Ch.6-Muscles at work Flashcards
(23 cards)
Types of muscle action
Static action
Dynamic action
Static Action
Isometric (iso=same, metric=length)
no visible change in muscle length
Load>muscle force
No work, high tension and energy
Defined by:
Rate of tension
Duration
Dynamic Action: Concentric action
Example: Flexion of biceps
Muscle overcomes a load
Shortens
Eccentric Action
Example: Extension of biceps
Muscle is overcome by a load
Lengthens
Isokinetic Action
iso=same kinetic=motion
Neuromuscular system works:
At a constant speed
During each movement phase
Against a preset high resistance
Independent of muscle force generated
Effective for strengthening muscles uniformly at all angles of motion
Requires specialized equipment
Plyometric Action
A sudden eccentric loading and muscle stretching followed by a strong concentric contraction
Sets off the Golgi tendon organ reflex. Protects muscle overstretching. Causes concentric contraction
Plyometric training includes: Leaping, bounding, depth jumping
Joint Angle
Muscle force production depends on joint angle.
Different muscle pulling efficiency and strength production.
Optimal angle=90-100
Muscle Cross-sectional Area
Strength is determined by lean body mass volume.
Greater body mass=greater strength. Provided body mass is composed of mainly muscle, not fat
Maximal/Absolute Strength
More Active muscle mass= more maximal strength
Inter/intramuscle coordination, anatomical structure and muscle elasticity= more maximal strength
Absolute strength is the maximum amount of force a person can produce in a single effort
Athletes needing to overcome partner or equipment
Maximal Strength
Ability to perform maximal voluntary muscular contraction in order to overcome powerful external resistance
Highest load lifted in one muscle contraction (1RM)
Not important in sports with low resistances and long periods
Relative Strength
Proportion of maximal strength relative to body mass
Athletes classified by weight and needing to overcome body mass
Speed of Movement
Linked to the main components: Maximal strength, Power, Muscular Endurance
Power/Speed Strength
Ability to overcome external resistance by developing a high rate of muscular contraction.
Important in sports requiring high push offs, quick movements and acceleration
Maximal strength and power
More strength= more acceleration. More strength left to accelerate weight after overcoming gravity.
Maximal strength important when overcoming medium to high resistance.
Muscular Endurance/Strength endurance
Ability to resist fatigue in strength performance of longer duration.
Important in sports where resitance is overcome over long periods (cyclic) and where demands are placed on strength and endurance (non-cyclic)
Strength/Endurance Issues
Strength development can hinder endurance and vice versus:
Cardiorespiratory training= lower fast twitch diameter & muscle volume= lower strength
Maximal strength training=More fast twitch diameter and muscle volume=lower endurance
Muscle Fibre Type
During maximal effort:
Fast twitch content= more force output, speed of contraction and lower endurance
Slow twitch content= lower force output, speed of contraction and more endurance
Age
As we Age= less FT
Genetically programmed cell death (apoptosis) “Use it or lose it”
Sarcopenia: Muscle loss. Ages 30-70, 30% muscle loss. Lose strength and balance, more falls and fractures
Sex
Average woman=70% of man’s strength
Strength to weight ratio
Total body mass: Women>Men. Less muscle and more adipose tissue
Lean body mass: Women=Men. Same strength produced by single muscle fibre
Muscle Cross-Sectional Area
Women< Men
More type 1 (ST) fibres (muscle endurance
Less type 2 (FT) fibres (muscle mass and strength
Testosterone
Anabolic hormone
Responsible for muscle growth
Women 20-30%< men
