Health Essentials: Biomechanics Made Simple

What is Biomechanics?
Biomechanics explains and identifies how internal and external forces affect the body relative to physiology, anatomy, and mathematics.

Laws of Motion, Types of Forces, and Your Body
Newton’s laws of motion are universally accepted. They are (i) the law of inertia (an object at rest tends to stay at rest, while an object in motion tends to stay in motion); (ii) Force equals acceleration (A) * mass (M), where A = change in velocity (V) over time (T), and Momentum = MV; and (iii) to every action there is an equal and opposite reaction. Your body has the tools to control force and move efficiently. Forces, which could be a push or pull, are measured in Newtons.

Your body may have to encounter forces internally, exerted by one part of the body on another; or externally, exertion of force outside the body; or tensile, stretching or pulling forces from both extremes of the body; or compressive, pushing force that tends to squeeze a body; and/or frictional, acting forces when the body is not in motion.

Balance and Stability, Motion, Gravity, Energy, Work, Power, Torque, and your body; So what does this mean?
Your body has to be able to manage the sum of all forces acting on the body (recall Newton’s third law). It needs the energy to work through all the forces and move. When you begin to think, your body and biomechanics is a pretty extraordinary thing.

For instance, static equilibrium is the sum of all forces which equals the torque (twisting force that tends to cause rotation) acting on a body. Balance is the cancellation of all forces by equal opposing forces. Torque is the product of the resistance * length of resistance arm. Ultimately, the higher resistance, the greater torque is being applied.

Motion is the measure of space and time; it may be linear (movement in the same distance, direction, and time) or angular (circular movements along a fixed axis). Additionally, the change in motion is propionate to the force applied to it. For example, gravitation pull is a force with an acceleration of -9.8 m/s. Therefore, when performing exercises, motion and the force of the body have to be greater than the gravitation pull.

Another concept that should be explained is stability. Balance and stability together help manage forces and torque. The gravitation pull is always towards the center of the mass. But because the body is so complex, we are able to manipulate our center of gravity, through our anatomical position. Eccentric force is force whose line does not pass through the center of gravity, while centric force does pass through the center. However, changes in the body’s center of gravity cause the body to work harder and manage forces. Thing to keep in mind with stability is that the degree of stability is indirectly proportionate to the height of the center of gravity.  When performing activity, the lower the center of gravity, the more efficient the body can perform.

Energy is required to produce forces within the body, and to perform work, the body uses energy. Because we are talking about biomechanics, we would logically concentrate on “mechanical energy”. Mechanical energy has two forms being kinetic (processed energy when in motion) and potential (stored energy by an object). Work is the product of force by the distance travelled. Work can be positive or negative, as it is contingent on displacement, which is a function on the direction of the distance being travelled. Power is a valuable measure to determine human performance. It is measured by work over time (faster the time the work is completed, the higher the power).

Let’s bring it all together
Think about workout that has us perform a bench press set and then dumbbell extensions on both extremes of the arms. 

When we are doing the bench press we have potential energy that has been stored. When performing the press, energy is transferred through the body’s kinetic chain. When bringing the barbell down, less work is required as gravity helps bring it down. When bringing the barbell up, the force has to be great enough to counteract the acceleration of gravity and mass of the weight.

Let’s say you now move on to the next set of extensions. You are still performing work and using energy. But this time, the rotating nature of the workout is now providing resistance or torque. The farther away you have the weights from the center of gravity, and the straighter you have your arms, the more resistance and torque you are applying. Generally, the greater the torque, greater force is needed to perform the workout. And ultimately, the less time it takes you to complete the workout, the more power you are exerting.

Final Statement
Knowledge of biomechanics is significant to understanding the human body. And having extensive knowledge on the relationship between forces, motions, and energy can help you employ new awareness for physical self-sustainment.