1. Muscles Part II

2. MUSCLE CONTRACTIONS Static Dynamic Isotonic Isometric Isokinetic
Constant External Resistance
Plyometrics
Variable Resistance

3. Muscle Contraction Static contractions Dynamic Contractions
The muscle tension or force exerted against an external load is equal to or weaker than the external force
No visible movement occurs
Dynamic Contractions
Internal & external forces are unbalanced
External force (gravity, weight of object) is not equal to the internal force (produced by athlete’s muscle)
Generates movement

4. Isometric Static Means “Same Length” Work = force x distance
Since no movement occurs, no work occurs
Instead measured by the rate of tension & duration that tension lasts
+ Causes hypertrophy
- Strength gains are specific to joint angle
This is called Specificity

5. Isokinetic Means “same speed”
Resistance is changed so speed of movement can be maintained
- Requires specialized equipment
+/- Trains single joint movements
+/- Strength gains are specific to the training velocity
Specificity
Used primarily in rehabilitative settings
+ Safe way to train muscles
+ Muscles can be isolated

6. Isotonic Means “same tension” Two Phases: + Mimics real life movements
- Difficult to achieve “same tension” through entire ROM
Beginning & end of ROM achieve less tension than middle
Two Phases:
Concentric:
Muscle shortens as it moves through range of motion
Moves against gravitational force (overcomes it)
Eccentric:
Muscle lengthens as it moves through range of motion
Moves with gravitational force (resists it)

7. Types of Isotonic Exercise
Constant External Resistance
Free weights, body weight exercises, medicine ball, etc
Enough resistance provided in parts of movement and not enough in other parts
Selection of weight is critical
- Often training doesn’t occur at ends of ROM
Result: appearance of joints that can’t be straightened
+ May mimic “real world” movements more
+ Increase activation of stabilizing muscles

8. Types of Isotonic Exercise
Variable Resistance Exercise
Machines that utilize cams and/or pulleys, elastic bands/tubing, etc
Automatically changes the resistive force throughout the ROM
+ Good for novice, older and/or recreational athletes
+ Help control motion
- Do not promote muscle coordination or balance

9. Types of Isotonic Exercise
Plyometric (AKA: Jump Training or Stretch-Shortening Cycling)
Trains muscle to reach maximal force in shortest possible time (power)
Amortization Phase: amount of time it takes muscle to change direction from “stretch” to “shorten”
Ideally this should be as short as possible
Places high stress on muscles, connective tissue & joints
Requires foundation of physical fitness
Intensity, repetitions & sets should be carefully prescribed

10. Training Muscle Trainable Factors Non-Trainable Factors
Number of fibers
Hyperplasia
Fiber Type
Fiber diameter
Hypertrophy
Atrophy
Coordination of muscle fibers
Nerve impulse frequency
Elasticity of muscle & tendons
Energy stores of muscle & liver
# of capillaries

11. Creating Movement Muscle attaches to bone via tendons
Origin of muscle on non-moving bone
Insertion of muscle on the moving bone
Motor neuron signals contraction
Muscle shortens and pulls on bone
Movement occurs about a joint
Insertion moves towards origin

12. Muscle Teamwork When one muscle contracts, another must relax
Agonist (prime mover) creates desired movement
Antagonist opposes the desired movement
When agonist contracts, antagonist must relax
Agonists & antagonists are typically on opposite sides of joints
Example:
Biceps brachii & Triceps brachii

13. Muscle Teamwork Synergist:
A muscle that surrounds the joint being moved
Aids the prime mover in creating desired movement
On same side of joint as the prime mover
Ex: Gluteus maximus & Gluteus medius extend thigh
Fixator or Stabilizer:
A muscle that contracts with no significant movement to maintain a posture or fixate a joint
Ex: Erector spinae during a push-up

14. Muscle Groups Gluteal Group Gluteus Maximus Gluteus Medius
Gluteus Minimus

15. Muscle Groups Quadriceps Group Rectus femoris Vastus lateralis
Vastus intermedius
Vastus medialis

16. Muscle Groups Hamstring Group Biceps femoris Semitendinosus
Semimembranosus

17. Muscle Groups Abdominals Rectus abdominis External oblique
Internal oblique
Transverse abdominis

18. Muscle Groups
Erector Spinae
Iliocoastalis
Longissimus
Spinalis