There’s no denying it: Caffeine is probably the most well-known and effective workout-boosting ingredient out there. It’s also the most widely researched.

Studies have shown that downing caffeine before a workout can make it feel easier, boost your performance, and help ward off soreness afterwards. Caffeine works its magic by stimulating your central nervous system, which increases your output of hormones like epinephrine and ups your heart rate to prep your body for movement and boost your reaction time.

Caffeine isn’t for everyone, though. Different people metabolize caffeine at different rates, so it can mess with some people’s sleep, upset their stomach, or make them feel nervous or jittery. Luckily, if you’re in the caffeine-free camp—or just like to hit the gym at night—there are plenty of caffeine-free workout supplements out there these days (thank you, science!).

Want to crush your next sweat session ‘stim-free’? Here are 11 expert- and research-backed power-ups worth trying.

1. The Obvious: Food

Working out without any calories in your system is like trying to drive a car that’s out of gas. Exactly what you eat before your workout depends on the type, intensity, and duration of exercise you’re doing, but your fuel should always include protein and carbs, says fitness expert Chris Freytag, C.P.T., C.H.C., founder of Get Healthy U. Carbohydrates provide the energy we need to perform while protein supports the repair and growth of our muscles.

Related: How To Pick The Perfect Pre-Workout Snack

Your go-to pre-workout could be a banana or slice of toast with a serving of peanut or almond butter, a handful of nuts, or a slice of deli meat—it’s as simple as that!

2. Creatine

Creatine is a popular performance ingredient both on its own and as part of other pre-workout formulas. This quick energy source is naturally produced from three amino acids and stored in our muscles. Studies show that supplementing with creatine can help you build muscle mass and strength over time by helping them work at a higher intensity, says Joy Dubost Ph.D., R.D., L.D.N., founder of Dubost Food and Nutrition Solutions.

One study published in Medicine and Science in Sports and Exercise, for example, found that men who supplemented with creatine made more strength and muscle mass gains after 12 weeks of strength training than those who did not. What’s more, another study found that those who supplemented with creatine also recovered from strength training significantly faster.

You’ll find anywhere between 250 and 850 milligrams of creatine in a three-ounce serving of meat and fish, but can power up your intake (and benefit) by adding a creatine supplement to your routine, says Jonathan Valdez, R.D.N., owner of Genki Nutrition and spokesperson for the New York State Academy of Nutrition and Dietetics. Most popular supplements use ‘creatine monohydrate’ and recommend a dose of around five grams a day.

Our Pick: BodyTech 100% Pure Creatine Monohydrate

3. Nitric Oxide Boosters

Nitric oxide (NO), a chemical naturally produced in our body, relaxes our blood vessels to increase blood flow. That circulation boost shuttles more oxygen, protein, and other nutrients to our heart, brain, and muscles—which can help our cells churn out more energy so we perform better.

One way to boost NO: beets. (Yes, beets.) Not only is this bright root vegetable chock-full of phytonutrients, antioxidants, and good-for-you carbohydrates, but it’s also packed with nitrates, which are turned into nitric oxide in our body, says Freytag. Drinking a cup of beet juice before exercise helped people work out for longer and use less oxygen to do so, found a study published in the Journal of Applied Physiology.

You can also ramp up your NO production by upping your amino acid intake, since these protein-building molecules contain the nitrogen our bodies need to produce nitric oxide. Two aminos in particular—arginine and citrulline—are best known for their NO and performance-boosting abilities. For example, cyclists who regularly supplemented with citrulline performed better on a timed test and reported feeling less fatigued afterwards than those who took a placebo, found one study published in the Journal of the International Society of Sports Nutrition.

You’ll find arginine and citrulline in combination pre-workout formulas and as stand-alone supplements.

Our Picks: Dynamic Health Beetroot Juice, PEScience High Volume Supreme Nitric Oxide Matrix    

4. Tomato Juice

You probably shouldn’t fuel your next HIIT class with a Blood Mary—unless you take your cocktail virgin. One small study published in Food and Nutrition Sciences found that people who drank tomato juice prior to an exercise test reported feeling less fatigued throughout than people who drank water.

Researchers credit the lycopene (a potent antioxidant), essential amino acids, and natural sugars in tomato juice for its fatigue-resistant benefits. While the amino acids and sugars provide the body with energy, the lycopene acts against free radical compounds produced during exercise.

5. Electrolytes

In an effort to cut down on sugar, we may have stopped slugging back Glacier Crush-flavored sports drinks—but that doesn’t mean we still can’t benefit from workout-boosting electrolytes. Electrolytes are electrically-charged minerals in our blood and body fluids that help balance the amount of water in our body, our blood pH, and muscle and nerve function. Calcium, chloride, magnesium, phosphorus, potassium, and sodium are all electrolytes. When we sweat a lot or are dehydrated, we lose a lot of these minerals—which research has associated with a decline in performance.

That’s why Freytag (like many athletes) adds an electrolyte tablet to her water bottle to sip on before and throughout her workouts. “It’s simple, inexpensive, and tastes good,” she says. Look for an electrolyte tablet or drink mix with a short ingredients list and less than five grams of sugar.

Our Pick: BodyTech Lemon Lime Electrolyte Fizz

6. BCAAs

Of the 22 amino acids we need to build all of the proteins in our body, we have to get nine from food (often animal proteins), since we can’t make them on our own. Of those nine, three aminos, known as the ‘branched-chain amino acids’ or ‘BCAAs,’ are particularly important for exercise.

The BCAAs consist of leucine, isoleucine, and valine—and when our muscles are low on stored energy from carbs called glycogen, they can use these aminos for fuel, says Freytag.

One study published in The Journal of Sports Medicine and Physical Fitness found that when glycogen-depleted people consumed 300 milligrams of BCAAs, they were able to exercise for longer and burn more fat while doing so.  Research also shows that supplementing with aminos can help you better handle back-to-back sessions if you’re churning out two-a-days.

Freytag recommends adding a scoop of BCAA mix to your water before strength and interval training—just look for one that’s low in sugar.

Our Pick: BodyTech Fruit Punch Critical Aminos XT

7. HMB

HMB (‘beta-hydroxy-beta- methylbutyrate’) first entered the fitness scene decades ago, when high price tags kept it from really taking off. But with today’s lower prices, HMB is back to stay. “In science-speak, HMB is a product of the amino acid leucine,” explains Dubost. While leucine promotes muscle synthesis (building), HMB prevents muscle breakdown from occurring in the first place.

One review published in Nutrition & Metabolism suggests HMB may decrease delayed-onset muscle soreness, along with markers of muscle damage and body fat, while increasing performance. Meanwhile, a study published in the European Journal of Applied Physiology found that three grams of HMB per day helped athletes make strength, power, and hypertrophy gains even while training vigorously.

Want to give it a shot? Aim for three grams total a day, suggests Dubost.

Our Pick: BodyTech HMB (1,000mg)

8. Ginseng

Ginseng has long been used to support energy and vitality by boosting blood circulation and neurotransmitter activity in our brain. A review published in the Journal of Ginseng Research suggests ginseng may benefit both mental and physical performance—though other research on its impact on athletic performance has been a mixed bag, says Dubost.

You can find ginseng in capsule supplements, but it’s also popular in herbal teas.

Our Pick: plnt American Ginseng (400mg)

9. Beta-Alanine

Beta-alanine is a modified version of the amino acid alanine that our body uses to form a compound called carnosine, which helps reduce the buildup of hydrogen ions in our muscles and delay fatigue. One review published in Amino Acids found beta-alanine to be particularly helpful during high-intensity exercise (think interval or circuit training with work periods lasting a few minutes).

Because levels of beta-alanine in our body are usually very low, the benefits of supplementing may take a few weeks to notice, says Valdez. Supplements often provide anywhere from 800 to 2,000 milligrams, so Valdez recommends talking with a health professional about the right dosage for you.

Our Pick: BodyTech Beta-Alanine (1,600mg)

10. Carnitine

Carnitine is a compound our body makes from amino acids to carry fatty acids into our cells for energy—and up to 99 percent of it is stored in our muscles. Though previous evidence has often been inconclusive, long-term research shows that six months of carnitine supplementation can significantly increase levels of carnitine in muscles and buffer the buildup of lactate, which contributes to performance declines during high-intensity workouts. This research also shows that people who supplement with carnitine use less muscle glycogen during lower-intensity exercise, suggesting it may support fat burning.

You’ll find carnitine supplements ranging in dose from 500 to 2,000 milligrams, says Valdez.

Our Pick: The Vitamin Shoppe Raspberry Carnipure™ L-Carnitine (3,00mg)

11. Cordyceps

Mushrooms for health and wellness are trendier than ever—and the cordyceps variety has proved especially helpful for holistic-minded fitness enthusiasts. Traditionally used in Chinese medicine, the mushroom has been shown to support our body’s production of ATP (a.k.a. energy), which can benefit everyone from world-class athletes to elderly people trying to stay active, says Valdez. (An added bonus: These ‘shrooms have also been shown to stimulate our immune response.)

You can load up on cordyceps by taking a tablet or capsule supplement, or using a drink mix, like Four Sigmatic’s Cordyceps Mushroom Elixir Mix. Valdez recommends between three and nine grams twice a day.

Our Pick: The Vitamin Shoppe Cordyceps (1040mg)