Ahh Caffeine – The drug consumed all around the world and more so in the United States than any other country. Today I’m going to answer the question – What is caffeine, how can it help us achieve our fitness goals, and how do we dose it correctly depending on our own genetics?

How does caffeine work?

To understand how caffeine works in the body – we must understand what adenosine is. Adenosine is a molecule that is responsible for causing drowsiness and signaling to our bodies that its time to sleep. This occurs when the adenosine molecules attaches itself to its own adenosine receptors. Whenever someone consumes caffeine, the caffeine molecule binds to the adenosine receptors –  hijacking the adenosine molecules rightful place in the brain causing feelings of alertness, improved focus and faster reflexes.


  • Adenosine molecule causes drowsiness when it binds to adenosine receptor.
  • When caffeine is ingested – caffeine molecule binds to adenosine receptor hijacking adenosine’s rightful place.
  • This promotes the opposite feeling – alertness, improved focus, faster reflexes.

How can caffeine help us achieve our fitness goals?
The reason we are so interested in caffeine is because the effects are not just cognitive, but physical as well– when consumed before a workout, you will see an increase in endurance and strength enabling you to train harder and longer.
Studies show an average of 12 percent increase in performance with more benefits noticed during endurance exercise than shorter high-intensity exercise. Caffeine also mitigates the effects of perceived pain by about 6 percent giving you that extra push to complete that last rep.
These physical effects occur when individuals consume between 3-6mg caffeine/kg bodyweight or between 1.5mg – 3mg/ lb bodyweight. So for a 150lb person – between 225mg to 450mg caffeine.


  • 12 percent increase in performance with more benefits noticed during endurance exercise.
  • Perceived Pain lowered 6% giving you courage to grind out that last rep.
  • Dose is HIGHLY individual but the sweet spot for most people seems to be between 3-6mg/kg bodyweight.

How do we dose it correctly depending on our own genetics
Caffeine CAN be very helpful in achieving fitness related goals and getting into the shape we all want if dosed correctly for the individual taking it. Caffeine generally has a half-life between 4 to 6 hours but can last a lot longer or shorter depending on the individual’s ability to metabolize caffeine. This means that a 200-mg caffeine tablet consumed at 12 PM noon will wither down to about 100mg at 6 PM and 50 mg caffeine at 12 AM. That being said: People generally fall into three camps when we talk about caffeine sensitivity/caffeine tolerance.

Hyposensitive – These people process caffeine very quickly and usually need higher doses to get the same effects as someone who has normal sensitivity to caffeine. You might be Hyposensitive if you can consume large quantities of caffeine close to bedtime and not notice any adverse effects on your sleep quality and quantity.

Normal Sensitivity – These people process caffeine at the normal rate. As long as these people consume caffeine early on in the day, between 200mg – 400mg or 2-4 cups of coffee is generally okay and will not lead to sleep disruptions at night.

Hyper-sensitivity – These people process caffeine very slowly and are extremely sensitive to its effects. A cup of coffee containing between 80-120mg in the morning might be the upper limit of what these people can handle. Even that might lead to sleep disruptions. A good alternative is switching to teas which contain half the amount of caffeine.

​Unsure about what levels of caffeine are safe for you? It’s something that you have to master through trial and error but the experienced personal trainers at Houston Personal Training can help you figure out a dosage right for you.

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