A CLOSER LOOK 24.3
The Lactate Paradox
When a submaximal test is conducted at altitude, the heart rate, ventilation, and lactate responses are higher than what are measured at sea level. This is no surprise for the heart rate and ventilation responses because there is less oxygen per liter of blood and air, respectively. The elevated lacate response is also not unexpected, the assumption being that the hypoxia of altitude provides additional stimulation of glycolysis. What is surprising is that when the same exercise is done after the subject has been acclimated to altitude for three or four weeks (Chronic hypoxia), the lactate response is substantially reduced. This is the lactate paradox – that the same hypoxic stimulus in chronic hypoxia gives rise to a lower lactate response than observed when the subject is first exposed (acute hypoxia) to altitude (107).