Caffeine is one of the most widely used and easily attainable supplements. Generally it is consumed in the form of coffee, tea or other caffeinated drinks. Caffeine, or 1, 3, 7-trimethylxanthine, in its pure state is a neural stimulant (legal) and is often manipulated to improve performance, both mental and physical. ‘Discovered’ in 1819 by Friedlieb Ferdinand Runge, it wasn’t until the work of Costill et al (1978) that caffeine’s benefits came to prominence. Costill’s work was the first to highlight the significant improvements to an athlete’s endurance capabilities and Time to Exhaustion (TTE) following ingestion. And so began Caffeine supplementation.
So how does Caffeine help?
The major benefit of Caffeine ingestion appears to be a change in pain perception. Rate of Perceived Exertion (RPE) is significantly lowered, increasing Work Intensity, Total Work Done (TWD), TTE and ‘voluntary’ exercise maximum. Put simply, exercise feels easier. This occurs due to Caffeine’s affinity with muscle Adenosine receptors. When Adenosine binds with its receptors, the reaction causes an increase in our perception of pain, making work feel harder and increasing the likelihood of the cessation of exercise. Caffeine is known as an Adenosine antagonist i.e. it works against Adenosine; binding to the receptors in place of Adenosine, preventing an elevation of pain levels. Caffeine, therefore, does not alter exercise difficulty or intensity, but our mental state/perception of pain.
As we have just discussed, Caffeine is, therefore, a potent Central Nervous System (CNS) stimulant and has been found to increase mental alertness, cognitive processing and decision making, particularly when in a state of fatigue or extreme stress. Research on elite military personnel, found that following prolonged sleep deprivation, caffeine ingestion led to greater performance both mentally and physically. For those of you who enjoy ultra-marathons, iron man races and triathlons this is an interesting area of study, suggesting that exercise intensity may well be prolonged following caffeine ingestion.
Supplementation has also been linked to an increased Catecholamine (Adrenaline) circulation, in turn promoting a greater availability of Free Fatty Acids and, consequently, increased Lipolysis (breakdown of fats for energy) at sub-maximal intensities.
Plasma beta-endorphin levels are also elevated, again lowering pain perception. Finally, Caffeine is believed to increase Calcium availability within the Sarcoplasmic Reticulum, resulting in an increased excitation-contraction capacity at the muscular level. Basically, in theory we will be able to contract muscles more forcefully – a definite bonus when attempting to power up from the bottom of a particularly heavy squat!!
As with most supplements, the answer is not necessarily. Caffeine is without doubt exceptionally beneficial for endurance events (cycling, running), intermittent team sports (Football, Rugby, etc.), intermittent sports (Tennis) and sustained high intensity sprints 60-180s (400m, 800m, etc.). However, research is less conclusive when it comes to Strength and Power athletes. As mentioned previously, Caffeine’s effects upon Calcium availability in the Sarcoplasmic Reticulum (home of the sliding-filament action) theoretically make Caffeine a natural ally to explosive heavy lifting. Studies are, as of present, somewhat contradictory. Many studies have found improved performance, just as many have found no improvement, and a very few have found detrimental effects of ingestion. Studies show an unusual peculiarity, in that Caffeine appears to have a much greater effect upon upper body exercises when compared to lower, and so supplementation for upper body sessions appears beneficial. Similarly, Caffeine appears to have much greater impact upon trained individuals. Those who supplement with Caffeine or regularly consume caffeinated drinks, do not become resistant to the effects of Caffeine over time, however, acute response decreases with continued exposure; lasting ~3hrs in users and ~6hrs in non-users.
If I decide to use Caffeine. How much should I consume?
Current recommendations for dosage lie between 3-6mg.kg, 45-60 minutes prior to exercise. It is not a case with Caffeine that more is better. In fact some research suggests >10mg.kg can be lethal. Whilst that is an extreme case (and a hellish amount of Caffeine to consume) it is worth noting that intake needs to be monitored. Above 6mg.kg has been shown to have no added positive effect on performance and is simply a way of spending more money. As well as becoming less cost efficient, dosages above 6mg.kg have been linked to inhibition of Glycogen Phosphorylase, a key enzyme in glycogen metabolism. In simple terms you will recover more slowly and less efficiently following exercise, glycogen stores not filled as quickly or fully and subsequent performance inhibited.
Caffeine is believed to be most beneficial when consumed in capsule form. However, if you prefer to consume beverages, then an espresso of ground ‘proper’ coffee offers your best option, containing 107mg per shot. Compare this to instant coffee (60mg.250ml), tea (27mg.250ml) and Red Bull (80mg.250ml) and you can see that consuming the required dosage for body weight could become difficult, requiring upwards of a 1L before required dosages are met.
A study from Bell and Mclellan (2003) has suggested that absorption may be effected by circadian rhythm (biological ‘clock’) and that ingestion in the morning may be more beneficial. This area of research is still in its infancy and so requires further studies before blanket recommendations can be made.
You mentioned that high dosages can be lethal, so is Caffeine safe?
As previously mentioned >10mg.kg can be lethal, so avoid excessive consumption. Caffeine reaction is highly individualised and what is fine for 1 person may be excessive or insufficient for another. Therefore, supplementation should begin at the lowest suggested dose and be altered from there. It is always better to be safe than sorry. Signs of reaction range from dizziness, nausea and headaches to heart palpitations so be aware and stop supplementation if these occur. If you’re unsure always seek medical advice first. Those with Blood Pressure problems, CV diseases or Nervous issues should avoid Caffeine. Outside of these populations supplementation is well researched and offers significant improvements to exercise. Recent research has also dispelled Caffeine as a diuretic, meaning ingestion should not led to dehydration (provided hydration is adequate). Caffeine is a great pre-workout stimulant, more cost effective and easier to consume than many branded pre-workouts and should be strongly considered when undertaking endurance or intermittent activities.
Take Home Points
· Caffeine aids endurance, intermittent sport/team sports and sustained -sprint events
· Caffeine may aid Strength/Power athletes – particularly upper body
· Recommended dosage is 3-6mg.kg, 45-60 minutes prior to exercise
· Capsule form appears most effective
· Start at lowest dosage possible and adjust from there
· Those with Blood Pressure, CV disease or Nervous issues should consult a Doctor before beginning a supplementation regime
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