THE EFFECT OF AN ACUTE BOUT OF EXERCISE ON SELECTED PULMONARY FUNCTION MEASUREMENTS.

Abstract

A series of five studies were conducted to examine the effect of exercise on selected pulmonary function measurements. Studies I and II determined the effect of an acute bout of exercise on various lung volumes immediately post-exercise and over a 24-hour post-exercise period. There were significant mean increases of 210 ml (20.6%) and 260 ml (20.8%) in the 5-minute post-exercise residual volume (RV) measurement for studies I and II, respectively. There also were significant mean increases of 170 ml (3.4%) and 190 ml (2.7%) in the 5-minute post-exercise total lung capacity (TLC) for studies I and II, respectively, while vital capacity (VC) remained unchanged. RV and TLC remained significantly increased over the pre-exercise values through 30 and 15 minutes of recovery, respectively. Studies III through V were undertaken to determine the physiological mechanism underlying the responses reported in studies I and II. In study III, transthoracic electrical impedance (TEI) was significantly decreased below the pre-exercise value through 30-minutes of recovery, indicating that there was an increase in thoracic fluid volume following exercise. However, TEI measurements alone cannot separate between intra- and extravascular fluid shifts. Therefore, studies IV and V attempted to identify whether the decrease in TEI and increase in RV reported in study III were due to intra- or extravascular fluid shifts. Study IV examined the TEI, RV, and TLC responses before and following exercise, as central blood volume (CBV) was experimentally increased via G-suit inflation, and decreased via venous occlusion tourniquets. The results suggest that RV is relatively insensitive to intravascular volume shifts within the thorax. Study V determined and followed the effect of an acute bout of exercise on lung diffusion capacity (D(,Lco)). D(,Lco)/V(,A) did not increase significantly following exercise, suggesting that the decrease in TEI following exercise is the result of extravascular fluid accumulation. It was concluded that a sub-clinical pulmonary edema occurs following exercise. A logical sequence of events based on the results of studies I through V was proposed as a possible explanation for the responses of RV and TLC following exercise.