Caffeine is absorbed by the stomach and small intestine, and takes 45-60 minutes to reach maximum concentration in the blood. Yet you can often feel the kick within 10 minutes when levels reach one-half its concentration, according to a 2008 University of Barcelona study. The full effect can last two to three hours and diminishes within 12 hours.
Make sure not to overdo it; you need to find your ideal tolerance level. Overindulging can trigger symptoms of caffeine intoxication such as insomnia, overexcitement, restlessness and, in severe cases, muscle twitching, and rambling thoughts and speech. These reactions often strike soon after consumption but wane as caffeine levels fall.
You can still benefit from caffeine by consuming it in smaller amounts.
Caffeine pills like NoDoz maximum strength may have higher amounts than most beverages (200 mg in one tablet) but take longer to digest. Caffeine in liquid form is absorbed and takes effect more quickly. The best liquid jolts: coffee and energy drinks. A regular 8-ounce home-brewed java boasts an average 133 mg of caffeine, if you need a stronger shot, a regular Starbucks coffee contains more than 300 mg per 16-ounce serving.
If coffee isn’t your idea of a pre-workout beverage, pop open an energy drink. Popular brands Amp, Red Bull and Rockstar vary from 74-80 mg. Additives like sugar and extras such as ginkgo biloba, ginseng and vitamin B won’t interfere with absorption or diminish effects, but be aware if you’re taking any prescription medication and check with your health care provider. Be conscious of any additional calories youre taking in as well (most likely all sugar).
Works for everyone
Research published in the International Journal of Sport Nutrition & Exercise Metabolism in 2009 compared pain tolerance of 25 college-age men who were split into two groups: high caffeine users (400 mg per day, or 3-4 cups of coffee) and low consumers (100 mg or less).