ACSM exam

acute exercise

individual bout of exercise, bodies immediate response to an exercise bout

heart rate

primary function of CV system: ensuring adequate blood flow throughout the circulation to meet metabolic demands of tissue

what controls heart rate

sympathetic response , adrenaline (epinephrine and norepinephrine)

HR will increase until it reaches stead state- with increase in intensity, it will take 2-3 more minutes to reach steady state 

as individual becomes more fit, what happens to heart rate?

heart rate decreases as individual becomes more fit 

HR vs relative workload: proportional to intensity, as intensity increases, HR will increase

HR max formula

207-(.7 * age in years)

Steady state

HR will increase until it reaches stead state- with increase in intensity, it will take 2-3 more minutes to reach steady state 

Good predictor of fitness level

During acute exercise what happens to blood pressure

systolic increases, diastolic does not change significantly during exercise it may slightly decrease

What are the receptors that modify BP?

baroreceptors: stretch receptors, chemoreceptors= pH and chemical aspects of blood, mechanoreceptors = GTOS, muscle spindles, skeletal muscle

Arm vs leg exercise an

Stroke volume

volume of blood pumped out of left ventricle per contraction

Major determinant of cardiorespiratory endurance capacity (VO2)

SV equation

EDV-ESV (ml)

Factors that determine SV

volume of venous blood returned to heart 

Ventricular dispensibality

Ventricular contractility 

Aortic or pulmonary artery pressure (after load)

SV increases proportional to work rate- plateaus at 40-60 % VO2 max 

What happens to SV as intensity of exercise increases?

increases

SV increases with acute exercise due to

Frank starling mechanism, sympathetic stimulation, decreased peripheral resistance due to increased vasodilation to active muscles

Frank Starling Mechanism

an increased volume of blood enters ventricle (EDV) causing it to stretch and consequently contract with more force

Cardiac output

total volume of blood pumped by left ventricle per minute

Cardiac output equation

Q= HR x SV (L/min)

Average resting cardiac output

5L/min

Total blood volume of a typical adult is 5 liters

Q with exercise

increases with increasing exercise intensity up to ~20 to ~40 L/min (up to 8x more than resting value)

3 functions of the blood important to exercise

transports oxygen, temperature regulation, acid-base balance (pH of blood around 7.3-7.5- more basic)

redistribution of blood flow

Caused by sympathetic response, blood flow into the exercising muscles increases from - 15-20 % of Q to 70-85 % of Q

Blood flow into skin also increases 5x resting values

Blood flow to digestive system decreases during exercise from -25% of Q to -5% of Q

Oxygen consumption (VO2)

rate of O2 and CO2 exchanged in lungs = rate of use and release by the body tissues

VO2 is the single best measurement of cardiorespiratory endurance and aerobic fitness

During sub max exercise related to oxygen consumption

during exercise at a constant power output (work rate) VO2 increases from resting values  to a steady state value within 2-3 mins

Increases in metabolism and VO2 are proportional with increases in work rate (exercise intensity) 

During max exercise VO2 max

maximal capacity for oxygen consumption by body during maximal exertion

Expressed relative to body weight (units: ml/kg/min)

Vo2 max declines after age 25-30 by 1% per year

Tidal volume

Amount of air that moves in or out of lungs with each respiratory cycle

Tidal volume increases with increase intensity of exercise (breath faster as increase in intensity)

What happens to ventilation rate at a constant workload

ventilation rate will plateau once steady state is achieved

What happens to ventilation rate with increasing workloads?

VR increases proportionally to workload until athlete reaches ventilatory threshold

Ventilatory threshold

point where ventilation rate rises exponentially with increasing exercise workload/ intensity due to body’s shift from an aerobic state to anaerobic state

Chronic adaptations to endurance training with regards to RESTING HR

decreases by 1 beat / min with each week of training due to increased parasympathetic (vagal) tone and increase stroke volume ; a bigger heart

Chronic adaptations to endurance training relating to sub max HR

Decreased HR for a given absolute exercise intensity 

Chronic adaptations in regards to max HR endurance training

unchanged, not determined by fitness level , only with age is it dependent

Heart rate recovery

time it takes the heart rate to return to resting rate after exercise

Training increases rate of recovery

Indirect measurement of cardiorespiratory fitness

Prolonged by certain enviornment such as heat and altitude

Blood flow to active muscles is increased due to 

Increased capillarization and recruitment, more effective redistribution, increase blood volume and plasma volume , increase in red blood cells and hemoglobin, blood viscosity decreases (due to increase in plasma volume which improves blood flow and O2 delivery)

What happens to blood pressure as person becomes more fit?

Systolic BP will reduce at rest as well as submaximal exercise, but max exercise blood pressure will actually increase since the heart is now stronger and able to generate greater pressure

Oxygen transport and chronic adaptations with aerobic exercise

Increased levels of erthryopoiteten (stimulates RBC production), increase in RBCS result in increase of oxygen transport, VO2 max thus increase by 10-15% with 20 weeks of endurance training

Chronic adaptations (aerobic exercise) ventilation 

Little effect at rest; increase pulmonary ventilation both tidal volume and respiratory rate at maximal exercise oxygen, strengthening of primary and accessory respiratory muscles 

Primary respiratory muscles

diaphragm, external intercostals

Accessory muscles involved with inspiration

scalens, SCM, pec minor

Accessory muscles involved with expiration 

recuts abdominius, lats, quadratus lomborum, intercostals 

Blood pressure responses: Static exercise

During isometric exercise, high BP responses are exacerbated by breath holding (Valsava maneuver espesially)

Valsava maneuver

breathing technique where air is trappedd in lungs against a closed glottis ; increase intra abdominal pressure

High BP during static exercise results in

decreased venous return, increased pressure in chest cavity, dizziness and fainting 

BP responses in resistance training

Typically greater in concentric phase vs eccentric phase

Proper RT programs can help reduce resting BP

BP and postural changes

Gravity eliminated<Sitting< standing

Orthostatic hypotension

form of low BP which can occur when standing up from sitting or lying down position , resulting in dizziness

ATP

serves as immediate source of energy for most body functions including muscle contraction

ATP- PCr

cells store small amounts of ATP, and phosphocreatine (PCr), which is broken down to regenerate ATP

Release of ATP from PCr is facilitated by enzyme creatine kinase

Does not require oxygen (anaerobic)

sustain muscles energy needs for 3-15 sec during all out sprint

Glycolytic system

requires 10-12 enzymatic reactions to break down glycogen to lactic acid producing ATP

Does not require oxygen (anaerobic)

Produce lots of lactic acid

Glycogen stored in liver and muscles

• ATP and PCr and glycolytic system combined provide energy for 2 min of all out activity

• 1 mole glycogen produces 3 moles of ATP

• 1 mole of glucose produces 2 moles of ATP

Oxidative system

uses O2 to generate energy (aerobic) 

Production of ATP occurs in mitochondria 

Slow to turn on (2-3 mins , steady state exercise)

Primary method of energy production during endurance events 

Krebs and electron transport cycle 

One mole glycogen can generate 37-39 molecules of ATP

What is RER?

ratio between CO2 released (VCO2) and oxygen consumed (VO2)

RER= VCO2/ VO2

• tells what primary substrate our body is using for energy production

RER value at rest

0.80

RER oxidation of fat

.70

RER oxidation of carbs

1.0

What is a MET?

amount of energy expended during 1 min of seated rest

1 MET

VO2 of 3.5 ml O2 kg/min

1.2 kcal/min for 70 kg individual

Skeletal muscles are ____ controlled by ___ nervous system

Voluntary, somatic

Sarcomere anatomy

I band- light portion (actin)

A band- dark portion (actin and myosin)

H- middle of A band

M line- myosin attaches thick filament

Events leading to muscle fiber contraction

1- Excitation: Motor neuron generates an action potential that travels down axon to NMJ , electrical impulse that triggers acetylcholine into synaptic cleft, ACh binds receptors to sarcolemma, opening sodium channels, depolarization occurs as (Na+ ) enters initiating action potential that spreads along sarcolemma down T tubules 

2- Excitation- Contraction Coupling: action potential in T tubules signals SR to release calcium ions into sarcoplasm, calcium binds to troponin C binding causes tropomuosin to shift exposing myosin binding sites on actin filaments

3- Cross bridge formation: myosin heads attatch by exposed actin sites, forming cross bridges 

4- power stroke: myosin heads pivot, pulling actin filaments toward M line of Sarcomere , shortens Sarcomere, moving z lines closer together producing muscle contraction

5- detachment and reactivaition: new ATP molecules binds to myosin head, causing it to detach from actin, ATP is hydrolyzed , cycle will continue if calcium available 

6- relaxation: neural signal stops ACH broken down by acetylcholinesterae, calcium pumped back into SR using active transport, as calcium detaches from troponin, tropomyosin covers actins binding sites again,

Sliding filament theory

muscle contraction occurs when myosin heads attatch to actin filaments and pull them toward center (M line) of sarcomere. Shortens the sarcomere, causing the entire muscle fiber to contract- without filaments themselves changing length

Cross bridge cycling will continue as long as calcium and ATP are present

Longitudinal/ parallel muscles

ends of muscle pull toward each other in Y direction

Sartorious, biceps femoris, biceps brachi

Pennate muscles 

pulls in x and y directions 

Greater the angle of pennation , less force produced by muscles 

Ex: tibialis posterior, rectus femoris, deltoid 

Type I fibers

slow twitch, oxidative (50%)

Rely heavily on fat oxidation and ideal for low intensity long duration exercise

Type IIa fibers

fast twitch (25%): fast oxidative/ glycolytic (FOG)

mid distance running, soccer, basketball, repeated sprints 

Type IIx 

fast twitch, fast glycolytic (25%)

Plyometrics, heavy lifting, sprints, throwing

Generate most force but fatigue rapidly ; highly responsive to high intensity , short duration training

SAID principle

Specific adaptation to imposed demands- adaptation based off type of exercise

Strength gains early on vs long term gains

influenced by more neural factors for early/novice athletes, long term gains result from hypertrophy

Hypertrophy

Net increase in muscle protein synthesis ( increase in size of the fiber)

Acute muscle soreness

immdediatley post exervise, results from an accumulation of end products of exercise in muscle, disappears within minutes or hours after exercise

Delayed onset muscle soreness (DOMS)

soreness felt 12-48 hrs after strenuous bout of exercise

Primarily from eccentric muscle activity but can also be caused by concentric contractictin

Eccentric is what brings micro tears- not great for novice athletes

Causes of muscle fatigue

1- energy depletion

2- accumulation of H+ which decreases pH

3- failure of muscle fibers contractile mechanism

4- muscle fiber type 

5- alterations in nervous system

6- fitness level 

Intrinsic properties of cardiac muscle

contains intercalated disks

Heart conduction system SA node—AV node— AV bundle— Purkinje fibers

Extrinsic fibers of cardiac muscle

Chronotropic effect: Autonomic nervous system; changes in HR caused by neural or hormonal influences on SA node- hearts natural pace maker

Inotropic effect: Relates to strength of contract and is influenced by frank starling mechanism which states force of cardiac contraction increases with amount of stretch placed on heart muscle fibers (Sarcomere) before contraction 

Organic compound of bones

35 percent collagen, slightly flexible

Inorganic compound of bone

65 % calcium phosphate , hard (mineral)

Compact (cortical) bone

80 % of body’s bone, (hard, dense, and compact)

Spongy (cancellous) bone

20% of body’s bone

• honeycomb appearance 

• Many trabeculae

• Red marrow located in spaces between trabeculae

Longitudinal growth (bones)

take place on epipheysal plates , plates produce new bone cells on disphyseal side of bone up to ages 18-25

epiphysis — end of the long bone

Diaphysis— shaft of the bone

Circumferential growth

internal layers of periosteum lays down concentric layers of bone

Bone resorption

occurs around medullary cavity

Osteoclasts resort bone while osteoblasts make new bone ; both cell types remain in balance until 40-60 years

Wolffs law

a bone grows or remodels in response to forces or demands placed upon it

Bone hypertrophy

bones become stronger, increase in bone density; exercising bones will get stronger 

First class lever

Effort- Fulcrum- Load : “See saw”

Best for balance

Ex; Triceps, Occiptal Atlanta joint

2nd class lever

Fulcrum - Load- Effort

Best for power “wheel barrow”

Ex: foot during plantar flexion

3rd class levers

Best for ROM 

Most joint sin body set up this way

F- E - L

Ex: biceps 

Law of inertia

No force= no movement

Movement will not change without an opposing force

Law of acceleration

F= ma

Acceleration proportional to force and inversely proprtional to mass

Acceleration

rate of change of velocity

Law of action- reaction 

any force creates an equal and opposite counter force

Ground reaction force 

GRF when walking

1.5x body weight exerted up through body

GRF when jogging

2x body weight exerted up through body

Sprinting GRF

2.5 to 3x body weight exerted up through body 

Frictional force

friction is proportional to force that is pushing two surfaces together

Static friction> dynamic friction

Friction forces acts parallel to two surfaces moving over each other

Contraction velocity

greater forces generated at slower velocities

Muscle length

eccentric (lengthening) contractions produce greater forces than concentric (shortening)

What angle is most force produced by muscle?

90 degrees of insertion into bone

Balance defined

ability to control one’s equilibrium

Stability defined

resistance to movement

Ways to improve balance 

increase body mass, increase friction, increase size of support base, position COG near edge of support base on side of oncoming external force; if no external force, COG should be in middle of support base , vertically position COG as low as possible 

Center of mass v center of gravity

center of mass= theoretical point around which body’s mass is equally distributed

Center of gravity= theoretical point where force of gravity acts on a body

“Balance point”

• in most instances COM and COG can be treated as same point

Positive risk factors

Age, family history, cigarette smoking, sedentary lifestyle, obesity, hypertension, dyslipidemia, blood sugar