If you're, like me, a fan of a good cup of coffee (especially first thing in the morning), this post is for you!
Coffee has become part of our routine. Not only because of its effect (which is very interesting for sports, I might add), but also because of the ritual it provides. There is a substantial amount of evidence that caffeine has ergogenic effects, especially in endurance sports, but do you know exactly how caffeine works?
Caffeine is both a drug and a nutrient. A cup of coffee in the morning is used to wake up, to work, and often to keep you awake late when needed. Athletes frequently use it to improve endurance performance, but it's also used in strength sports for explosive power. There was a theory that caffeine improves fat metabolism, but does that work? The short answer is no . There is little evidence that the small effects caffeine may have on fat metabolism in some situations are responsible for the performance effects. So, what is the real relationship between caffeine and athletic performance ?
Caffeine improves performance in a variety of sports and exercise types through three main possible mechanisms:
- Adenosine blockade
- Increased release of calcium from muscles
- Effects on catecholamines
I'll briefly explain each of these points. Let's go:
Caffeine has a chemical structure similar to a molecule called adenosine. This molecule is naturally produced in the body and is responsible for feelings of tiredness, fatigue, and even pain when it binds to its receptors in the brain. Simply put: more adenosine means more fatigue. Due to the structural similarities between caffeine and adenosine, caffeine can prevent adenosine from binding to these receptors, reducing feelings of tiredness and pain. This effect of caffeine is often referred to as a central effect in the brain.
Caffeine increases the release of calcium in muscle cells. This release is responsible for muscle contraction. It is understood that caffeine supplementation could increase muscle force production for this reason.
The initial theory about how caffeine improved exercise performance was that caffeine stimulates fat metabolism and spares muscle glycogen. We now know that this is unlikely to be the primary explanation. While caffeine may have minor effects on fat metabolism (at least in some situations), this is not the reason for its performance-enhancing effects.
Caffeine can stimulate the breakdown of triglycerides (the storage form of fat), and the fatty acids released through this breakdown can be used for energy. Additionally, caffeine can cause an increase in the family of hormones called catecholamines , which includes the " fight or flight " hormone adrenaline (also called epinephrine). This increase in catecholamines can also increase fat breakdown.
If conditions are favorable and more fatty acids are available, they will then be used for energy during exercise (but not in all situations). If more fat is used, this can lead to reduced glycogen breakdown—the body's stored form of carbohydrate—meaning it is available for energy later, perhaps delaying fatigue or exhaustion and leading to better performance.
Now everything makes more sense, right?
And more:
Many studies have shown that caffeine, when consumed before exercise, can reduce sensations of pain and exertion during a variety of exercise types. It is believed that this reduced pain sensation with caffeine allows athletes to exert themselves for longer during training or competition, gaining a greater willingness to tolerate the discomfort of exercise.
Some studies also show that taking caffeine before a workout can reduce muscle soreness in the days following exercise. The evidence that calcium increases the strength of muscle cell contraction is quite strong. However, most experiments showing this were done using muscle cells (usually from animals) that were removed and measured in a Petri dish. Therefore, it can be concluded that caffeine may affect calcium release in the amounts used by humans, but it is probably not a major contributor to exercise performance in most sporting events.
Although some studies have shown that caffeine can increase catecholamines and the use of fat for energy, this is not always the case. Interestingly, many of these studies that did not see an increase in the use of fat for energy still saw performance improvements with caffeine intake, meaning that this may not be the primary mechanism for caffeine. Furthermore, studies that measured the amount of glycogen in muscle after resistance exercise did not see higher levels at the end of exercise after taking caffeine compared to a placebo.
In short…
It appears that the main mechanism by which caffeine may improve athletic performance is through its effect on blocking the action of adenosine, resulting in reduced fatigue and decreased pain sensation. It is possible that caffeine may increase the strength of muscle contraction, but if this occurs, it probably won't have a large effect.
It's important to note that too much caffeine can have the opposite effect and that the effects of caffeine are highly individual . Like almost everything in nutrition!
The nutritionist's tip is: careful experimentation is the best way to discover what works for each person! Try this before, during, or after your workout and see how you feel.
Thank you for reading, and until the next post!
Gabi,
Nutritionist at Z2.
References:
Graham TE. Caffeine and exercise: metabolism, endurance and performance. Sports Med. 2001;31(11):785-807. doi: 10.2165/00007256-200131110-00002. PMID: 11583104.
McLellan TM, Caldwell JA, Lieberman HR. A review of caffeine's effects on cognitive, physical and occupational performance. Neurosci Biobehav Rev. 71:294-312, 2016.
