a motor neuron and the muscle it innervates 

-usually several hundred muscle fibers in a motor unit

Primary source of ATP at rest and during low intensity activities 

uses primarily carbs and fats

at rest fat is main source (70%) during high intensity activity carbs are 100% of energy supply 

-the level at which blood lactate begins an abrupt increase above the baseline concentration of blood lactate

begins at 50-60% max oxygen uptake in untrained 70-80 in athletes 

-Increased surface area

-greater total length of nerve terminal branches 

ACTIN SLIDES ON MYOCIN pulling z lines in

Actin filliments at end of sarcomere slide inward on myosin filaments pulling the z-lines towards the center of sarcomere and thus shorten muscle fiber and cause contraction; 

♥calcium is released during excitation;

♥calcium binds with troponin

♥causes shift in tropomyosin 

♥moysin cross bridges attach more rapidly 

♥happens when the stimulation of motor nerve stops

♥calcium pumped back into sarcoplasmic recticulum 

this prevents linking between actin and myocin 

Basically just means that actin and myocin are returned to their original places and states

Type I 

♥develop force and relax slowly

♥long twitch time 

♥fatigable, rapid force development 

type IIa greater resistance to fatigue due to more capillaries surrounding them than type IIb 

muscle control:

more control: less muscle fibers per motor neuron

Less control more force: More muscle fibers per motor neuron

♥Change in the frequency of activation of motor units

♥change in the number of activated motor units

♥they are proprioceptors that consist of several modified muscle fibers cover in sheaths of connective tissue

They indicate the degree the muscle must be contracted to overcome resistance 

as muscle is stretched to a greater extent the muscle spindles indicate greater force activation is necessary 

Proprioceptors located in tendons;

activated when the muscle they are attached to is stretched

inhibits activation of muscle to reduce tension 

Hemoglobin- carries oxygen and acts as acid base buffer

Red blood cells facilitate CO2 removal 

Elevate rib cage

Contracted: external intercostals and diaphragm 

RELAXED: internal intercostals 

the flow of energy in a biological system;

conversion of macronutrients into energy 

Breakdown of larger molecules into smaller ones

releases energy 

sythesis of larger molecules from smaller ones 

endergonic (requiring energy)

triglycerides in fat cells are broken down releasing free fatty acids into blood to be carried to muscle fiber

-some free fatty acids come from intramuscular sources 

phosphagen energy system

(Active at the start of all exercise regardless of intensity) 

High intensity activities for short duration 

Resistance training and sprinting

replenishes ATP rapidly through the creatine kinase reaction

-Breakdown of carbs to resynthesize ATP

Glycogen from muscle or glusoce in blood

1)Pyruvate can be converted to lactate

-fast glycolosis(anaerobic); short duration

2) Pyruvate can be shuttled into the mitochondria

-ATP synthesis rate is slower but duration is longer

pyruvate forms lactate

catalyzed by lactate dehydrogenase

END RESULT NOT LACTIC ACID

Lactate is not the cause of fatigue 

from blood glucose: 2 ATP per one molecule 

From muscle glycogen: 3 ATP molecules per one molecule 

creatine runs low within first 30 seconds of high intensity exercise

-repletion of ATP takes about 3-5 min

and resynthesis of creatine within 8 minutes 

-rate of depletion is related to intensity of exercise

can be completely depleted during some exercises 

-repletion of muscle glycogen is related to post-exercise carb ingestion (.7 to 3g carbs per kg body weight every 2 hours after exercise) 

-more efficent energy transer by using predetermined intervals of exercise and rest periods 

-much more training at higher intensities 

-work to rest ratios are difficult to find

-from adrenal cortex and gonads

-passively diffuses

binds to receptor to form receptor hormone complex and enters cells nucleus to expose transcriptional codes to synthesis proteins 

-made of amino acids

(growth hormone and insulin)

-bind to receptors in blood or in cell membrane

-need secondary messanger to get into cell 

-primary androgen hormone that interactis with skeletal muscle 

-promotes growth hormone in pituitary to synthesis protein 

-increases force production potential in muscles

-increases strength and size of muscles 

(Men: exercising later in the day is more effective for increasing overall testosterone concentrations over an entire day) 

-Large muscle group exercises: dead lift, squat, power cleans) 

-heavy resistance; One rep max 

-moderate to high volume(multiple sets and exercises)

-short rest times

-2 years of training experience 

-pituitary gland

interacts directly with target tissues: bone, immune cells, skeletal muscle, fat cells, and liver tissue

-regulated by neuroendocrine feedback mechanisms

-alters by age, gender, alcohol consumption, sleep, nutrition, and exercise 

-GH responds to exercise stressors i.e. resistance exercise

-women have more than men(depnds on cycle)

-converts amino acids to carbs, increases breakdown of proteins, and inhibits protein synthesis

-increases with resistance training

Catecholamines:

-increase force, contraction rate, blood pressure, evergy availability, blood flow

-augment secretion of other hormones, testosterone. 

Increasing testosterone: large muscle groups, heavy intensity, high volume, short rest 

Increasing Growth hormone: High intensity, high volume, and short rests 

Increasing cortisol and cats: large muscle groups, varying intensity and rest times, high volume 

muscle force and resistive force are on opposite sides of the fulcrum 

muscle force and resistive force act on same side of fulcrum 

-muscle force moment arm is longer than resistive force

-mechanical advantage yeilds the required muscle force is smaller than the resistive force 

Third class lever

(elbow flexion)

same side of the fulcrum 

--moment arm shorter than resistive arm 

ratio is less than one therefore the muscle force must be greater than resistive force 

angle between muscle fibers and imaginary line between muscles origin and insertion 

0 equals no pennation 

glottis is closed keeping air from escaping the lungs and abs and rib cage contract

creates ridgid compartments of liquid in the lower torso and air in uper torso 

-end-diastolic volume is increase

-at begining of exercise stoke volume is increased 

3.5 ml of oxygen per kg of body weight per minute

defined at 1 MET 

coorlation with results of tests assessed and other recognized measures of construct 

"comparing to the gold standard"