Friday, 4 July 2008

Caffeine and carbohydrate coingested can speed up muscle glycogen resynthesis

A very interesting paper from Prof. John Hawley's lab was recently published on the Journal of Applied Physiology suggesting that large amounts of Caffeine (8mg/kg of body mass) together with CHO can help in replenishing glycogen stores in well trained individuals after exhaustive exercise.

The abstract is here:

J Appl Physiol (May 8, 2008). doi:10.1152/japplphysiol.01121.2007
This Article
Submitted on October 18, 2007
Accepted on April 30, 2008

HIGH RATES OF MUSCLE GLYCOGEN RESYNTHESIS AFTER EXHAUSTIVE EXERCISE WHEN CARBOHYDRATE IS CO-INGESTED WITH CAFFEINE
David J Pedersen1, Sarah J Lessard2, Vernon G Coffey3, Emmanuel G Churchley4, Andrew M Wootton4, They Ng5, Matthew J Watt6, and John A. Hawley7*
1 Diabetes and Obesity, Garvan Institute of Medical Research, Sydney, New South Wales, Australia
2 School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia
3 exercise Metabolism Group, RMIT University, Melbourne, Victoria, Australia
4 Melbourne, Victoria, Australia; School of Medical Sciences, RMIT University, Melbourne, Victoria, Australia
5 School of Medical Sciences, RMIT University, Melbourne, Victoria, Australia
6 Protein Chemistry and Metabolism, St. Vincent's Institute of Medical Research, Fitzroy, Victoria, Australia
7 Exercise Metabolism Group, School of Medical Sciences, RMIT University, Bundoora, Victoria, Australia

We determined the effects of the co-ingestion of caffeine with carbohydrate on rates of muscle glycogen resynthesis during recovery from exhaustive exercise in 7 trained subjects who completed 2 experimental trials in a randomized, double-blind crossover design. Prior to an experiment subjects performed exhaustive cycling and consumed a low-carbohydrate diet. The following morning subjects reported to the lab and rode until volitional fatigue. Upon completion of this ride subjects consumed either carbohydrate (CHO; 4 g.kg BM-1) or carbohydrate plus caffeine (CAFF, 8 mg.kg BM-1) during 4 h of passive recovery. Muscle and blood samples were taken throughout recovery. Muscle glycogen levels were similar at exhaustion and increased by a similar amount after 1 h of recovery. After 4 h of recovery CAFF resulted in higher glycogen accumulation (313 ± 69 vs. 234 ± 50 mmol±kg- d.w, P<0.001). The overall rate of resynthesis for the 4 h recovery period was 66% higher in CAFF compared to CHO (57.7 ± 18.5 vs. 38.0 ± 7.7 mmol±kg-1 d.w.h-1, P < 0.05). Phosphorylation of CAMKThr286 was similar post-exercise and after 1 h of recovery but after 4 h CAMKThr286 phosphorylation was higher in CAFF than CHO (P<0.05). Phosphorylation of AMPKThr172 and AktSer473 was similar for both treatments at all time points. We provide the first evidence that in trained subjects, the coingestion of large amounts of caffeine with carbohydrate has an additive effect on rates on post-exercise muscle glycogen accumulation compared to when carbohydrate alone is consumed.

Very interesting, however, such a high dose of caffeine might make sleep a bit difficult!

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