Pt 2 Exercise Physiology Exam 1

Oxidative capacity is determined by

-number of mitochondria

-number of capillaries surrounding the fiber

-amount of myoglobin within the fiber

Type of myosin isoform

ATPases with high activity=rapid shortening

Amount of contractile protein

more crossbridges =greater contraction force

Speed of contraction

maximal shortening velocity

high ATPase activity =greater speeds

Maximal Power Output

Power= force x velocity

Contractile properties

maximal force production

speed of contraction

maximal power output

muscle fiber efficiency

Type 1 biochemical features

slow fibers

most oxidative enzymes

high mitochondrial density

surrounded by more capillaries than fast fibers

higher myoglobin concentrations

Type 1 contractile features

• slowest maximal shortening velocity- lower myosin ATPase activity

• Lowest specific tension- fewer actin/myosin per cross-sectional area

• More efficient- more force produced per ATP than fast fibers

Type IIx fibers biochemical features

• rich in glycolytic enzymes

• limited capacity for aerobic metabolism

• lowest mitochondrial density

• fatigues quickly

Type IIx contractile features

• highest Vmax of all fiber types (fastest ATPase)

• highest specific tension

• highest power output

• least efficient of all fiber types

AKA fast-glycolytic, fast-twitch, or white fibers

Type IIa fibers

fast-oxidative glycolytic or intermediate fibers

biochemical and contractile features are somewhere between I and IIx

Weight lifters and non athletes fibers composition

50%-50%

Dynamic

movement

Isometric

no movement

Concentric contraction

muscle contracts with force greater than resistance and shortens

Eccentric contraction

Muscle contracts with force less than the resistance and lengthens (eccentric contraction)

Eccentric exercise benefits

has potential to produce 2-3x greater muscle force than concentric or static contractions

produce equivalent forces at a fraction of the energy cost

ex. lower more weight than you can bench press

Two ways fast-twitch fibers twitch fast

1. They have high ATPase activity

2. The sarcoplasmic reticulum in fast fibers releases Ca++ at a faster rate

Force regulation in a whole muscle depends on- the amount of force a whole muscle or group of muscles can generate depends on:

• Number and types of motor units recruited

• the initial length of the muscle (optimal overlap) (starting in blocks)

• the nature of neural stimulation (strength of stimulus and frequency- summation to tetanus

Force-velocity

• at any given velocity, force produced is greater in fast-twitch fibers

• regardless of fiber type, maximum force is created at the lowest shortening velocity (isometric contraction)

Power Velocity

• Power output is greater at any velocity for fast-twitch fibers

• There is optimal speed of movement to produce the greatest power(punch at the perfect speed)

PRE

progressive resistance exercise

overload

to stress the system above the level to which it is accustomed

specificity

the adaptation of a tissue is dependent on the type of training undertaken

reversibility

when training is stopped, the training effect is lost

Exercise intensity

expressed in terms of a percentage of 1 repetition maximum (1RM) also indicated by # of reps to fatigue

Exercise volume

total number of reps and sets that are performed

Specificity

Match training closely to the intended performance you want to improve

• speed of muscle shortening

• Repetitions should tax appropriate energy systems

Periodization

varying the volume, intensity, and frequency over time may overcome progression plateaus

• classic or linear periodization

• undulating periodization

Strength Training FITT-VPP

Include all major muscle groups

• frequency

• intensity

• time

• type

• volume

• pattern

• progression

Frequency

2-4 days per week

Intensity

beginners 40-50% 1 RM, intermediate 60-70% 1 RM< experienced > 80%

Time

no time requirement

Type

apply specificity principle, focus on muscles used in competition/daily activities, mimic speed

Volume

multiple sets (2+), 8-12 reps for strength, 15-20 reps for endurance

Pattern

Rest interval of 2-3 min for strength, 1 min for endurance, 48 hours between sessions

Progression

Gradual progression

Pros of free weights vs machines

• low cost

• practice balance

• machiens- safer

Is there a gender difference for strength

same strength for cross sectional area of a muscle and progression of improvement

What transfers from cross training

• Removal of neural inhibition

• Altered motor neuron firing rates

• An improved ability to recruit motor units

• Enhanced motor unit synchronization

What doesn’t transfer from cross training

increased protein synthesis

hypertrophy

neural vs muscular adaptations

the first few weeks is muscular adaptations and it plateaus and is mostly hypertrophy

Muscular response to resistance training

shift from 5-11% IIx to IIa with a 20-week program

resistance training: muscular response; muscle fibers

single muscle fibers can express more than one type of MHC 

they are called hybrid fibers

resistance training: muscular response; oxidative capacity

Standard duration studies give mixed results

Longer duration studies indicate slight increases

resistance training: muscular response; antioxidants

RT increases several important antioxidants significantly

What do you lose in detraining

• mostly neural based

• actual atrophy is minimal

• retraining for only 6 weeks restores

• training 1 day a week can maintain dynamic strenght for 12 weeks

DOMS

delayed onset muscle soreness

appears 24-48 hours after exercise

DOMS primary damage

mechanical

• sarcolemma dsrupted

• Z line streaming

• (creatine kinase) elevated

DOMS secondary damage

inflammation

Steps leading to DOMS

• structural damage to muscle fibers

• membrane damage

• calcium leaks out SR

• Protease activation- results in breakdown of cellular proteins

• inflammatory response

• edema and pain

what are NOT solutions to DOMS

• ibuprofen and NSAIDS

• static stretches

• eccentric contractions

• foam-rolling muscles

Solutions to DOMS

prevention is best

• start progression slowly

• reduce the eccentric component of lift

• be patient and wait it our

• look forward to the repeasted bout effect

Repeated bout effect

body adapts to muscle damage by increasing intramuscular connective tissue so when faced with repeated bout of exercise there is less muscle damage

Cons of ballistic stretching

• chance of injury

• muscle spindle reflex response

• chances of muscle soreness