CYCLING PERFORMANCE TIPS
J Appl Physiol. 2008 Jul;105(1):7-13. Epub 2008 May 8
Pedersen DJ, Lessard SJ, Coffey VG, Churchley EG, Wootton AM, Ng T, Watt MJ, Hawley JA.
School of Medical Sciences, RMIT University, Bundoora 3083, Victoria, Australia
We determined the effect of coingestion of caffeine (Caff) with carbohydrate (CHO)
on rates of muscle glycogen resynthesis during recovery from exhaustive exercise
in seven trained subjects who completed two experimental trials in a randomized,
double-blind crossover design. The evening before an experiment subjects
performed intermittent exhaustive cycling and then consumed a low-CHO meal.
The next morning subjects rode until volitional fatigue. On completion of this ride
subjects consumed either CHO [4 g/kg body mass (BM)] or the same amount of
CHO + Caff (8 mg/kg BM*) during 4 h of passive recovery. Muscle biopsies
and blood samples were taken at regular intervals throughout recovery.
Muscle glycogen levels were similar at exhaustion [ approximately 75 mmol/kg dry wt (dw)]
and increased by a similar amount ( approximately 80%) after
1 h of recovery (133 +/- 37.8 vs. 149 +/- 48 mmol/kg dw for CHO and Caff, respectively).
After 4 h of recovery Caff resulted in higher glycogen
accumulation (313 +/- 69 vs. 234 +/- 50 mmol/kg dw, P < 0.001). Accordingly,
the overall rate of resynthesis for the 4-h recovery period was 66% higher in Caff
compared with CHO (57.7 +/- 18.5 vs. 38.0 +/- 7.7 mmol x kg dw(-1) x h(-1), P < 0.05).
After 1 h of recovery plasma Caff levels had increased to 31 +/- 11 microM (P < 0.001)
and at the end of the recovery reached 77 +/- 11 microM (P < 0.001) with Caff.
Phosphorylation of CaMK(Thr286) was similar after exercise and after 1 h of
recovery, but after 4 h CaMK(Thr286) phosphorylation was higher in Caff than CHO (P < 0.05).
Phosphorylation of AMP-activated protein kinase (AMPK)(Thr172) and Akt(Ser473) was
similar for both treatments at all time points. We provide the first evidence
that in trained subjects coingestion of large amounts of Caff (8 mg/kg BM) with
CHO has an additive effect on rates of postexercise muscle glycogen accumulation
compared with consumption of CHO alone.
A 7 oz cup of coffee has the following caffeine (mg) amounts, according to Bunker and McWilliams in J. Am. Diet. 74:28-32, 1979:
Coca-Cola Classic contains 2.83 mgs of caffeine per fluid ounce (or about 36 mg in
a 12 ounce can)