By Dwayne N. Jackson, Ph.D.
90% of North Americans enjoy a shot of caffeine (in one form or another) to wake up the mind first thing in the morning or to overcome afternoon sleepiness. However research over the past several years has shown that caffeine is much more than just a jolt of energy to the brain. In fact, caffeine works in the brain (as stimulant) and in the body to promote potent increases in training intensity and volume. Hence, you will find caffeine in most supplements marketed to increase focus, energy, and athletic performance. Caffeine’s ergogenic effects are so remarkable that many sports governing bodies have strict limits for its use in their athletes.
The basics behind caffeine’s effects in the brain and body
In the brain: Caffeine rapidly goes to work in the central nervous system (CNS; aka the brain), as such caffeine’s stimulant effects can be felt soon after ingestion (within 30 min). The brain stimulating effect of caffeine is mainly the result of its adenosine blocking actions in the CNS. Normally, adenosine binds to nerve cells in the brain to slow down nerve activity (which makes you mellow). However, with a dose of caffeine on board, adenosine’s actions are blunted and nerve cells become hyperactive. Nerve hyperactivity is an environment that the pituitary perceives as an emergency, which promotes the release of noradrenaline, adrenaline, and dopamine— giving the user a feeling of energy, wakefulness, and well-being.
In the body: Caffeine modifies the actions of several enzymes. One in particular, called phosphodiesterase (PDE), is inhibited by caffeine. In cells, PDE works to break down cyclic adenosine monophosphate (cAMP), which is a very important cell signaling substance called a second messenger. Overall, the blunting of PDE allows cAMP to build up in the body, which intensifies and prolongs the effects of energizing neurotransmitters and hormones like adrenaline and noradrenaline.
Five science backed ergogenic properties of caffeine supplementation
1) Energy Booster
Although caffeine is a CNS stimulant, its effects on energy levels go far beyond its energetic buzz. For example, a study published in the Scandinavian Journal of Medicine and Science in Sports illustrated that preworkout caffeine supplementation dampens perceived exertion during and after exercise by almost 6% compared with a placebo. This effect of caffeine has been shown to improve endurance in aerobic and anaerobic sports. Your aerobic workouts will benefit from increased free fatty acid mobilization, because they get used to fuel extended performances, which improves time to exhaustion. For short duration anaerobic performances (like weight training and power sports) scientists speculate that the caffeine induced increase in dopamine signaling in the brain promotes increased time to exhaustion. All in all, these data illustrate that preworkout caffeine supplementation promotes higher intensity and volume in your workouts and sports performances.
In a study published in the International Journal of Sport Nutrition and Exercise Metabolism researchers reported that pre-workout caffeine can overcome poor workout performance due to sleep deprivation (something that we all deal with from time to time). In this study, sleep deprivation led to large decreases in total workout load; however, sleep deprived subjects who took caffeine performed as well as those who were well rested. Notably, non-sleep-deprived individuals who received caffeine performed better than all groups. Furthermore, caffeine ingestion boosted testosterone levels pre- and post-workout in non-sleep-deprived subjects. Unfortunately, there was an increase in catabolic cortisol levels associated with caffeine ingestion, which was greatest in sleep-deprived subjects. However, by digging a little deeper into the data (and doing a little math) the hormonal effects of caffeine supplementation resulted in a net anabolic effect in those who had regular sleep cycles.
2) Strength Enhancer
A recent study published in the Journal of Strength and Conditioning demonstrated that caffeine ingestion an hour prior to intense bicep training (to failure) significantly increased training volume. As well, in other research published in the same journal it was reported that taking caffeine one hour before training increased bench press 1 RM strength better than a placebo. In terms of lower body strength, an earlier study reported that caffeine supplementation increased knee extension and flexion power and strength in elite athletes.
3) Fatloss Enhancer
Ingestion of caffeine prior to low intensity aerobic exercise has been scientifically shown to boost lipolysis (fat burning). This significant fat burning effect is based on two scientifically known mechanisms. First, there is a synergistic increase in norepinephrine (noradrenaline) and epinephrine (adrenaline) release associated with the combination of exercise and caffeine supplementation. Norepinephrine is a key regulator of fatty acid release from fat cells into the circulation to be burned for energy. Second, caffeine competes with adenosine on adenosine receptors in fat cells. Under normal conditions, adenosine binds to fat cells and decreases the release of fatty acids. Therefore, taking caffeine blocks this inhibitory effect of adenosine on fatty acid release, resulting in greater fat mobilization and availability for metabolism.
4) Recovery Booster
Believe it or not, there are alleged benefits to taking caffeine post-exercise. In an article published in the Journal of Applied Physiology, it was reported that high dose postworkout caffeine supplementation combined with ingestion of fast sugars (like dextrose) results in 66% greater glycogen repletion than carbs alone. In fact, the authors concluded that the augmented rate of glycogen repletion observed in their study was the highest ever reported in humans under normal physiological conditions. The scientists also noted that throughout a 4h recovery period, those who ingested caffeine with carbohydrate had much higher levels of insulin and blood glucose, a potent signal for anabolic drive.
5) Pain reliever
In an article published in the Journal of Strength and Conditioning Research, researchers from the University of Rhode Island reported that athletes who took caffeine before resistance training had significant immediate reductions in postexercise pain. As well, subjects reported robust decreases in delayed-onset muscle soreness (DOMS) days after training. Along similar lines, in a recent double blind placebo controlled study from the University of Georgia it was found that caffeine ingestion (approximately 300 mg) before maximal voluntary isometric contraction reduced muscular pain intensity by almost 50%!
It is hypothesized that dramatic decreases in muscular pain are due to caffeine’s ability to block adenosine receptors in the brain and spinal cord that are involved in pain processing and perception. To put this finding in perspective, a study concluded that the powerful nonsteroidal anti-inflammatory (NSAID) and analgesic drug Naproxen produced only a 30% reduction in postexercise muscle soreness.
Based on the scientific evidence there are a few facts you must know before taking caffeine to enhance your workouts:
- More is not better; in fact (as with most stimulants) the benefits of caffeine diminish if more than an optimal dose is taken. In science we call this the inverted U effect.
- Caffeine can dehydrate you (it is a diuretic), therefore you must increase your water consumption when taking it.
- Caffeine has a relatively long half-life of 6 hours. This means that if you drink a large coffee (with about 200 mg of caffeine) at 6 pm before you workout, you will have 100 mg still active in your body at midnight. This can severely affect your sleep cycle–and sleep is of primary importance to strength and muscular gains.
- Caffeine is addictive! Use it in moderation and do not use it to make up for poor sleep habits.
SIDE BAR 2
How to use caffeine:
Base on the literature, one thing is clear—you can reap all the benefits of caffeine supplementation by taking it an hour before working out. However, the dose of caffeine needed to produce an ergogenic effect is not carved in stone (i.e., single effective doses range from 200-700mg).
If you have never consumed caffeine, start with the lowest dose and work up accordingly. If you exhibit symptoms like shaking, nervousness, heart palpitations, or anxiety then you have taken too much.
For optimal results:
2 equal daily doses at 100-300 mg each
Take one dose upon waking and the other 1-hour before training.
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