REF-059 · Pedersen et al., 2008 · Journal of Applied Physiology, Vol. · Paper

Carbohydrate Plus Caffeine Increases Glycogen Resynthesis by 66%

Blimited evidenceMeasured on trained to highly trained athletesWritten before October 2026, being re-checked

Participants

n=7 trained subjects, two trials in a randomized, double-blind crossover. The evening before: intermittent exhaustive cycling and a low-carbohydrate meal. Next morning: ride to volitional fatigue, then 4 h of passive recovery ingesting either carbohydrate (CHO, 4 g/kg body mass) or the same CHO plus caffeine (8 mg/kg body mass). Biopsies and blood samples at intervals through recovery.

Protocol

Randomized, double-blind crossover: seven trained subjects, two experimental trials (from the abstract).
Evening before: intermittent exhaustive cycling, then a low-CHO meal; next morning: ride to volitional fatigue.
Then 4 h of passive recovery ingesting CHO (4 g/kg body mass) or the same CHO + caffeine (8 mg/kg body mass).
Measures: muscle biopsies and blood samples at regular intervals through recovery (muscle glycogen, plasma caffeine, CaMK, AMPK and Akt phosphorylation).

Overview

Pedersen et al. tested whether a large caffeine dose taken with post-exercise carbohydrate changes muscle glycogen resynthesis. Glycogen at exhaustion was similar (~75 mmol/kg dry weight) and rose by a similar ~80% in the first hour (133 ± 37.8 vs 149 ± 48 mmol/kg dw for CHO and CHO+caffeine).

After 4 h, glycogen was higher with caffeine: 313 ± 69 vs 234 ± 50 mmol/kg dw (P < 0.001), so the overall 4-h resynthesis rate was 66% higher (57.7 ± 18.5 vs 38.0 ± 7.7 mmol·kg dw⁻¹·h⁻¹, P < 0.05). Plasma caffeine reached 31 ± 11 μM at 1 h and 77 ± 11 μM at 4 h. CaMK(Thr286) phosphorylation was higher with caffeine at 4 h; AMPK and Akt phosphorylation did not differ.

The authors describe this as the first evidence that co-ingesting large amounts of caffeine with CHO adds to post-exercise glycogen accumulation in trained subjects.

Key Findings

Muscle glycogen after 4 h: 313 ± 69 (CHO + caffeine) vs 234 ± 50 mmol/kg dw (CHO alone), P < 0.001
4-h resynthesis rate: 57.7 ± 18.5 vs 38.0 ± 7.7 mmol·kg dw⁻¹·h⁻¹ — 66% higher with caffeine
Caffeine dose: 8 mg/kg body mass (a very large dose); CHO 4 g/kg over 4 h
No difference at 1 h; the divergence appeared between 1 and 4 h
Signalling: higher CaMK phosphorylation at 4 h with caffeine; AMPK and Akt unchanged

Practical Application

In 7 trained subjects, adding 8 mg/kg of caffeine to 4 g/kg of carbohydrate over 4 h of recovery raised muscle glycogen to 313 vs 234 mmol/kg dw, a 66% higher resynthesis rate — a real but single-study effect obtained with a very high caffeine dose, relevant only when the next hard session is hours, not a day, away.
Not from this paper; the base's own practice: when two hard sessions fall within the same day, a normal caffeine dose (a strong coffee or two) with the recovery carbohydrate is a reasonable, cheap addition; we do not prescribe the study's 8 mg/kg, and we keep caffeine out of evening recovery for sleep's sake.
Inference, not tested here: the effect appeared after the first hour, so a caffeine + carbohydrate strategy is about the 2-4-h window, not the first 30 min.

Limitations

A 66% increase in glycogen resynthesis is a large single-study effect in a small sample and has not been consistently replicated; treat the magnitude as provisional.
The caffeine dose used in this protocol is high (8 mg/kg, well above a habitual coffee), with sleep consequences that matter more than the resynthesis if the session is in the evening.
Glycogen resynthesis over hours is a surrogate — no performance outcome in a subsequent session was measured.
Relevant only when the next hard session is within hours; with a normal recovery day, total carbohydrate intake settles the matter and caffeine adds nothing.
Trained subjects, laboratory conditions, 2008; habitual caffeine use, which modifies the response, was not the variable of interest.
How this entry was checked and changed
Why this level

regraded 2026-09-27 from A: crossover, n=7

Content correction 2026-09-27
Caffeine dose "~300 mg (3 cups coffee)" -> 8 mg/kg body mass (abstract); the CHO dose (4 g/kg) added.
"234 / 313 mmol/kg resynthesis rate" -> these are 4-h glycogen concentrations; the rates were 38.0 vs 57.7 mmol·kg dw⁻¹·h⁻¹.
Removed the unsourced mechanism "caffeine potentiates insulin secretion and glucose uptake" (the abstract reports CaMK phosphorylation, with AMPK and Akt unchanged) and the "80-100 g", "300 mg tablet", "within 30 minutes", "8-24 h" prescriptions; Level A -> B (crossover, n=7).
2026-09-28: added Protocol from the abstract (Europe PMC PMID 18467543).