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Exercise Associated Collapse

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Other Names

  • EAC
  • Exercise-Associated Collapse


  • Exercise associated collapse (EAC) is defined as a collapse in conscious athletes who are unable to stand or walk unaided as a result of lightheadedness, faintness and dizziness or syncope causing a collapse that occurs after completion of an exertional event[1]
    • Important to distinguish from other, more serious causes of collapse


  • Up to 25 of every 1000 marathon participants seeks post race medical attention[2]
    • However this is highly dependent on environmental conditions
  • The Gothenburg half marathon, the worlds largest, reports an incidence of 1.53 per 1000 runners[3]
    • They also reported a 2:1 male to female treatment ratio
  • EAC represents the most common condition to seek medical attention
  • 59-85% of visits after marathons and ultramarathons[4]
  • Incidence of EAC appears to increase as the race distance, temperature, and humidity increase[5]


  • Due primarily to pooling of blood in lower extremities once athlete stops running[6]
    • Lower extremities require increased blood flow during exercise, resulting in a decrease in peripheral vascular resistance
    • Upon cessation of activity, the legs no longer assist in venous return and large volumes of blood pool in the lower extremities
    • This is sometimes termed orthostatic intolerance (OI)
    • Studies support increased susceptibility to in exercise-trained athletes
    • Increase in lower extremity compliance, increased diastolic chamber compliance, distensibility contribute to OI[7][8]
    • Trained athletes have increased vascular volume and stroke volume
    • The baroreflex, responsible for maintaining blood pressure, is impaired due to this increase in volume[9]
    • Thus endurance athletes are more dependent on venous return, especially when upright and following exercise
  • Hyperthermia
    • Heat stress, increased skin temperature do contribute to OI[10]
    • It may also impair the aforementioned baroreflex
  • Dehydration
    • Currently no compelling evidence to support dehydration as contributor to OI and EAC[11]

Risk Factors

  • Increased distance
  • Increased temperature
  • Increased humidity
  • Endurance events

Differential Diagnosis

Clinical Features

  • History
    • Witnessed collapse
    • The athlete will likely endorse lightheadedness, faintness and dizziness or syncope
  • Physical Exam
    • Patient should be lucid, full conscious and A+Ox3
    • Often HR >100, BP <100


  • Primarily a clinical diagnosis
  • Exclude hyperthermia related causes by checking vital signs including core temperature and weight
  • Exclude hyponatremia by checking point of care blood gas or electrolytes
  • Serum glucose should be checked
  • Exercise Associated Postural Hypotension (EAPH) can present similarly
    • Distinguished from this entity by having no change in blood pressure from supine to standing position


  • N/A


  • The most important thing in collapsed athletes is to exclude other, life threatening etiologies
    • Vital signs and point of care electrolytes, glucose should be checked
  • Treatment directed at prevention of pooling of blood in lower extremities
    • The easiest treatment is to have post-activity athletes continue walking and not stop and stand in one position
    • Oral hydration is preventative and therapeutic[12]
    • Trendelenberg can promote restoration of normal hemodynamics[13]
    • Peripheral skin cooling may increase peripheral vascular resistance, decrease cardiovascular strain and improve OI[14]
    • Conservative therapy should lead to recovery in 60-90 minutes
  • Individuals prone to OI
    • consider wearing compression stockings while running[15]
    • Can also consider Antihistamine medications
  • Hyperthermia and dehydration are not considered primary etiologies of EAC
    • Total body cooling and IV fluids should be avoided

Rehab and Return to Play


  • Needs to be updated

Return to Play

  • Needs to be updated


  • The most feared complication is missing other causes of collapse

See Also


  1. Asplund, Chad A., Francis G. O'Connor, and Timothy D. Noakes. "Exercise-associated collapse: an evidence-based review and primer for clinicians." Br J Sports Med 45.14 (2011): 1157-1162.
  2. Roberts, William O. "A 12-yr profile of medical injury and illness for the Twin Cities Marathon." Medicine & Science in Sports & Exercise 32.9 (2000): 1549-1555.
  3. Lüning, H., et al. "Incidence and characteristics of severe exercise-associated collapse at the world’s largest half-marathon." PloS one 14.6 (2019).
  4. Holtzhausen, L. M., and TIMOTHY D. Noakes. "The prevalence and significance of post-exercise (postural) hypotension in ultramarathon runners." Medicine and science in sports and exercise 27.12 (1995): 1595-1601.
  5. . O’Conner FG, Pyne S, Brennan FH, Adirim T. Exercise associated collapse: An algorithmic approach to race day management. Am J Sports Med 2003;5:212-217. 229.
  6. Holtzhausen, L. M., and T. D. Noakes. "Collapsed ultraendurance athlete: proposed mechanisms and an approach to management." Clinical journal of sport medicine: official journal of the Canadian Academy of Sport Medicine 7.4 (1997): 292-301.
  7. Levine, Benjamin D., et al. "Left ventricular pressure-volume and Frank-Starling relations in endurance athletes. Implications for orthostatic tolerance and exercise performance." Circulation 84.3 (1991): 1016-1023.
  8. Levine, BENJAMIN D., et al. "Physical fitness and cardiovascular regulation: mechanisms of orthostatic intolerance." Journal of Applied Physiology 70.1 (1991): 112-122.
  9. Ogoh, Shigehiko, et al. "Cardiopulmonary baroreflex is reset during dynamic exercise." Journal of Applied Physiology 100.1 (2006): 51-59.
  10. Crandall, Craig G. "Heat stress and baroreflex regulation of blood pressure." Medicine and science in sports and exercise 40.12 (2008): 2063.
  11. Noakes, Timothy D. "Exercise in the heat: old ideas, new dogmas." International SportMed Journal 7.1 (2006): 58-74.
  12. Davis, J. E., and S. M. Fortney. "Effect of fluid ingestion on orthostatic responses following acute exercise." International journal of sports medicine 18.03 (1997): 174-178.
  13. Anley, Cameron, et al. "A comparison of two treatment protocols in the management of exercise-associated postural hypotension: a randomised clinical trial." Br J Sports Med 45.14 (2011): 1113-1118.
  14. Durand, S., et al. "Skin surface cooling improves orthostatic tolerance in normothermic individuals." American Journal of Physiology-Regulatory, Integrative and Comparative Physiology 286.1 (2004): R199-R205.
  15. Privett, Sheena E., et al. "The effectiveness of compression garments and lower limb exercise on post-exercise blood pressure regulation in orthostatically intolerant athletes." Clinical Journal of Sport Medicine 20.5 (2010): 362-367.
Created by:
John Kiel on 13 June 2019 05:41:38
Last edited:
28 January 2020 01:39:57