The Chemistry of Arm Wrestling


YouTube Video

Arm wrestling is one of the few sports that puts extreme stress on the humerus bone.  Very few sports and activities cause this to happen.  I decided to chose arm wrestling because it is an activity that many people participate in and something I enjoy as well.  I use arm wrestling as a way for my family and friends to determine who is stronger, and sometimes smarter, than the other.  

Composition of ...

Muscle Composition:

Many factors play into arm wrestling:  

- Skeletal muscle is the muscle that is connected directly to the bone.  

- Sacromela- is the membrane surrounding the muscle fiber

- transverse tubules- part of the sarcoplasmic reticulum that releases and stores calcium

during contraction and relaxation.

- Myoneural junction- where motor nerve endings terminate on the sarcolemma

- Motor end plate- structure at myoneural junction that forms a small mound on the

surface of a muscle fiber.

- Sarcoplasm- cytoplasm of muscle fibers

- Nuclei- “brain” of the cell, Muscle fibers contain many of these

- Myofibrils- long and thin cylindrical rods that run parallel to muscle fibers

- Myofilaments- made up of thin and thick filaments, thick comprised of  myosin, thin

ones comprised of actin, troponin, and tropomyosin.  

- Z-disk ultrastructure- comprised of Z-filaments; connects sarcomeres.

- Proteins of the myofilaments- mostly actin and myosin (65%). also includes troponin

tropomyosin in the filaments. (C proteins that surrounds myosin filaments from thick

filaments), desmin (which encircles the Z-disks and radiate out to connect nearby


All of these allow ATP Hydrolysis to take place and cause the muscles to work.

Main Chemicals, Compounds, Components

ATP Hydrolysis (Muscle Contraction) is the most important factor for arm wrestling because it is the basis of all muscle contraction in the body.  Without it, nobody could arm wrestle, none the less do anything.

Furthermore, because arm wrestling is stressful on bones, it is important to note that strong and healthy bones are key to arm wrestling and allowing the participant to avoid injury.

Bone is made made up of collagen, a protein that is weaves into a flexible framework. Bone also contains calcium phosphate and calcium carbonate, minerals that are used to strengthen and harden the framework. The combination of calcium and collagen gives bone its strength and increased flexibility. The flexibility (or ability to withstand stress) of the bone protects it from breaking or fracturing. Bones are strong due to calcium, but bones also acts like a warehouse for calcium. More than 99% of the body's calcium is contained in the bones and teeth. The remaining 1% is in the contained in the blood in the body.  

Chemistry's Role

ATP Hydrolysis:

- Muscle contraction is created by a nerve cell.

- Receives an electrical signal that causes the cell to release acetylcholine into the

sarcolemma, the membrane that encompasses muscle fibers.

- Acetylcholine attaches to special sites on muscle fibers

- Acetylcholine causes the sarcolemma to become permeable to sodium ions.

- Sodium floods into the sarcolemma thereby causing electrical signals to travel to muscle fibers

- Electrical signals awakes sarcoplasmic reticulum (organelles) in muscle cells

- sarcoplasmic reticula respond by pumping Ca2+ ions into muscle cells

- 4 Ca2+ ions combine with the troponin-tropomyosin complex, changes the shape of tropomyosin and showing high polar binding sites on actin strand

- myosin heads, also polar, crosses between space in myosin and the actin and binds with highly polar sites on the actin.

- “The attraction between the myosin head and the actin is so strong and the myosin head has so much potential energy that once the tropomyosin moves out of the way the myosin head will spontaneously bond with the actin, without any activation energy to initiate the reaction. The myosin head springs from its place like a mousetrap and bond with the actin.”

- spring motion of myosin continues and actin fiber pulled along relative to myosin fiber.

- 1 ATP binds with myosin head (that's attached) at myosin head’s active site

- 1 ATP reacts (one above) to water through ATP hydrolysis turning ATP to ADP thereby releasing energy needed to breaking actin-myosin attraction

- the myosin head attaches to with the next active actin site and pulls  actin along again

- The continuous pulling of actin towards the center of sarcomeres along the full length of the muscle fiber and through the entire muscle causes it to

shorten and release a force.

- When the muscle  finally relaxes, the nerve ending stops to supply the sarcolemma with the chemical acetylcholine.

- The rest of the acetylcholine is then broken down by the enzyme Acetylcholinesterase and the electric signal turns off.

- The calcium is reabsorbed into the sarcoplasmic reticulum and the troponin moves back into position, restoring the shape of the tropomyosin and blocking the actin active sites from the myosin heads, which then return to their original position.

- The whole process ends in an instant and the muscle is ready to contract once more.

ATP + H2O <=> ADP + inorganic phosphate (Pi)

Background Research

It is very common for diagonal breaks in the humerus bone to occur in arm wrestling due to the fact that people cause extreme stress on that particular bone and the position that they put their arm in.  When arm wrestling the player must ALWAYS keep their shoulder in line or behind the arm.  Referees in professional matches will stop the athletes from arm wrestling if the shoulder is out of line.  Arm strength, stability, and technique are key in arm wrestling.  


- Arm wrestling background

- Technique of arm wrestling in order to win

- How muscles need oxygen when working and how it affects the body

- How to deal with injuries common in arm wrestling

-More information about Tendonitis

- Information about inflammation

- Chemical process of ATP Hydrolysis

- Structural information regarding the muscle

- ATP Hydrolysis formula and information

About the Author
Joaquin Bodine is a junior at Billings Senior High School.  He enjoys learning how things work and loves to explore the vast subject of history.  He in an Honor Roll student involved in high school track, orchestra, and Billings Senior’s Academic Team.  He is interested in advancing into a career involving teaching and education.