Respiratory System Response to Exercise

alveolar capillary diffusion equilibrium

-alveolar capillary surface area -diffusion gradient from alveolar to capillary PO2 -time available for equilibrium in pulmonary capillary

causes of EIAH

-excess increase in (A-a) PO2 diff *non-uniformity in alveolar ventilation and cardiac output distribution *extrapulmonary/intrapulmonary shunts where RBCs don't come in contact with O2 *mechanical constraints *alveolar capillary diffusion disequilibrium -ventilation perfusion inequality causes: edema, fast mvmt of RBCs through capillaries, lack of further increase in pulmonary capillary volume

reasons for increased oxygen extraction during short term light to moderate submax aerobic exercise

-increased PO2 gradient: O2 stored in muscle is used -increased PCO2: shifts oxygen dissociation curve to right; more O2 released at given pressure vs resting conditions -decreased pH: shifts oxygen dissociation curve to right based on how much H+ is present -increased temperature: shifts oxygen dissociation curve to right

females have

-lower lung volumes/capacities than males -similar max RR as males -higher RR and lower VT than males at same submax ventilation (females require increased O2 and more ventilatory work than males to achieve same relative VE) -lower max VE than males -smaller airways relative to lung size than males -higher (A-a) PO2 diff (increased pressure gradient, easier gas exchange) -lower PaO2 -slightly lower PaCO2

EIAH

Exercise-induced arterial hypoxemia - decrease of >= 10mmHg PaO2 or decreased SaO2 by 4% - PaO2 can decrease 18-38 mmHg - reduces VO2 max by 1.5-2% for each 1% reduction in SaO2 (after initial 3% SaO2) - seen in highly trained w/ VO2 max >= 4.5 ml/kg/min and occurs at 60-90% VO2 max -female elite athletes -untrained, low fit females -non elite athletes following high intensity interval training -EIAH athletes adapt to extract more O2 at working muscles -EIAH at sea level is poor performance

incremental to max aerobic exercise internal respiration reasons

PaCO2: decreases due to alveolar hyperventilation PVCO2: sharp rise due to metabolic CO2 and non metabolic (buffering) CO2

long term moderate to heavy submax aerobic exercise internal respiration reasons

PaCO2: decreases slightly due to increased volume of air exhaled PVCO2: linear rise due to increased work= increased O2 utilization= increased CO2 production SVO2%: decreases due to increased O2 utilization

internal respiration response to incremental aerobic exercise to max

PaCO2: is level than decreases PVCO2: has sharp rise; levels slightly PVO2: decreases sharply then levels off SVO2%: decreases sharply; never reaches 0 a-VO2 diff: shows rectilinear rise to 40-60% VO2 max; plateaus

internal respiration response to long term moderate to heavy submax exercise

PaCO2: is level than decreases slightly PVCO2: shows a gradual linear rise; plateaus PVO2: decreases rapidly; plateaus SVO2%: decreases initially; plateau a-VO2 diff: increases rapidly; plateaus; positive drift

internal respiration response to short term light to moderate exercise

PaCO2: is level then decreases slightly PVCO2: shows slight linear rise PVO2: decreases rapidly; plateaus SVO2%: decreases initially; plateaus a-VO2 diff: increases rapidly; plateaus

long term moderate to heavy submax aerobic exercise external respiration reasons

PaO2: increase coincides w/ ventilatory drift (A-a) PO2 diff: increase rapidly at first then reverses due to initial inefficiency in gas exchange

short term light to moderate submax aerobic exercise internal respiration reasons

SVO2%: decreases due to decreased O2 in muscle and increased O2 extraction into muscles a-VO2 diff: increases due to increased O2 extraction (increased O2 arterial and decreased O2 venous= increased difference)

moderate EIAH

SaO2%: 88-93%

mild EIAH

SaO2%: 93-95%

severe EIAH

SaO2%: <88%

incremental to max aerobic exercise external respiration reasons

SaO2%: decreased O2 carried in arterial blood

short term, light to moderate submax aerobic exercise external respiration reasons

VA: increases due to the need to keep pp of O2 the same in alveoli (drives gas exchange) SaO2%: similar to resting values

external respiration response short term light to moderate submax aerobic exercise

VA: increases rapidly; plateaus PAO2: shows no change PaO2: shows no change (A-a) PO diff: decreases slightly or shows no change (light), increases slightly (moderate) SaO2%: decreases less than 1% has U shaped curve

external respiration response to long term moderate to heavy submax exercise

VA: increases rapidly; plateaus; positive drift PAO2: shows no change PaO2: has small u shaped curve (A-a) PO2 diff: has truncated, inverted U shaped curve; increases rapidly initially; has incomplete reversal SaO2%:

external respiration response to incremental aerobic exercise to maximum

VA: shows initial rectilinear rise; two breakpoints PAO2: shows no change until approximately 75% of maximum; then positive experimental rise PaO2: shows no change until approximately 75% of max; then increases slightly (A-a) PO2 diff: shows no change until approximately 75% of max; then positive exponential rise SaO2%: remains steady until approximately 75% of max, then declines slightly

response to exercise short term, light to moderate and submaximal aerobic exercise

VE: increase rapidly; plateau VD: decreases VT: increases rapidly f: slowly increases; plateaus VD/VT: decreases initially; plateaus

long term moderate to heavy submax aerobic exercise pulmonary ventilation reasons

VE: increased and higher absolute value than light to moderate because of increased VT and f VD: decreases due to bronchodilation VD/VT: decreases but may slightly increases after ~1hr of exercise

short term, light to moderate submax aerobic exercise pulmonary ventilation reasons

VE: increases due to hyperpnea VD: small decrease due to bronchodilation VT: increases due to bronchodilation f: slowly rises but minimal contribution VD/VT: decreases to allow alveolar ventilation

response to longterm to heavy submaximal aerobic exercise

VE: increases rapidly; plateaus; positive drift VD: decreases VT: increases rapidly; plateaus f: increases slowly; plateaus; positive drift VD/VT: decreases rapidly initially; plateaus

response to static exercise

VE: minor gradual increase; rebound rise in recovery all responses the same as for short term, light to moderate submax exercise (VT, f, VD/VT)

incremental to max exercise pulmonary ventilation reasons

VE: rise w/ two breakpoints (VT1: 75% VO2 max cutoff moderate intensity; VT2: 85-90% VO2 max cutoff heavy intensity) f: responsible for continued increased VE despite no increase in VT VD/VT: decreases about 90% of VT is available for gas exchange in alveoli

response to incremental aerobic exercise to maximum

VE: shows initial rectilinear rise; has two breakpoints VD: decreases VT: has truncated, inverted, U-shaped curve; increases greatly, incomplete reversal f: positive curvilinear rise VD/VT: decreases rapidly initially; levels off at 60% of maximum and is maintained

older adult characteristics respiration

decreased PaO2 at rest but similar PAO2 widening of (A-a) O2 diff at rest saturation of Hb with O2 decreased, 2-3% from age 10-70 during exercise PaCO2 and PaO2 are similar to young adults a-VO2 diff is greater at rest and in submax exercise SVO2% is lower

excessive fluctuations in intrathoracic P

excessive positive intrathoracic P decreases SV, thus decreases Q

when oxygen dissociation curve shifts to right

increased CO2, increased temp., decreased pH

older adult on respiration

increased dead space, decreased elasticity, decreased bronchodilation, decreased mobility in thoracic cage and intervertebral spaces lung volumes and capacities: TLC may stay same or decrease, VC and IC decrease, RV and FRC increase, FEV1 and MVV decline steadily after 35 yrs of age pulmonary ventilation: absolute VE is higher, VE max is lower, VD/VT is 15-20% higher, expiratory flow limitations which worsen w/ increasing exercise intensity, ventilatory breakpoints occur at lower absolute and relative workloads

children on respiration

lung volumes and capacities changes over time as they grow pulmonary ventilation: control is similar to adults; PCO2 set point is lower in children response to exercise: children tend to hyperventilate compared to adults -tend to take in more air than metabolic demand -increase ventilation

respiratory muscle fatigue

metaboreflex: accumulation of metabolites within skeletal muscles activate afferent neurons and send signals to brain, increases sympathetic vasoconstriction in exercising muscles, decreased blood flow= decreased O2 extraction= peripheral muscle fatigue/increased RPE/decreased exercise performance -more anaerobic metabolism

in healthy individuals respiration is typically

not a limiting factors of exercise

respiratory response discussed by

pulmonary ventilation external respiration internal respiration

internal respiration response to static exercise

shows no change or decreases slightly a-VO2 diff: no change during; rebound rise in recovery

locomotor respiratory coupling during exercise

timing of breathing w/ movement -may reduce work of breathing -may delay onset of respiratory muscle fatigue and/or improve respiratory efficiency