Fore arms

BARBELL WRIST CURLS

PURPOSE OF EXERCISE:To develop the inside (flexor muscles) of the forearms.Heavy Barbell Curls make the forearms work very hard, but Wrist Curls allow you to more fully isolate these muscles.

EXECUTION:(1) Take hold of a barbell with an underhand grip, hands close together. Straddle a bench with your forearms resting on the bench but with your wrists and hands hanging over the end, elbows and wrists the same distance apart.Lock your knees in against your elbows to stabilize them.

(2) Bend your wrists and lower the weight toward the floor. When you can't lower the bar any farther, carefully open your fingers a little bit and let the weight roll down out of the palms of your hands.Roll the weight back up into your hands, contract the forearms, and lift the weight as high as you can without letting your forearms come'Up off the bench. Forearms, like calves, need a lot of stimulation to grow, so don't be afraid to make them really burn.

DUMBBELL ONE-ARM WRIST CURLS

PURPOSE OF EXERCISE:To isolate and develop the forearms.This is a variation of Wrist Curls that allows you to isolate one forearm at a time.

EXECUTION:(1) Take hold of a dumbbell and sit on a bench. Lean forward and place your forearm on your thigh so that your wrist and the weight extend out over the knee, with your palm and the inside of your forearm facing upward. Bend forward, reach over with your free hand, and take hold of the elbow of the working arm to stabilize it. Bend your wrist and lower the weight as far as possible toward the floor, opening your fingers slightly to let the dumbbell roll down out of your palm.

(2)Close your fingers again and, keeping the effort in your wrist, rather than the biceps, curl the weight up as high as you can. Finish your repetitions, then repeat using the other wrist.

BEHIND-THE-BACK WRIST CURLS

PURPOSE OF EXERCISE:To develop the flexor muscles of the forearm. This is a real power exercise for the forearm flexors, and you can go for the heaviest possible weight.

EXECUTION:(1) Back up to a barbell rack and grasp a bar. Lift it off the rack and hold it down at arm's length behind you, hands about shoulder width apart, palms facing toward the rear.

(2) Keeping your arms steady, open your fingers and let the bar roll down out of your palms. Close

your fingers, roll the bar back up into your hands, and then lift it up and back behind you as far as possible, flexing your forearms. Make sure only the wrist moves in this exercise.

REVERSE WRIST CURLS WITH BARBELL

PURPOSE OF EXERCISE:To develop the outside (extensor muscles) of the forearms.

EXECUTION:(1) Grasp a barbell with an overhand grip, hands about 10 inches apart. Lay your

forearms on top of your thighs or across a preacher bench so that they are parallel to the floor and your wrists and hands are free and unsupported.Bend your wrists forward and lower the bar as far as you can.

(2) Then bring the wrists back up and lift the bar as far as possible, trying not to let the forearms move during the exercise.This movement can also be done with your forearms on top of your thighs.

REVERSE WRIST CURLS WITH DUMBBELLS

Reverse Curls work the forearm extensors.Using dumbbells, you ensure that each side of the body will work up to its own capacity, with no help from the other.

REVERSE BARBELL CURLS

PURPOSE OF EXERCISE:To develop the biceps, the forearm extensors, and the brachio radialis.

EXECUTION:(1) Grasp a barbell with an overhand grip, hands about shoulder width apart. Let the bar hang down at arm's length in front of you.

(2) Keeping your elbows fixed in position at your sides, curl the bar upward, beginning the movement with a curling motion of the wrist. (3) Bring the bar up to a position just under the chin, contract the biceps as fully as possible on top, then lower the weight slowly back down to the starting position.

REVERSE PREACHER BENCH BARBELL CURLS

PURPOSE OF EXERCISE:To develop the biceps and forearm extensors.

EXECUTION:(1) Position yourself with your arms extended over a preacher bench. Grasp a barbell

with an overhand grip, hands about shoulder width apart. Let the bar hang so that your arms are fully 

extended.

(2) Curl the bar upward, beginning the movement with a curling motion of the wrist, and bring it up as far as possible toward your chin.Your position on the bench should be such that, at the top of the movement, your forearms have not come up completely to a perpendicular angle. From the top of the movement, lower the weight slowly back down to the starting position.

REVERSE CURLS MACHINE

PURPOSE OF EXERCISE:To develop the forearm extensors.This movement works the forearm muscles all the way to their origin at the elbow. In addition to flexing the wrist, you lift the forearm.

Although machines are designed with limited functions, a little thought and imagination will allow you to get the maximum benefit from their use.By reversing your grip on a Curl machine, you can perform very strict Reverse Curls.

EXECUTION:(1) Grasp the handle on a Curl machine in an overhand grip. Place your elbows firmly on the pad.

(2) Starting at full extension, lift the handle up and toward your head as far as it will go. Lower the weight again slowly and under control until you have returned to a position of full extension.

ONE-ARM CABLE REVERSE CURLS

PURPOSE OF EXERCISE:To isolate and develop the forearm extensors.Using one arm at a time with cables, you get constant, full-range-of motion resistance that doesn't vary with position as much as when you use dumbbells. This makes this exercise an excellent specialized one for overcoming weak points in the forearm extensors, especially if one arm is bigger than the other.

EXECUTION:(1) Using a floor-level pulley, grasp a handle with one hand, using a palms-down grip. 

(2) Concentrating on keeping your elbow completely still as a pivot point, curl the back of your hand up as far as possible toward your shoulder. At the top of the movement, lower your hand again, resisting all the way down. Finish your set with one arm, then repeat with the other.

by Arnold Schwarzenegger Encyclopedia Of Modern Bodybuilding.

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Triceps exercises

TRICEPS CABLE PRESS DOWNS(OR LAT MACHINE PD)

PURPOSE OF EXERCISE:To work the biceps through a full range of motion.

EXECUTION:(1) Hook a short bar to an overhead cable and pulley, stand close to the bar and grasp it with an overhand grip, hands about 10 inches apart. Keep your elbows locked in close to your body and stationary.Keep your whole body steady-don't lean forward to press down with your body weight.

(2) Press the bar down as far as possible, locking out your arms and feeling the triceps contract fully. Release and let the bar come up as far as possible without moving your elbows. For variety, you can vary your grip, the type of bar you use, how close you stand to the bar, or the width between your hands; or you can do a three-quarter movement, going from all the way up to three-quarters of the way down in order to work the lower triceps more directly.

Arms Blaster Pressdowns . . . I frequently did Pressdowns using an Arm blaster to keep the elbows from moving and to create a super strict movement.

When doing Pressdowns with an incline board, you force the triceps to work at an unfamiliar angle, and you can't cheat.

Changing from an overhand to a reverse grip will change the feel-and muscle recruitment.

ONE-ARM CABLE REVERSE PRESS DOWNS

PURPOSE OF EXERCISE:To isolate the triceps and develop the horseshoe shape of the muscle.This exercise is especially good for contest or weak point training because by using a cable
you can work each arm separately in isolation.

EXECUTION:(1) Using an overhead cable and pulley, take hold of the handle with a reverse grip, palm up.

(2) Keeping your elbow fixed and unmoving, straighten your arm until it is  locked out and extended straight down. Flex the triceps in this position for extra contraction.Still not moving the elbow, let your hand come up as far as possible until the forearm approaches the biceps, feeling a complete stretch in the triceps. Finish your repetitions, then repeat with the other arm.

SEATED TRICEPS PRESSES

PURPOSE OF EXERCISE:To hit all three triceps heads, especially the long head.

EXECUTION:Grasp a barbell with an overhand grip, hands close together.(1) Sit on a bench and raise the bar straight up overhead, arms locked out.

(2) Keeping your elbows stationary and close to your head, lower the weight down in an arc behind your head until your triceps are as stretched as possible. Only the forearms should move in this exercise. From this position, using only your triceps, press the weight back up overhead to full extension. Lock your arms out and flex your triceps. You might prefer doing this exercise using an EZ curl bar or on an incline bench.

STANDING TRICEPS PRESSES

PURPOSE OF EXERCISE:To develop the full sweep of the triceps.Doing this movement gives your triceps a full look to complement the biceps when doing a double-biceps pose.Performing Triceps Presses standing instead of seated allows you to do a cheating movement and thus use more weight. This exercise can also be done with a cable and rope through a floor-level pulley, which puts greater emphasis on the long head of the triceps.

EXECUTION:(1) Grip a straight or E-Z curl bar with an overhand grip, hands about 10 inches apart. Stand upright and hold the bar extended straight overhead.

(2) Keeping your elbows stationary and close to your head, lower the weight down behind your head as far as possible, then press it back up to the starting position through a semicircular arc.

LYING TRICEPS EXTENSIONS

PURPOSE OF EXERCISE:-To work the triceps all the way from the elbow down to the lats.

EXECUTION:(1) Lie along a bench, your head just off the end with knees bent and feet flat on the bench. Take hold of a barbell (preferably an E-Z curl bar) with an overhand grip, hands about 10 inches apart.

(2) Press the weight up until your arms are locked out, but not straight up over your face. Instead, the weight should be back behind the top of your head, with your triceps doing the work of

holding it there. Keeping your elbows stationary, lower the weight down past your forehead, then press it back up to the starting position, stopping short of the vertical to keep the triceps under constant tension. Keep control of the weight at all times in this movement to avoid banging yourself on the head with the bar.When you can't do another rep, you can still force the triceps to keep working by repping out with some Close-Grip Presses.

Close-Grip Presses starting position.

Close-Grip Presses ending position.

LYING DUMBBELL EXTENSIONS

PURPOSE OF EXERCISE:To work the triceps.

EXECUTION:(1) Lie on a bench, head even with the end, knees bent, feet flat on the bench. Hold one dumbbell in each hand overhead, arms straight, palms facing each other.

(2) Hold your elbows stationary and lower the dumbbells down on either side of your head until your triceps are fully stretched and the weights almost touch your shoulders. Press them back up through a sweeping arc, 
but lock your elbows out before your arms are pointed straight up overhead and flex your triceps.

LYING CROSS FACE TRICEPS EXTENSIONS ( OPTIONAL)

Lying Dumbbell Extensions also can be done with one dumbbell at a time by bringing the dumbbell across your body to the opposite shoulder. When you finish your reps with one arm, repeat with the opposite one. Changing the angle changes the feel in your triceps.

DUMBBELL KICKBACKS

PURPOSE OF EXERCISE:To develop the triceps, especially the upper area.

EXECUTION:(1) Stand with knees bent, one foot in front of the other, putting one hand on a low bench for balance. Take a dumbbell in the opposite hand, bend your arm and raise your elbow back and up to about shoulder height, elbow close to your side and letting the dumbbell hang straight down below it.

(2) Keeping your elbow stationary, press the weight back until your forearm is about parallel to the Roar. Hold here for a moment and give the triceps an extra Rex, then slowly come back to the starting position. For added triceps development, twist your hand slightly as you lift the weight, bringing the thumb up, and twist back the other way as you come down. Finish your set, then repeat the movement using the other arm. Make sure that only your forearm moves in this exercise, not the upper arm. This exercise can also be done with cable pulleys.

ONE-ARM TRICEPS EXTENSIONS

PURPOSE OF EXERCISE:To work the entire triceps and separate the three triceps heads.

EXECUTION:(1) Sitting on a bench, take a dumbbell in one hand and hold it extended overhead.

(2) Keeping your elbow stationary and close to your head, lower the dumbbell down in an arc behind 

your head (not behind the shoulder) as far as you can. Feel the triceps stretch to their fullest, then

press the weight back up to the starting position. It is essential to do this as strictly as possible. Looking in the mirror helps you check your form. Finish your set, then repeat the movement with the other arm. Be sure to go back and forth from one hand to the other without stopping to rest in between.

VARIATION:Various machines allow you to do Triceps Extensions with one arm at a time or both together, and many give the opportunity to work the full range of motion of the triceps under constant resistance.Use these machines for variety in your workout or to allow your training partner to help you with forced reps and forced negatives when you feel like working extra heavy.

DIPS

PURPOSE OF EXERCISE:To develop the thickness of the triceps, especially around the elbow.Dips are often thought of as a chest exercise, but they can be done in such a way as to hit the triceps really hard as well.

EXECUTION:(1) Taking hold of the parallel bars, raise yourself up and lock out your arms.

(2) As you bend your elbows and lower yourself between the bars, try to stay as upright as possible the more you lean back, the more you work the biceps; the more you bend forward, the more you work the pectorals. From the bottom of the movement, press yourself back up until your arms are locked out, then give an extra flex of the triceps to increase the contraction. You can also increase the effort involved in this exercise by using a weight hooked around your waist and by coming up only about three-quarters of the way rather than locking out the movement and taking the tension off the triceps.

DIPS BEHIND BACK

PURPOSE OF EXERCISE:To develop the thickness of the triceps.This movement is also known as Bench Dips, or Reverse Push-Ups.

EXECUTION:(1) Place a bench or bar behind your back and hold on to the bench at its edge, hands about shoulder width apart. Place your heels on a bar or another bench, preferably at a level higher than the bench you are holding on to. Bending your elbows, lower your body as far as you can toward the floor.

(2) Then push back up, locking out your arms to work the upper triceps. To work the lower triceps, stop just short of locking out.If your own body weight is not enough, try doing the movement by having a training partner place a plate on your lap.

FIXED BAR TRICEPS EXTENSIONS

PURPOSE OF EXERCISE:To fully stretch and develop the triceps.Using this movement, you can completely stretch the triceps more safely than with any other exercise.

EXECUTION:(1) Using a fixed horizontal bar positioned at about waist height, grasp the bar with an overhand grip, hands about shoulder width apart. Lock your arms out to support your weight,  then move your feet back until you are in a semi-Push-Up position above the bar.

(2) Bend your arms and lower your body so that your head comes down below and under the bar as far as possible.When you feel the maximum stretch in your triceps, press forward with your arms and

raise yourself back to the starting position, arms locked out.

by Arnold Schwarzenegger Encyclopedia Of Modern Bodybuilding 

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Biceps exercises

STANDING BARBELL CURLS

PURPOSE OF EXERCISE:To develop the overall size of the biceps.This is the most basic and popular of biceps exercises.

EXECUTION:(1) Stand with feet shoulder-width apart and grasp the bar with an underhand grip, hands about shoulder width apart.Let the bar hang down at arm's length in front of you.

(2) Curl the bar out and up in a wide arc and bring it up as high as you can, with your elbows close to the body and stationary. Keep the arc wide and long, rather than bringing the bar straight up and making the movement too easy. Fully flex at the top. Lower the weight again, following the same arc and resisting the weight all the way down until your arms are fully extended. A small amount of body movement in this exercise is acceptable because it is a mass-building movement, but this is to be kept to a minimum unless you are doing deliberate Cheat Curls. Bending forward and leaning back cut down on your range of motion.

ARM BLASTER CURLS (OPTIONAL)

Doing Curls with an Arm Blaster-a piece of equipment that, unfortunately, you don't see very often today-is a very strict way of working the biceps that minimizes cheating. By using the Arm Blaster, you get the same kind of effect as with a preacher bench-no elbow movement 

at all and strict isolation of the biceps.

CHEAT CURLS

PURPOSE OF EXERCISE:To develop extra mass and power in the biceps.

EXECUTION:Stand and hold the bar as for Barbell Curls, but use enough weight so that it becomes difficult to do more than just a few strict repetitions.At this point, you begin to swing the weight up, using your back and shoulders to help your arms. The trick is to keep your biceps working as hard as they can, and cheat only enough to keep the set going.Keep the elbows stationary at the waist. I like to combine Barbell Curls and Cheat Curls, doing a normal set of Curls and, when my arms are too tired to do any more strict repetitions, loading on extra weight and doing some Cheat Curls to really blast the biceps.

PREACHER CURLS

PURPOSE OF EXERCISE:To develop the biceps especially the lower end.This is especially good for anyone who has space between the lower biceps and the elbow joint, to help fill in and shape this area.

EXECUTION:Preacher Curls are an even stricter movement than regular Barbell Curls.

(1) Position yourself with your chest against the bench, your arms extending over it. This puts the arms at an angle, which transfers additional stress to the lower area of the muscle. Take hold 

of a barbell with an underhand grip.

(2) Holding your body steady, curl the bar all the way up and then lower it again to full extension, resisting the weight on the way down.You can use an E-Z curl bar for this movement, or even use the bench for One-Arm Dumbbell Curls.Don't lean back as you lift the bar, and deliberately flex the muscle extra hard as you come to the top of the movement, where there is little actual stress on the biceps muscles.

Preacher Curls can also be done with an E-Z curl bar.

Doing Preacher Curls with dumbbells forces each arm to work independently.

doing this exercise with the dumbbells held closer together works the outer biceps to a slightly greater degree and doing it with the dumbbells apart works the inner biceps more strongly.

3-PART CURLS (21S)

PURPOSE OF EXERCISE:To develop and shape the entire biceps area.This exercise, a combination of partial- and full-range movements, is a great test of endurance. Because of the combination of 3 sets of 7 repetitions each, this exercise is also known as 21s.

EXECUTION:(1) From a seated or standing position, take a dumbbell in each hand, holding the weights at arm's length down at your sides.

(2) Curl the weights upward but stop half Way, when your forearms are about parallel to the floor, then lower them again to the starting position. Do 7 repetitions of this movement. Then, without stopping.

(3) curl the weights all the way up but stop half Way down and do 7 repetitions of this partial movement. At this point, even though exhaustion will be setting in, finish off the set by doing 7 full-range Dumbbell Curls. I like to do this exercise in front of a mirror so that I can really be sure of lifting in exactly the proper range.

INCLINE DUMBBELL CURLS

PURPOSE OF EXERCISE:To stretch the biceps and for overall biceps development.This exercise develops mass and biceps peak at the same time.If you do the movement to the front, it is a general biceps exercise.If you do it to the outside, it becomes a specialized exercise that emphasizes the inner part of the biceps.

EXECUTION:(1) Sit back on an incline bench holding a dumbbell in each hand.

(2) Keeping your elbows well forward throughout the movement, curl the weights forward and up to shoulder level.Lower the weights again, fully under control, and pause at the bottom to keep from using momentum to swing the weights up on the next repetition. I find I get the best results with this exercise by pronating and supinating my wrists during the movement turning the wrists so that the palms face each other at the bottom, then twisting the weights as I lift so that the palms turn upward, then outward, with the little finger higher than the thumb at the top.

SEATED DUMBBELL CURLS

PURPOSE OF EXERCISE:To build, shape, and define the biceps.Doing a standard curl with dumbbells rather than a barbell means you will use slightly less weight, but the arms are left free to move through their natural range of motion and you can achieve an even greater degree of contraction. As with Barbell Curls, you can cheat a little with this exercise, but keep it to a minimum.

EXECUTION:(1) Sit on the end of a flat bench, or against the back support of an incline bench adjusted to an upright position, a dumbbell in each hand held straight down at arm's length, palms turned toward your body.

(2) Holding your elbows steady as unmovable pivot points, curl the weights forward and up, twisting your palms forward as you lift so that the thumbs turn to the outside and the palms are facing up. Lift the weights as high as you can and then give an extra flex of the biceps to achieve maximum contraction.Lower the dumbbells down through the same arc, resisting the weight all the way down, until your arms are fully extended, the biceps stretched as far as possible. Twisting the wrists as you lift and lower the dumbbells causes a fuller contraction of the biceps and develops the inner biceps and separation between biceps and triceps. You can also do this exercise standing instead of seated, which will allow you to use a little more weight, although the movement will not be as strict.

HAMMER CURLS (OPTIONAL)

This is done the same way as regular Dumbbell Curls except the palms face inward and stay that way throughout the movement. This way you train the forearms as well as the biceps.

ALTERNATE DUMBBELL CURLS

PURPOSE OF EXERCISE:To isolate the biceps of each arm.This is a variation of a Dumbbell Curl in which you curl the dumbbells alternately, first one arm and then the other, to give you that extra bit of isolation, allowing you to concentrate your energy on one arm at a time and to minimize cheating.

EXECUTION:Stand upright, a dumbbell in each hand hanging at arm's length. Curl one weight forward and up, holding your elbow steady at your waist and twisting your wrist slightly,bringing the thumb down and little finger up, to get maximum biceps contraction. Curl the weight as high as you can, then bring it back down under control through the same arc, simultaneously curling the other weight up so that both dumbbells are in motion and twisting the wrist of the other hand as you bring it up.Continue these alternate Curls until you have done the required repetitions with both arms. Make sure you fully extend and contract the arm to get the fullest possible range of motion.

Using the Arm Blaster you get the strictness of a Preacher Curl, with the elbows fixed solidly in place, which is especially good for training the lower biceps.

You can do Alternate Dumbbell Curls in a sitting position as well.

CONCENTRATION CURLS

PURPOSE OF EXERCISE:To create maximum height in the biceps, especially the outside of the biceps.
I like to do this exercise at the end of my biceps training because it is one of the best means of peaking the muscle. This is a very strict movement, but it is for height, not definition, so use as much weight as you can handle. The name Concentration Curl is significant: You really need to concentrate on the biceps contraction and on being strict to make this exercise effective.

EXECUTION:(1) In a standing position, bend over slightly and take a dumbbell in one hand. Rest your free arm on your knee or other stationary object to stabilize yourself.

(2) Curl the weight up to the deltoid and without moving the upper arm or the elbow and make certain you don't allow your elbow to rest against your thigh. As you lift, twist the wrist so 

that the little finger ends up higher than the thumb. Tense the muscle fully at the top of the Curl, then lower the weight slowly, resisting it all the way down to full extension. At the top of the Curl, the biceps are taking the full stress of the weight. Don't curl the weight to the chest-it should be curled to the shoulder.

LYING DUMBBELL CURLS

PURPOSE OF EXERCISE:To build the entire biceps throughout a maximal range of motion.This is an exercise I learned from Reg Park, and it is particularly effective because it gives you a great biceps stretch and helps lengthen the muscle.Also, due to the angle, the biceps must contract fully to offset the pull of gravity.

EXECUTION:Use an exercise bench and, if necessary, place it on blocks to raise it higher off the

ground. (1) Lie on your back on the bench, a dumbbell in each hand, your knees bent and feet flat on the bench. Let the dumbbells hang down (but not touching the floor) and turn your palms forward.

(2) With your elbows steady, curl the weights up toward the shoulders, keeping the movement very strict. Then lower the dumbbells back toward the floor, resisting the weight all the way down.

TWO-HAND CABLE CURLS

PURPOSE OF EXERCISE:To develop and shape the biceps, particularly the height of the biceps peak.

EXECUTION:Attach a bar to a floor-level cable and pulley.(1)Grasp the bar with an underhand grip, hands about shoulder width apart. Keeping your elbows fixed at your sides, extend your arms out and down until your biceps are fully stretched.

(2) Curl the bar upward, not letting your elbows move, to a position just under your chin. Contract your biceps as hard as possible on top, then lower the bar slowly back down until your arms are fully extended, biceps stretched. This is not generally considered a mass exercise, so the key to doing it properly is a slow, smooth, controlled motion.

CABLE CURLS WITH PREACHER BENCH (OPTIONAL)

EXECUTION:To do this movement with a preacher bench.

(1) sit down and place your arms over the bench to hold them steady as you.

(2) curl the weight up and slowly lower it again, resisting the weight all the way down.

REVERSE CURLS

PURPOSE OF EXERCISE:To develop the biceps.This exercise is also good for forearm development.

EXECUTION:(1) Standing with your feet shoulder-width apart, grasp a barbell with an overhand grip and hold it down in front of you at arm's length.

(2) Keeping your elbows steady, curl the weight out and up to a position about even with your chin. Lower the weight through the same arc, resisting all the way down. Gripping the bar this way, you put the biceps in a position of mechanical disadvantage, so you will not be able to curl as much weight. The reverse grip makes the top of the forearm work very hard. Reverse Curls for the biceps rather than the forearms do not 

begin with any kind of Reverse Wrist Curl.Keep the wrists steady as you curl the weight up. Notice that the thumb is kept on top of the bar.

REVERSE PREACHER BENCH CURLS

PURPOSE OF EXERCISE:To develop the biceps and the top of the forearm.Using a preacher bench, the movement is done very strictly.

EXECUTION:(1) Grasp a bar with an overhand grip, hands about shoulder width apart.

(2) Lean across a preacher\bench and extend your arms fully. Let your arms hang toward the floor, then curl the weight up, with the wrists as well, keeping the elbows firmly anchored.Curl the weight as far as possible, then lower it again, keeping it under control and resisting all the way down. Keep your body steady throughout the movement and avoid rocking back and forth.

BICEPS MACHINES

A lot of equipment companies make Curl machines designed to allow you to subject your biceps to full-range rotary resistance. One advantage of these machines is that they allow you to do heavy forced negatives, your workout partner pressing down on the weight as you resist during the downward part of the movement. Another is that you can often get a longer range of motion, giving you more stretch and total contraction.However, machines lock you into one narrow movement path, which will not allow for a really full development of the biceps. Use machines as a method of getting more variety in your workouts in addition to, but not instead of  free-weight Curls.

MACHINE CURLS

PURPOSE OF EXERCISE:To work the biceps through the longest range of motion possible.When you do Curls on a machine, the movement becomes extremely strict and you are able to contract against resistance over the longest range of motion possible, from the point of full extension to that

of a full peak contraction. Because of this, Machine Curls are a shaping, finishing exercise rather than one designed to build mass.

                         There are a wide variety of Curl machines found in gyms.With some, the resistance is provided by loading the machine with weight plates, while others use a cable attached to a weight stack. With many machines you grasp a bar and curl both arms simultaneously. With others, like the one pictured here, the two sides of the machine work independently, so you can either curl your arms simultaneously or, as shown here, use the machine to do Alternate Curls.

EXECUTION:When doing Curls on any machine, position yourself with your elbows on the pad and grasp the bar or the handles with an underhand grip.

(1) For two-handed Curls, contract the biceps and curl both arms as far as possible, feeling a full peak contraction at the top, then extend downward under full control to a point of full extension.

(2)For Alternate Curls, contract one arm to a point of peak contraction, extend it downward under full control to a point of full extension, then do the same with the other arm, and continue to alternate the two arms until your set is complete.

by Arnold Schwarzenegger Encyclopedia Of Modern Bodybuilding 

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