Exercise and the Musculoskeletal System



Exercise and the Musculoskeletal System

Pages 267-270 and 431-439

Terms

Muscular strength. What is it?

Muscular endurance. What is it?

Adaptations

Neural first

Contractile, second

Neural Adaptations

What neural changes occur with training that contribute to an increase in muscle strength?

Neural Adaptations

Recruitment of additional MU (IIb or Fast Twitch B)

Increase rate of MU stimulation

Enhance synchronization of MU firing

Neural dis-inhibition (ignoring GTO)

Neural dis-inhibition

Golgi tendon organs inhibit continued contraction

Muscle Adaptations

What muscular changes occur with training that contribute to strength grains?

What is hypertrophy?

What contributes to muscle hypertrophy?

Does one fiber type hypertrophy more than another?

Muscular Adaptations

Cell Hypertrophy or Cell Hyperplasia?

Muscle cell hypertrophy accounts for 95-100% of overall muscle hypertrophy

The remainder is the result of hyperplasia

Strength and Endurance Training

Some studies show combined aerobic endurance and strength training may limit strength gains.

Other studies show no effect

Once aerobic training reaches a plateau, strength training can improve time to exhaustion.

Progressive Resistance

Principle of Overload

Milo of Crotona

Milo of Crotona, Greek athlete, lived about the end of the 6th century B.C. He was six times crowned at the Olympic Games and six times at the Pythian for wrestling, and was famous throughout the civilized world for his feats of strength - such as carrying an ox on his shoulders through the stadium at Olympia. In his native city he was much honored, and he commanded the army which defeated the people of Sybaris in 511.

The traditional account of his death is often used to point a moral: he found a tree which some woodcutters had partially split with a wedge, and attempted to rend it asunder; but the wedge fell out and the tree closed on his hand, imprisoning him until wolves came and devoured him. His name became proverbial for personal strength.

Encyclopaedia Britannica

Strength Training Principles

Intensity

Frequency

Duration

Reps

Sets

Rest

Discussion

What are the general recommendations for the following resistance training programs: strength, power, hypertrophy and endurance. [Kraemer and Koziris, 1992]

Why are there differences in these programs? Think physiological.

What is plyometric training? What gained from plyometric training?

Strength Program

Heavy resistance (< 6-RM)

Moderate to long rest periods (> 2 min)

Moderate to high number of sets (4-10 and 1-3) for primary exercises

Why so much time in between?

Power Program

Speed overload increases neural stimulation and minimizes the slowing effects of hypertrophy

High resistance (< 10 RM) that is varied over time; rarely more than 5 reps per set.

Moderate to long rest periods (> 2 min.)

Moderate to high number of sets (4-10 and 1-3)

Plyometric exercises

Power Program - Plyometrics

Plyometric Physiology

Plyometric Loading

What is it?

Eccentric contraction followed by a fast, explosive concentric contraction

What’s the physiology behind it?

Stretch-shortening cycle

greater or quicker fiber recruitment with help from muscle spindles

Elastic energy

Hypertrophy Program

Greater volume and variety

Moderate to high intensity (12-20 RM)

Less rest (less than 90 sec.)

High total number of sets per muscle group (> 3)

Unproven

Great size and number of type I fibers

Endurance Program

Low intensity (12-20 RM)

Moderate rest depending on number of reps (2-3 min or 30-60 sec.)

Moderate sets (2-3)

Toning?

Summary Table

Discussion

Periodization

Load Period (Hypertrophy)

2-3 months with microcycles or day to day variations

Recovery Period (Endurance)

2-3 weeks

Peak Period (Strength)

Same length as load cycle

Conditioning Period (Power)

Weeks

Periodization

Periodization

No advantage to untrained

No clear advantage to trained

Myth Busters

Muscle size (hypertrophy) is not a synonym for muscle strength

Muscle size (hypertrophy) does not necessarily lead to inflexibility

Endurance programs (high reps) are not effective for weight loss

Muscle tissue has only a slightly higher “metabolism” than fat tissue

Resistance Training

Isometric

Isotonic or Dynamic

Isokinetic

Isometric Training

Is isometric training effective?

What are its limitations?

What are its advantages?

Isotonic Training

Concentric and eccentric muscle contractions

Examples of isotonic exercises

Free Weights

Machines

Variable resistance

Eccentric

Isotonic Free Weights

What are the advantages?

What are the disadvantages?

Isotonic Machines

What are the advantages?

What are the disadvantages?

Variable Resistance

Variable Resistance

What are the advantages?

What are the disadvantages?

Eccentric Loading

Isokinetic

Speed kept constant with “accomodating resistance”

What are the advantages?

What are the disadvantages?

Comparison

Gender Differences

DISCUSSION

In what ways does the principle of specificity apply to resistance training?

Is strength re-grained faster than the initial gains?

SPECIFICITY

Intensity of contraction

Speed of contraction

Muscle group

Type of contraction

Specificity & Functional Training

Functional Training

Muscle Group Specificity

Type of exercise matters even in the same muscle groups

Reversibility

Return of strength after periods of inactivity

Flexibility

Streching/Flexibility

F = 3-7 days a week

I = stretching

T = 15-60 sec., 1-3 sets

Flexibility

Can decrease or increase the risk of injury.

Training for Flexibility

Static stretching

Prevents muscle spindles from shortening the muscle

Dynamic stretching

May activate muscle spindles which produce muscle shortening

Training for Flexibility

Proprioceptive Neuromuscular Facilitation

Contract muscle to stimulate GTO

GTO cause muscle to relax

Stretch relaxed muscle further

The Impact of Stretching on Sports Injury Risk: A Systematic Review of the Literature

THACKER, S. B., J. GILCHRIST, D. F. STROUP, and C. D. KIMSEY, JR.

Med. Sci. Sports Exerc., Vol. 36, No. 3, pp. 371-378, 2004.

Impact of Stretching on Sports Injury

Little evidence of link between flexibility and injury rate

Lack of flexibility does not account for many muscles injuries the occur w/i a normal range of motion

Imbalance in flexibility may increase injury risk

Stretching may increase performance or it may decrease performance

Impact of Stretching on Sports Injury

“There is not sufficient evidence to endorse or discontinue routine stretching before or after exercise to prevent injury among competitive or recreational athletes.”

“Further research, especially well-conducted randomized controlled trials, is urgently needed to determine the proper role of stretching in sports.”

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