Chapter 5: Biomechanics and Applied Kinesiology Flashcards
Biomechanic
The study of mechanical law relates to living organisms’ movement or structure.
Applied Kinesiology
The science of human movement.
Length-Tension Relationship
A muscle produces its greatest force in the mid-range of its sarcomere length.
- Generates max force starting @ 1.2x at resting length.
- Weakest at inner and outer ranges; these two points are called the “sticking points”
Sticking Points
The force produced by muscles is the weakest at its inner (50% length) and outer ranges (> 120% length); these two points are called the “sticking points” because there are fewer cross-bridges formed.
Body’s Lever Systems
Most of the joints in our body offer mechanical disadvantages. However, the speed of rotation created by 3rd class levers is significant.
- Shortening of Mr allows lifting easier.
1st Class Lever
The Joint lies between muscle and load.
- Seen between C1 and Atlas.
2nd Class Lever
Load lies between joint and muscle.
- Since Mr < Mm, it provides mechanical advantage > 1.0, thus being more advantageous.
- Seen in muscles involved in calf raises.
3rd Class Lever
Muscle lies between joint and load.
- Since Mm < Mr, it provides mechanical advantage < 1.0, thus being more DISadvantageous.
- Seen in most joints like elbows.
Isometric (static) Contractions
The muscular force is generated while the joint angle remains the same.
Strength gains only occur @ specific angles of contraction.
Teaches muscle-mind connection.
Practice stabilization and better for anyone with limited joint mobility and posture work.
Isotonic (dynamic) Contractions
The muscular force is generated while the joint angle changes.
2 Phases:
Concentric (working) phase - Muscle overcomes resistance and muscle contracts.
Eccentric (recovery) phase - decelerating load, resisting gravity while muscle lengthens.
- Causes more cellular damage leading to DOMs.
- Muscle can bear more load during this phase.
Open Chain Excercise
An open chain exercise allows the furthest part of the chain to move freely.
- Used to target or isolate one muscle group; also increases the focus transmitted to the involved joint.
- Muscles are isolated by open chained exercises such as a bicep curl.
Closed Chain Excercise
Closed-chain movements involve the body moving whilst the limbs are relatively stationary.
- Seen in compound movements and typically transmits less force to the joints.
- Doing a squat is a closed chain exercise as your feet are fixed to the ground whilst your quadriceps do all the heavy lifting.
Agonist
A muscle that is contracting to achieve the desired movement. This muscle is directly engaged in the contraction and is the prime mover causing the movement.
Antagonist
A muscle that is typically anatomically opposite to the prime mover or agonist’s muscle. The antagonist muscle can stop or slow down the action caused by the agonist.
Synergist
The synergist muscles are the muscles that assist the agonist muscle in its function. Synergist muscles typically lie on the same side of the joint as the agonist and are capable of similar movements with similar lines of pull.
