Wk 8 Focus

Aim of the Lecture Series: The next three lectures will build upon prior studies in biomechanics and functional anatomy, targeting advanced understanding of human movement.
- Essential Understanding: How to optimize movement patterns in individuals with varying physical conditions (e.g., stroke, spinal cord injury, osteoarthritis).
- Exercise Interventions: Exploring how exercise can serve as an engineering tool to enhance human movement.
- Next Topics: Discussion will eventually lead to footwear impact in biomechanics.
- Crucial Takeaway: Acknowledge the vast unknowns in training; expertise is limited to current knowledge gaps.

Muscle Mechanisms: Muscles are effective mechanical machines.
- Muscular Strength Example:
- Calf muscles can lift immense weight (up to 500 kg) when stimulated electrically.
- The Myosin-Actin Interaction: The myosin heads attach to actin to exert force despite the low lever arm distance.
- Torque Implications: Small moment arms yield limited torque, enabling muscles to operate effectively under low resistance (similar to bikes in low gear).

Types of Muscle Contractions:
- Concentric: Muscle shortens while exerting force (e.g., lifting).
- Eccentric: Muscle lengthens while resisting force (e.g., lowering).
- Isometric: Muscle exerts force without changing length (e.g., holding a position).
- Training Implication: To optimize motor skills, training should address all contraction types based on specific movement tasks.

Speed Limitations: Muscles can't produce maximum force at high speeds; constrained by the force-velocity relationship, limiting movement performance and energy economy.
Muscle Energy Use: They consume significant energy; the need arises to integrate biomechanics for maximizing power output.

Power Production: The focus will be on producing power through biomechanics.
- Mechanisms of Power:
- Improve muscle efficiency through size and force output.
- Use muscle architecture for optimal force-speed relationships.
Storing Elastic Energy: Tendons play a crucial role in energy storage and conversion during high-speed movements.

Fiber Length:
- Longer muscle fibers relate to faster muscle contraction capabilities.
Cross-Sectional Area: An increase in muscle thickness typically results in greater force output.
Elastic Components: Tendons facilitate faster movements by storing and releasing elastic energy, which muscles alone cannot achieve effectively.

To increase muscle power, focus on hypertrophy in proximal muscles and utilize plyometrics and explosive training to enhance elastic energy storage.
Example: Training sprinting athletes' glutes while ensuring the calves develop accordingly to optimize vertical jump performance.

The Stretch-Shortening Cycle: This cycle refers to the muscle-tendon system converting stored elastic energy into kinetic energy, effectively enhancing the velocity and height of jumps through pre-active stretches and rebounds of tendons.
- Mechanisms enhancing SSC effectiveness:
- Elastic strain energy storage.
- Muscle-tendon interaction optimizing energy use.
- Forced preload enhancing jumps.
- Increased time for activation enhancing power output.
- Stretch reflexes triggering muscle activation for more forceful contractions.

Elastic energy storage depends on stiffness and elongation of tendons:
- Performance can be significantly influenced by energy stored in tendons.
- Overcoming force-velocity limitations in muscles allows for faster movements through tendon elasticity, akin to a jet engine powering through speed.

Frog Mechanics: Similarities between human and frog jumping mechanics emphasize the functional evolutionary adaptations of our limbs.
- Performing frog-like jumps offers insight into human biomechanics as both depend on maximizing muscular tendencies and elastic energy in a catapult fashion.

Assessing Movement Patterns: Evaluating individuals' jump mechanics can help define their reliant muscle groups, suggesting a tailored exercise program focusing on enhancing strength and speed.
Natural Biomechanics: Training should adopt a foundational understanding of the natural movement’s biomechanics in significant sports, ensuring alignment with both strength and speed requirements in specific training programs.
Injury Prevention: Understanding the principles of muscle-tendon interactions can aid in designing preventive strategies against sports-related injuries.

Continuing Education: Students should focus on how the body’s mechanisms create powerful movements, while future lessons will delve deeper into building optimized movement systems for athletes by understanding both the mechanics and training principles needed.
Discussion Reminder: Questions and clarifications on the day's lecture's mechanisms and their implications for training methodologies should be brought forth in the next session.
A reminder for students to reflect on learned concepts as they will be pivotal in future discussions about how to engineer optimal human performance and movement efficiency.