Your muscles store sugar (glycogen) to use as quick energy when you lift weights.

Scientific Claim

Muscle glycogen serves as the primary endogenous fuel source for high-intensity resistance exercise.

Original Statement

“The body primarily relies on stored carbohydrates, namely glycogen that is stored in our muscles.”

From video:You need this many carbs to maximize muscle growthbyMenno Henselmans

Context Details

Domain

exercise

Population

human

Subject

muscle glycogen

Action

serves as

Target

primary endogenous fuel source for high-intensity resistance exercise

Intervention Details

Type: exercise

Dosage: strength training sessions

Duration: single session

Evidence from Studies

Supporting (1)

Muscle Glycogen Resynthesis after Short Term, High Intensity Exercise and Resistance Exercise

Narrative Review

1996 Feb

The study shows that during intense workouts like weightlifting, your muscles use up a lot of glycogen (a stored form of sugar), which means glycogen is the main energy source you're burning during those exercises.

Contradicting (1)

The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review

Systematic Review

Human

2022 Feb 18

The study didn’t measure muscle glycogen directly — it just gave people different amounts of carbs and saw if they lifted heavier. Turns out, carbs didn’t help much unless they were already super tired from lots of exercise. So, glycogen might not be the main fuel for most weightlifting.

Similar Assertions

After a short, super-hard workout, your muscles refill their energy stores way faster than after a long, slow one—even if you eat the same amount of carbs.

74%

Even after a really tough weightlifting session, your muscles don’t run out of fuel fast enough to slow you down, and they can refill just fine even if you don’t eat carbs for a while.

73%

Lifting weights refills muscle energy slower than sprinting or HIIT, maybe because you don’t build up as much lactic acid and your muscles get more sore from stretching under load.

73%

Even if your muscles are low on stored sugar (glycogen), your body still builds muscle just as well after lifting weights, as long as you eat enough protein.

72%

Even when eating almost no carbs after a race, athletes who’ve been on a high-fat, low-carb diet for months can still rebuild their muscle sugar stores just as well as those eating lots of carbs.

71%