When it comes to getting ready for your workout, there are two main things you want to dial into before you head to the gym: getting mentally focused and keeping your energy level high. If you’re lacking focus, you run the risk of simply going through the motions of your workout without fully reaping the benefits. And when your energy level is lagging, the quality of your workout suffers, to the point that you might even be tempted to quit before you’re done. Pre-workout supplements are designed to address both of these points. To do so, they typically include the following ingredients:

Caffeine: In addition to increasing overall energy levels, caffeine boosts focus, alertness, and metabolic rate. A review in the Journal of Strength and Conditioning Research found that caffeine was an effective performance enhancer for endurance athletes, with an optimal dose pre-workout of 3–6mg per kg of body weight. (For a 130-lb woman, that’s 177–354mg.)

Caffeine From Green Tea: Caffeine extracted from green tea has the added bonuses of catechins like EGCGs. This may act as a metabolic booster, helping you burn fat at a much quicker rate. Plus, EGCGs are antioxidants that can help protect your body against damage done by harmful free radicals from foods you eat, regular body processes, and environmental pollutants.

Higenamine HCL: Derived from plants such as bamboo, the stimulant causes the heart to contract at a faster rate, which can boost athletic performance by increasing blood and oxygen flow to muscles.

Schisandra Extract: This ingredient can help reduce stress while upping endurance, performance, and energy. Adaptogens such as this work by recharging adrenal glands, which are responsible for counter-acting the compounds released when stress is high.

L-Taurine: Taurine is an essential amino acid with many important functions. While your body can produce it, it’s important to get adequate levels through the diet. Taurine may help act as a fat metabolizer. It also can aid in brain health and boosts short-term focus and muscular endurance.

L-Carnitine: Carnitine is another amino whose main role is as a fat metabolizer, working to help burn fat cells for energy at a faster rate. It can also help athletic endurance by lowering lactic acid buildup and maintaining creatine-phosphate levels.

Raspberry Ketones: Derived from fruits and veggies such as kiwi, peaches, and grapes, this compound works to break down fat cells and helps increase your metabolism, while also helping to curb your appetite.