title: Heart rate variability, QT variability, and electrodermal activity during exercise.
abstract: OBJECTIVE
  Various measures of autonomic function have been developed, and their applicability and significance during exercise are controversial.
  
  
  METHODS
  Physiological data were therefore obtained from 23 sport students before, during, and after exercise. Measures of R-R interval variability, QT variability index (QTvi), and electrodermal activity (EDA) were calculated. We applied an incremental protocol applying 70%, 85%, 100%, and 110% of the individual anaerobic threshold for standardized comparison.
  
  
  RESULTS
  Although HR increased stepwise, parasympathetic parameters such as the root mean square of successive differences were not different during exercise and do not mirror autonomic function satisfactorily. Similar results were observed with the approximate entropy of R-R intervals (ApEnRR). In contrast, the increase in sympathetic activity was well reflected in the EDA, QTvi, and ApEn of the QT interval (ApEnQT)/ApEnRR ratio.
  
  
  CONCLUSIONS
  We suggest that linear and nonlinear parameters of R-R variability do not adequately reflect vagal modulation. Sympathetic function can be assessed by EDA, QTvi, or ApEnQT/ApEnRR ratio.
authors: Department of Psychiatry and Psychotherapy, University Hospital, Jena, Germany.
authors: Silke
authors: S
authors: Boettger
authors: Christian
authors: C
authors: Puta
authors: Vikram K
authors: VK
authors: Yeragani
authors: Lars
authors: L
authors: Donath
authors: Hans-Josef
authors: HJ
authors: Müller
authors: Holger H W
authors: HH
authors: Gabriel
authors: Karl-Jürgen
authors: KJ
authors: Bär
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D056352:Athletes; D001341:Autonomic Nervous System / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006329:Heart Conduction System / Q000502:physiology*; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D055815:Young Adult