Muscle Insufficiency

Types of Muscle Insufficiency

Active Muscle Insufficiency

• Occurs with muscles crossing multiple joints.
• Example: Hamstrings
  • Functions: Extend the hip, flex the knee.
  • Issue: Unable to perform both movements simultaneously to the full range.
• Cause: Insufficient cross-bridge formation (myosin and actin are too close).

Passive Muscle Insufficiency

• Occurs when a muscle acts as an antagonist and is stretched.
• Example: Hamstrings
  • Difficulty in bending to touch toes with knees extended.
  • Easier with knees slightly bent.
• Cause: Myosin and actin are too far apart, limiting cross-bridge formation.
• Protective mechanism to prevent muscle damage.

Clinical Relevance

Spinal Injury (C6 Damage)

• Issue: Limited wrist flexion and finger movements.
• Solution: Utilize passive insufficiency
  • Gravity-induced wrist flexion stretches finger extensors, helping open the hand.
  • Wrist extension causes passive insufficiency in finger extensors, aiding in grasping.
• Term: Teno desis
  • Refers to exploiting passive insufficiency in finger extensors for spinal cord injury patients.

Posture Correction

• Issue: Poor posture leading to muscle imbalances.
  • Back muscles stretched, chest muscles shortened.
• Solution:
  • Strengthen stretched back muscles (e.g., through muscle strengthening exercises).
  • Stretch shortened chest muscles (e.g., PEC minor and major).