The Basics 08: Biomechanical Modeling

Up to this point, I have posted some unique ideas related to Biomechanics (see The Basics 01, 02, 03, and 07).  I am not aware of any other Biomechanist who has written about these ideas.  I have also posted some very traditional Biomechanical concepts (see The Basics 04, 05, and 06).  However, I do believe my interpretations of these traditional concepts is unique.  I will finish this introduction to The Basics with the following statement:

No matter what kind of movement (linear or angular) you are performing, the seven basics I have posted so far WILL be a part of every explanation on how to achieve your desired movement outcome.

Of all my ideas, this statement is the most unique aspect of my understanding of Biomechanics.  It implies that their is a key set of Biomechanical Principles that are relevant to the creation of all human movements. To demonstrate my rationale for making this statement, I need to introduce an organizational tool I call Biomechanical Modeling.  As I go through the analyses of many types of movements, I will utilize this tool to show the cause and effect relationship between Biomechanical Principles and desired movement outcomes.  Through these analyses of movement, it will become apparent why I made the statement above.

Click on "read more" to learn about Biomechanical Modeling. 

The Basics 07: The Sum of Joint Linear Speeds Princiiple

In The Basics 06, you learned that the Angular Velocity - Linear Speed Principle tells us that joint angular velocities will cause all points on a rotating body segment, and all points on any body segment attached to a rotating body segment, to move with linear speed.  If two joints are rotating, then the linear speeds of any common points due to each individual joint's angular velocity are summed (added) together.  If a third joint rotates, the linear speed of any common point would increase again.  This  represents The Summation of Joint Linear Speeds Principle.

Click on "read more" to view my description of the Real-World Application of the Sum of Joint Linear Speeds principle to the vertical jumping for maximum height.

The Basics 06: The Angular Velocity - Linear Speed Principle

After reading The Basics 04 and 05, you now know that joint torque, application time of joint torque, and angular inertia are the three modifiable factors that can increase joint angular velocity.  The Angular Velocity - Linear Speed Principle explains the relationship between joint angular velocity and the linear speeds of points that are part of, or connected to, the rotating body segment.

Click on "read more" to learn more about The Angular Velocity - Linear Speed Principle.

Muscle Memory

I had another interesting discussion today with my students.  The topic was the term "muscle memory".  I want to share my thoughts on the topic with all of you.  The most important thing you need to know is that muscle fibers have "no memory".  If you pull out a muscle fiber and apply an electrical stimulus to it, you will see it contract.  When you remove the electrical stimulus, it will relax.  You can do this ten times, a hundred times, even a thousand times and every time it will do the same thing.  That's all a muscle fiber does.  There is nothing to memorize.

Learning requires a permanent change in the long-term memory of a motor program (i.e, the pattern and intensity of electrical signals to the muscles that create the movement).  Motor programs are stored in long-term memory (LTM) and LTM is part of the brain.  The problem is this: I hear people use the term "muscle memory" when they are talking about learning a motor program.  This unfortunately leads to incorrect ideas about how we learn to perform movements.  People believe all you need to do is move the body a few hundred times and the muscles will remember what to do.  Nothing could be further from the truth.

Click on "read more" for an explanation of how movements are actually learned.

The Basics 05: The Angular Impulse - Momentum Principle

If you read the Basics 04, you know that joint torques create joint rotations; and, you would be correct to conclude that stronger joint torques create faster joint rotations (i.e., faster  angular velocities).  But, is joint torque the only factor that creates faster angular velocities?  According, to the Angular Impulse - Momentum Principle, joint torques are not the only factor that creates faster angular velocities.