needs a constant supply of energy. The body’s go-to for that energy source is Adenosine triphosphate (ATP).

ATP is essential for repeated muscle contraction, but there's not a lot of it. So when your ATP runs out during high-intensity exercise, your body looks for glycogen. And because it's stored within the muscle, it's right there when your body needs it most.

What is muscle glycogen depletion?

Our body can store enough glycogen to power up to 15 seconds of additional exercise. After the body uses all of the glycogen, we say it is “depleted.”

And when the glycogen runs out, it stimulates molecular changes that tell your body to work harder. It's simple human evolution – the “fight or flight” mechanism – which is triggered at the point of exhaustion, making your body use all of its glycogen as fuel.

What happens to muscle glycogen levels during CAROL rides?

CAROL workouts are all about short “supra-maximal” sprints. Put simply: your body works beyond its maximal aerobic capacity for very short durations.

The real magic of CAROL Bike is in its 2x 20-second sprints—and what happens in-between. Research shows with this frequency and duration of sprints that the maximal rate of glycogen breakdown is achieved.

A CAROL Bike intense ride kicks off two important metabolic events that carry on while you recover:

Activation of signaling pathways: Glycogen depletion triggers the release of a glycogen-bound enzyme called AMPK. That switches on an important signaling cascade that gets the cells more active.

Activation of transporter proteins: After CAROL Bike sprints muscle glycogen stores need to be replenished. That means getting glucose from the bloodstream into the muscle cell, via a transporter protein known as GLUT-4—which stays active for up to 48 hours after exercise. And it's great for your blood sugar levels, too.

In short, you only need really short sprints to maximize glycogen breakdown. Which means simply, CAROL Bike is the quickest, most efficient way to deplete glycogen and improve your aerobic capacity.

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