Caffeine Tolerance and Sensitivity

There is nothing like the first sip of coffee or caffeinated beverage in the morning. The caffeine “high” of improved mood, increased focus, sense of more energy, and overall heightened performance is what makes it the world’s most popular drug. For athletes, it is well documented that acute bouts of caffeine consumption have performance enhancing benefits like improved power, aerobic endurance, max strength, and muscular endurance (We have a podcast all about caffeine. Check it out here!)

All these benefits make it very easy to start habitually and chronically consuming caffeine. Chronic caffeine use seems par for the course these days. I mean, who doesn’t start their day with caffeine? Yet, recent research suggests chronic caffeine may cause caffeine tolerance.

 

Caffeine and Your Brain

Caffeine’s effects on the body are primarily due to its role as an adenosine receptor antagonist. Caffeine stops adenosine from being able to bind to adenosine receptors. Adenosine is a hormone responsible for slowing our metabolic processes and making us sleepy. In blocking adenosine binding, caffeine not only blunts these effects, it also triggers the pituitary gland to release adrenaline producing the rush of “energy”.

Overtime, it appears our bodies may adapt to caffeine by creating more adenosine receptors. Studies have shown intakes of 10 mg/kg/bodyweight per day to cause an increase in the number of adenosine binding sites in the brain cortex of rats after just two weeks (1). This would mean over time our same serving of caffeine would be less effective as there are more opportunities for adenosine to bind to receptor sites making us sleepy, even in the presence of caffeine.

 

Caffeine and Performance

If our brain is adapting to our caffeine intake, we would assume the effects we receive from caffeine would decrease overtime. Multiple studies have examined this hypothesis with mixed results. A 2018 by Pickering and Kiely review summarized the finding from four different studies on the effects habitual caffeine use has on caffeine’s performance enhancing benefits. From this research, they conclude habitual caffeine use of 3-6 mg/kg/bodyweight daily may indeed lead to reduced ergogenic effects over time. They also determined this reduced ergogenesis can be offset by increasing one’s caffeine intake on the day of an event.

 

Strategies for Decreasing Caffeine Tolerance

So, what does this mean for us? While there are no clear answers or specific strategies guaranteed to attenuate caffeine tolerance, there are some tentative strategies proposed by researchers, as well as strategies I have found to work well in practice. Here are five ways to manipulate your caffeine intake to avoid creating a tolerance.

Keep Daily Intake Low to Moderate: Rather than going ham day in and day out (it me), keep your daily intake relatively low (2-3 g/kg/bw). Not only will this minimize adaptations and negative effects, it also allows for increases in intake on the days when we really need it.

Increase Intake Before an Event: As previously mentioned, research has shown increases in caffeine prior to an event may boost the ergogenic effect you receive. However, increased caffeine intake can have negative effects like gastrointestinal distress, increased anxiety, or headache. Be sure to experiment with this prior to an event.

Have Deload Days: On lighter training days or off days, limit or abstain from caffeine. While the research is mixed, I have found doing one or two “deload” days a week to increase my own caffeine sensitivity afterwards.

Caffeine Timing: Timing your intake around your workouts can help you capitalize on any benefit you may be getting from caffeine. Research suggests a bolus of caffeine one hour prior to a workout or event can improve performance.

Pre- and Intra-Dosing: If you want to get really specific, you can even split your consumption of caffeine into a dose prior to training or an event and a smaller dosing during the event (1). This may improve performance by staving off fatigue during longer or more intense work.

 

Like most things in life, caffeine is great… but in moderation. Trust me, it hurts me just as much to type this as it may hurt to read. The addictive buzz of caffeine makes it very easy to habitually and chronically consume caffeine. Yet, we may want to be more mindful of our intake if we want to enjoy the ergogenic and lifestyle benefits of caffeine when we really need it. For more on the history of caffeine and how it has us all under its thumb, we recommend checking out the book Caffeine: How Caffeine Created the Modern World by Michael Pollan (2019).

 

References:

Pickering, C., & Kiely, J. (2018). What should we do about habitual caffeine use in

athletes?. Sports Medicine, 49(6), 833-842.