barbell curls

8/6/2019 Barbell Curls

http://slidepdf.com/reader/full/barbell-curls 1/14

http://www.exrx.net/WeightExercises/Biceps/BBCurl.html

http://www.exrx.net/Kinesiology/AnglePull.html

http://www.fitstep.com/Library/Exercises/Standing_barbell_curls.htm

http://www.great-workout.com/biceps/barbell-curl.cfm

Barbell Curl

The barbell curl emphasises your bicep muscles. Make sure you keep good form when performing the bicep curl. Stand upright throughout the motion - don't sway back and forth as

you're lifting the weight.

How to perform the barbell curl

Technique

1. Stand straight, holding the barbell with a supinated (under-hand) grip atabout shoulder width.

2. Keeping your elbows at locked at your sides, slowly lift the bar until itsunder your chin.

3. Slowly lower the weight back.4. Repeat steps 2 & 3 until you've repeated the desired number of reps

Number of Reps

For building muscle size: 3 sets of between 6 - 8 reps. For muscle tone: 3 sets of between 12 - 15 reps.



Muscles Used

Primary

Muscles

y Biceps Brachii (Biceps)

Biceps Brachii

The Biceps Brachii is attached to the forearm bone called the radius and originates at thescapula in two places (the Bicep gets it's name from these two heads - called the short headand the long head).

The Biceps runs down the anterior or front side of the humerus and makes up approximately1/3 of the muscle mass of the upper arm..

The Biceps are among the most famous muscles in the body. When somebody asks you to"make a muscle", they aren't asking you to flex your hamstrings. They want to see your biceps!



Secondary

Muscles

y Brachialis (Lower Biceps)

The brachialis muscle is located on the front of the arm, just above the bend in your elbow.

The biceps bracii muscle sits on top of the brachialis and both muscles work together to flex

the forearm. The biceps bracii is the larger, and more visible, of the two muscles, however,

the brachialis muscle is actually the stronger of the two, according to "The Trail Guide to the

Body."



y Brachioradialis (Forearm)

Brachioradialis is a muscle of the forearm that acts to flex the forearm at the elbow. It is

also capable of both pronation and supination, depending on the position of the forearm;

for this reason it is also called "the beer drinker muscle." It is attached to the distal styloid

process of the radius by way of the brachioradialis tendon, and to the lateral supracondylar

ridge of the humerus.



Stabilizer

Muscles

y Deltoid, Anterior (Shoulder - front)

The Deltoid is a three-headed muscle that caps the shoulder.

The three heads of the Deltoid are the Anterior, Lateral, and Posterior.

All three Deltoid heads attach to the humerus. The Anterior and Lateral heads originate onthe collar bone, while the Posterior head originates on the scapula.

The Anterior Delt contributes to many Pec-related movement, e.g. bench press. The LateralDelt is most active in dedicated lateral movements. The Posterior Delt is often activated inback exercises that involve the Teres Major and Rhomboid muscles.



y Trapezius, Upper (Back - upper)

Trapezius is a flat triangular muscle that is divided into two parts, the upper trapezius and

the lower trapezius. Both of these muscles are responsible in maintaining the proper

orientation of the scapula, or shoulder blade. When the upper trapezius acts alone, it

elevates the shoulder and supports the shoulder girdle when lifting a load.The upper

trapezius is located in between the neck and the shoulders,



y Levator Scapulae (Shoulder - upper)

The levator scapulae is an upper-back muscle that runs along the side of the neck. Its primary responsibility is to assist the trapezius, the largest and most superficialmuscle of the upper back, in shrugging the shoulders. Latin in origin, its name means

³elevator of the shoulder blades,´ and this muscle is likewise responsible for pullingupward on the inside or medial edge of the scapulae.

Situated beneath the trapezius in the upper back, alongside the splenius capitusmuscle in the back of the neck, the levator scapulae originates along the spinous

processes, sideways protrusions of the first four cervical vertebrae. It then runsvertically down the side of the neck to attach to the upper medial edge of the shoulder

blade. This narrow, band-shaped muscle is relatively small, much smaller than the

large trapezius muscle, but it performs several complex functions involving the neck,head, and shoulder blades.



y Wrist Flexors (Inner forearm)

The forearm muscles are the muscles on your lower arm, and you use them whenever you openor close your hand or when your move your wrist.



Mechanics In Exercise



Angle of Pull

Gravity / Force Vectors

y Load offers varying degrees of resistive force against muscles

o Very little force is required of agonist muscles when load moves perpendicular to

gravity (signified by orange arrow).

Perpendicular to gravity / force vector = almost 0 effort

Except for forces required to overcome inertial and maintain posture for

supporting musculature.

o Moderate motive forces are required to overcome resistive forces when load moves

diagonal to to gravity / force vector.

Examples: 30° = effort is half load, 45° = effort is 71% load

o Greatest resistive forces are offered to agonist muscles when load moves parallel to

gravity.

Parellel to gravity = 100% load

Incidentally, rotary forces from working muscle acting upon load are greatestin Components of Force Diagram below.

o Orange arrow can also signify resistive force vector of pulley cable with relative

positioning of motive force angles of pull.

y Articulations in isolation follow a curvilinear path

o Load is moved in and out of line of gravity.

o Load tends to be shifted from muscles to skeletal frame and joints, and vice versa

y Compound movement seemingly move in a linear motion (line of push or line of pull)

o Compound movements can be seen as a coordinated combination of two or more

isolated movements

o Beginning posture:

primarily tension or compression forces

on bones and joints

o Execution

Pushing movements:

muscles begin to contract

eccentrically

Pulling movements

muscles begins to contract

concentrically

Analysis of Arm Curl

o Arm straight

weight in hand pulls arms (joint

supporting bone) down

o Initiation of flexion with arm straight.

arm flexors overcome inertia (see

Newton's first law)

smaller brachialis has slightly better

angle of pull as compared to biceps at



this wide angle

dumbbell moves nearly perpendicular to gravity offering relatively low resistive

forces.

with this angle of pull, rotary force of biceps is weakest

o Approaching 90 degrees

resistive force (R) progressively increases

at 30 degrees, approximately 50% of weight * lever arm ratio


o 90 degrees

resistive force is greatest when path of weight is parallel to gravity.

100% of weight * lever arm ratio

rotary force of biceps is strongest [see angle of pull above (2nd diagram

above)]

o Traveling beyond 90 degrees

resistive force progressively decreases



rotary force of brachialis and then biceps diminishes [see angle of pull above(3rd diagram above)]

o End of movement or change to eccentric contraction

antagonist muscles may be activated to overcome inertia

biceps torque force is only relieved at the flexed position if slight shoulder

flexion positions forearm perpendicular.

Also see Tension Potential and its impact on force production.

Components of Force

y Definitions:o Angle of Pull: angle between muscle insertion and bone on which it inserts.

y Components of Force

o Rotary component: force of a muscle contributing to bone's movement around a joint

axis; greatest when muscles angle of pull is perpendicular to bone (i.e. 90 degrees).

o Stabilizing component: degree of parallel forces generated on the lever (bone and

joint) when the muscles angle of pull is less than 90 degrees.

o Dislocating component: degree of parallel forces generated on the lever (bone and

joint) when the muscle's angle of pull is greater than 90 degrees.



Components of force due to angle of pull

>90 degrees

includes stabilizing component

=90 degrees

100% rotary force

<90 degrees

includes dislocating component



Shoulder abduction force vector

diagram

E.g.: Dumbbell Lateral Raise and Lying

Lateral Raise.

y Angle of Pull

o Upper: Supraspinatus

o Lower: Lateral Deltoid

y Rotary component

o perpendicular to lever arm

y Stabilizing component

o parallel to lever arm

from insertion

through fulcrum

Also see SupraspinatusWeakness

K nee flexion abduction force vector diagram

E.g.: Lever Lying Leg Curl. Color codes on diagram are same as Components of Force above.

y Hamstring

o Agonist

Active insufficient

position

o Rectangle force vectorabove knee

knee flexion

y Q uadriceps (Rectus Femoris)

o Antagonist Stabilizer

Passive insufficient

position

o Rectangle force vector

through knee

Counters posterior

forces of hamstring

See pulley-like

arrangement of

Patella at knee.

o Vertical arrow by hip

Flexes hip

Attempts to

position hamstring

back in active

sufficiency

barbell curls

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