01:377:370 Lecture Notes - Lecture 27: Vo2 Max, Chronic Obstructive Pulmonary Disease, Alkalosis
17 Sep 2019
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During maximal exercise the respiratory muscles require a significant portion of total blood flow (up to 15%) This limits o2 available to the active locomotor muscles. Copd may triple the o2 cost of breathing at rest. This severely limits exercise capacity in copd patients. Cost of breathing can be 40% of total o2 during exercise. Smoking increases reliance on cho during exercise even at low intensities. Less cho available for high intensity exercise. All of this goes away after about 6 months of cessation. This is actually less adaptation in pulmonary structure and function than in cardiovascular and neuromuscular systems with aerobic exercise. Healthy individuals actually over breathe at higher levels of o2 consumption. Produces decreased alveolar pco2 and increased po2. At max exercise there usually is a breathing reserve. Ve at vo2 max equals only 60-80% of maximal voluntary ventilation (mvv) Ventilation in healthy individuals is not the limiting factor in exercise.
