Many athletes take supplements to boost energy, particularly ginseng, ephedra, and caffeine.
Ginseng functions as an adaptogen, or immune system stimulant, but it does not have an effect on athletic performance. (Athletes who choose to take ginseng should look for Panax ginseng standardized to 4–7 percent; ginsenosides, with the following dosing regimen: 100–200 milligrams per day for two–three weeks, then one–two weeks of no use before resuming).
Ephedra (also called Ma Huang, epitonin, and sida cordifolia) is a central nervous system stimulant that is sold as an energy booster or “fat-burning” supplement. Marketed as Metabolife, Xenadrine, Herbal Rush, Energy Rush, Thermoburn, or Thermofuel (among others), ephedra may delay fatigue by sparing the body’s glycogen reserves during exercise. However, it can also increase blood pressure, respiration rate, heart rate, anxiety, migraines, and irregular heartbeat, and it can cause insomnia, psychosis, and nervousness. Ephedra and caffeine are often present in the same product, which can be detrimental to the heart. The maximum safe level of ephedra is 24 mg per day, but many products contain over 300 mg per dose. This supplement is contraindicated in those with a history of heart disease or hypertension, kidney or thyroid disease, seizure disorder, or diabetes.
Caffeine is a stimulant that in certain athletes may increase free fatty acid availability to delay fatigue, improve reaction time, and reduce the perceived effort of exertion. It tends to be most effective in caffeine drinks, trained endurance athletes with a dose of 200 to 300 milligrams one hour prior to a sporting event. The legal limit of caffeine is 800 milligrams, but this level can cause nervousness, anxiety, irritability, headaches, increased urination, and diarrhea. In addition to products such as Vivarin, No-Doz, and Excedrin, caffeine can be found in herbal form in guarana and kola nut. Caffeine also augments the stimulatory effects of ephedra.