Every Muscle & Fitness HERS reader worth her biceps knows the importance of protein for muscle growth and maintenance. And just about everyone who has seen the inside of a gym knows that amino acids are the building blocks of protein. But how many dedicated weight-trainers know that aminos are responsible for more than just promoting major muscle gains? In fact, amino acids, taken either alone or in various combinations as supplements, can enhance other components of your training. Research constantly teaches us more about the roles individual amino acids play in all kinds of bodily functions — from digestion and metabolism to blood flow — and manipulating this knowledge to reach your fitness goals is relatively straightforward. Here, we show you how.

First, a little background on amino acids. Here’s the confusing part. There are about 80 aminos found in nature. Of those, only 20 are used by the human body. But every single one of those 20 is absolutely essential for the body to function normally. So why do you always hear about “nonessential amino acids”? It comes down to diet.

The body can naturally produce 11 aminos by itself, but the other nine the body needs must come from the food you eat. If you’re not eating enough complete protein to get the full complement of aminos in your system, your body will start to break down your muscle tissue to make up the difference, making it impossible to either maintain your current physique or build upon it.

Say it with us now: The HERS protein mantra is that you should consume 1 gram of protein per pound of bodyweight per day. If that sounds familiar, it’s exactly the same advice our brothers over at Muscle & Fitness follow. When it comes to maintaining and gaining muscle, the protein rule is the same no matter your gender.

Although you don’t often think of it this way, the main reason for eating complete proteins (those that contain all 20 amino acids, such as meat, fish, soy, eggs, whey and casein) is to take in a full complement of amino acids with which to build muscle. As your body digests protein, it breaks it down into individual amino components before sending each type of amino where it’s needed most. Some of them will be reassembled into protein, also known as muscle. Since different types of protein contain different amounts of amino acids, however, eating a variety each day guarantees you’ll get as many different aminos as possible. For example, a juicy piece of tofu contains large amounts of arginine, gluta-mine and BCAAs, whereas eggs boast high amounts of alanine and serine.

That’s how aminos work when they’re consumed as whole foods. The interesting thing about aminos, however, is that when they’re consumed individually in concentrated doses as supplements, they can perform vastly different functions that go way beyond muscle-making. This is why manipulating amino acid intake through supplementation can bring your workout goals within reach faster. To help you get there, we’ve compiled this list of the eight most beneficial single amino acids, complete with a description of the benefits and dosages — specially tailored to women — of each.

Dudes love this stuff because it helps boost the elusive “pump,” but it’s good for everyone interested in feeding muscle. Arginine increases nitric oxide production, which in turn improves blood flow, bringing those muscle fibers more nutrients to help them grow faster. Research shows it effectively increases strength.

Dose: Arginine is most often found in three forms: L-arginine (the simplest form but also thought to be the least readily absorbed by the body), arginine alpha-ketoglutarate and arginine alpha-ketoisocaproate. The dose for each is 1—3 grams in the morning, 30—60 minutes before your workout, and before bed, each on an empty stomach.

As we all know, women have lower levels of circulating testosterone than men, so what woman wouldn’t want to put what she has to better use? Carnitine can not only increase levels of the muscle-building hormone but also make it more efficient at the work it does in muscle cells. It plays a critical role in helping the body burn fat and is thought to enhance blood flow to exercising muscle, preventing fatigue and damage.

Dose: Look for L-carnitine or acetyl-L-carnitine (thought to improve absorption of carnitine by the brain) and take 1—2 grams in 2—3 divided doses on an empty stomach.

Want to be stronger and go longer? Take carnosine, a pro at boosting both muscle strength and endurance. It also functions as an antioxidant, meaning it destroys the free radicals that can damage muscle.

Dose: Don’t get confused if you find only bottles that say beta-alanyl-L-histidine on them. Carnosine is actually two aminos in one: histidine and beta-alanine. Take 1—1.5 grams before and after training.

Citrulline is mostly known in bodybuilding circles for its easy conversion into arginine in the body. But citrulline’s no one-trick pony. It also helps remove ammonia from the body. When ammonia builds up in muscle fibers, they fatigue more easily, so less ammonia means longer, better workouts.

Dose: One of the only ways to take citrulline is together with malic acid (which helps burn lactic acid as you work out, preventing muscle fatigue) as citrulline malate. Take 2—3 grams twice daily on an empty stomach, with one dose 30 minutes before workouts and another immediately after.

Glutamine is just about the ideal bodybuilding amino. It enhances muscle growth, boosts recovery and immune function, aids digestion, prevents fatigue and might even blunt your sweet tooth.

Dose: Glutamine can make your digestive tract very unhappy, so start with a smaller dose and work your way up to 1—3 grams 2—4 times per day on an empty stomach.

Another bodybuilding powerhouse, glycine can increase growth hormone levels, boost the production of creatine in the body and enhance the firing of nerves that stimulate muscles to contract (which can increase strength). On top of all that, a new study concludes that maintaining glycine levels may help prevent sports injuries such as muscle strains and sprains.

Dose: Take 1—2 grams 30—60 minutes before workouts and before bed on an empty stomach.

Taurine’s main claim to fame is as the energy in energy drinks. But you’ll want to take it because it enhances a muscle’s ability to contract. And it’s not picky — it affects both skeletal and heart muscle, meaning that not only will you lift weights better but you might even be able to do it longer. Great for grueling weight workouts or long hauls on a treadmill or bike.

Dose: Research has shown that taurine levels in muscle fibers drop during exercise, so supplement with 1—2 grams both before and after working out.

Wake up! Tyrosine can help you do just that — it functions as a stimulant because it boosts norepinephrine production in the body. Norepinephrine is a hormone that enhances fat loss and can control appetite, making tyrosine a great thermogenic.

Dose: If your energy levels are low before you begin a workout, tyrosine should rev you up. Take 1—2 grams of L-tyrosine on an empty stomach twice a day or 1—2 grams about an hour before training.

While taking amino acids is generally safe (though you should always consult a doctor before starting any new diet or supplementation plan), you should follow certain rules for best results.

>> Tyrosine has a few warnings attached to its use. First of all, because it’s a precursor for the neurotransmitter dopamine, those with mental disorders should not take it. Tyrosine is also related to melanin production, which means that skin cancer sufferers should avoid it. Tyrosine is involved in thyroid hormone production as well, so those with hyperthyroidism shouldn’t supplement with it either. And finally, if you don’t fall into any of the above categories but find that tyrosine’s stimulant qualities are keeping you awake, avoid taking it after 3 p.m.

>> Arginine has been shown to trigger herpes outbreaks, so sufferers beware.

>> Don’t take amino supplements with food — take them on an empty stomach. This allows them to do their job without any inter-amino competition from those you’re getting from whole foods.