Once a banned substance, caffeine is now one of the only legal stimulants allowed for use in competitive sport. In a recent study, over two-thirds of tested Olympic athletes tested positive for caffeine:  Simply put, caffeine is the most popular drug in sports.
How Caffeine Works:
Caffeine has been scientifically proven to increase the number of fatty acids circulating in the bloodstream. This ergogenic property means that muscles can absorb and burn fat for fuel allowing the body to save precious glycogen stores until the end of a workout when everything else is depleted. This is called “glycogen sparing.” The longer you can keep your glycogen stores topped off the longer you can delay muscle fatigue -- and the brain is a muscle, so caffeine delays mental fatigues as well. Caffeine also increases the amount of adrenaline in the body. When adrenaline is dumped into the system a rush of glucose and oxygen is flushed into the muscles. At the same time caffeine increases heart rate and improves blood flow throughout the body. So now there is extra oxygen in the body, and more blood flowing. Put this together and you’re at an advantage, whether it’s athletically, or just trying to stay awake, alert and focused in life.
Caffeine is most effective used before and during endurance events. During long events using caffeine before fatigue sets in, will delay digging into the glycogen stores. For example, during a marathon, ingesting caffeine releases pain-reducing endorphins that delay physical and mental fatigues. Caffeine also boosts power in the short term by reducing the burning sensation felt in the muscles as a result of lactic acid. Lactic acid builds up in the muscles as glycogen is depleted. If you can reduce the amount you need to dig into your glycogen reserves, you also reduce the pain associated with burning that fuel. In a 2009 University of Illinois study found that 300mg of caffeine taken prior to a workout significantly reduced the burning feeling in athletes.
Caffeine is a drug. That means, the more you use it, the more your body adapts to it and the effects of using it will reduce over time. One cup of coffee in the morning will not habituate you, but if you drink in excess of 5 cups a day, you will lose the athletic advantages caffeine can provide. The other thing to note is that the body will habituate differently to different forms of caffeine. If you drink coffee based caffeine you may not be habituated to green tea or yerba mate. Ideally you want to ingest 2- 3mg of caffeine per kilogram of body weight 30 minutes -1 hour prior to workout. Caffeine takes 30-45 minutes to absorb into the bloodstream and have effects. A University of Exeter study found that athletes who consumed caffeine one-hour prior to workouts felt more able to invest in a hard effort. “They would put more work into the training session, and when the session was finished, in the presence of the caffeinated drink, they were more psychologically ready to go again.” said Michael Duncan, a senior lecturer in Sport Science. During exercise caffeine use should be limited toward the end of a workout, but before the body has to begin dipping into glycogen stores. This translates to the last 1 hour of a long 3+ hour ride. Or if you are a triathlete or ultra runner, using caffeine evenly throughout the second half of a multi-sport workout or run. The first part of the workout should be caffeinated by a pre-workout drink like Vega Pre-Workout, First Endurance Pre-Race or X2 Performance. NOTE: As with all nutrition, it is important to test them before using them on race day. Every body and gut are different and react differently to products depending on sensitivity.