When eight trained bodybuilders did arm curls with heavy weights, their muscles used up a bit of stored sugar—12% after one round and 24% after three rounds—showing that even short, intense...

When eight trained bodybuilders did arm curls with heavy weights, their muscles made more lactic acid the more sets they did — which means their bodies were working so hard they had to rely on a fast, oxygen-free energy system.

When eight trained bodybuilders did heavy arm curls, their muscle energy stores dropped a lot after just one set and still stayed low after three sets, showing their muscles were burning through quick energy fast.

Glycogen depletion during resistance training is negligible in non-fasted individuals performing ≤10 sets per muscle group per session.

Typical resistance training sessions deplete muscle glycogen by no more than 40%, even under high-volume conditions.

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.