Caffeine is a research-proven compound for performance enhancement, but where do we draw the line with this popular ergogenic aid? Let’s explore whether caffeine’s devil is in the dose.

Most ergogenic aids, or protocols that look at performance enhancement and physical output, often involve caffeine. Leaving behind the notion that it is many people’s favorite morning elixir and the second most traded commodity on Earth, we need to explore where caffeine stops being a performance-enhancing ingredient, and becomes a performance hindrance.

Firstly, identification of caffeine’s current use by users is important:

• Increased mental alertness
• Increased concentration
• Increased decision-making ability
• Increased endurance capacity
• Increased time to fatigue
• Increased fatty acid mobilization
• Increased strength output
• Increased power output

What does the research say?

We can analyze the research across many sports to see where caffeine’s inclusion is one of benefit. For example, cyclists competing in endurance bouts are observed to see a performance increase with a dose of both three, nine and 13 mg of caffeine per kilogram of body weight. This is accompanied by an increase in free flowing fatty acids and glycerol in the blood stream, which alone could be considered a performance enhancement. Elite level strength and power-based athletes also see a performance benefit when accounting for muscle fiber type, caffeine sensitivity and individual motivation at seven mg per kg body weight.

It appears that adenosine receptor antagonism most likely accounts for the primary mode of action in enhancing exercise performance with caffeine, and that dosing with pure caffeine seems more effective than using coffee to gain the same increase in performance. Whenever we dose an ergogenic aid to stimulate the central nervous system, we usually see an increase in physical performance. Utilizing activation of the central nervous system in sport and athletic performance is key. We can draw a secondary example to muscle activation by looking at a traditional physical warm up, something that is used to prep the nervous system at a muscular level. So increasing central nervous system output is paramount in maximal athletic performance.

Is more better?

At this stage in our comparison, it is worth noting two things. Firstly, that five mg per kg of body weight is the safest predictable dose of caffeine. Dosing at five mg per kg causes urine caffeine concentrations to fall below the doping limit of the International Olympic Committee of 12-μg ml-1 urine in all individuals. So in an 80kg, male this would work out as 400 mg, more than any cup of strong black coffee. As a result, many athletes should be safe with traditional methods of caffeine dosing, but be warned that five mg should be your upper limit if competing in this arena. Secondly, that caffeine is observed to have no dose dependent increase in performance, so taking nine or 13 mg per kg of body weight will result in the same ergogenic effect as five mg of caffeine per kg of body weight. On the other side of high dose caffeine we can observe side effects, which to the athlete could potentially be very damaging to performance, especially in periods of competition.

Side effects of caffeine:

• Irritability
• Anxiety
• Restlessness
• Headaches
• Insomnia
• Twitching and possible seizure
• Rapid or irregular heart rate
• Nausea and vomiting
• Increased breathing rate

With a list of possible side effects such as the above, it is important that we explore the other side of caffeine, the potentially damaging effect of caffeine. With any nutritional compound there is a risk of side effects, one reason most advice in the health and sports arena is that we take a “moderate approach,” hopefully ensuring that no over dosing or side effects are seen, especially seeing as no beneficial effect comes from high doses of caffeine above and beyond what is seen as a low to moderate dose. The same goes for macronutrients, micronutrients, trace elements, antioxidants, and ergogenic aids. Anything could be potentially damaging or toxic at the wrong dosage, so creating balance is key.

What is important at this stage is to identify, as with many ergogenic substances, that there is a degree of individual tolerance for such products, and caffeine is no different. Individual tolerance can vary hugely, so the amount of caffeine you consume and the regularity of consumption needs to be monitored and assessed based on the possible adverse symptoms listed above. To avoid any potential side effects, especially with the athlete, this is a very important consideration to make. As coaches, we can keep a continual eye on this with simple communication and feedback with the athlete.

Looking at the science of metabolism, we know that people utilize caffeine differently, something we can quantify as slow and fast oxidizers. Some get a quick buzz and a performance boost; others can get anxiety and the jitters with just a moderate dose. This can be quantified, biochemically as to whether you have much of the active enzyme P450 1A2 (CYP1A2); lack this enzyme (a slow oxidizer) and troubles could lurk, namely myocardial infarction. Lesson: If you know caffeine is an issue and you react badly then avoid it, stick to decaffeinated coffee or other hot drinks. It is thus not a performance enhancing aid for you, but a potential performance hindrance and a health risk.

While we are on the topic of tolerance’ to caffeine, it is worth touching on a myth that is still prevalent. While caffeine does pose a marginal increase in urine output, or diuresis, it does not actively dehydrate the body in any way. We know that tolerance to a substance can keep physiological norms in check, so as an individual that might be a slow oxidizer to caffeine could have a higher risk of developing a fluid-electrolyte imbalance as a result, also known as shifting out of a physiological norm. Lesson repeated, people that tolerate caffeine as a whole should not experience any dehydrating or mineral imbalance inducing side effects.

Hormones

Seeing as the hormones in our body drive nearly every physiological reaction, it is important to clarify whether caffeine plays a role. We all know the power of certain hormones such as testosterone, growth hormone, insulin and IGF-1, but what about the non-anabolic hormones, such as cortisol and melatonin, which are directly correlated to stress and relaxation? After all, hormones work synergistically, so accounting for what happens when one hormone is high is paramount, especially if there is a potential down side to the synergistic hormone.

Cortisol, our body’s stress hormone, is released upon ingestion of caffeine, regardless of external stressors. With this in mind, we need to be aware of when and for what reason we would want to stimulate excessive cortisol release in an individual. If we look at the natural physiology of cortisol release in the human body, it peaks in the am upon waking, and a few hours afterwards as part of our natural get up and go cycle, and then during exercise (an induced environmental stressor).

Cortisol’s release in exercise is two-fold: firstly, to aid the body in up regulating central nervous system output, and secondly, to help mobilize fuel for that training or exercise session. With this in mind, we can start to hypothesize that the two key times for an individual or an athlete to consume caffeine, or in its classic form in the modern diet as coffee, would be in the AM period upon waking, and pre-exercise. Exercise is going to stimulate a heightened cortisol response anyway, so knowing that caffeine improves performance through an increase in cortisol output and central nervous system drive would mean that it is it advisable to make caffeine part of a pre-training regime. Thus, we work with our natural physiology and not against it.

Seeing as cortisol is released in response to caffeine ingestion, it would not be ideal to consume caffeine throughout the whole day. I make this recommendation based on previous and current work with athletes, it being commonly observed that athletes often struggle with optimal recovery due to the stress from training along with their busy schedules and lifestyle demands. Anything I can do as a coach to minimize external stress and internal biochemical stress I try to employ. After all, coaches are responsible not only for the optimal performance of an athlete or high performing individual, but for their long term well being, recovery, and emotional outlook. It’s the holistic picture, and caffeine is just another factor that needs to be accounted for.

Abuse and timing

Seeing as caffeine is a substance that can be abused, optimizing intake and dosage is important. As a coach, I aim to minimize the risk of potential side effects. Large doses of caffeine or long term excessive use can lead to such detrimental side effects as mentioned above. This is important in times of stress. Visualize an athlete going through a peaking phase of training: more volume, more intensity, trying their best to stay on top of their recovery, often feeling tired or lethargic. This scenario can easily lead to excessive consumption of caffeine to aid in a time of stress, a habit people employ just to get through it. And seeing as caffeine increases the body’s circulating levels of stress hormones, this is not an ideal scenario. It may be a scenario that an athlete can handle for very short periods of time, but long-term this is likely to lead to burn out, fatigue, and overtraining, especially through inability to sleep and recover effectively. All we are doing here as coaches is catering for an athlete’s long-term mental health.

Although we have covered the overall consumption of caffeine, timing should also be considered. Seeing as caffeine has a half-life of five to six hours in healthy populations (half-life being the amount of time caffeine stays in the blood), we should consider whether timing presents a secondary issue. It is worth noting at this stage that unhealthy populations detox caffeine from the blood stream far slower. One study on alcoholics, for example, noticed that some individuals took up to 160 hours to fully detoxify normal doses of caffeine.

Here’s something to be wary of when working with other populations, or when optimal detoxification is impaired in an individual. If we work on the assumption that caffeine has a half-life of five and a half hours, and many athletes work on an optimal sleeping time, we should work back from that optimal time when considering caffeine as an ergogenic aid. If optimal sleeping time is 10:30pm at night, five and a half hours before this time would be 5pm. Talking from an idealist’s perspective, caffeine ingestion wouldn’t be ideal past this time, so late training times that rely on caffeine as an ergogenic aid might not be ideal from the perspective of optimal rest and recovery, both short and long term.

Recommendations

Looking at the available research, it seems safe to include caffeine doses for performance enhancement at three to four mg per kg of body weight. This dose gives both maximal performance enhancement, and falls under the safe limit of the International Olympic Committee. For a caffeine source, strictly speaking, caffeine pills or powder seem the best way to manage an optimal dose, and get maximal benefit. Caffeine content in drinks can vary, and often come with many undesirable added ingredients. Ideal timing of caffeine should come only when maximal central nervous system output is desired: first thing in the morning, and before exercise. For most individuals, this will result in two doses of caffeine daily, or three if training twice a day. Ideal timing for caffeine would be no later than 5pm depending on optimal sleeping time, considering that caffeine half life is around five and a half hours.

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