Journal Title (Medline/Pubmed accepted abbreviation): J. Sports Sci.
Page numbers: 509-515
doi (if applicable):10.1080/02640414.2010.541480
Summary of Background and Research Design
Background:Caffeine is the most widely used ergogenic aid in the world. As tolerance and dependence of caffeine is easily (and commonly) built up, withdrawal from caffeine may have significant, deleterious effects on performance. It is unknown whether withdrawal from caffeine for 4 days before an event is long enough a time to affect performance, or if this time is long enough to be able to reap ergogenic benefits from caffeine prior to an endurance event. Additionally, it is unknown if caffeine ingestion immediately before the event could counteract withdrawal effects (if any).
Hypothesis:Caffeine will improve performance to the greatest extent if ingested before an event after a 4 day withdrawal period compared to if caffeine withdrawal was not implemented.
Subjects:Twelve well-trained male cyclists and triathletes (28.3 ± 5.8 yrs old) who habitually consume 240 ± 162 mg caffeine per day.
Experimental design:double-blind, placebo-controlled, randomized, cross-over design
Treatments and protocol:Each subject visited the laboratory 7 times. During visits 1-3, their VO2max was determined and the subjects were familiarized with the exercise protocol. The exercise consisted of cycling, as fast as possible, to achieve an amount of work equal to cycling at 75% of their peak power output for 1 hr. For visits 4-7, the subjects underwent 4 different experimental protocols:
1) 4 days of placebo (Metamucil® psyllium) and then placebo the morning before the trial
2) 4 days of placebo and then caffeine (3 mg/kg body weight) the morning before the trial
3) 4 days of caffeine (1.5 mg/kg body weight) and then placebo the morning before the trial
4) 4 days of caffeine (1.5 mg/kg) and then caffeine (3 mg/kg) the morning before the trial
1.5 mg/kg caffeine body weight is equal to 112.5 mg for a 165 lb. (75 kg) individual. Standard meals were provided in the 24 hrs proceeding the trials as well as breakfast the morning of the trials. Gatorade® was provided during cycling at specified intervals to ensure available carbohydrates.
Summary of research findings:
- Withdrawal symptoms were reported by 11 out of 12 of the participants during the 4 days of caffeine withdrawal, including mostly headaches. Most participants also reported fatigue.
- No effects in performance were noted for the caffeine withdrawal trials vs. the caffeine trials, indicating no significant effects of caffeine withdrawal on performance.
- Acute caffeine ingestion immediately before the time trial improved performance regardless to caffeine ingestion for the 4 days before the trial (3.6% increase in performance when comparing caffeine-placebo to caffeine-caffeine and a 3.0% benefit when comparing placebo-placebo to placebo-caffeine). Acute caffeine ingestion also increased heart rate 3 ± 1 beats/min regardless of caffeine ingestion for the 4 days prior.
Interpretation of findings/Key practice applications:
A 4-day withdrawal period did not affect the ergogenic properties of 3 mg/kg during endurance cycling.
The caffeine consumption habits of individuals are greatly varied (type, timing, etc.) In addition, caffeine was provided in supplementary form (caffeine citrate) as opposed to caffeine as consumed in beverages such as coffee, tea, soda, etc. Therefore, these findings may not translate to all caffeine users.