September 2009 – The Biomechanics Behind Pain
Ask any physical therapist and they will tell you that one of the most challenging and enjoyable aspects of our work lies in deciphering WHY pain has started without trauma. The word “idiopathic” is a term used in medicine to describe a condition which has an “unknown origin.” It is very common to find that the reasons behind idiopathic pain lie in understanding the biomechanics of the musculoskeletal system.
The musculoskeletal system is the system of muscles, tendons, ligaments, bones, and joints that move the body and help maintain its form. This system is built to work together in a precise way and can accomplish amazing things when everything works in harmony. Even when things don’t work in harmony we can perform many tasks, but the body will wear down more rapidly. Biomechanics is the study of how forces act within the body as the body moves through space. As you study the human body, you learn that our bodies are motion machines. The bone-levers and muscle-pulleys, which account for 60% of the body’s weight, make that perfectly clear.
Our nervous system is directly linked to our musculoskeletal system and usually has the ultimate control over intentional movements performed by this system. Just as a light switch sends a signal down a wire to light a light bulb, so too does the brain send a signal down the nervous structures to move the musculoskeletal system. Both of these systems are essential for life as we know it, and survival depends upon the coordination of these two systems. When these systems do not work in proper coordination, the biomechanics that result can be damaging over time. The result is usually PAIN, which will often bring you in to see your physical therapist.
Let’s take running for example. The brain sends multiple signals down the spinal cord to the peripheral nerves. These nerves interface with the muscles that move our legs and arms, which then propel us forward as we run down the street. Our muscles contract, pulling on bones which are allowed to bend at joints, which are supported by ligaments. As the foot hits the ground, joints and muscles absorb shock and become spring loaded. A signal from the joint is sent back to the brain, which interprets where the foot is, and then the process starts all over again. If your biomechanics are not what they should be, then running will eventually cause pain.
There are many different examples of how running biomechanics gone wrong can eventually result in pain. For example, let’s say that your gluteus maximus (or buttocks) is weaker on your right side due to daily activities which demand strength from your left side and not your right.
Your gluteus maximus is responsible for making sure your femur moves in the right way when you land on your foot. If this muscle is weak, your femur will movemore to the inside than it should as you roll over your foot. This abnormal tracking may result in one or more of the following painful scenarios.
- You may overstretch your IT band and eventually cause pain in your knee or hip as this band moves over the bursa in your hip.
- Excessive forces going to the inside of the knee may overstrain the tendons and ligaments on this side.
- Your knee cap may not stay in the right place as you move and will therefore cause excessive knee cap pain.
- Your foot may roll over escessively in the wrong direction, which can lead to arch pain, heel pain, or even bunion formation.
- Excessive dropping of the pelvis on one side can irritate the joints in your back and eventually result in back pain.
And that is just the tip of the iceberg!
Physical therapists are biomechanical experts. We have an understanding of the interrelationship between your musculoskeletal system and nervous system, and are able to discern the biomechanical factors which lead to idiopathic pain. If you are having pain during movement and don’t know the reasons why, contact your physical therapist today for a thorough biomechanical exam.
Your musculoskeletal system will thank you.
September 2009 – The Biomechanics Behind Pain