1. Improving Muscular Strength and Endurance
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2. Learning Objectives
Explain the benefits of developing muscular strength and endurance
Describe how muscles contract
Distinguish between the muscle fiber types
Classify the types of muscular contractions
Identify the changes that occur in response to strength training
List the factors that determine muscle strength and endurance
Outline the principles used in designing a strength and endurance program
Distinguish between the types of training programs
Design a program for improving strength and endurance
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3. Strength Training in Daily Life
Reduces joint and/or muscle injuries from exercise
Reduces low back pain
Delays and reduces age-related decreases in strength
Helps prevent osteoporosis
Increases resting energy expenditure (also called resting metabolic rate)
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4. Muscle Structure and Function
There are about 600 skeletal muscles in the body
Primary function: provide force for movement and maintain posture and regulate temperature
Muscles shorten or lengthen, causing bones and body to move
Muscle structure: fibers, fascia, tendons
Muscle function: motor nerves and muscle fibers are a motor unit
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5. Structure of Skeletal Muscle
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6. Major Muscles of the Body
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7. A Motor Unit
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8. Skeletal Muscle Exercise Classifications
Isotonic (dynamic)
Movement of a body part at a joint
Most exercise and sports are isotonic
Isometric (static)
Uses muscle tension but involves no movement
Good way to develop strength after injury
Isokinetic
Performed at a constant velocity
Uses machines that provide resistance throughout the full range of motion
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9. Muscle Action Classifications
Isometric Action
Actions are static and involve no movement
Occurs during isometric exercise
Concentric Action (positive work)
Muscle shortens during movement against gravity or resistance
Example: upward arm movement during a bicep curl
Eccentric Action (negative work)
Muscle lengthens during movement against gravity or resistance
Example: downward arm movement during a bicep curl
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10. Concentric and Eccentric Muscle Actions
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11. Skeletal Muscle Fibers Types
Slow-Twitch Fibers
Contract slowly
Generate little force but are resistant to fatigue
Fast-Twitch Fibers
Contract quickly
Generate lots of force, but fatigue quickly
Intermediate Fibers
Serve as a combination of the other two types
Contract rapidly, produce great force, and resist fatigue
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12. Fiber Type Variations
Most people have roughly equal numbers of all three types
Elite endurance runners/marathoners have more slow-twitch fibers
Elite speed runners/sprinters have more fast-twitch fibers
There is a possible genetic link between a predominance of fast-twitch fibers and certain diseases, such as obesity and diabetes
Research indicates fibers might be able to convert from one type to another through training
Fiber recruitment - process involving more muscle fibers to increase muscle force
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13. Recruitment of Muscle Fiber Type
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14. Muscular Strength Amount of force muscle can generate, based on
Size of the muscle (primary factor)
The larger the muscle, the greater the force produced
Number of muscle fibers recruited during a movement
The more fibers that are stimulated, the greater the force generated
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15. Muscle Fiber Recruitment and Muscular Force
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16. Evaluating Muscular Strength and Endurance
Muscular Strength Test
One-repetition maximum (1 RM) test
Measures maximum amount of weight that can be lifted one time (recommend for experienced lifters only)
See lab 4.1 for evaluation worksheet
Estimated 1 RM test, to reduce possible injury (recommended for beginner to intermediate lifters)
See lab 4.2 for evaluation worksheet
Muscular Endurance Tests
Push-up test
Sit-up or curl-up test
See lab 4.4 for evaluation worksheet
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17. Program Design Principles
Progressive Resistance Exercise (PRE)
Application of overload principle
Progressively increase amount of resistance in the training
Specificity of Training
Development is specific to
muscle group being exercised
training intensity
High-intensity training increases muscle size and strength
Low-intensity training increases endurance
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18. Improving Muscular Strength and Endurance
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19. Strength Training Adaptations
Physiological Changes
Fiber recruitment patterns change
Hypertrophy: increase in muscle size due to fiber size increase
Not common: hyperplasia, the formation of new muscle fibers
Rate of Improvement
Depends on initial strength level
Rapid strength gains in relatively untrained beginners
More gradual gains in trained people with high levels of strength
Gender Differences
Little difference in initial responses to strength training
After long-term training, men show greater gains due to higher testosterone levels
Women DO NOT exhibit bulky muscles
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20. Weight Training Program Design
Safety Concerns
Use spotters
Don't drop weights
Always warm up
Breathe during exercises
Use slow movements
Start with light weights and work up gradually
Types/Modes of Programs
Isotonic–most common
Isometric–least common, valsalva maneuver
Isokinetic–not practical
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21. Exercise Prescription
Frequency
Number of training days per week
2–3 days per week is optimal for strength gains
Intensity
Measured by the Repetition Maximum (RM)
The number of consecutive repetitions performed without resting is a set
Time (duration)
Total number of sets performed
Programs utilizing 3 sets result in greatest strength gains
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22. Strength Gains: Based on Sets and Repetitions
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23. Exercise Prescription
Starter Phase
1–3 weeks
Lighter weights, more repetitions
Do only 1 set per exercise
Frequency: twice a week
Slow Progression Phase
4–20 weeks
Heavier weights, fewer repetitions
Increase sets per exercise to 2–3
Increase frequency to 2–3 times per week
Maintenance Phase
Starts around week 20
Requires a long-term commitment to maintain gains
The effort needed to maintain gains is not as great as the initial effort
As little as one workout a week can maintain strength
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24. Guidelines and Precautions Prior to Beginning a Strength-Training Program
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25. Staying Motivated Make time to train regularly Make training fun
Find workout space or a facility you like
Plan a program that's challenging but enjoyable
Develop a realistic routine: don't make it so hard you'll get discouraged
Work out with a friend or training partner
Remember the benefits of strength training: better appearance, higher self-esteem, improved metabolism, and a feeling of accomplishment
Complete the Steps for Behavior Change activity in the chapter if you feel reluctant to strength train
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26. Sample Exercise Prescription for Weight Training: Beginner
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27. Sample Exercise Prescription for Weight Training: Intermediate
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28. Sample Exercise Prescription for Weight Training: Advanced
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29. Exercise Videos: Safety Techniques
Free Weights
Safety Tips: Dumbbells
Resistance Bands
Safety Tips: Resistance Bands
Stability Ball
Safety Tips: Stability Ball
PLAY
PLAY
PLAY
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30. Summary
Strength training can reduce back pain, decrease injuries, enhance bone health, and maintain age-related working capacity
Strength is dependent on muscle size and fiber recruitment
There are three major types of human skeletal muscles: slow-twitch, fast-twitch, and intermediate
The amount of slow, fast, and intermediate muscles varies among individuals. There is a relationship between fiber type and success in some athletics. There may be a genetic connection between muscle fiber types and some diseases.
Fiber recruitment is the process of involving more muscle fibers to produce increased force
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31. Summary (cont.)
Progressive resistance exercise (PRE) is the overload principle applied to resistance training
Individualized programs can be specific for strength or endurance gains through mode, number of repetitions, and sets
Isotonic (dynamic) exercises involve movement of a body part at a joint. Isometric (static) exercises use muscle tension but involve no movement. Isokinetic exercises are peformed at a constant velocity, often using machines.
A strength training program has three phases: starter, slow progression, and maintenance
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