Is it a performance enhancer or a performance killer?

Right, thought it was about time given my love of coffee that I put pen to paper and discussed the effects of caffeine on performance. Is it a natural performance enhancer, or will it detract from performance in the gym or competition?

Physiological responses to caffeine:

The foundation of whether caffeine will benefit or detract from performance lies within the physiological responses the body has to caffeine ingestion. 

 Caffeine is the world’s most commonly used drug. It acts as a central nervous system (CNS) stimulant acting on the sympathetic nervous system, in essence it will create the same reactions as the fight or flight response. So what does this mean? 

 When caffeine is detected in the blood stream and in the brain it has the effect of increasing the release of adrenaline and catecholamines, coupled with inhibiting adenosine receptors in the CNS and brain. The increase in adrenaline will increase stiffness plus limit vasodilation of major blood vessels leading to an increase in systolic blood pressure. Along with this the increase in adrenaline coupled with the increase in catecholamines will create an increase in heart rate. 

 Some studies and research have found that the increase in adrenaline that comes from caffeine ingestion increases the lactic acid production and removal within the muscles (glycolytic flux). One thing that has been well proven is that the ingestion of caffeine does lead to an increase in lactic acid production. Many of the studies that have shown the increase in lactic acid have also shown an increase in performance too. (More on this later). One potential rationale for the increase in glycolytic flux lies with the effect caffeine has stimulating the CNS while at the same time dampening pain perception. 

 With the increase in adrenaline from the adrenal medulla in the brain following caffeine consumption, we will also see an increase in the amount of glucose circulating in the blood. 

 The ingestion of caffeine will also increase the levels of potassium in blood plasma, in turn this will increase the excitation-contraction coupling in the muscles with enhanced Na+/K+ ATPase activity. A number of studies have shown an increase in plasma K+ levels both at rest and during exercise. This enhanced excitation-contraction coupling that comes with the greater Na+/K+ ATPase activity can potentially delay fatigue when performing forceful contractions. While this has been shown in aerobic activity, given how plasma K+ levels increase with exercise intensity it is thought that the effect of caffeine on this relationship has an even greater impact on high intensity exercise. 

 As mentioned earlier is the effect that caffeine has on dampening pain through the effect it has on the CNS. With pain we will get a reduction in maximum voluntary contraction of the muscles, muscle contraction velocity and movement. As caffeine blocks the adenosine receptors (in this case A2a receptor in particular) we will see a reduction in perceived pain, allowing for a sustained force of muscular contraction and a higher force output to be maintained. This can be seen in a reduction in the rating of perceived exertion during exercise, in some studies by as much as 5.6%.

Effects of caffeine on performance

The physiological impact caffeine has on the body detailed above in turn has an effect on performance in a number of ways. While some of the exact mechanisms of the performance effects are still being researched and debated the fact they occur is pretty well established.  

On the very basic level caffeine ingestion 30-60 minutes prior to exercise has been shown to increase muscular strength, strength endurance and delay fatigue in endurance based activities. It has been shown to increase short term high intensity exercise as well although this and the increased fat utilisation as fuel sources aren’t fully understood as of yet. 

Muscular Strength: When it comes to muscular strength caffeine ingestion has been shown to increase strength by up to 4% in both bench press, leg extension.

Muscular Endurance: Arguably there is a greater improvement in performance from caffeine ingestion when we are looking at muscular endurance. Research across a number of settings has shown increases of up to 14%. In both muscular endurance based events and short term high intensity exercise there is some suggestion that this comes from the blunting of pain perception through the blocking of the A2a adenosine receptors, in turn allowing an individual to push past the stage they would experience pain significant enough to terminate exercise without caffeine. 

Cognitive Performance: One other area in which caffeine has an effect is on cognitive performance, the ingestion of caffeine has been shown to increase concentration and clarity of thinking through the way in which it stimulates the brain. 

Cardiovascular Performance: The ingestion of caffeine prior to endurance performance when tested with low intensity exercise has increased VO2 by 0.67ml.kg-1.min-1 as well as increasing resting energy expenditure and resting VO2

Practical Examples: So what does this mean in practical terms? Well when caffeine ingestion has been tested in a number of environments there has been a delay in fatigue and increased ability to maintain speed during repeated 100m swimming time trials, endurance runners have been able to cover an extra 1.3-2 miles (2-3.2lm) and workload in cyclists increased by 7.4% and in 1500m runners there was a 4.2 second improvement in times compared to the same runners drinking decaf. 

So research would suggest that there is a significant improvement to be found in endurance performance across a wide range of activities. Plus the increase in strength tested in a number of exercises using 1RM testing. So if looking to get that little bit extra from a training session or to increase performance in particular in endurance events there is a significant benefit to be had from consuming caffeine. 

Practical Application 

When looking to maximise performance the ideal does of caffeine is roughly 3-6mg per kg of body mass, or about 200-400mg for an individual. Research would suggest that the optimal time for the ingestion of caffeine is roughly 60 minutes prior to training or performance. 

Acute caffeine use can be particularly beneficial with important competitions or when there is a training bout that has a higher volume or load over an acute bout of time when looking at both resistance training or endurance performance. 

However it would be worth experimenting prior to a competition with the use of caffeine ingestion as the extent to which it will impact on performance will vary with each individual. 

Overall though research would suggest that if you are looking to maximise training and results caffeine is a performance booster.