Glycogen supercompensation

Story

Connected to · 4

synergy · 1

Carbs & Fiber
Glucose enters the muscle fiber through a door called GLUT4, but building that sugar into more glycogen than usual is the work of glycogen synthase. An open door only explains how the sugar gets in; glycogen supercompensation happens because the synthase stays switched on after the glycogen has been used up (Hingst 2018).

cofactor · 1

First half or full
The second half of a full marathon runs on the glycogen in your legs: in endurance events over about 90 minutes, exhaustion usually arrives together with very low muscle glycogen, and starting with more can postpone fatigue by about 20%; in runs of 60 to 90 minutes the extra glycogen goes unused. Eating somewhat more starchy food for a few days before the race is enough to raise glycogen, without starving first and then flooding.

regulates · 1

Muscle
Glycogen supercompensation happens in the muscle that just did the work, not through a whole-body hormone filling every muscle at once. When one leg is exercised until its glycogen runs out and carbohydrate is eaten afterward, only the exercised leg overshoots its old glycogen level; the rested leg stays where it was (Bergström 1966).

contrast · 1

Gut during exercise
These two are often lumped together, but they happen in different places: glycogen supercompensation is synthase inside the muscle staying on after exercise has emptied it; gut trouble during exercise is the stretch before sugar reaches the muscle, involving blood flow, stomach emptying and the two sugar-absorption doors. Do not reduce both to just eating more carbohydrate.

Read full story

Stop 1/4

Only in the muscle that was used

THE SHORT ANSWER

When a muscle has used up its glycogen and you then eat carbohydrate, it stores more than usual, but only in the muscle that just did the work. The switch sits inside the muscle cell itself.

WHO IT'S FORThis is about a muscle that has just been emptied of glycogen; a resting muscle given the same carbohydrate only tops back up to around its usual level.

WHAT IT MEANS FOR YOU

Do not read it as a pre-race menu: how much gets stored depends first on which muscle just worked and was emptied; carbohydrate is only the raw material.

EVIDENCEOPEN 1

Where it stops:It rests on a 1966 one-leg experiment with very few volunteers; its weight comes from the two-leg comparison, and the local effect was later reproduced by other studies.

READ THE ORIGINAL

Glycogen supercompensation means this: once a muscle has used up its glycogen (its store of linked glucose), eating carbohydrate afterward lets it store more glycogen than usual. It sounds like a race-week menu, but what actually happens is local. When people cycle with one leg to exhaustion and then eat carbohydrate, glycogen climbs past its usual level only in the leg that had done the work, not in the leg that rested.

The reason lies inside the muscle cell. After the cell has been emptied, the enzyme that links glucose into glycogen, one unit at a time, stays switched on longer than usual, so the same carbohydrate gets stored past the usual level.

So this is not about what to eat before a race: how much can be stored depends first on which muscle just did the work and was emptied. Carbohydrate is the raw material, but the switch sits in the muscle.

Educational content, not medical advice. See a clinician about your own case.

Back

Glycogen supercompensation

Story

Connected to · 4

synergy · 1

Carbs & Fiber
Glucose enters the muscle fiber through a door called GLUT4, but building that sugar into more glycogen than usual is the work of glycogen synthase. An open door only explains how the sugar gets in; glycogen supercompensation happens because the synthase stays switched on after the glycogen has been used up (Hingst 2018).

cofactor · 1

First half or full
The second half of a full marathon runs on the glycogen in your legs: in endurance events over about 90 minutes, exhaustion usually arrives together with very low muscle glycogen, and starting with more can postpone fatigue by about 20%; in runs of 60 to 90 minutes the extra glycogen goes unused. Eating somewhat more starchy food for a few days before the race is enough to raise glycogen, without starving first and then flooding.

regulates · 1

Muscle
Glycogen supercompensation happens in the muscle that just did the work, not through a whole-body hormone filling every muscle at once. When one leg is exercised until its glycogen runs out and carbohydrate is eaten afterward, only the exercised leg overshoots its old glycogen level; the rested leg stays where it was (Bergström 1966).

contrast · 1

Gut during exercise
These two are often lumped together, but they happen in different places: glycogen supercompensation is synthase inside the muscle staying on after exercise has emptied it; gut trouble during exercise is the stretch before sugar reaches the muscle, involving blood flow, stomach emptying and the two sugar-absorption doors. Do not reduce both to just eating more carbohydrate.

Read full story

Stop 1/4

Only in the muscle that was used

THE SHORT ANSWER

When a muscle has used up its glycogen and you then eat carbohydrate, it stores more than usual, but only in the muscle that just did the work. The switch sits inside the muscle cell itself.

WHO IT'S FORThis is about a muscle that has just been emptied of glycogen; a resting muscle given the same carbohydrate only tops back up to around its usual level.

WHAT IT MEANS FOR YOU

Do not read it as a pre-race menu: how much gets stored depends first on which muscle just worked and was emptied; carbohydrate is only the raw material.

EVIDENCEOPEN 1

Where it stops:It rests on a 1966 one-leg experiment with very few volunteers; its weight comes from the two-leg comparison, and the local effect was later reproduced by other studies.

READ THE ORIGINAL

Glycogen supercompensation means this: once a muscle has used up its glycogen (its store of linked glucose), eating carbohydrate afterward lets it store more glycogen than usual. It sounds like a race-week menu, but what actually happens is local. When people cycle with one leg to exhaustion and then eat carbohydrate, glycogen climbs past its usual level only in the leg that had done the work, not in the leg that rested.

The reason lies inside the muscle cell. After the cell has been emptied, the enzyme that links glucose into glycogen, one unit at a time, stays switched on longer than usual, so the same carbohydrate gets stored past the usual level.

So this is not about what to eat before a race: how much can be stored depends first on which muscle just did the work and was emptied. Carbohydrate is the raw material, but the switch sits in the muscle.

Educational content, not medical advice. See a clinician about your own case.