Caffeine May Interfere With Muscle Building

An online article in the Journal of Sports Science and Medicine by Wu and Lin (vol 9, pp 262-269, 2010) indicates that going heavy on the caffeine before resistance training may be counterproductive.


Experimental method
Ten men performed a workout consisting of 3 sets of 8 exercises. Each set consisted of 10 repetitions of 75% of the weight that could be lifted only once. On one day, the workout was performed an hour after caffeine ingestion and on another day an hour after ingesting a non-caffeinated placebo. The amount of caffeine was 6 mg/kg or about 475 mg for a 175 lb man. That’s about the amount of caffeine in one-and-a-half 16 oz Starbucks Grande coffees or four-and-a-half 8 oz cups of home-brewed coffee. Blood was analyzed at various times for levels of insulin, testosterone, cortisol, growth hormone, glucose, free fatty acid and lactic acid.

Results
As has been observed in previous studies, blood levels of free fatty acids were higher in those who ingested caffeine than in those who did not. That is why caffeine is considered an ergogenic aid (performance enhancer) for endurance sports. Long distance runners often take in caffeine to promote the burning of fats in preference to carbohydrates, allowing the limited store of carbohydrates in the muscle and liver to last longer, sparing the athlete from “hitting the wall’ later in the race.

A result not noted in previous studies was that blood concentration of human growth hormone (HGH) was significantly lower when the subjects had previously ingested caffeine than when they hadn‘t. Since HGH is a muscle-building hormone, caffeine ingestion prior to resistance training can be considered counterproductive.

There were no significant differences in blood levels of insulin, testosterone and cortisol between caffeine and no-caffeine conditions.

Bottom Line
It appears prudent to avoid caffeine consumption for at least 3 hours prior to a resistance training session in order to maximize results. Since the time it take for the body to rid itself of half of ingested caffeine is approximately 5 hours in healthy adults, then excessive caffeine consumption is not recommended, even several hours before a workout.

Coffee and Tea Said to Reduce Diabetes Risk

In its March 2010 issue, the Nutrition Action Healthletter, a publication of the Center for Science in the Public Interest, reported that a review of 18 studies with a total of 450,000 subjects around the world revealed that people who drank 3-4 cups of regular coffee per day had a 25% lower risk of diabetes than people who drank 2 or less cups per day. One might think that this was due to the caffeine content of coffee, but the effect was even stronger for decaffeinated coffee (35% reduced risk). The same quantity of tea had a more moderate effect (20% reduction). As with any cross-sectional study, one must be cautious about concluding cause-and-effect because people who choose to drink coffee or tea may be in some way constitutionally different from people who don't. A longitudinal study will be necessary to determine if people randomly assigned to drink or not drink coffee or tea have different risk of diabetes. In the meantime, this and other studies indicate that moderate consumption of coffee or tea appears beneficial.