Exercise Physiology Flashcards
Venous blood enters which heart chamber?
Right atrium
Which side of the heart receives venous blood?
The right side
Where in the lungs does the exchange of gasses occur?
The pulmonary capillaries
Where does blood from the pulmonary veins enter the heart?
left atrium
describe the two circulatory patterns
1) pulmonary
2) systemic
what are the two phases in the rhythmic pattern of cardiac contraction and relaxation?
systole and diastole
what is systole? what happens during systole?
the contraction phase; the atria contract first, pumping blood to the ventricles - which themselves contract a fraction of a second later, sending blood to the lungs and body.
what happens during diastole?
as the heart muscle relaxes blood fills the left and right chambers of the heart in preparation for the next contraction. During diastole the heart itself is supplied with oxygenated blood through the coronary arteries.
describe one benefit of cardiopulmonary fitness as it pertains to the cardiac cycle
in people with a high level of cardiopulmonary fitness the heart spends more time in diastole at any submaximal exercise intensity.
what is cardiac output (Q)?
the amount of blood that is pumped out of each ventricle each minute.
what is the ratio of Q between each ventricle?
1 - the cardiac output from each ventricle is the same
which ventricle generates the most force during systole? why?
blood from the left ventricle is ejected with significantly greater force because blood from the left ventricle has to be pumped with enough force to reach the entire body; blood from the right ventricle only has to travel to the lungs and back
cardiac output (Q) is the product of which two factors?
heart rate and stroke volume
what is stroke volume?
the amount of blood pumped from each ventricle each time the heart beats
what are the units of SV?
ml/beat
what is a fairly typical SV? Q at rest?
a typical SV is ~70ml. a typical Q at rest is ~4200ml (about a gallon).
what is ejection fraction?
the amount of blood that fills the ventricles during diastole is not always completely ejected during systole. the percentage of the total volume of blood in the ventricle at the end of diastole that is subsequently ejected during contraction is called the ejection fraction.
what is the ejection fraction at rest?
about 50%
what is oxygen extraction?
the amount of oxygen taken from hemoglobin to be used by exercising muscles
what is the major limitation to exercise performance?
the capacity of the muscles to extract oxygen from circulating hemoglobin
where does anaerobic ATP production occur?
in the cell, outside the mitochondria
what is ischemia?
diminished blood flow
what is the primary substrate for anaerobic ATP production?
glycogen
aside from glycogen, name another source of anaerobic ATP production
creatine phosphate
what are phosphagens?
creatine phosphate and ATP
in a well trained athlete approximately what duration of maximal effort can be fuelled by phosphagens?
~10s
what is maximal oxygen consumption or VO2 max?
the total capacity to consume oxygen at the cellular level
what two factors determine VO2 max?
the delivery of oxygen to the working muscle by the blood (cardiac output (Q)) and the ability to extract the oxygen from the blood at the capillaries for use by mitochondria (oxygen extraction)).
cardiac output(Q) max * oxygen extraction max = ?
VO2 max
how is VO2 max expressed?
as either mL of oxygen consumed per kg of body weight per minute (mL O2/kg/min) or as litres of oxygen consumed per minute (l O2/min)
what is arterio-venous oxygen difference (A-VO2 diff)?
the increase in oxygen extraction during exercise resulting from increases in temperature, acidity, and CO2 levels in the bloodstream
what is a MET?
Metabolic Equivalent; the resting VO2 of 3.5 mL/kg/min
how do you determine the VO2 equivalent of any MET value?
multiply the MET value by 3.5
what happens to blood pressure during exercise?
Systolic pressure should increase in response to an increasing demand from muscle tissue, while diastolic pressure should either stay the same or decrease slightly.
why should diastolic pressure decrease slightly during exercise?
dilation of the blood vessels in the muscles and the skin reduces the amount of residual pressure in the system.
what cardiopulmonary adaptations occur in response to proper aerobic training?
1) RHR decreases (stroke volume at rest increases (so the same cardiac output (Q) can be maintained at a lower heart rate)),
2) stroke volume during exercise increases (the HR at any given submaximal intensity will be lower)
3) maximum cardiac output (Q) increases significantly
4) new capillaries are produced in the active skeletal muscle (increasing the area of gaseous exchange)
5) significant increase in mitochondrial density (which leads to a significant increase in the aerobic enzyme activity in the cell and, therefore, an increase in oxygen extraction)
6) elevated anaerobic threshold
7) more fat is used for energy at any submaximal intensity
8) during submaximal exercise more glycogen is stored and less lactic acid is created
9) we become more tolerant of lactic acid
10) finally, training also increases one’s tolerance for stressful situations and improves our ability to effectively deal with stress
fitness training is based on what principle?
the overload principle
what is the overload necessary to cause significant improvement in the cardiovascular system?
an increased venous return sustained for a prolonged period (the exercise must cause a sustained increase in the amount of blood returning to the heart.
what are the four rules required to maximize overload during aerobic training?
the exercise should be:
1) the correct type
2) done at the proper intensity
3) of sufficient duration
4) with adequate frequency
for maximal effectiveness, aerobic exercises need to be…
1) rhythmic and continuous
2) involve the large muscle groups (generally the hip flexors and extensors (iliopsoas, rectus femorus) and the knee flexors and extensors (hamstrings, quadriceps) should be involved)
what is the muscle pump?
the rhythmic squeezing action of the large muscles against the veins within these muscles, which causes a significant increase in venous return (which is required for effective aerobic conditioning)
what is the optimum exercise intensity range for fitness improvement (pertaining to aerobic conditioning)?
50-85% of max O2 consumption (which corresponds to about 60-90% of max HR)
how can clients monitor aerobic exercise intensity?
the talk test or Borg’s Ratings of Perceived Exertion (for most people exercising at an RPE of 13-15 (somewhat strong to hard) correlates well with an appropriate HR.
what is the minimum duration for effective aerobic training?
15-20 min
about how many calories per minute are expended when the cells of the body consume 1L of O2/min?
~5 calories (1L O2/min=5cal/min)
what is the difference between performance and fitness interval training?
performance interval training requires short bursts of maximal (or near maximal effort); fitness interval training requires the client to periodically increase intensity throughout a workout (intensity is capped at anaerobic threshold).
what is the minimum frequency necessary for effective cardiovascular training?
3 days/wk
how long does it take to acclimate to an altitude of 8000’?
~2 wks
how long does it take to become acclimated to an altitude of 12k’?
up to 4-5 weeks
what are some of the potential problems associated with high altitude?
headache, insomnia, irritability, weakness, dizziness (these should be reported to a physician)
what does training in hot environments do to venous return, stroke volume and HR?
blood vessels near the skin dilate to facilitate cooling which causes a reduction in venous return and stroke volume, and a consequent increase in HR
how much water should be consumed during exercise in hot weather?
at least 3-6 oz every 10-15 min - the cooler the water the better (because cooler water empties more rapidly than warm water from the stomach into the intestines). One should also drink 8 oz of H2O 20 min before exercise and another 8-10 oz in the 30 min following exercise
is it more important to replenish body fluids during hot or cold weather? why?
it’s equally important to replenish body fluids during hot or cold weather. Water is lost as vapour in exhaled air and urine production is increased in the cold
what are the three primary types of muscle cells?
1) cardiac
2) smooth muscle cells (in the walls of arteries and intestines)
3) skeletal muscle cells
what are the 2 primary types of skeletal muscle fibre?
slow twitch (type I) and fast twitch (type II)
what are the characteristics of slow twitch (type I) muscle fibre?
slow twitch (type II) muscle fibres contract more slowly, have many mitochondria, have a high aerobic capacity, are fatigue resistant and are smaller in cross section than fast twitch (type II) fibres.
what are the characteristics of fast twitch (type II) muscle fibres?
fast twitch (type II) fibres are larger than slow twitch (type I) fibres, provide more force and speed
what are the different types of fast twitch (type II) fibres?
type IIa (also known as fast twitch oxidative because they have more mitochondria than type IIb), and type IIb (which are referred to as fast twitch glycolytic
which have more mitochondria, type I or type IIa muscle fibres?
type I
can training change type I to type II muscle fibres, or vice versa?
no. however, aerobic training can increase the aerobic capacity of type II fibres
what is the functional difference between type I and II fibres?
type II fibres contract to maximum force more rapidly than type I fibres; the process of contraction is the same, however
what are myofibrils?
A myofibril (also known as a muscle fibril) is a basic rod-like unit of a muscle. Muscles are composed of tubular cells called myocytes, also known as muscle fibers, and these cells in turn contain many chains of myofibrils.
what are the proteins in myofibrils that need to be considered in relation to the process of muscle contraction?
actin and myosin
what is a sarcomere?
repeating units along the length of the muscle cell (myocyte). A muscle cell (myocyte) has many sarcomeres along its length.
what is the sliding filament theory of muscle contraction?
in order for muscle contraction to occur, there must be sufficient ATP present near the actin and myosin proteins and a nervous impulse from the CNS. When these two factors are present the tiny projections from the myosin (myosin heads) attach to the actin, forming an actin-myosin cross bridge. The energy from ATP causes the myosin heads on each end of the myosin to swivel towards the centre of the sarcomere, pulling the attached actin myofilament so that the actin slides inward toward the centre of the sarcomere. This process causes each sarcomere along the length of the muscle fibre to shorten, and since all of the sarcomeres shorten at the same time, the overall length of the muscle fibre is decreased.
what is concentric contraction?
a shortening contraction
describe an eccentric contraction
an eccentric contraction occurs when individual fibres contract, but the resistance is greater than the force generated, so the muscle actually lengthens.
what is an isometric contraction?
an isometric contraction is one in which there’s a contraction of muscle fibres but no change in the length of the whole muscle.
the amount of force that is generated during contraction in the whole muscle depends on what factors?
- 1)the size of the individual fibres contracting (larger fibres are stronger fibres)
- 2)the number of muscle fibres that contract simultaneously (more fibres are recruited to generate more force)
3) the force generated by a muscle contraction is also related to the speed of movement at the associated joint and the initial length of the muscle belly (the “force-velocity” relationship suggests that, in general, the faster the speed of movement the lower the force generated by the contracting muscle. The “length-tension” relationship demonstrates that a muscle generates maximum force when it begins its contraction at 1.2X its resting length
what is a motor unit?
a single motor nerve (from the spinal cord) and all the muscle fibres it stimulates is called a motor unit
what is the fibre type composition of motor units?
motor units are comprised of either all fast twitch (type II) or all slow twitch (type I) muscle fibres.
what is hypertrophy?
an increase in the size of a muscle as an adaptation to training, which results from an increase in the number and size of myofibrils inside muscle fibres and the number of sarcomeres in muscle fibres.
what is the Golgi tendon organ?
a sensor (part of the nervous system), which protects against generating too much contractile force.
what are the adaptations to strength training?
1) muscle fibre adaptation
2) connective tissue adaptation
3) increased nervous system activity
4) decreased nervous inhibition
what is an isotonic exercise?
isotonic = same tone or tension; one that uses a given amount of external resistance. Note - the tension in the muscle throughout the range of motion in an isotonic exercise is not constant - the force generated by a muscle will change throughout the movement because of the biomechanics at the joint or joints involved.
what is “dynamic constant external resistance”?
a better description of isotonic exercise
what is “dynamic variable external resistance”?
exercises on machines with shaped cams, wherein the force generated by the overloaded muscles changes throughout the movement.
what is an isokinetic exercise?
one performed at a constant speed; isokinetic exercises cause the muscle to generate a maximum amount of force throughout the entire range of movement by keeping the speed of movement constant.
What are muscle spindles?
fibres in muscle tissue that protect against over-stretching
