• Definition: inability to stand or walk without assistance (i.e., collapse) after vigorous exertion
• Epidemiology: occurs most commonly in athletes (especially upon completion of endurance running)
• Pathophysiology
  • During exercise, ↑ blood flow to muscles of the lower extremities → ↑ skeletal muscle pump activity → ↑ venous return to the heart
  • Sudden cessation of exercise → loss of skeletal muscle pump activity → ↓ venous return → large volumes of blood pool in the lower extremities → postural hypotension → collapse
• Clinical features
  • Dizziness, weakness (usually, no loss of consciousness)
  • Body temperature is normal or mildly elevated.
• Diagnostics: diagnosis of exclusion