In a new study in the Journal of Strength & Conditioning Research, men completed eight exercises on two separate occasions. On one day they took a placebo before the session, and the second time they took pre-workout that contained caffeine, leucine, tyrosine, and other common ingredients. The researchers found that the men lifted nine percent more volume during upper-body exercises and 14 percent more during lower-body moves after taking the supplement.
Most of these benefits come from caffeine, says Brian St. Pierre, RD, CSCS, director of performance nutrition at Precision Nutrition. The stimulant speeds up your reaction times, makes you more alert, and helps you train longer. Out of all the legal options, it might be the most science-backed performance enhancer there is, he says.
Most pre-workout formulas also contain other ingredients like creatine, leucine, tyrosine, and citrulline-malate that help you build muscle and burn fat more efficiently, but they’re only beneficial in the long term, he notes. While caffeine’s effects set in almost immediately, you’d have to take pre-workout consistently over time to get those benefits.
For advanced athletes or those who have hit a plateau, he recommends taking a supplement 30 minutes before each session, St. Pierre says. Avoid proprietary blends that don’t disclose the ingredients and always look for a third-party seal of approval from NSF International, Informed-Sport, or Informed-Choice.