Lecture 2 Flashcards
What are two competing events that occur during muscle strain healing?
Muscle Regeneration
Production of scar/fibrous tissue
What are common complications to Muscle strain healing?
Re-rupture from too early or overly vigorous mobilization
What is the fibril change when there is damage to C.T. and muscle fibril?
Break in to individual sarcomeric units
Disruption of mitochondria and sarcoplasmic reticulum
Interruption of sarcolemma
What do you want when you have damaged C.T. and muscle fibril with Satellite cells present?
Satellite cells are transformed into myoblastic cells
All satellite cells respond to a focal injury
What are the four stages of injury and repair?
Inflammatory reaction with hematoma formation
Macrophage inflitration
Fibroblastic and Collagenous proliferation
Function of the satellite cells
Which stages of injury and repair always occur and which stage does not?
Stages 1-3 always occur.
Stage 4 occurs when damage to the myofibril has occured
When will injury occur?
When the active tension in the muscle tendon unit exceeds the tension of the weakest structural element
Where are the most common injuries for muscle strain incidences?
Two joint muscles Hamstrings Gracillis Sartorius Rectus femoris Gastrocnemius
What percent of musculotendinous injuries are in the hamstring?
33%
For those with hamstring injuries, what percent are sprinters?
50%
For those with hamstring injuries, what percent are middle distance runners?
20%
When do hamstring injuries occur?
Early or Late stages of practice
What are the mechanism of injury for muscle strains?
Intrinsic force production
Extrinsic for production
Combination of both intrinsic and extrinsic force production
What are the 6 causative factors of muscle strains?
Inadequate flexibility Inadequate strength/endurance Dy-synergistic muscle contraction Insufficient warm-up Poor biomechanics/style Inadequate rehabilitation from previous injury
Physiologically, what occurs with inadequate flexibility?
Steeper stress strain curve (Poor dissipation of stress, viscoelastic response, and greater impact of force relaxation)
Change in length-Tension relationship
Clinically, what occurs with inadequate flexibility?
Higher incidence of microtrauma- (muscle strains, tendinitis)
Decreased Efficiency/effectiveness- (Movement dysfunction, Postural/functional imbalances
Physiologically, what occurs with inadequate strength/endurance?
Potentially weaker connective tissue
Neuromuscular changes inthe GTO and muscle spindle
Overload of normal tissue caused by abnormal biomechanics from fatigue.
Fatigue overload from repetitive stress
Clinically, what occurs with inadequate strength/endurance?
Inadequate muscular strength/endurance leading to macrotraumatic or microtraumatic injury
Ipsilateral or contralateral strength imbalance
Physiologically, what occurs with dys-synergic contraction?
Hybrid muscle with separate innervation (biceps, semitendinosis)
Fiber type and force development (hamstrings, rectus femoris, gastrocnemius/soleus)
Agonist-antagonist relationship
Clinically, what occurs with dys-synergic contraction?
Injury specific activities and positions (Hamstring deceleration v. acceleration)
Injury specific activities (Sprinters, higher angular velocity activities)
Over-strengthened (powering) antagonists
What is econcentric?
Where the distal part of the muscle in concentric while the proximal part is eccentric (or reversed)
Physiologically, what occurs with insufficient warm-up?
Lower intramuscular temperature
Decreased response of mechanical and physical properties of other tissues
Effect on muscle spindle and GTO interaction
Clinically, what occurs with insufficient warm-up?
Increased frequency of microtraumatic injury
Poorer performance
Increased incidence of dys-synergistic contractions
Physiologically, what occurs with inadequate rehabilitation?
Insufficient tissue maturation
Insufficient load tolerance
Sub-optimal condition and performance
