Daily Failures, Part 2

The following examples concentrate on daily failures with a focus on biomechanical aspects and reflexes. These aspects are vital to improve movements in view of e.g. force, momentum or speed. There is a very good book on biomechanics. “Biomechanics of Sport and Exercise” from Peter M. McGinnis (Link), which gives a very good introduction to this topic using many examples. I’ll write a little review about it later.


Example for low body tension

Dog pulls girl

A young girl is pulled by a dog. The dog stops, when he feels the resistance of her body. Watch out. I looked at it very often. The more you analyze it, the more you recognize that she fell nearly unchecked. You really sympathize with her.

This is a classic example for a disturbance that was not anticipated. Her body tension is too low to counter the dog´s pull. At the beginning, her left arm is at her hip. Then you can see how it swings forward, just like a pendulum. Her right arm is trapped in the dogs leash and gets stretched. Both arms are therefore trapped in a fixed movement. The righting reflex (a reflex to counter the fall) seems to trigger, but the forces in the movement “overwrite” it. You can see her arms in the typical fall position, bent against her body. She is kind of lucky. The dog stopped pulling her and so giving her body the chance to execute the reflex. The reflex isn’t strong enough to counter the movement of her head. Her hair indicates the full movement. Her head swings backward, then forward.

It is very important to notice that her inner control was not able to counter the sudden pull. The reflex triggered, but it could not exert the necessary counterforce. Very fast movements will certainly bring you out of balance without sufficiently planned body tension.


Example for an incorrect motor program

Boy tries to kick a ball

The boy throws the ball to the ground and then tries to kick it. He fails and falls to the ground: So far, so good. The interesting part is the combination of an incorrect motor program and some biomechanical aspects.

Whether planned or not, the ball bounces forward and he tries to offset the distance by moving his body forward. Furthermore, he throws his kick at the beginning with some real effort. The problem is that he pushes himself forward with his right foot and upward with his left foot (his heel is raised). His body is now in abeyance. In that state, he is unable to counter the incorrectly scaled kick. His kick and the forward movement were initialized when he still had ground contact. Now, since the contact is lost, the possibility to counter the forces is lost too.

Another interesting aspect is the throwing movement at the beginning. He throws the ball downward and his arms swing backward. For the following, you have to look carefully to see this. The kick needs a certain counter movement. Usually, a right kick is countered with the left arm. Well, his left arm is still in a backward movement, when he initiates the kick with a push. They are not synchronized at the beginning. The delayed counter movement to the kick destabilizes him even more.

The post was published 13. December 2013 related to the category Miscellaneous and tagged with , , , , .