Bio Mechanics of Arm Wrestling

BIOMECHANICS OF ARM WRESTLING

by

ACHITA AHUJA MEPN 2ND SEM

Arm-wrestling is a complex sports that involves most of the muscles acting on the arm, wrist and shoulder. Which of these muscles become the limiting factor for arm wrestling success is determined by the specific arm wrestling technique used by the athlete.

Each participant places one arm (either the right or left, but both must be the same) on a surface with their elbows bent and touching the surface, and they grip each other's hand. The goal is to pin the other's arm onto the surface, with the winner's arm over the loser's arm. • It involves most of the muscles acting on the arm, wrist and shoulder. • Which of these muscles become the limiting factor for arm wrestling success is determined by the specific arm wrestling technique used by the athlete.

TECHNIQUES INVOLVED IN ARM WRESTLING

There are two techniques used in arm wrestling • Hook • Top-roll These two techniques when coupled tactfully with a strong finish can make a successful winner. Implementation of these techniques are fast and seamless to get over the opponent.

MUSCLES INVOLVED IN VARIOUS MOVEMENTS

The Hook The goal of the hook is to force the opponent’s hand back, thus increasing power and leverage. The player forces the opponent’s hand back, and exposes opponent’s wrist by twisting his own wrist towards self and finishes the game by dropping arm down. There are many different ways to perform the hook and depending on the specific technique used by the athlete the muscle activation may vary slightly, but in general three important factors will be most important. The ability of the arm wrestler to: • To Flex the wrist • To Flex (bend) the arm at the elbow • To statically hold or medialy rotate the upper arm (Humerus) basically keeping the arm from rotating outward down to the pad.

Muscles involved in wrist flexion • Flexor carpi radialis • Flexor digitorum superficialis (also closes the hand) • Palmaris longus ( also closes the hand) • Flexor carpi ulnaris If full flexing force is applied to the wrist hand is locked automatically since they are largely controlled by the same muscles.

Muscles involved in elbow flexion ( bending the arm at the elbow) • Biceps brachii (also supinates the hand, turning it outward) • Brachialis • Brachioradialis ( actually located in your lower arm) Note that if your hook technique is to turn the wrist down and inward (supinate and flex) your are to a large extent using your biceps which also locks your arm at the elbow.

Muscles involved in medial rotation ( turning the arm inward often referred to as side pressure) • Teres major ( also adducts the arm pulling it inward towards your body) • Latissimus dorsi (Lats) ( biggest muscle of the upper body) • Pectoralis major (your chest muscles) • Subscapularis The muscles involved in medial rotation are the biggest and strongest muscles of the upper body but they have a limited range of motion where they can perform at their best, they are also at a huge biomechanical disadvantage.

The strongest biomechanical position in arm wrestling Shoulder elevated and placed slightly in front of your body. Arm squeezed in adduction. This is locked position and involves chest muscles like Subscapularis and Latissimus dorsai. These two muscles work statically to keep arm from rotating outward and away from the body. Experienced arm wrestler keep their arm in this position at all times and lean over with their entire body to pin their opponent. All muscles are stronger statically (locked in the same position) than dynamically (moving) So by keeping the arm and shoulder at it´s strongest biomechanical position and holding it statically they can exert the greatest force.

Top-roll The top-roll is the most effective arm wrestling technique. Toprolling turns arm wrestling from a showdown of bicep and forearm strength to a contest of hand, finger, and wrist prowess. The goal of Top-roll is to wrap hand around the top part of opponent’s hand with him holding the bottom part of yours. In order to get in this position, one needs to start as soon as ‘go’ hits. Pulling hand towards self in order to force opponent’s hand away from his body. messes up opponent’s leverage and increases leverage of self. This will lead to slipping of the opponent’s grip and can defeat the opponent easily.

Example of a successful Top-roll Pulling opponents arm flexion of biceps, pronation or arm and slight flexion of hand takes the wrist of opponent and then pushing the arm of the opponent for a successful Top-roll. The muscles involved are to a large extent the same as for the hook but with two significant differences. • The involvement of Extensor Carpi radialis • The involvement of Pronator Teres

• The involvement of Extensor Carpi radialis that cause radial deviation of hand and extension of wrist. A strong Extensor Carpi prevents from dropping wrist (thumb down). For this muscle static strength is most important, It is often the limiting factor of how much bicep power can be utilized when Top-rolling especially if the opponent has a high grip on hand. Arm wrestlers doing wrist curls but rarely wrist extensions which are equally important for the Top-roll technique. In arm wrestling one never wants to extend wrist in a match but those same muscles keep your hand from ulnar deviating (dropping your wrist in direction of little finger)

• The involvement of Pronator Teres that acts in pronation. Pronation of the arm is very important in Top-roll as by doing so one can extend the wrist of opponent, which is more or less what top rolling is all about.

Spiral fractures of Humerus During an arm wrestling match forearm works as a lever on elbow joint creating a huge twisting torque on Humerus ( upper arm) This is the cause of most arm wrestling injuries creating a spiral fracture of the Humerus. Arm wrestling puts enormous torque/twist on the upper arm's humerus bone to a degree seen in few other physical activities. The arm typically fails because of a diagonal break at or below the midpoint between the shoulder and the elbow.

The natural tendency of an inexperienced arm wrestler is to push the hand, wrist, and shoulder in the same coordinated direction, against the force being applied by the opponent. This is how we throw a baseball or hit a tennis ball. However, turning one's shoulder this way simply adds to the torque already being applied to the humerus by the opponent.

We can calculate the torque exerted on the Humerus quite easily. Torque = Force x length of lever (M=F*d)

Example If opponent A exerts a side pressure on opponent B hand with 20kg of force which is about 200Newton (N). The length of forearm is apx 40cm. The Twisting Torque exerted on your Humerus is then 200*0.4 = 80Nm which is about half of what you get in a normal car. So there is a tremendous force. This force must be absorbed by muscles and tendons because such amount of force would cause fracture in Humerus, if it were not supported by muscles, tendons and ligaments.

Medial Epicondylitis Many arm wrestlers experience more or less constant pain or irritation on the inside of the lower arm near the elbow. This is also known as golfers elbow. The pain originates from the medial Epicondyle Medial Epicondylitis is caused by over use of the wrist and hand flexors resulting in small ruptures and micro trauma of the tendons attaching these muscles to the Epicondyle.

Many arm wrestlers damage their Epicondyl during a competition or hard training session. It is very important to take rest and let the tendon heal before arm wrestling again, It usually only takes 3-4 weeks if allowed to heal properly.

If the tendons and ligaments are too weak to support the pressure, the muscles can cause a complete tendon blow (pop). However, tendons can be strengthened with many methods. When tendons are in pain, they require blood so they can heal faster. Training/therapy, exercising with light weights and many repetitions for 30 – 45 minutes non-stop to pump the blood into arms.