MRI OF SKELETAL MUSCLE: SPORTS RELATED INJURIES
JAVIER BELTRAN

RESUMO
Normal Skeletal Muscle
• Muscle fibers
– Type I (slow twitch): Slow contraction and relaxation.
More fatigue resistant (distance runners)
– Type II (fast twitch): Intense activity of short duration.
More resistance to tension (sprinters)
• Tendon, myotendinous junction
• Motor unit: nerve axon and fibers
• Cross one joint or two joints
Delayed Onset Muscle Soreness (DOMS)
• 1-2 days after exercise. Persists over 1 week
• Untrained individuals
• Rapid adaptation with continued exercise
• Eccentric lengthening
• Ultrastuctural damage of fibers with disruption of Z lines.
Creatin Kinase
• Extreme cases (“boot camp”) myoglobinuria and renal