So many people hold on while on the treadmill. As I watch, it is clear to me this act of holding on causes an unnatural swing to the pelvis. I can only think that, over time, this will lead to some kind of injury. Am I correct in thinking that?
Great question. Holding onto the treadmill while walking, jogging or running alters one’s biomechanical gait and potentially increases the risk of injury for the body as excessive movement will be forced into joints that otherwise would work as a team. However, the treadmill is not the same as walking, jogging or running outside. Exercise outside involves the body moving on a non moving surface, and this is therefore an open chain exercise. Treadmill activity involves the surface underneath moving, and therefore this is a closed chain exercise. If we look at running as a closed chain exercise, the body works as a unit, and we develop a particular “engram” or memory trace for running. If we run on a treadmill and also hold onto it while running, we will change our biomechanics and train a different engram, potentially increasing the risk of injury.
Naturally gait occurs mostly in the sagittal plane, with movement also coming from both the frontal and transverse planes of movement. As we all know, during the contact stance phase of gait, the heel strikes the ground where the subtalar joint moves into pronation, the leg is internally rotating and the foot is absorbing shock and functioning as a mobile adaptor to the ground surface. From here, we begin to see the body pass over the foot, and the leg will bear the body weight as the opposite leg goes through swing phase. During the midstance phase, the leg is externally rotating, and the subtalar joint is supinating. We then see the foot begin to lock into a more stable adaptor that will allow for propulsion. At the propulsion phase of stance, we see the heel raise, and we toe off through the first ray. The swing phase will begin immediately as the foot leaves the ground. Now the effects of this further up the body involves the pelvis tilting and rotating anteriorly and moving in the frontal plane. Rotation then follows up through the spine where the thoracic spine works in rotation. The opposite arm to the leg will be moving in the opposite direction to help propel the body forward in gait.
How this relates to the rest of the body is that at heel contact, the pelvis is in slight external rotation. As we move from heel contact into the midstance phase, we will see the pelvis rotate internally. Just before toe off, we will see it rotate externally until the end of swing phase. During running, we will see primarily transverse plane movement through the thoracic spine and the arms swinging in the sagittal plane to help propel the body forward. If the runner swings his arms across his body, we will see a compensatory increase in pelvic motion, possibly leading to altered limb and knee function and potential injury. Altered mechanics in any region of the body will often result in a compensatory change to allow for movement. If one is holding onto the treadmill while running, you could argue that the body is not being allowed to move in a natural gait pattern as the arms are not swinging and the spine is not assisting in all three planes of movement. More stress will be placed on the lower limb mechanics, possibly leading to more wear through the body’s structures (muscles, ligaments, tendons, bones, joints, fascia) of the lumbopelvic region and lower limb. Proprioceptively, the body will be trained in non-functional movement that could alter one’s biomechanics. The osteopathic principles that say “the body is a unit” and “structure and function are interrelated” demonstrates that if we don’t allow for optimal biomechanics within the whole body, then we will see a change in both structure and function, thereby increasing one’s risk of injury.