The use of stimulants by athletes is controversial with some saying that stimulant use leads to over-reliance on their use to boost training performance. Similarly, an oft heard refrain from the anti-stimulant crowd is that usage of stimulants can lead to elevated cortisol level which more than offsets the performance advantage.
For those who like their black coffee before training or who simply like to consume a pre-workout drink before training, a new study (1) investigating the effects of caffeine on sprint performance revealed some interesting facts.
Objective: The researchers from New Zealand set out to investigate if caffeine boosts performance as well as its effect on hormonal response during repeated sets of cycle sprints with competitive cyclists.
Methods: 9 male cyclists completed four high intensity sessions which comprised 4 sets of 30 second sprints, with 5 sprints in each set of 4 (20 total sprints). They were provided either caffeine or placebo via the use of chewing gum which either contained caffeine or inactive compounds following their second set of each session. Testosterone and cortisol samples were collected via the use of saliva testing both at rest and after each set of sprints.
Results: Power output declined by 5.8% in the placebo trial between the first ten sprints and the second ten sprints. By contrast, those who were provided a caffeinated gum after the second set experienced a drop of only 0.4% during the last ten sprints. The researchers measured this as a 5.4% reduction in fatigue in the caffeine group compared to placebo. Testosterone levels increased rapidly from baseline (by approximately 53%) and prior to treatments in all trials. Those who then received caffeine had a further 12-14% increase relative to placebo. Cortisol concentrations did not elevate above baseline until after the third set but even then cortisol in the caffeine group was 21% lower than the placebo group.
Conclusion: This study concluded caffeine attenuated fatigue in repeated sprints and also increased testosterone and reduced fatigue relative to placebo.
Our Comments: Far from lowering testosterone, this study shows that an acute dose of caffeine can actually raise testosterone while showing a different effect on cortisol than the anti-stimulant naysayers would predict.
While the effects on hormone output are impressive, it is very doubtful that a single dose of caffeine could raise baseline testosterone levels once the effects of the caffeine wore off. Frustratingly the study did not measure testosterone and cortisol levels a few hours after the training bout. Previous research on weightlifters (2) has shown that intensive spells of training are associated with a drop in testosterone which will revert to normal once a period of lowered training intensity or volume is implemented. This doesn’t necessarily mean that by training harder we would expect testosterone and cortisol levels to drop more after use of caffeine, but to note that if we use stimulants to attempt to perform workouts at ever greater intensities and volumes, that the effect shown in this study on testosterone and cortisol is likely to reverse as the greater stress of the workouts overwhelms the body’s ability to adapt to them.
If we assume that the effect on testosterone and cortisol levels produced by caffeine is transient in nature, will it help us at all? While it is hard to quantify what difference a temporal rise in testosterone can achieve by itself, it is worth remembering that caffeine will also assist in the oxidation of fat and enhanced performance directly. As such, even if a small rise in testosterone is not helping our performance, the increased central nervous system activity is.
The study here is not a green light to consume caffeine several times a day in the belief it will spike testosterone since, being a stimulant, the body will accommodate to its effects and, in any case, this study specifically showed its effects on testosterone while training. As such the possibility exists that the greater training performance may have temporarily spiked testosterone levels and reduced cortisol as opposed to the caffeine having a direct effect. As with all stimulants, we would recommend reserving their use for those workouts which are a priority as opposed to relying on them for every workout which would lead to a diminution in effect.
Author: Reggie Johal
1. Paton CD et.al (2010): Caffeinated chewing gum increases repeated sprint performance and augments increases in testosterone in competitive cyclists.
2. Hakkinen et.al (1987): Relationships Between Training Volume, Physical Performance Capacity, and Serum Hormone Concentrations During Prolonged Training in Elite Weight Lifters
© 2012, Reggie Johal. All rights reserved.