Exercise Phys week 8

winniesmith2's version from 2017-11-20 13:57

Section 1

Question Answer
Gas exchange between alveoli and capillaries• Inspired air path: Bronchial tree -> alveoli. • Blood path: Right ventricle  pulmonary arteries  pulmonary capillaries • Capillaries surround alveoli
PO2 gradient across respiratory membrane: 65 mmHg
Arterial O2 content:20 mL O2/100 mL blood
Mixed venous O2 content varies – Rest: 15 to 16 mL O2/100 mL blood
Mixed venous O2 content variesheavy exercise 4 to 5 mL O2/100 mL blood  a-vതO2 difference: ~15-16 mL O2/100 mL blood  O2 gradient in lungs increased, too
vital capacity increase with height, weight, fat free mass. not affected by PA
what is residual volume effected by age but no effect of training
Dead space ventilation• Volume of air which is inhaled that does not take part in the gas exchange: – Air that remains in the conducting airways (anatomical dead space) – alveoli that are not or poorly perfused (alveolar dead space)
Anatomic dead space ~150 mL
Why does the endurance athlete have a better breathing pattern1. greater tidal vol. 2. lower respiratory frequency
Training differences in minute ventilation (܄VE)?H+, CO2: increasing ventilation
In general endurance training is associated with…Submaximal Exercise – Tidal volume slightly ↑, breathing frequency slightly ↓ – Efficiency ↑ (lower dead space ventilation) Maximal Exercise – Tidal volume slightly ↑, respiratory rate ↑↑ – V Emax ↑
O2 cost of increased ventilation (hyperpnea) during exercise Respiratory muscles use 5% at 70% VO2 max, but 10% at 100% VO2 max. Oxygen cost of exercise hyperpnea is a significant fraction of the total VO2max

Section 2

Question Answer
The respiratory system and performance• Traditionally, the respiratory system was not considered to be performance limiting – maximal voluntary ventilation is significantly greater than ventilation at maximal exercise – However, may pulmonary ventilation be a limiting factor during very high intensity exercise in highly trained athletes?
Loading and unloading respiratory muscles• Cycling to exhaustion at 92% of maximum power (Pmax). .  Measurement of quadriceps twitch force (stimulation of femoral nerve). if you can support ventilation system you can improve performance of locomotor system/muscle function (assisted ventilator)
Leg blood flow and leg oxygen uptake• Work of breathing manipulated with proportional assist ventilator or by increasing cycling workload • 2.5 min exercise bouts at Vሶ O2max • Femoral blood flow measurements. If make breathing easier, legs consume more oxygen.
The metaboreflex“Security system” of the body, causing reduced blood flow to working muscles via sympathetic vasoconstriction when respiratory muscles are fatigued