What is a valid reason for lowering the intensity of exercise at higher altitudes?
a. exposure to higher altitudes causes a decrease in pulmonary ventilation and heart rate
b. high altitudes cause a decrease in cardiac output at submaximal workloads
c. high altitudes cause an increase in pulmonary ventilation, heart rate, and cardiac output at submaximal workloads
d. the angina threshold is lower due to a 25% reduction in maximal oxygen consumption
Answer: c. high altitudes cause an increase in pulmonary ventilation, heart rate, and cardiac output at submaximal workloads