Clarifying the Caffeine Controversy - Page 2
Running the Risks
Bumping your doses to 500 milligrams and higher, you run the risk of more serious side effects, which may include nausea, heart palpitations, diarrhea and tremors. Because electrolytes play an important role in regulating cardiac rhythm, combining caffeine with electrolyte disturbances—very common in the later stages of an ultramarathon—may prime a runner’s heart for trouble.
Antony Chu, M.D., Director of complex Ablation in Arrhythmia Services at the Rhode Island and Miriam hospitals, warns, “Within the trail-runner’s world, the effects of electrolyte abnormalities that can exist under conditions of extreme physiologic stress and concomitant high-caffeine ingestion are unknown.”
Caffeine may also exacerbate heat intolerance by acting as a diuretic. Because caffeine is a stimulant, it boosts perspiration and metabolic rate, speeding fluid losses during intense exercise and leading to dehydration.
Life or Death
Runners have been spooked after reading of relatively young runners dying near the finish lines at the 2009 Detroit Free Press Half Marathon, the 2011 San Antonio Rock ‘N Roll half Marathon, the 2011 Chicago Marathon and others. The IMMDA released an advisory statement in 2010 warning that caffeine may contribute to the majority of marathon cardiac episodes and deaths. The prevailing theories suggest caffeine may contribute to heart-rhythm problems or blood-flow changes in the heart and/or blood vessels, forcing a blood clot or plaque to be released. To help prevent blood clots, the IMMDA recommends runners limit caffeine intake and take about 80 milligrams of aspirin prior to racing.
Further studies are underway, and more definitive information relating to caffeine use with exercise should be available by June 2013, following a summer consortium of medical professionals held in Spain.