Muscle contractions
Class Announcements
After class, the first quiz will be administered on Blackboard.
Completion: Students will complete this independently at home.
Due Date: Due before class the following Tuesday after Thursday.
Review: The quiz will be reviewed in the following class session.
Additional Information:
Quiz two will be available next Thursday and similarly due on the following Tuesday.
Currently on pace to finish essential content by next Thursday.
Course Schedule
Biometrics Unit Plan
This week will focus on biomechanics, and a final class session will be held to wrap it up.
Review of quiz two and review of the overall unit will occur before the first exam in two and a half weeks.
Anxiety and Clarifications
Instructor acknowledges students may feel anxious regarding content.
Slides and worksheets may not correspond perfectly; no need to stress or worry.
Class Content Overview
Focus: Review of muscle types and classifications.
Continuation from muscle classification (Muscles 1) to Muscles 2.
Major focus on muscle contractions and exercise prescription terminology.
Muscle Contraction Classifications
Isometric Contractions: Contractions where the muscle generates tension without changing length.
Definition: "ISO" (same) + "metric" (length), so the angle at the joint remains constant.
Example: Holding a water bottle with a constant elbow angle preventing elbow extension.
Isotonic Contractions: Muscle changes lengths while contracting.
Breaks into:
Concentric Phase: Muscle shortens while overcoming resistance (e.g., lifting weights).
Eccentric Phase: Muscle lengthens under tension while controlling the fall against gravity (e.g., lowering weights).
Example: Bicep curl involves concentric phase when lifting and eccentric phase when lowering down.
Misconceptions: Some may think of the ground force applied when descending as the elbow extensors working, but it is still controlled by the elbow flexors.
Definitions of Key Terms
Agonist Muscle: The primary muscle that creates movement during an action.
Example: In a bicep curl, the bicep is the agonist during elbow flexion.
Antagonist Muscle: Opposes the agonist and relaxes during movement.
Example: In a bicep curl, the tricep is the antagonist during elbow flexion.
Synergists: Muscles that assist the agonist in performing movement.
Stabilizers: Muscles that help maintain joint stability during movement.
Neutralizers: Muscles that counteract unwanted motion by stabilizing the action.
Force Couples: Two or more muscles working together to create movement around a joint.
Passive and Active Movements
Active Contractions: Developed muscle tension is created to prevent movement (isometric) or control movement (isotonic).
Passive Movement: Movement caused by an external force without active muscle contraction.
Practical Applications of Muscle Contraction Knowledge
Understanding muscle contractions is crucial for exercise prescription.
Example: To strengthen elbow extensors, an exercise should target the eccentric contraction phase under load.
Muscle Physiology
Voluntary contractions are initiated through neurological connections between the brain and muscle fibers.
Muscles can have multiple nerves innervating them, and one nerve can affect multiple muscles.
Tendons and Connective Tissues
Tendons: Connect muscle to bone; distinguished by their white connective tissue appearance.
Aponeurosis: A flat sheet forming a broad tendon attachment point (e.g., palmar aponeurosis).
Fascia: A connective tissue that envelops, separates, or binds together muscles or organs in the body.
Specific types such as retinacular fascia serve to hold tendons in place to prevent bowstringing.
Class Activities and Applications
Students performed breakdown exercises on muscle contractions in various scenarios to understand concentric and eccentric actions.
Emphasis on recognizing how muscles engage in specific motions and the importance of terminology in discussing muscle actions.