Even a hard weightlifting session only uses up about 40% of your muscle sugar stores.
Scientific Claim
Typical resistance training sessions deplete muscle glycogen by no more than 40%, even under high-volume conditions.
Original Statement
“The reductions in glycogen stores from a typical strength training session are at most 40%.”
Context Details
Domain
exercise
Population
human
Subject
typical resistance training sessions
Action
deplete
Target
muscle glycogen by no more than 40%
Intervention Details
Evidence from Studies
Supporting (2)
Glycogen resynthesis in skeletal muscle following resistive exercise.
This study had people do a tough leg workout and found their muscles lost about 40-44% of their stored energy (glycogen), which is right around the 40% maximum the claim says happens — so it supports the claim.
The Effect of Carbohydrate Intake on Strength and Resistance Training Performance: A Systematic Review
The study didn’t measure glycogen directly, but it found that even when people did lots of weightlifting, they only needed carbs to perform better if they were really tired or hadn’t eaten — meaning their muscles probably didn’t run out of fuel completely.
Contradicting (1)
Acute effects of resistance exercise on skeletal muscle glycogen depletion: A systematic review and meta‐analysis
The study found that a single workout can drain way more than 40% of your muscle energy stores — sometimes over 70% — especially if you do lots of sets, which goes against the claim that it never goes above 40%.