Lecture Notes: Muscles and Their Development

Introduction to Muscles

• Human body comprises over 600 muscles.
• Muscles account for 1/3 to 1/2 of body weight.
• Function along with connective tissues to support, bind, and facilitate movement.

Muscle Function and Movement

• Brain and Muscle Coordination
  • Brain sends signals to motor neurons.
  • Neurons cause muscle contraction and relaxation.
  • Movement generated by pulling on bones.
• Response to Increased Demand
  • Brain increases signal strength for greater challenges.
  • Involvement of additional muscles for complex tasks.

Cellular Changes in Muscles

• Exposure to stress causes microscopic damage.
• Repair and Growth Process
  • Release of cytokines triggers immune response for repair.
  • Cycle of damage and repair leads to muscle growth.

Muscle Growth: Hypertrophy

• Stimulating Muscle Growth
  • Requires higher workloads than usual activities.
  • Eccentric contractions facilitate growth.
• Muscular Atrophy
  • Lack of resistance leads to muscle shrinkage.

Factors Influencing Muscle Development

• Nutrition and Hormones
  • Protein provides amino acids for new muscle tissue.
  • Hormones like insulin-like growth factor and testosterone aid growth.
• Rest and Recovery
  • Muscle repair occurs primarily during sleep.
  • Variations due to gender and age (e.g., young men and testosterone).
• Genetic Factors
  • Differences in immune response to muscle damage.
  • Influence on muscle-building potential.

Conclusion

• Growth and Challenge
  • Muscle growth mirrors life; requires stress and challenge.
  • Proper training, nutrition, and rest critical for muscle development.