An overview of the problem: exercise training and orthostatic intolerance

Area of Science:

• Cardiovascular Physiology
• Exercise Physiology
• Autonomic Nervous System Function

Background:

• The impact of endurance exercise training on orthostatic intolerance has been a subject of scientific debate since the 1970s.
• Understanding blood pressure regulation during orthostasis is crucial for cardiovascular health.

Purpose of the Study:

• To present and evaluate data addressing whether endurance exercise training induces orthostatic intolerance.
• To investigate if endurance exercise training alters blood pressure regulation during orthostatic stress.
• To explore the underlying baroreflex and hemodynamic mechanisms involved.

Main Methods:

• Review of existing data supporting and refuting the effects of endurance exercise on orthostatic responses.
• Utilization of invasive and noninvasive measurement techniques.
• Investigation of baroreflex and hemodynamic mechanisms during lower body negative pressure (LBNP) to simulate orthostasis.

Main Results:

• Presentation of conflicting data regarding the induction of orthostatic intolerance by endurance exercise.
• Evidence suggesting alterations in blood pressure regulation during orthostasis in trained individuals was discussed.
• Data on baroreflex sensitivity and hemodynamic responses during simulated orthostasis were analyzed.

Conclusions:

• The role of endurance exercise training in orthostatic intolerance remains inconclusive, with supporting and refuting evidence presented.
• Further investigation into baroreflex and hemodynamic mechanisms is necessary to fully explain the observed effects.
• A hypothetical mechanism was proposed to reconcile the "pro and con" findings regarding exercise and orthostatic responses.