5. Muscular Strength

Question 1

What is Muscular Strength?

Answer 1

the greatest amount of force that muscles can produce in a single maximal effort

Question 2

What is Power? (Formula)

Answer 2

Power - work per unit time - force X velocity.
– Power involves strength and speed.

Question 3

Benefits of Strength Training?
(5)

Answer 3

Strength provides a foundation for other components of physical fitness such as:

– Cardiorespiratory Capacity
– Muscular Endurance

• Slows down muscle loss
• Increased functional mobility so that daily activities are made both possible and easier

Question 4

More Benefits of Strength Training
(6)

Answer 4

• Increase the size and strength of muscle fibers
• Increased tendon, ligament and bone tensile strength.
• Stronger muscles better protect the joints
• Improved physical appearance.
• Improved metabolic health.
• Improved mental health

Question 5

Even More Benefits of Strength Training
(3)

Answer 5

• Better strength in the muscles of the trunk, improves POSTURE.
• Stronger muscles are LESS likely to be STRAINED and INJURED.
• Improvements in self-concept and self-esteem for both patient and athletic populations.

Question 6

Key Points to Remember about Strength Training (7)

Answer 6

• Quality training and quality recovery
• Continually change up your routine
• Use free weights and machines
• Use whole-body exercises
• Complete a warm-up and cool down
• Make it enjoyable!!!
• Consistency and Variety

Question 7

Types of Muscular Contraction

Answer 7

1. Isotonic contraction
2. Isometric contraction
3. Isokinetic contraction

Question 8

What is Dynamic/Isotonic contraction?

Answer 8

– iso (same) tonic (tone/force/weight) tension is the same throughout the range of motion.

• Machines or free weights

Question 9

Machine for Dynamic Movements

Answer 9

Question 10

What is an Isometric Contraction?

Answer 10

Isometric contraction - static contraction. Tension is developed but there is no change in the angle of the joint or the length of the muscle.

Question 11

What is Isokinetic Contraction?

Answer 11

Isokinetic contraction -
the muscle is shortened at a constant velocity determined by instrumentation which allows a person to exert maximal force throughout the full range of motion

Question 12

Purpose of Strength Assessment (5)

Answer 12

1. Assess muscular FITNESS
2. Identify specific areas of WEAKNESS
3. Monitor PROGRESS in a rehabilitation program
4. Measure the EFFECTIVENESS of a resistance training program
5. MOTIVATION for training

Question 13

3 Strength Assessment Techniques

Answer 13

1. One Repetition Maximum
   - Estimated from Variable Repetition Maximum
2. Dynamometer Techniques
3. Computer-Assisted, Isokinetic Methods

Question 14

What is a One Repetition Maximum? (3)

Answer 14

• Maximum amount of weight lifted once.
• Use free weights or machines that allow dynamic muscle contractions
• Only appropriate for very experienced

Question 15

How to Estimate One Repetition Maximum?
(1 RM)

Answer 15

• Estimated from repetitions to failure on machines
• Variable-repetition maximum tests.
• 1 RM = (weight lifted) / [1.0278 - (n X 0.0278)]
• n = repetitions to failure (not to exceed 10)
• Safer than using 1-RM, especially with beginners

Question 16

What are Dynamometer Techniques?

Answer 16

A strength-testing dynamometer usually consists of a spring of some type which is deformed by a certain amount when a specific force is applied to it.

(eg) - hand grip dynamometer
- measures isometric strength
- relatively inexpensive, and high reliability if the body position is carefully standardized for each trial of the test.
- high correlation between grip strength and
longevity

Question 17

What are Computer-Assisted, Isokinetic Methods?

Answer 17

• equipment such as Biodex, KIN/COM, etc.
• has a computer which can be programmed at any initial and final force, angle, velocity, or number of repetitions.
• measure peak torque using a force transducer and joint angle using an electrogoniometer.
• extensive manipulations can be performed on collected data using computer software
• accurate and reliable, but expensive
• used for research and elite athlete assessment

Question 18

What are the 7 Strength Assessment Considerations?

Answer 18

1. STANDARDIZED instructions should be given before testing.
2. If a warm-up is given, it should be of
   uniform DURATION and INTENSITY
3. Ensure that the ANGLE of measurement
   on the limb or test device is consistent
   among subjects
4. Consider individual differences in body SIZE and PROPORTION when evaluating strength scores between individuals and groups.
5. Test and training mode SPECIFICTY is important for optimal expression of true strength gains.
6. SAFETY is an important consideration when performing strength evaluations. Ensure that all equipment is in proper working order and that standard weight room safety procedures are being followed.
7. Test administrators should be WELL-TRAINED and have a thorough understanding of all testing procedures and protocols.

Question 19

5 Effect Of Various Factors On Strength

Answer 19

1. Muscle Cross-Sectional Area
2. Body Size
3. Muscle Fiber Composition
4. Mechanical Factors
5. Sex and Age

Question 20

What is Muscle Cross-Sectional Area?

Answer 20

• There is a strong positive relationship between muscle CSA and strength.
• Muscles increase in strength by increasing their size and by enhancing the recruitment and firing rates of their motor units.

Question 21

2 Types of Tissue/Cell Growth

Answer 21

• Hypertrophy - an increase in the size of a cell such as a muscle fibre
• Hyperplasia - an increase in the number of cells such as adipose cells

Question 22

What accounts for most, if not all, of the increase in muscle cross-sectional area due to an overload training program?

Answer 22

hypertrophy

Question 23

Body Size Effect On Strength

Answer 23

• There is a positive correlation between body size or mass and absolute strength.
• There is a negative correlation between body mass and the strength/mass ratio.
  The strength-to-mass ratio directly reflects an athlete’s ability to accelerate his or her body.
• All else being equal, smaller athletes are stronger kilogram for kilogram than larger athletes.

Question 24

Relationship Between Body Size and Strength

Answer 24

Large athletes dominate sports events which require a high level of absolute strength (e.g., throwing events in track and field)

Smaller athletes dominate sports events which require a high strength/body mass ratio (e.g., gymnastics).

Question 25

Effect Of Muscle Fiber Composition

Answer 25

for a given size of a muscle, there is a positive correlation between the percentage of fast twitch fibers and strength.

Question 26

Effect Of Mechanical Factors

Answer 26

Mechanical Factors The force exerted by a muscle is affected by: A. the initial length of the muscle fibers B. the angle of pull of the muscle on the bony skeleton C. the speed of shortening

Question 27

Effect Of Sex On Strength

Answer 27

- After age 16, the average female is about 2/3 as strong as the average male when the measure of strength is the absolute amount of force exerted or weight lifted. - Sex differences in strength in adults are greater in the ARMS/SHOULDERS than in the legs

Question 28

Reasons why on Average Males are Stronger? (3)

Answer 28

– The average male is physically larger (height and weight) than the average female. – Differences in body composition - the average male has more muscle and less fat due to the male sex hormone, testosterone, which stimulates muscle growth. – Because most human muscles can produce approximately 16 to 30 newtons of force per square centimetre cross-sectional area, larger muscles are stronger muscles. – Body proportion differences - during adolescence, the skeletal proportions change: boys' shoulders broaden relative to their hips, and girls' hips broaden relative to their waists and shoulders. – The broader shoulders of the adult male allow more muscle to be packed onto the skeletal frame and create a mechanical the advantage for muscles acting on the shoulder.

Question 29

What is the difference between male and female muscle tissue?

Answer 29

You cannot distinguish male muscle from female muscle under a microscope. * Female muscle tissue does not differ, unit for unit, in potential force output from male muscle tissue. * This indicates that the training potential and methods of training for men and women should be similar.

Question 30

Effect of Age On Strength

Answer 30

Muscle strength in children: – Muscle strength progressively improves as children age and mature, principally as a result of increasing muscle size. – Hormonal influences at puberty (testosterone) are responsible for the dramatic increase in muscle bulk and strength in males. * During this time period the increase in muscle mass in both sexes is due to hypertrophy of individual muscle fibers and not hyperplasia. The maximum strength of men and women is generally achieved between the ages of 20 and 30 years, at the time when muscle Cross-sectional area is usually the greatest. * These changes are more pronounced in the fast-twitch fibers. These changes in muscle volume are due to a combination of decreased physical activity patterns and aging.

Question 31

Summary of Adaptations to Aging and Resistance Training

Answer 31

Question 32

What is Muscular Endurance?

Answer 32

the ability of a muscle group to perform repeated contractions against a light load for an extended period of time. E.g. Push-ups

Question 33

What is Muscular Power?

Answer 33

ability to produce force quickly. (units: Watts, Kg m min-1) Eg. Vertical jump

Question 34

What is a Concentric Contraction?

Answer 34

the muscle shortens with varying tension as it lifts a constant load.

Question 34

What is an Eccentric Contraction?

Answer 34

the muscle lengthens while developing force as the external resistance (weight) exceeds the muscle force. Eccentric contractions are usually used in resisting gravity