Caffeine is one of the oldest and most accessible performance enhancing aids. It is a metabolic stimulant that affects the central nervous system and decreases the perception of fatigue; studies suggest that caffeine may even enhance muscle contractions. Fat is known to slow sugar absorption and digestion, allowing you to feel satiated longer and have stable energy release instead of a spike. A benefit of caffeine is that it increases fatty acids in the blood, thus reducing the reliance on limited glycogen stores in the muscles. Glycogen is the body’s energy source and when it is depleted, the body is forced to slow down or stop.
Over the past 20 years, numerous studies of caffeine’s effects have produced various contradictions, though most have produced auspicious results for endurance athletes. However, most studies have shown that caffeine is only beneficial for intense events lasting an hour or longer when 300-600 milligrams (two to three cups of coffee) are consumed 45 minutes to an hour before the start of a race or workout. If you are an athlete that drinks coffee in the morning on most or all days, it would be a benefit to continue that habit before a race because otherwise you’ll be in a cranky fit of withdrawal. Whether or not it causes a complex chemical change in the muscles that stimulates more forceful contractions has yet to be confirmed.
The most substantial perk to consuming caffeine is that it simply spares muscle glycogen allowing an athlete to maintain a fast pace for a longer time as it conserves precious fuel. Another beneficial effect of this stimulant is one that doesn’t influence performance, rather it assists in recovery. Scientists are finding that consuming a moderate amount of caffeine with your post-workout meal increases the rate of carbohydrate assimilation. What this means is that when your muscles are needing to be replenished, caffeine will deliver the nutrients and replace glycogen faster. Beware that caffeine inhibits calcium and iron metabolism.
Having one cup of coffee does not execute its diuretic effect on frequent users. Coffee drinkers absorb the fluid just as you would a drink sans caffeine as long as the caffeine content is limited to around 180 mg. Most studies find that 1.4-2.8 milligrams of caffeine per pound of body weight taken an hour before exercise benefits most subjects. For athletes without a caffeine tolerance, it may bring on a few unfavorable side effects such as anxiety, the jitters, gastrointestinal cramps, diarrhea, and nausea, though studies suggest that the benefits are more pronounced in non-coffee drinkers than for regular users.
My conclusion is that a modest amount of caffeine taken before a long workout or race is, at least, slightly beneficial and worth practicing. It’s not illegal, it does not set you apart unfairly and it’s rather enjoyable. Coffee is the first thing I think about in the morning and creates just enough excitement for me to get out of bed after hitting the snooze button 2 (or 5) times.