Respiratory mechanics during exhaustive submaximal exercise at high altitude in healthy humans.

Respiratory energetics during exercise at high altitude.

The purpose of this study was to assess the effect of high altitude (HA) on work of breathing and external work capacity. On the basis of simultaneous records of esophageal pressure and lung volume, the mechanical power of breathing (Wrs) was measured in four normal subjects during exercise at sea level (SL) and after a 1-mo sojourn at 5,050 m. Maximal exercise ventilation (VEmax) and maximal W...

A Numerical Simulation of Inspiratory Airflow in Human Airways during Exercise at Sea Level and at High Altitude

At high altitudes, the air pressure is much lower than it is at sea level and contains fewer oxygen molecules and less oxygen is taken in at each breath. This requires deeper and rapid breathing to get the same amount of oxygen into the blood stream compared to breathing in air at sea level. Exercises increase the oxygen demand and make breathing more difficult at high altitude. In this study, ...

Sex differences in cardiovascular function during submaximal exercise in humans

Differences in cardiovascular function between sexes have been documented at rest and maximal exercise. The purpose of this study was to examine the sex differences in cardiovascular function during submaximal constant-load exercise, which is not well understood. Thirty-one male and 33 female subjects completed nine minutes moderate and nine minutes vigorous intensity submaximal exercise (40 an...

Respiratory Changes at High Altitude.

Dynamic cerebral autoregulation during exhaustive exercise in humans.

We investigated whether dynamic cerebral autoregulation is affected by exhaustive exercise using transfer-function gain and phase shift between oscillations in mean arterial pressure (MAP) and middle cerebral artery (MCA) mean blood flow velocity (V(mean)). Seven subjects were instrumented with a brachial artery catheter for measurement of MAP and determination of arterial Pco(2) (Pa(CO(2))) wh...