Squat
Can be done with bodyweight or weights. Start with your feet hip-width apart, toes slightly pointed outward. With your chest high, head up and back slightly arched, bend your knees and hips as if you're sitting back in a chair until your thighs are parallel to the floor. Reverse the motion by driving through your heels and pressing your hips forward to return to the starting position.
Training Tip: Keep your back upright throughout the movement in order to place more stress on your quads and less on your spinal erectors.

Lunge
With a barbell across your traps or a dumbbell in each hand, alternate right and left legs in the following manner: Take a long (but stable) step forward with one leg, drop your rear knee toward the floor, then push back up with your forward leg. Keep your torso upright.
Training Tip: If you only push yourself up three quarters of the way or just short of full extension, you will keep constant tension on your quadriceps.

Lying Leg Curl
Lie facedown on a leg-curl machine and position your Achilles' tendons below the padded lever with your knees off the edge of the pad. Keep your back flat as you raise your feet toward your glutes in a deliberate motion. Squeeze the muscles and lower your feet with a controlled speed.
Training Tip: Keep your hips down on the bench; letting them rise to get more leverage will take emphasis away from the hamstrings.

Standing Leg Curl
Adjust the roller so it hits near your ankle, between your foot and the bottom of your calf muscle. Grasping a spot on the machine for support, fully tense your working leg as you slowly curl the roller as high as you can. On the descent, stop before your foot touches down, then begin the next repetition.
Training Tip: Avoid using the rest of your body to lift the weight, don't rock forward as you bring the roller up, and keep your thigh firmly against the pad.

Incline Dumbbell press
Adjust an incline bench so that the angle is no more than approximately 30-40 degrees. Grasp a pair of dumbbells and lie back on the bench. Start with both arms fully extended above your upper chest (not over your head). Lower the weights toward your upper chest, then press back up to the starting position.
Training Tip: Don't overly arch your back while pressing; keep it flat against the bench.

Cable Crossover
Grasping both handles, stand up relatively straight with a slight arch in your back. With your arms completely out to your sides, slightly flex your elbows and turn them up so that they're pointing behind you and parallel to the floor. Maintain this elbow and body position as you pull the handles down and slightly in front of your body, squeezing your chest when your hands come together.
Training Tip: To increase the stress on your pecs, keep the angle in your elbows constant throughout the range of motion, which will decrease the involvement of your triceps.

Front Pulldown
Adjust the height of the seat so that your knees fit snugly under the knee pads and your feet are flat on the ground. Grasp the overhead bar with a wide grip and sit down with your arms extended. With a slight arch in your lower back and your chest held high, pull the bar into your upper chest area, keeping your elbows pointed back. Keep your lats momentarily tensed before slowly releasing.
Training Tip: When pulling the bar down, drop your shoulders and focus on pulling with your back muscles, visualizing
your arms only as hooks to which the bar is attached.

Back Extension
Lie facedown on a back-extension bench with your heels under the pad. With your body straight, head neither flexed forward nor extended backward, and your arms crossed over your chest, lower your torso so your body forms an angle that approaches about 90 degrees. Use a smooth motion to rise back up to the starting position.
Training Tip: Don't use a ballistic motion or go too high.

Seated Dumbbell Press
Sit on a low-back seated bench with a pair of dumbbells. Hold them outside your shoulders, palms facing forward, head up. Press the weights up in an arc until your arms are fully extended overhead, then lower to shoulder level and repeat.
Training Tip: As the weights come together at the top, don't let them bang together, which briefly removes the muscular tension.

Dumbbell Lateral Raise
Stand erect and hold dumbbells at your sides, palms facing each other. Keeping a slight bend in your elbows, lift your arms out to your sides until they're about parallel to the floor, leading with your elbows. Slowly reverse to the start position.
Training Tip: As you raise the dumbbells, rotate your hands so your little finger is higher than the thumb at the top of the movement. Reverse this as you lower the dumbbells.

Seated Alternate Dumbbell Curl
Sit on a bench with a dumbbell in each hand. Start with your arms at your sides, palms facing in. Contract your biceps to lift one dumbbell upward; while doing so, twist your palm so that it faces up when you reach a full contraction. Your elbow should remain by your side throughout the lift. After squeezing your biceps at the top, slowly lower the weight and twist your wrist so that your palm again faces your thigh at the starting position. Alternate arms for reps.
Training Tip: Don't swing your body to get the weight up. You can also do the exercise with both arms simultaneously.

Pressdown
Attach a curved or a straight bar to a high pulley. Standing erect with both elbows remaining at your sides, press the bar down to full extension, squeezing your triceps at the bottom. Slowly allow the bar to come back up until your forearms are about parallel to the floor.
Training Tip: Don't lean forward into the weight or let your elbows flare out to your sides.

Crunch
Lie faceup on the floor with your calves up on a bench so that your hips and knees form 90-degree angles. Cross your arms over your chest. Curl your torso up by contracting your abs, simultaneously pressing your lower back into the floor. This is a very small movement: Your shoulder blades should rise only 1-2 inches. Hold for a brief second and slowly lower to the starting position.
Training Tip: Don't relax between repetitions; keep constant tension on your abs. You can put your hands lightly behind your neck or place them overhead to make the movement more difficult, but don't pull on your head.

Crossover Crunch
Lying faceup on the floor, bend your knees and support your head and neck with your hands. Lift your torso and cross your shoulder toward the opposite knee, alternating side to side.
Training Tip: Make sure your lower back stays flat on the floor to avoid injury. You don't need to actually touch your elbow to your knee.

Reverse Crunch
Lie on the floor with your head resting flat. Bend your knees so that your thighs are perpendicular to the floor and place your hands out to your sides for balance; this is the starting position. Roll your pelvis toward your ribcage, slowly bringing your knees up over your chest as far as you can. Your hips should rise slightly off the floor but your upper body shouldn't move. Return to the starting position in a smooth motion.
Training Tip: To keep tension on the lower abs, make sure your back stays flat against the floor at all times. If you relax and arch your lower back, you'll stress the lower back and lessen the effectiveness of the exercise.