What is caffeine?Caffeine is a central nervous system stimulant. It is the worlds most used psychoactive drug (1). Caffeine is naturally found in nuts, seeds and plants but you are probably most familiar with it in the coffee bean. Caffeine is effectively a drug that stimulates the central nervous system which produces physiological and psychological responses such as:
- Increased alertness and reduced perception of effort
- Heightened competitiveness
- Reduced fatigue
- Increased heart rate, blood pressure and muscle tension
What does the evidence say?There is strong evidence to back up these claims that caffeine does improve both mental and physical performance. One study looked at the effect of caffeine on endurance exercise. They confirmed the ergogenic aid of caffeine on endurance events, the athletes saw an average increase in performance of 3% (2,3). The evidence doesn't stop at endurance events; caffeine has also been shown to have a positive effect on muscular performance. A massive review study looking at 34 relevant studies concluded that caffeine ingestion improves maximal muscular voluntary contraction and muscular endurance (4). There are a few variables that come into play that will dictate whether you receive a positive effect from a caffeine dose. The first factor is your level of habituation to caffeine. This is based on the fact that you will build a tolerance to caffeine consumption and therefore will need a higher does over time to elicit the same effect. Habituation can interestingly be entirely reset if you abstain from caffeine for a week. So if you feel like you’re not getting the same effects from your morning coffee, try taking a week off. Your level of training will also influence caffeine's impact on the body as someone carrying more lean muscle tissue will require a higher caffeine dose. The diet can even play a role in the uptake of caffeine.
So how much caffeine do you need?In studies of caffeine and performance, it appears the dose that exerts an ergogenic aid is around the 3-9g/kg body weight. So for an 80kg male, they would be looking at a caffeine dose of between 240-720mg a day. Below I have compiled a chart of the comparisons of caffeine levels in the most popular high street drinks. This should make it easy to find out what drinks you can consume to hit your caffeine requirements. Drink I Serving (ml) I Caffeine Content (mg)
- Starbucks - 355ml - 75mg
- Caffe Nero - 355ml - 80mg
- Costa - 355ml - 185mg
- Coca Cola - 330ml - 32mg
- Diet Coke - 330ml - 42mg
- Monster Energy Drink - 473ml - 160mg
- Red Bull - 245ml - 80mg
- Tea - 250ml - 40mg
- UPYOURGAME - 15g - 400mg
Does caffeine dehydrate you?
There is a conception that caffeine and coffee are dehydrating, and this is partially true. It depends on the level of concentration and the caffeine to water ratio. Take for example an expresso. The ratio of caffeine to water is high and it would dehydrate you. A medium mug of coffee wouldn’t on the other hand. Although it has similar levels of caffeine it comes diluted in more liquid which wouldn’t put your water balance in negative.
ConclusionCaffeine is one of those supplements that has a lot of backing from evidence in the scientific community. There is no doubt that it works but will have a different response based on the individual. If you participate in sport or regularly train in the gym and you want that slight edge in your performance, I would highly recommend taking caffeine. How you consume it is up to you, I’m old school, so I work well with just plain coffee, but there are a variety of products on the market that have an equal amount of caffeine. There are many pre-workout supplements on the market you can take that do the job just as well. Just make sure to read the labels to see exactly how much caffeine is inside the product and make sure you’re taking the correct amount of your body composition.