Showing papers in "Journal of Applied Physiology in 1972"
TL;DR: Succinate dehydrogenase and phosphofructokinase activities and the histochemical identification of fiber types and localization of oxidative activity were determined on biopsy samples from the vastus lateralis and deltoid muscles of 74 untrained and trained men.
Abstract: GOLLNICK, P. D., R. B. ARMSTRONG, C. W. SAUBERT IV, K. PIEHL, AND B. SALTIN. Enzyme activity and Jiber composition in skeletal muscle of untrained and trained men. J. Appl. Physiol. 33(3): 3 12-3 19, 1972.-Succinate dehydrogenase (SDH) and phosphofructokinase (PFK) activities and the histochemical identification of fiber types and localization of oxidative activity were determined on biopsy samples from the vastus lateralis and deltoid muscles of 74 untrained and trained men. SDH activities were highest in the muscles of the groups participating in endurance training. Highest activities existed in the muscles that were extensively engaged in the endurance work. Only minor differences existed for PFK activities. Only slow twitch (ST) and fast twitch (FT) fibers were identified in the muscle samples. ST fibers predominated in the muscles of the endurance athletes. A wide variety of fiber populations existed in all groups. The percent distribution of a fiber was found to be indicative of the relative area that the fiber occupied in the muscle. Oxidative capacity of both fiber types was greater in the endurance athletes than in the other groups. Muscle glycogen was highest in the trained subjects. No consistent pattern for glycogen storage in the two fiber types existed.
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TL;DR: For exercise at oxygen consumption rates exceeding 1.5 L/min in a dry environment with a water vapor pressure of 10 mm Hg, the total rate of weight loss via the respiratory tract is on the order of 2-5 g/min.
Abstract: Evaporative water loss from the respiratory tract was determined over a wide range of exercise. The absolute humidity of the expired air was the same at all levels of exercise and equal to that measured at rest. The rate of respiratory water loss during exercise was found to be 0.019 of the oxygen uptake times (44 minus water vapor pressure). The rate of weight loss during exercise due to CO2-O2 exchange was calculated. For exercise at oxygen consumption rates exceeding 1.5 L/min in a dry environment with a water vapor pressure of 10 mm Hg, the total rate of weight loss via the respiratory tract is on the order of 2-5 g/min.
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TL;DR: With prolonged submaximal exercise there was a net gain in plasma protein, which contributes to stabilization of the vascular volume, and this loss of plasma protein probably plays an important role in recumbency hypovolemia.
Abstract: The interrelationships between the changes in plasma volume, hematocrit, and plasma proteins during muscular exercise and bed rest were investigated. Proportionally, the changes in hematocrit are always smaller than the changes in plasma volume. For this reason changes in the concentration of blood constituents can only be quantitated on the basis of plasma volume changes. During short periods of intensive exercise, there was a small loss of plasma proteins. With prolonged submaximal exercise there was a net gain in plasma protein, which contributes to stabilization of the vascular volume. Prolonged bed rest induced hypoproteinemia; this loss of plasma protein probably plays an important role in recumbency hypovolemia.
TL;DR: It is concluded that FMBF is not increased by direct whole-body heating and maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min.
Abstract: Changes in forearm muscle blood flow (FMBF) during direct whole-body heating were measured in 17 normal subjects using three different methods. We conclude that FMBF is not increased by direct whole-body heating. Since renal and splanchnic blood flow fall 30% under these conditions, maximal total skin blood flow in 12 previously studied subjects can be estimated from the rise in cardiac output to be 7.6 L/min (3.0-11.1 L/min).
TL;DR: Three-part experiment in which five subjects were exposed to lower body negative pressure (LBNP) at -50 mm Hg below the iliac crests, decreased splanchnic conductance accounted for approximately 33%; skin plus muscle conductance decreased similarly.
Abstract: Three-part experiment in which five subjects were exposed to lower body negative pressure (LBNP) at -50 mm Hg below the iliac crests Duration of LBNP to earliest vagal symptoms was 7 to 21 min; all data are expressed as changes from control period to the last measurements before these symptoms In part I, forearm blood flow (by Whitney gauge) fell 45% during LBNP In part II, splanchnic blood flow (from arterial clearance hepatic extraction of indocyanine green) fell 32% and splanchnic vascular resistance rose 30% In part III, cardiac output fell 28%, stroke volume 51%, and central blood volume 21% Total peripheral resistance and heart rate rose 19% and 52% Of the reduction in total vascular conductance, decreased splanchnic conductance accounted for approximately 33%; skin plus muscle conductance decreased similarly