Not only will you be happier during a workout, you'll also be stronger if you get your caffeine on before exercising. Recent research shows that using caffeine before a workout can help your muscles produce more force. Here's how it works: Caffeine lowers your body's levels of adenosine – a substance that builds up in your muscles during exercise and causes them to contract less forcibly. If you have less adenosine, you'll have stronger muscle contractions and you'll produce more force, whether you're running, cycling, shooting hoops, or lifting weights.