Acute resistance exercise reduces heart rate complexity and increases QTc interval

Kevin Scott Heffernan, J. J. Sosnoff, S. Y. Jae, G. J. Gates, B. Fernhall

Research output: Contribution to journalArticlepeer-review

37 Scopus citations


Acute resistance exercise (RE) has been shown to reduce cardiac vagal control. Whether this would in turn affect QTc interval (an index of ventricular depolarization/repolarization) or heart rate complexity is not known. Heart rate variability (HRV), heart rate complexity (SampEn), and QT interval (rate corrected using Bazett, Fridericia, Hodges, and Framingham) were measured before and 5 min after an acute RE bout in twelve healthy young men. Normalized high frequency power of HRV (an index of cardiac parasympathetic modulation; HF nu), and SampEn were reduced following RE (p < 0.05). Bazett corrected QTc interval increased following RE (p < 0.05). Change in HF nu from rest to recovery was correlated with both change in SampEn (r = 0.51, p < 0.05) and change in QTc interval for each method of correction (r = -0.67 to -0.70, p < 0.05). Acute RE reduced HF spectral power of HRV and this was related to both reduced heart rate complexity and increased QTc length. Thus, during recovery from acute RE, there is prolongation of depolarization and repolarization of the ventricles concomitant with reduced cardiac irregularity, and this may be related to a reduction in cardiac vagal control.

Original languageEnglish (US)
Pages (from-to)289-293
Number of pages5
JournalInternational Journal of Sports Medicine
Issue number4
StatePublished - Apr 2008
Externally publishedYes


  • Acute exercise
  • Heart rate variability
  • Sample entropy

ASJC Scopus subject areas

  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation


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