Does cutting carbohydrate after a double add signal?

Nine men ran 8 × 5 min at 85% VO2peak in the morning and again in the afternoon, 3.5 h between sessions, under three diets: high carbohydrate (HCHO, about 12 g/kg, energy availability about 60 kcal/kg fat-free mass), reduced carbohydrate with high fat (LCHF, about 3 g/kg, about 60 kcal/kg) and reduced carbohydrate with reduced energy (LCAL, about 3 g/kg, about 20 kcal/kg).

Glycogen fell to about 200 mmol/kg dry weight straight after the afternoon session in all three arms, then stood at 171, 194 and 316 mmol/kg dry weight 17 h later, lower in both restricted arms than in HCHO.

The signalling readouts rose with exercise and showed comparable responses across arms. βCTX after exercise was lower in HCHO than in the other two, and the exercise rise in IL-6 was larger in LCAL than in the other two.

The authors conclude that, with glycogen kept at 200-350 mmol/kg dry weight, restricting carbohydrate and energy for under a day after exercise does not add to these signals, while carbohydrate around the sessions blunts a marker of bone resorption.

Our reading: useful against the idea that restriction of this depth after a double buys extra signal at the time points sampled, and it fits the idea that a low glycogen threshold matters more than the restriction itself. It does not show what happens over weeks.