Biomechanics is the study of movement, more specifically, the movement (technique) involved in a strength exercise, or in execution of a sports skill. It deals mainly with physical factors such as speed, mass, acceleration, levers, force, and the physical functions of the movement. Some think of biomechanics as the science of movement based on principles derived from physics and anatomy. It explains the “why” and “how” of a movement and strategies to improve it through scientifically-based modificatio

1. Prime Mover, Agonist, or Muscle Most Involved. A muscle is called a prime mover, agonist, or muscle most involved when it is the main muscle involved in a concentric contraction.

2. Assistant Mover. An assistant mover usually plays a secondary role to the prime mover muscles involved.

3. Antagonist. An antagonist muscle is one which has an action directly opposite that of the agonist.

4. Stabilization. When a muscle acts as a stabilizer it steadies or holds a limb and/or body part in place.

5. Synergy. In the field of exercise synergy should be used in two ways. One is helping synergy in which two muscles contract simultaneously to produce one movement for which they are suited, while their other actions cancel each other out. Second is true synergy in which a different muscle contracts to stop the secondary action of another muscle.

1. Concentric Strength. In a concentric contraction the muscles shorten and produce movement. Concentric strength is sometimes known as overcoming strength. In other words, when the muscle contracts, it overcomes the resistance and puts the object or your body into motion.

2. Eccentric Strength. In an eccentric contraction (often known as a yielding contraction), the muscle lengthens (stretches back to its original length) as it contracts. The more the muscle lengthens or the faster it is stretched the greater the tension that is developed. The eccentric contraction plays a very important role in controlling and stopping movement and in preparing the muscles for an explosive type contraction.

3. Isometric Strength. In an isometric contraction you exhibit strength, but there is no movement of the limbs. The muscle develops tension and there is some shortening of the muscle fibers and tendon, but there is no limb or body movement.

When executing a strength exercise, all three muscle contraction regimes are involved. As you perform a movement, the main muscles (agonists) undergo a concentric contraction while the opposing antagonist muscles undergo an eccentric contraction. The adjacent joints and parts of the body that are not in use are stabilized via the isometric contraction. Thus, all three muscle contraction regimes are in operation at the same time, each with a very important purpose.

There are 3 Planes of Movement

Sagittal - Lies vertically and separates the body into left and right parts.

Frontal - Lies vertically and divides the body into anterior and posterior parts.

Transverse (Horizontal) - Lies horizontally and divides the body into superior and inferior parts (top and bottom).

There are 3 Axes of Movement

Sagittal - Passes horizontally from posterior to anterior and is formed by the intersection of sagital and transverse planes.

Frontal - Passes horizontally from left to right and is formed by the intersection of the frontal and transverse planes.

Vertical - Passes vertically from inferior to superior and is formed by the intersection of the sagital and frontal planes.

Also known as dorsi flexion, or the movement of the toe area of the foot toward the shin. In this action there is a combination of inversion at the subtalar joint and dorsiflexion at the ankle joint when executing ankle joint flexion. In dorsi flexion(raising the toe area of the foot toward the shin), the tibialis anterior, extensor digitorum longus, and peroneus tertius muscles are the major muscles involved. The toe raise exercise involves dorsi flexion.

Also known asplantar flexion, or the movement of the toe area of the foot away from the body. In plantar flexion there are simultaneous movements of the foot around the subtalar and ankle axes, i.e., a combination of eversion at the subtalar joint and extension at the ankle joint. When you are in contact with the floor, ankle joint extension raises your body, and when you are airborne, it points your toes. In plantar flexion the major muscles of the posterior shin are involved. They are the gastrocnemius, which shapes the back surface of the shin, and the soleus, which is slightly wider than the gastrocnemius and lies directly underneath it. The heel raise and seated heel raise exercises involve plantar flexion.