HK 100 Test 1

motor unit

a single motor neuron (nerve) and all the muscle fibers it innervates

structural and functional unit of the neuromuscular system

motor unit

where is the motor unit found

ventral horn

components of a motor unit

dendrite, cell body, axon, myelin sheath

skeletal muscle

a muscle that is connected to the skeleton to form part of the mechanical system that moves the limbs and other parts of the body

why does 1 neuron innervate 100 muscle fibers in leg but only 10 in the eye?

gross vs fine movements

tendon

muscle to bone

muscle

bundle of fascicles

fasicle

bundle of muscle fibers

muscle fiber

consists of myofibrils

myofibrils

repeating sarcomeres

sarcomere

contractile unit of a muscle fiber

structural and functional unit of a muscle

sarcomere

sliding filament theory

theory that actin filaments slide toward each other during muscle contraction, while the myosin filaments are still

z-line to z-line becomes shorter -\> sarcomere shortens -\> muscle shortens

correct but we need to know more!!**

cross-bridge hypothesis (in short)

theory starts with electrical signal--\> release of Ca ions--\> exposes active binding sites--\> myosin attaches and pulls

cross-bridge hypothesis (in depth process)

1. chemical released at the end of a nerve fiber which changes the voltage of a muscle
2. an electrical signal travels along the muscle fiber
3. calcium ions are released into the cytoplasm of the muscle fiber
4. calcium ions expose the active sites on actin
5. myosin attaches to sites; actin is pulled towards the center

types of muscle contractions

concentric, eccentric, isometric

types of isotonic contractions

concentric and eccentric

concentric contraction

muscle shortens, typically up

eccentric contraction

muscle lengthens, typically down

isometric contraction

muscle contracts but there is no movement, muscle stays the same length

delayed onset muscle soreness (DOMS)

a temporary muscle soreness and stiffness that occurs 24 to 48 hours after performing unaccustomed eccentric muscle contractions and last for 4 to 6 days

what type of movement causes more doms

eccentric because of stabilization

The energy for muscle contraction comes from \______

ATP

transduction

conversion of one form of energy into another

ATP

adenosine triphosphate - human energy

energy of muscular work

adenosine-P-P-/-P \= ATP
adenosine-P-P + P \= ADP + P

3 energy systems that resynthesize ATP

phosphagen - immediate
anaerobic glycolysis - lactic acid
oxidative - aerobic

substrate of each energy system

phosphagen - ATP, PCr, glucose
anaerobic glycolytic - glycogen or glucose
oxidative - glycogen, fat, protein

relative rate of ATP production for each energy system

phosphagen - very fast
anaerobic glycolytic - fast
oxidative - slower

duration of each energy system's max

phosphagen - 0-30 seconds
anaerobic glycolytic - 20-180 seconds
oxidative - \> 3 min

limiting factors of each energy system

phosphagen - PCr depletion
anaerobic glycolytic - lactic acid accumulation
oxidative - glycogen depletion

examples of activities for each energy system

phosphagen - pwr/weight lifting, short sprints, jumping, throwing
anaerobic glycolytic - longer sprints, mid distance, team sports
oxidative - endurance events + team sports

how does PCr split to resynthesize ATP

PCr (creatine+phosphate) + ADP -\> ATP + CR

how does adenosine help resynthesize ATP

ADP + ADP -\> ATP + AMP

T or F - when completing a 10s sprint, you only use the phosphagen system

FALSE - 3 systems work together as a continuum

ex. 55% phosphagen, 40% anaerobic, 5% oxidative

how are protein, carbs, and fats used as ATP

broken down to release energy from chemical bonds and used to resynthesize ATP

what type of exercise are carbs used for

aerobic or anaerobic

what type of exercise are fats and proteins used for?

aerobic only

when are proteins used for energy?

only when all carbohydrates and lipids are gone

during extremely long exercise (hrs) - ex. triathalon

when is the start of oxygen deficit

during phosphagen and anaerobic

what happens during sub maximal constant exercise (02 wise)

VO2 reaches steady state

what happens during maximal exercise (02 wise)

02 increases till VO2 max is reached

what is EPOC

EPOC (excess post-exercise oxygen consumption) is the amount of oxygen needed after exercise has ended compared with the resting rate.

breathing stays fast then eventually slows down

aerobic power

the ability to perform exercise for a long time

VO2 max

the maximum amount of oxygen the body can take in and use during exercise

mL x kg x minute

what does a greater vo2 max mean

greater capacity for ATP regeneration via oxidative respiration

what is vo2 max influenced by

1. genetics (40-50% vo2max)
2. training (can increase vo2max up to 40%)

when is aerobic power better

in long distance athletes and males

examples of athletes with high aerobic power

cyclists, distance runners, swimmers

NOT WEIGHTLIFTERS OR SPRINTERS

anaerobic power

the maximum amount of energy that can be generated within 2-5 seconds, that can be achieved with all out exercise

how to measure aerobic power

vo2 max

anaerobic capacity

the total amount of work (watts/kilo joules) that can be done in a specific time (30-60 seconds)

reasons to measure exercise capacity (4)

1. to identify current fitness levels - to prescribe exercise/monitor progress
2. determine effectiveness of training
3. talent identification
4. evaluate effectiveness of rehab on cardiopulmonary function

components of VO2 max uptake (3)

pulmonary - pulmonary ventilation
cardiovascular - cardiac output
peripheral adj - blood flow

pulmonary ventilation

vol of air brought into the lungs per minute

1. respiratory rate
2. tidal volume

cardiac output

volume of blood pumped through the body per minute

HR x SV

how does cardiac output change with increased exercise

increases linearly

who has a higher max HR

females

stroke volume

volume of blood pumped with each heart beat

muscle 02 extraction at rest vs max

rest - 25%
max - 75-85%

how is blood flow affected by exercise

increased exercise \= increased blood flow to working muscles

where is most of the blood flow at rest

viscera

where is most of the blood flow during exercise

skeletal muscle

50% at start
80% at maximal

muscle fiber types

slow twitch
fast twitch a
fast twitch b

fiber size of each muscle fiber type

slow twitch - small
fast twitch a - large
fast twitch b - large

contraction speed of each muscle fiber type

slow twitch - slow
fast twitch a - fast
fast twitch b - fast

force of each muscle fiber type

slow twitch - low
fast twitch a - high
fast twitch b - high

glycolytic capacity for each muscle fiber type

slow twitch - low
fast twitch a - high
fast twitch b - high

oxidative capacity and capillary supply for each muscle fiber type

slow twitch - high
fast twitch a - moderate high
fast twitch b - low

how fatigue resistant is each muscle fiber type

slow twitch - high
fast twitch a - moderate
fast twitch b - low

what color are slow twitch oxidative fibers

red

high mitochondria

what color are fast oxidative glycolytic fibers (fta)

red

what are fast twitch a fibers a combination of

slow twitch and fast twitch b

what color are fast glycolytic fibers (ftb)

white

what is an example of muscles with more fast twitch fibers

quads and hamstrings

what is an example of muscles with more slow twitch

posture muscles in neck, soles, and upper shoulders

T or F - all muscles have different proportions of fast and slow twitch fibers

true

what type of muscle fibers do nonathletes have

everyone has a different combination of muscle fiber types but the ratio of slow to fast muscle fibers is usually about 50:50 in nonathletes

what type of muscle fibers do distance runners have

mostly slow twitch (85%)

what type of muscle fibers do swimmers have

mostly slow twitch (65%)

what type of muscle fibers do sprinters have

mostly fast twitch (70%)

what type of muscle fibers do weightlifters have

mostly fast twitch (75%)

what are type 1 muscle fibers

slow twitch fibers or slow-oxidative fibers

what are type 2 muscle fibers

fast twitch muscle fibers

what causes fatigue in brief high intensity exercise that takes place for less than one minute?

PCr depletion, moderate - high lactate levels

b/c of phosphagen and a little anaerobic glycolytic system

what causes fatigue in longer high intensity exercise that takes place for one-seven minutes?

Pcr depletion, high lactate levels

b/c of anaerobic glyc and little bit of oxidative system

what causes fatigue in prolonged, moderate to high intensity exercise that takes place for 10-40 minutes?

moderate lactate accumulation, partial glycogen depletion
dehydration

b/c of oxidative system

what causes fatigue in very prolonged exercise that takes place for greater than 40 minutes?

glycogen depletion, dehydration
increased body temp, low blood glucose levels

what are the metabolic adaptations for strength and sprint training? (7)

1. increased muscle ATP & PCr - more ATP for exercise
2. increased muscle glycogen - more glycogen, delays fatigue
3. increased anaerobic enzymes - more ATP synthesis via glycolysis
4. increased lactic acid - increased tolerance for lactic acid levels
5. increased motor unit synchronization - increased power generated by muscles
6. less distance of muscle cell chemical gradient (especially potassium and calcium) - increased force generated and strength
7. increased muscle fiber size - increased muscle strength and power

do muscle fibers increase in size or do you gain more muscle fibers

increase in size

what are the metabolic adaptations of endurance training? (9)

1. increased vo2 max - greater endurance
2. increased muscle glycogen - more work before fatigued
3. increased mitochondria enzymes - increased oxidative capacity
4. increased use of fats as substrate - less reliance on glycogen, less glycogen depletion
5. enhanced lactic acid removal and oxidation - more work before onset of fatigue
6. increased lactic acid threshold - more work before onset of fatigue
7. increased capillary number - more blood oxygen, substrate, lactase, co2
8. increased oxygen extraction by the muscle - more o2 available for ATP production
9. increased myoglobin content - more o2 delivered to mitochondria

how do cardio respiratory systems respond to endurance training

1. increased vo2 max - increased endurance performance
2. decreased resting and sub maximal heart rate - less work done by heart
3. increased resting and exercise stroke volume - increased cardiac output during maximal exercise
4. increase maximal cardiac output - increase blood and oxygen delivery to muscles
5. increased blood volume, red blood cells, hemoglobin content - increased oxygen delivery to muscles
6. increase oxygen extraction from blood - increased oxygen delivery to mitochondria
7. decrease blood viscosity (thickness) - easier movement of blood through body
8. increase maximal minimum ventilation - increased removal of carbon dioxide

an increased vo2max is a characteristic of what training?

endurance training

an increased muscle glycogen is a characteristic of what training?

strength, endurance, and sprint

an increased muscle fiber size is a characteristic of what training?

sprint

what is muscular strength related to?

size of muscle, fiber type distribution, neural factors, and hormones

how much can muscular strength increase

20-100%

what is muscle adaption specific to

intensity and volume

what fiber type is recruited above 70% max strength?

ftb