Exercise Physiology: Cardiovascular Responses to Acute Exercise ; Adaptation to aerobic and anaerobic training

As exercise intensity increases, does heart rate increase?

• yes

• direct proportion, increase intensity, increase heart rate

• have to match oxygen carrying capacity

As heart rate increases, how do the parasympathetic and sympathetic nervous systems respond?

• PNS decrease raises heart rate to 110 bpm

• SNS increase raises heart rate from 110 to maximum

Heart rate max (exercise)

• HRmax=208-(0.7 x age)

What is steady state heart rate?

• the optimal heart rate for circulatory demands at a given intensity

Is steady state heart rate immediate? when does it kick in?

• stead state HR not immediate

• achieved in 3-4 minutes

What does a lower steady state HR indicate?

• better cardiorespiratory fitness

Why does an untrained person have a higher heart rate than a trained individual?

• untrained has a lower stroke volume

How does exercise affect stroke volume?

• stroke volume increases in direct proportion to exercise intensity, but only to 40-60% of VO2 max

• stroke volume plateaus; although might not be true for elite athetes

how much greater is stroke volume max than at rest?

• double

Why does exercise increase stroke volume?

• as you exercise, more blood is pumped and returned to venous, stretch ventricles

What is the Frank-Starling mechanism?

• increased venous return leads to increased end diastolic volume, which increases ventricular stretch

• increase stretch optimizes cross-bridge formation (lead to more forceful contraction)

What mechanisms explain increased stroke volume during exercise?

• Frank-Sterling mechanism

• Contractility

What happens to contractility during exercise? How does this impact stroke volume?

• increases

• stimulated by SNS and/or catecholamines

• increased contractions increase the amount of blood being pumped out

What are the normal values for cardiac output?

• 5 L/min at rest

• 25 L/min at max in average person

• up to 40 L/min in elite athletes

How does arterial O2 respond to exercise?

• stays constant

How does venous O2 respond to exercise?

• varies by tissue

How does exercise affect a-VO2 difference?

• a-VO2 increase

• due to increased O2 extraction at the tissues

What is a-VO2 at rest and max exercise?

• Rest - 5mL/100mL

• Max exercise - 15-17mL/100mL

O2 consumption is the product of…..

• product of blood flow and the amount of o2 extracted by the tissues

What is the Frick equation?

• O2 consumption is the product of blood flow and the amount of O2 extracted by the tissues

• VO2 = Q x (a-vO2diff)

• VO2 = HR x SV x (a-vO2diff)

How to systolic and diastolic blood pressure respond to exercise?

• systolic blood pressure increases in proportion to exercise intensity

• diastolic stays the same or decreases

During exercise, what controls blood flow redistribution?

• arterioles

How does blood flow respond to exercise?

• vasoconstriction in areas that aren’t essential during exercise

• vasodilation in skeletal muscle

  • stimulated by decrease pH, increase CO2 and temp

• Increased blood flow to the skin in hot environments

What is cardiovascular drift? How does this impact stroke volume?

• gradual heart rate increases over time

• long duration exercise results in decreased stroke volume. This is compensated by an increase in heart rate to maintain cardiac output

What are some causes of cardiac drift?

• increase skin blood flow

• decrease blood volume

• increase heart rate

Why does stroke volume decrease during long duration exercise?

• heart rate increases

• losing water to through sweat

• heart has to work harder

What environment does cardiac drift typically occur in?

• hot environment

What is the primary reason as to why blood plasma volume decreases during exercise?

• hydrostatic pressure: blood pressure forces plasma out of the capillaries

• Blood pressure increases during exercise; plasma gets put in intracellular space

What are the secondary factors as to why blood plasma volume decreases during exercise?

• oncotic pressure

• sweating (lose blood plasma volume)

What are the results due to decreased blood plasma volume?

• decreased blood flow to active tissues

• impaired regulation

  • decrease blood pressure

  • temperature (can’t cool if you can’t sweat)

what are the pH and lactate levels in the muscle and blood after high intensity exercise?

• Muscle: pH 6.64, lactate 19.7

• Blood: pH 7.10, lactate 12.3

What is the best recovery method post exercise for lactate clearance?

• active recovery

  • maintain blood flow to tissue

  • enhances removal of La- (lactate), H+, and other metabolites from muscle

Adaptation to Aerobic and Anaerobic Training

What are adaptations to aerobic training?

• Cardiorespiratory endurance

  • ability to sustain prolonged, dynamic exercise

  • improvements achieved through multisystem adaptations (cardiovascular, respiratory, muscle, metabolic)

• Aerobic training

  • increased maximal endurance capacity = increased VO2 max

  • increase submaximal endurance capacity

  • lower heart rate at same submaximal exercise intensity

  • related to competitive endurance performance

What is the easiest adaptation from aerobic training?

• improved VO2 max

• initial gains due to increasing blood volume

Why does VO2 max increse?

• heart size increase

• stroke volume increase

• blood volume increase

• cardiac output increase

• blood flow increase

  • max HR and blood pressure stay about the same

What are adaptations to aerobic training?

• increased heart sizes: heart mass increase, left ventricle volume increase, wall thickness increase (volume loading effect)

• increased stroke volume: increased at rest, submax, and max

• Blood volume increases in plasma and RBC (typically more in plasma) and hematocrit either stays the same or decrease

How is heart rate affected by aerobic training?

• decrease at rest

• decrease submaximal exercise for given intensity

• maximal exercise stays the same or decrease

How is heart rate-stroke volume interaction affected by aerobic training?

• increased heart size = increased stroke volume

• decreased heart rate

How is cardiac output affect by aerobic training?

• rest: stays same

• max exercise: increase

Does heart rate recovery improve witjh aerobic training?

• yes

How is the cardiovascular system affected by aerobic training?

• blood flow increases to active muscle; decrease to inactive regions

• Capillary fiber ratio increase; increase in total cross-sectional area for capillary exchange

• more dropping off O2 and picking up CO2

How is blood pressure affected by aerobic training?

• decrease at given submaximal intensity

• increase systolic blood pressure

• decrease diastolic blood pressure at maximal intensity

How is respiration affected by aerobic training?

• Ventilation

  • decrease at submaximal intensity

  • increase at maximal intensity = increase tidal volume and respiratory frequency

• Pulmonary diffusion

  • unchanged during rest and submaximal intensity

  • increase at maximal intensity due to increase lung perfusion

• Arterial-venous O2 diff.

  • increase due to increased oxygen extraction and active muscle blood flow

How is muscle affected by aerobic training?

• Fiber type

  • increase size and number of type one fibers (type 2 - type 1)

• Capillary supply

  • increase number of capillaries supplying each fiber

  • may be key factor in increase VO2 max

• Myoglobin

  • increase myoglobin content by 75 to 80%

  • increased oxidative capacity in muscle

• Mitochondrial function

  • increased size and number

• Oxidative enzymes (SDH,CS)

  • increase with training

  • continue to increase after VO2 max plateau

  • glycogen sparing

How is lactate threshold affect by aerobic training?

• increased to higher percentage of VO2 max

• decreased lactate production, increased clearance

• allow higher intensity without lactate accumulation

How is the respiratory exchange ratio (RER) affected by aerobic respiration?

• decrease at absolute and relative submaximal intensities

• increase dependence on fat, decrease dependence on glucose

How is resting submaximal VO2 max affected by aerobic training?

• resting VO2 unchanged (unless muscle mass increased)

• Submaximal VO2 stay the same or decrease slight (improved efficiency)

How is VO2 max affected by aerobic training?

• best indicator or cardiorespiratory fitness

• increased substantially with training (15-20%). Due to increased cardiac output and capillary density

When is the highest VO2 max achieved?

• after 12-18 months

• performance continues to increase after VO2 max plateaus

• lactate threshold continue to increase with training

What are individual responses dictated by?

• training status and pre-training VO2 max

• heredity

Is race speed faster with increased lactate threshold?

• yes

How does power and capacity affected by anaerobic training?

• increase with training

• wingate anaeroibc test closest to gold standard

How is muscle adapted from anaerobic training?

• increase type IIa fiber, IIx cross-sectional area

• increase in type one cross-sectional area

• decrease in type one (slow), increase type 2 (fast)

How is ATP-PCr affected by anaerobic training?

• little enzymatic change with training

• atp-pcr system specific training = increase strength

How is the glycolytic system affected by anaerobic training?

• increase in the key glyolytic enzyme activity with training (phosphorylase, PFK, LDH, hexokinase)

• increase muscle strength

High intensity interval training adaptations

• mitochondrial enzyme cytochrome oxidase (COX) increases like moderate intensity endurance training

Adaptation of specificity of training and cross training

• Specificity training

  • VO2 max substantially higher in athlete’s sport-specific activity

• Cross-training

  • training different fitness components at once or training for more than one sport at once

• Concurrent exercise

  • mix of aerobic and resistance training

  • no interference effect