"Caffeine Boosts Muscle Rebound After Exercise"

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Kenny Croxdale
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"Caffeine Boosts Muscle Rebound After Exercise"

Post by Kenny Croxdale » Sat Jul 05, 2008 10:24 am

This may be of interest to some readers.
Here is some more interesting information on caffeine. It was posted on the Supertraining Message Board by:

Ralph Giarnella MD
Southington Ct USA

Caffeine Boosts Muscle Rebound After Exercise

By Crystal Phend, Staff Writer, MedPage Today
Published: July 02, 2008
Reviewed by Zalman S. Agus, MD; Emeritus Professor
University of Pennsylvania School of Medicine.

BUNDOORA, Australia, July 2 -- Caffeine may help muscles recover quickly after a major workout or competition, a small trial showed.

Muscles regained 66% more glycogen -- their primary fuel -- in the four hours after intense exercise when athletes took the equivalent of five or six cups of coffee with carbohydrates than when they ate carbohydrates alone (P0.05), reported John A. Hawley, Ph.D., of the Royal Melbourne Institute of Technology University here, and colleagues.

Caffeine normally impairs glucose metabolism during rest in nonathletes, but the opposite appeared to be true after exercise in endurance-trained athletes, they said online in the Journal of Applied Physiology.
Action Points

Explain to interested patients that the study looked at trained athletes taking in large quantities of caffeine after intense exercise, which may differ from the average routine.

Caution patients that further study would be needed to know if lower doses of caffeine would have the same effects.
The rate of glycogen recovery with caffeine was the highest ever reported for humans under real life conditions, the researchers noted.

However, further research is needed to see if smaller doses could be as effective because caffeine can disturb sleep and cause jitteriness, they said.

Dr. Hawley's group studied seven endurance-trained cyclists and triathletes in the randomized, double-blind trial. The evening before an experiment, they came in to the laboratory to cycle until exhausted then ate a low-carbohydrate dinner.

The next morning subjects again rode until fatigued to maximally deplete muscle glycogen stores, mimicking race conditions.

They were then randomized to consume carbohydrates -- sports bars, gels, and sports drinks conforming with current sports nutrition guidelines -- alone or with 8 mg of caffeine per kg of body weight during four hours of passive recovery.

The same experiment was repeated about 10 days later with the opposite randomization. Participants did not have a caffeine habit and did not eat or drink caffeine-containing substances for two days before the trials.

Blood glucose levels increased in both groups when they ate after exercising. Glucose concentrations gradually decreased over the next 60 to 90 minutes during recovery with carbohydrates alone (P0.05) but not with caffeine, which was associated with higher levels at three and four hours as well (P0.05 versus levels at exhaustion).

After exercise, muscle glycogen levels were depleted similarly between groups (74 versus 76 mmol/kg dry weight for control and caffeine, respectively) and recovered to a similar degree after one hour of recovery (133 versus 149 mmol/kg dry weight).

However, caffeine intake boosted glycogen accumulation over the next three hours such that glycogen levels were significantly higher at the end of the four-hour recovery period (313 versus 234 mmol/kg dry weight, P0.001) for a higher overall resynthesis rate (57.7 versus 38.0 mmol/kg dry weight per hour, P0.05).

The authors wrote that "the overall (4 h) rate of resynthesis observed in the present investigation with caffeine ingestion is, to the best of our knowledge, the highest reported for human subjects under physiological conditions."

Muscle metabolites showed no impact from the addition of caffeine during recovery, but signaling proteins thought to play roles in skeletal muscle glucose transport were higher with caffeine at the end of the recovery period for phosphorylation of CAMKThr286 (P0.05) and AktSer473 (P=0.06).

The study was supported by a research grant from GlaxoSmithKline. Dr. Hawley made no financial disclosures.

Primary source: Journal of Applied Physiology
Source reference:
Pedersen DJ, et al "High rates of muscle glycogen resynthesis after exhaustive exercise when carbohydrate is co-ingested with caffeine" J Appl Physiol 2008.

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Post by WSUdj_ExMet » Sat Jul 05, 2008 12:36 pm

This is very interesting. The only reason I can think of why caffeine might have this effect is the increased rate of absorption during digestion. Although this is still controversial. While caffeine speeds gastric emptying and sympathetic response in the small intestine, its diuretic capabilities eliminate water needed for digestion.

Possibly by enhancing absorption of carbohydrates, more quickly go into glycogen storage... I don't know, too many factors here!

I would like to see this study repeated under larger sample size to see further effects. This has huge benefits for endurance athletes! Increasing glycogen stores has proved difficult in past research since carb loading isn't always beneficial and I'm not sure of too many other ways (besides training) to achieve increased glycogen.

Great article find!

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