Some people are genetically blessed with great legs, but knockout legs have to be earned. Knockout legs look beautiful, sure, but they can also move some serious weight and perform incredible feats in a pinch. No one is born with them; they have to be forged by iron and shaped with smart training.

Nike trainer, CityRow instructor, and Cellucor ambassador Alex Silver-Fagan knows a thing or two about building a pair of knockout gams. She understands how to build an effective workout that burns fat, gets her blood pumping, and helps her add strength and shape in the process.

Learn Silver-Fagan's nine top leg-training tips, then try her special knockout leg circuit to build a pair of legs you love!

1. Never Neglect Your Warm-Up

A good warm-up is like that first glorious sip of your morning coffee—it's absolutely essential to start your workout properly. Always start every training session by getting your muscles ready for the day's work with a variety of mobility drills. "Our hip flexors and leg muscles are especially tight, especially if you sit at a desk all day long," explains Silver-Fagan, "so a good warm-up is critical."

Warm-up drills like butt kicks, bodyweight walking lunges, and side lunges will drive blood into your muscles, warm your joints, prime your lower body for heavier work, and lower your risk of injury. Just a few rounds should do the trick!

If you're still tight, don't jump right into heavy weight. A little time foam-rolling your hip flexors can also go a long way to loosen tight structures.

2. Tune In With Your Mind

In order to truly get your best workout possible, you need to be mentally engaged. "Harness the power of the mind-muscle connection and focus on the muscle you're working whenever you train," Silver-Fagan says.

If you're just going through the motions, this means two things: You're not working as hard as you could, and you're not maximizing the benefits of each training session. With each rep you perform, you should feel the muscle contracting intensely.

If you can't seem to get this feeling, you may need to have someone examine your technique and form. It may also help to visualize the muscle contracting in your mind, or you can even place a free hand on the muscle to feel it working.

3. Pay Attention to Your Form

"Before you proceed with any intense training, be sure your form is on point," says Silver-Fagan. "Because the legs are such a large muscle group, they affect a lot of other parts of your body and can be the cause of injury if trained improperly."

While it's important to lift with maximum personal effort, don't lift more than you can handle. This will only degrade your form and set you up for injury. Heavy lifting is safe only when the weight is lifted with precise technique and form, so start light with technical movements and rep your way to mastery.

In fact, it's a good idea to do a regular "form check-up" session with a trainer or advanced training partner once every two months or so. During this time, lighten the load, focus on using the best form possible, and have your partner give you cues and corrections. This will help keep you from getting into bad habits that later become challenging to break.

4. Don't Be Afraid of Big Weights

It's commonly misunderstood that lifting heavy will automatically add extreme size and mass to the worked area. If you're a lady who already has a pronounced lower-body region, you might fear going too heavy, but don't! To gain a considerable amount of mass, you would need to train really hard and have sufficient calories to support additional muscle growth.

For our purposes, lifting heavy weights will only make you stronger and add desirable shape to your legs, not bulk them up. "Go heavy," says Silver-Fagan. "Your legs are the biggest muscle group in the body and carry you throughout your day. Really focus on pushing it with the weight!"

5. Go Compound First

When designing your workout, compound exercises like squats and deadlifts should always be situated at the beginning of your session. You want to have maximum energy for these big, max- bang-for-your-buck exercises.

If you tire out the smaller muscle groups with isolation moves, you will be less likely to "kick glute" at larger compound moves, where your full effort really counts and is required. At the end of the day, it's these compound moves that really bring about the best changes to your physique.

"Always start with compound movements before moving on to isolated exercises," says Silver-Fagan. "For example, start with a squat before moving on to a cable glute kick-back."

6. Be Kind to Your Knees

Knees are a commonly injured area among lifters and athletes of various stripes, so it's crucial to approach lower-body training with great care. "Be careful with your knees," Silver-Fagan says. "Don't lock out, and be sure to keep your knees aligned with your toes with each bend you take."

If you catch your knees moving past your toes, your form might be in trouble from either fatigue or the weight being too heavy. Either way, you need to stop and compose yourself before an injury happens. Don't let your knees collapse during squats or track too far forward during lunges.

7. Keep Your Core Contracted

To protect your spine and move the most weight possible, focus on keeping your core contracted throughout your workout—especially during big lifts like the squat and deadlift. While some people prefer to train with a lifting belt, it's not essential for these exercises. In fact, Silver-Fagan recommends strengthening your core without a belt before relying on one.

"Unless you're on a platform for a powerlifting meet or performing a max-effort lift, take off the belt," she says. "Use your abdominal pressure to protect the spine instead."

8. Use All the Angles

Any time you train your lower body, be sure to hit your legs from different angles and points of overload. "Change up where you face your toes on the leg press, for example, or how close together your feet are," says Silver-Fagan. "Simple changes like these will help prevent plateaus while emphasizing different areas of the muscle during each session."

Making small tweaks in your workouts over time adds variety to your training sessions and can also keep you more mentally engaged. This, in turn, can keep you fired up and pushing throughout every workout.

9. Train in Proper Shoes

Don't neglect your choice of footwear, as wearing the wrong shoes could compromise your exercise technique. You need to train in stable, secure shoes that keep you grounded and allow you to perform the exercise at hand to the best of your ability.

"For higher-intensity circuits, use cross-training shoes," Silver-Fagan says. "For heavier lifting sessions, make sure you're wearing shoes that are flat on the floor, or simply take your shoes off. Converse Chuck Taylors, for example, are great for heavy deadlifts and squats, but I prefer to be barefoot for these movements."

Build Your Own Knockout Legs!

Ready to put all of Silver-Fagan's tips to good use? Try this killer leg circuit, which will help you build lower-body strength and shape while challenging your cardiovascular fitness.

Perform each circuit as indicated, doing three rounds before moving on to the next circuit. Rest between circuits to catch your breath. Be sure to start the workout with a good warm-up.