benefits of resistance exercises
- enhance muscle performance
- increase strength of connective tissue
- increase bone density
- decrease joint stress
- reduce risk of soft tissue injury
- improved capacity for repair and healing
- improve balance
- enhance physical performance
- positive body composition
- physical well being
- positive perception of disability and quality of life
muscle performance
- strength
- power
- endurance
muscular strength
the greatest measurable force that can be exerted by a muscle or muscle group to overcome resistance during a SINGLE maximum effort
strength training
using muscle force to raise, lower, or control heavy external loads for a relatively LOW number of repetitions or over a short period of time
- nervous system adapts
- muscle fiber size increases
work
weight times distance (WxD)
power
- force x distance/time
- the work produced by a muscle per unit of time
- the rate of performing work
- single time or repeated bursts
power training
increasing the work a muscle performs during a specific period of time OR reducing the amount of time required to produce the work
muscular endurance
- ability to perform repetitive or sustained muscular contractions against some resistants for a period of time.
- fighting fatigue
endurance training
- using muscle to control a light external load over a prolonged period of time
- may have more positive impact on improving function than strength training
muscle strength, endurance, and power are affected by ..
muscle size, number of muscle fibers, efficiency, biomechanical considerations, age, overtraining, fiber type
isotonic contractions
- performed against resistance
- muscle contractions with constant tension
- concentric : muscles shorten
- eccentric : muscles lengthen
isometric contractions
- muscles produce tension but no change in muscle length
- usually performed against immovable object
- used frequently in rehab, acute and subacute phases
isokinetic contractions
- velocity is held consistent
- constant maximal speed and variable load
- reaction force is identical to the force applied to the equipment
- can be achieved with manual resistance
neural adaptations of resistance exercise
- increases in strength are related to motor learning an improved coordination
- brain is learning how to lift the brain by recruiting motor units
- minimal evidence of hypertrophy in first 4-8 weeks
skeletal muscle adaptations of resistance exercises
- hypertrophy : increase size and volume of muscle fibers, increase levels of protein synthesis with moderate-intensity exercise
- Type IIB fibers increase in size most readily
NOT DUE TO HYPERPLASIA
muscle hypertrophy adaptations of resistance exercises
- increase in size of fibers caused by more myofibrillar volume
- becomes important in strength gains
- usually seen after 4-8 weeks
type 1 fibers
twitch slow, low force, high fatigue, use triglycerides
- high capillary and mitochondria density
- red muscle
- aerobic energy
- small diameter
example - postural muscles
type 2 A fibers
fast twitch, high force, medium fatigue, use glycogen
- more resistant to fatigue than type 2B but greater amount of tension than type 1
- high capillary and mitochondria
- low myoglobin
- aerobic energy
type 2 B fibers
very fast twitch, very high force, low fatigue, use glycogen
- white muscle
- low capillary, metachondria, and myoglobin
- large diameter
- anaerobic energy
muscle fiber type adaptations
- type 2B hypertrophy with heavy resistance training
- type 2B may transform to type 2A with endurance training
- little evidence of conversion of type 2 to type 1
hyperplasia
- increase in numbers of muscle fibers
- don’t not occurs or it is minimal
reversibility principle
- muscle has to be challenged with same level of resistance or greater
- adaptation in muscle with resistance training must be regularly used
- muscle atrophy - decrease in strength and mass
- can begin in 48 hours
WHAT YOU DON’T USE YOU WILL LOSE
overload principle
for muscle performance to improve, load has to exceed the metabolic capacity of the muscle, forced to work at a higher level than it is accustomed
S.A.I.D principle
specific adaptations to imposed demands
* training mirrors the goal
