KIN Test #2

concentric muscle contractions

muscle shortens (Lifting a dumbell)

eccentric muscle contraction

muscle lengthens (lowering a dumbell)

isometric muscle contractions

muscle produces force without movement (holding a plank)

where are sarcomeres located within skeletal muscle

in myofibrils and responsible for muscle contraction

are sarcomeres the “true” cell of the muscle?

no! they are the smallest units inside a muscle cell

sarcomeres’ two proteins

actin and myosin

what is the actin protein

a thin filament

what is the myosin protein

a think filament that pulls on actin

how many steps in cross bridge cycle for muscle contraction

4

1. attachment (crossbridge cycle)

mysin attaches to actin

2. power stroke (crossbridge cycle)

myosin pulls actin which shortens the muscle

3. detachment (crossbridge cycle)

ATP binds to myosin, actin is released

4. reactiviation (crossbridge cycle)

ATP is broken down, myosin resets, cycle repeats

what changes with skeletal muscle hypertrophy

muscle fibers get larger because they gain more actin and myosin

how is an increase in capillarization/vascularization within a muscle beneficial?

allows muscles to receive more oxygen and nutrients

a motor unit is comprised of

one motor neuron and the muscle fibers that control it

resting membrane potential

electrical charge across the membrane when its not sending a signal

action potential

fast electrical charge that travels across membrane that allows cells to send signals

why is Ca2+ critical for contraction

removes the physical block that stops actin and myosin from attatching

type I, slow twitch

slow, fatigue resistance, high aerobic capacity / marathon runner

type IIa, fast twitch

fast, moderate fatigue resistance, uses anaerobic & aerobic energy / middle distance runners

type IIx, fastest twitch

very fast, fatigues quickly, high anaerobic capacity / sprinters & powerlifters

type I happens in

oxidative energy system

type IIa happens in

nonoxidative energy system

type IIx happens in

immediate energy system

who needs medical clearance before beginning an exercise program

people with known CVD, metabolic or kidney disease, or concerning symptoms (chest pain, dizziness, shortness of breath)

what information should we know

medical history, current activity level, goals, medication, consent

how can exercise reduce the risk of hypertension

strengthens the heart which allows more blood to flow easily while lowering BP

how can exercise reduce the risk of dyslipidemia

can lower triglycerides, increase good cholestrol (HDL), and can sometimes lower LDL

how can exercise reduce the risks of emotional stress and CVD

reduces stress, stabilizes nervous system, lowers BP, improves mood and sleep, improves blood vessel function

why is exercise beneficial for cardiac patients

strengthens CVS, improves endurance, reduces symptoms, lowers risk of future heart problems

BMI obesity classification

BMI is overall ≥ 30

BMI obesity class 1

BMI ≥ 30

BMI obesity class 2

BMI ≥ 35

BMI obesity class 3

BMI ≥ 40

what other CVD risk factors does obesity impact

high BP, high cholesterol, insulin resistance, heart disease

what determines fiber types

mainly genetics

can fiber types be changed to a different one?

no. training can shift IIa to IIx but not I to IIa/x

what region of the brain is involved with movement

the motor cortex (which is next to sensory cortex)

how are complex movements/patterns learned

through repetition, practice, and feedback

what is myoplasticity

ability of skeletal muscles to adapt and change

how are muscle adaptations beneficial for daily function and fitness

they improve strength, endurance, balance, and mobility

endurance training does what to skeletal muscle

increases mitochondria, capillaries, and aerobic enzymes

resistance training does what to skeletal muscle

increases muscle hypertrophy, strength, force production

inactivty does what to skeletal muscle

causes muscle atrophy, reduced strength, decreases endurance

why is flexibility important

helps maintain joint range of motion and improves movement

why is specificity important in cardiorespiratory endurance training

the body adapts to the type of exercise happening

circulatory adaptations from cardiorespiratory endurance training

increase Sv, improved BF, more capillaries, lower RHR

metabolic adaptations from cardiorespiratory endurance training

increased mitochondria, improved O2 use, greater fat oxidation, increased aerobic enzyme activity

what are the general exercise recommendations for a healthy adult

150-300 mins of moderate aerobic activity, 75-100 mins of aerobic vigoruous activity. strength 2 days/week. flexibility 2-3 days/week

what components comprise an optimal ExRx

warm up, conditioning, cool down, stretching

modifiable risk factors

high blood pressure, high cholestrol, inactivity, smoking, unhealthy diet

nonmodifiable risk factors

age, sex/gender, family history, race

2 most common types of diabetes

type 1 & type 2

type 1 diabetes

body produces little to no insulin

type 2 diabetes

body becomes resistant to insulin

which type of diabetes is modifiable

type 2 diabetes

what are the benefits of exercise on diabetes

lowers BG, improves insulin sensitivity, and reduces the risk of heart disease