Caffeine comes in a variety of ways but do you know what it does to the body?

some popular branded caffeinated drinks

Many of us rely on caffeine day-to-day to give us that much needed boost, whether it is your morning coffee, cup of tea, energy drink or pre-workout before the gym.

So what is caffeine?

Caffeine is a natural compound and acts as a stimulant to the body’s central nervous system which is typically associated with an increase in alertness.

However, the affects will be different for each person and will depend on the amount you usually consume.

coffee beans beside coffee powder on brown wooden board

How much is included in your favourite drink?

Here is a useful table with estimated levels of caffeine in commonly consumed drinks.

DrinkVolumeCaffeine (mg) / Range
Coffee125ml85 / 60-135
Tea150ml32 / 20-45
Soft drinks330ml41 / 26-57
Energy drinks330ml80 / 70-120
Pre-workout supplements10g175 / 150-200
Table 1. Adapted from

So, what's a safe amount to drink?

The US Food and Drug Administration (FDA) recommends that around 400mg of caffeine (4-5 cups of coffee!) a day is safe and not associated with dangerous, negative, or adverse effects.

However, as previously mentioned, the effects will differ from person to person therefore should be tailored to your own body.

In addition, it is important to monitor levels or avoid completely, in some cases. For example, pregnant women or those with arrythmia’s (irregular heartbeats).

Similarly, the FDA has suggested that teens and adolescents avoid caffeine where possible.

What symptoms can occur with over consumption of caffeine?

  • Reduced sleep or insomnia
  • Anxiousness
  • Fast heartbeat
  • Nausea
  • Headaches
  • Decreased mood

It is important to remember that these side effects can be short lived and may be more exaggerated in some people based on their tolerance levels.

The positive side to caffeine...

Caffeine consumption isn’t all negative. In fact, it can be very beneficial in your day-to-day life as well as in sport and performance.

Low (~40mg) to moderate (~300mg) levels were shown to improve

assorted beverage bottles

alertness, vigilance, attention and reaction time which resulted in a significant increase in occupational productivity (McLellan, Cadwell & Lieberman, 2016).

Similarly, caffeine consumption was shown to have positive effects on:

  • Muscular endurance
  • Movement velocity
  • Muscular strength

Due to the reasons stated above, the type of exercise which shows the largest benefits from caffeine use is aerobic exercise.

The recommended dosage is 3-6 mg/kg 30-60 minutes pre-exercise (Guest et al., 2021).

Final thoughts...

It is important to remember that caffeine consumption is safe and it can be utilised to benefit us positively with regards to our day-to-day and sporting lives.

In conclusion, too much (like anything) can cause unwanted side-effects.

Therefore, it is important to monitor your daily consumption – based on your own tolerance...and not Dave who is 10 cups down at 10am!

If you wish any Physiotherpay advice, treatment or have any questions you can ask us by contacting us here Contact - Physioflexx Ayrshire


McLellan, T. M., Caldwell, J. A., & Lieberman, H. R. (2016). A review of caffeine’s effects on cognitive, physical and occupational performance. Neuroscience & Biobehavioral Reviews71, 294-312.

Guest, N. S., VanDusseldorp, T. A., Nelson, M. T., Grgic, J., Schoenfeld, B. J., Jenkins, N. D., ... & Campbell, B. I. (2021). International society of sports nutrition position stand: caffeine and exercise performance. Journal of the International Society of Sports Nutrition18(1), 1-37.

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