Reversal of runner's bradycardia with training overstress

Clin J Sport Med. 2000 Oct;10(4):279-85. doi: 10.1097/00042752-200010000-00010.


Objective: To elicit a criterion elevation (> 10%) in resting heart rate (HR) with training overstress, and subsequently test the hypothesis that such "reversed bradycardia" (RB) negatively affects running performance.

Design: Prospective before-and-after intervention with a comparison group.

Setting: General community.

Participants: 21 healthy male marathon runners.

Intervention: Voluntary doubling of training miles on 14 consecutive days.

Main outcome measures: Left ventricular (LV) function by echocardiography, HR, and plasma epinephrine (PE) at rest and during submaximal exercise, and 15 km road run performance.

Results: Two days after the training overstress, 12 runners met the criterion (RB group), showing an average elevation in resting HR of 16% (range: 11 to 23%). The RB group also exhibited hyperkinetic LV shortening (p < 0.05), elevated exercise HR (p < 0.001), increased PE at rest and during exercise (p < 0.05), and reduced 15 km performance (p < 0.05). The other nine runners who maintained a stable resting HR during the intervention showed no significant outcome changes.

Conclusions: In addition to muscular overuse, heightened sympathetic drive likely contributed to the observed reversal of bradycardia. The development of this stress-related cardiac perturbation was associated with a decrement in running performance, confirming the hypothesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adaptation, Physiological / physiology
  • Adult
  • Analysis of Variance
  • Biomarkers / blood
  • Case-Control Studies
  • Heart Rate / physiology*
  • Humans
  • Least-Squares Analysis
  • Male
  • Middle Aged
  • Physical Education and Training / methods*
  • Physical Endurance / physiology*
  • Prospective Studies
  • Running / physiology*
  • Ventricular Function, Left / physiology


  • Biomarkers