Recording-2025-03-12T15:36:16.549Z

Introduction to Action Potential and EMG

• Depolarization of Nerve:

  • Action potential is necessary for signal transmission in nerves.

  • The process allows the nerves to transmit signals to the receiver, especially in muscle function.

• EMG Data Collection:

  • Equipment can be used outdoors (e.g., on a running track) to collect Electromyography (EMG) data.

  • Concerns about noise interference when equipment is not optimally positioned.

Muscular Force Generation

• Cross-Bridge Formation:

  • Question raised about whether it's easier to release cross bridges compared to forming new ones, with implications for muscle contraction conditions.

• Force Differences:

  • Eccentric vs. Concentric Contraction:

    • Eccentric Force Generation:

      • More force can be generated during eccentric contractions than concentric contractions due to greater opposition to stretching.

      • Muscles do not have to exert as much effort because of the natural resistance from elastic components when stretching.

    • Concentric Contractions:

      • Require more muscle input for force generation.

  • Implication for EMG Activity:

    • EMG activity does not equate perfectly with force output, especially in dynamic movements.

Torque and Muscle Mechanics

• Moment Arm and Torque:

  • The longest moment arm generates the greatest torque (Torque = Force × Perpendicular Distance).

  • When the lever arm is at a maximum length, the muscle must exert the highest effort.

• Force Generation Capacity:

  • Limited overlapping of z lines in muscle fibers affects force production.

  • In expanded positions, muscles may not generate as much force due to close z line distances.

Velocity of Contraction and EMG

• Contraction Velocity:

  • Observations that contraction velocity is faster under certain conditions.

  • Faster contractions might involve fewer motor units being activated.

• Average EMG Comparisons:

  • Slow contractions typically exhibit higher EMG readings compared to fast contractions due to longer contraction times.

Lab Exercises and Questioning

• Lab Report Guidelines:

  • Emphasis on typing out questions for clarity in the lab write-up.

• Importance of Listening:

  • Students are encouraged to follow instructions for optimal lab outcomes.