Related Experiment Video
Updated: Aug 19, 2026

Surgical Placement of Catheters for Long-term Cardiovascular Exercise Testing in Swine
Published on: February 9, 2016
Blood volume changes in outdoor exercise of 8-10 hour duration
Abstract:
1. Blood volume was measured with carbon monoxide on six hill-walkers before and immediately after a 28-mile walk on two occasions. The subjects had free access to food and fluid.2. Blood volume increased and haematocrit fell significantly on both occasions compared with the control observations. The mean increase of blood volume was 204 ml. or 3.9% (P < 0.01) and the mean reduction of haematocrit was 2.1% (P < 0.02). Plasma volume calculated from these results increased by 233 ml. or 7.3%. There was no significant change in red cell volume or plasma protein concentration.3. These changes are the opposite of those taking place in short-term exercise and suggest that in the absence of dehydration a compensatory adjustment of blood volume takes place during exercise of many hours duration.
More Related Videos
07:09Assessment of Pulmonary Capillary Blood Volume, Membrane Diffusing Capacity, and Intrapulmonary Arteriovenous Anastomoses During Exercise
Published on: February 20, 2017
07:26Conducting Maximal and Submaximal Endurance Exercise Testing to Measure Physiological and Biological Responses to Acute Exercise in Humans
Published on: October 17, 2018
Related Concept Videos
Cardiac Output and Stroke Volume
In an average resting adult male, the typical cardiac output averages...
Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...
Hormonal Regulation of Blood Pressure
Epinephrine and Norepinephrine
The adrenal medulla releases epinephrine and norepinephrine, catecholamines that enhance and extend the sympathetic or "fight or flight" physiological response. These hormones escalate heart rate and the force of contraction while...
Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
Body Water Content and Fluid Compartments
Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...