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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.”