title: Heart rate and its variability in response to running-associations with troponin.
abstract: OBJECTIVE
  The objective of this study is to investigate the time course of autonomic tone changes after a first-time endurance running race participation and associations with postexertional high-sensitivity troponin (hsTnT) levels in middle-aged males.
  
  
  METHODS
  Male (n = 42) first-time long-distance running race (Lidingöloppet 30 km) participants ≥45 yr (50.5 ± 5) were examined. HR and HR variability (HRV) in the time domain (SDANN) was measured continuously from 2 d before to 4 d after the race using a wireless cardiovascular monitor that also recorded arrhythmia episodes. In addition, subjects were assessed pre- and postrace by medical history and physical examination, 12-lead ECG, blood tests including hsTnT, and echocardiography.
  
  
  RESULTS
  Compared with corresponding prerace values, nighttime (2:00-4:00 a.m.) HR was significantly elevated (63.6 ± 9.4 vs 53.9 ± 8.3 bpm, P < 0.001) on the first night postrace, whereas HRV remained reduced for a median of 64 h (interquartile range, 51-102 h). A prolonged HR recovery period (r = 0.48, P = 0.005) and a larger reduction in postrace HRV (r = -0.49, P = 0.003) correlated with higher postrace hsTnT levels. The association between reduced HRV and higher hsTnT remained significant after multivariate analysis (β = -0.48, P = 0.01). No sustained ventricular arrhythmias were recorded, but atrial fibrillation occurred in two subjects.
  
  
  CONCLUSIONS
  Endurance running race participation caused a prolonged alteration of autonomic tone. More marked and prolonged changes were associated with higher levels of hsTnT, suggesting that the magnitude of troponin increase after strenuous exercise may reflect the magnitude of exercise-induced cardiovascular stress.
authors: 1Department of Cardiology, Karolinska Institutet, Karolinska University Hospital, Stockholm, SWEDEN; 2Department of Medicine, Montefiore Medical Center, The University Hospital of Albert Einstein School of Medicine, Bronx, NY; and 3Department of Molecular and Clinical Medicine, Sahlgrenska Academy, University of Gothenburg, SWEDEN.
authors: Philip
authors: P
authors: Aagaard
authors: Anders
authors: A
authors: Sahlén
authors: Lennart
authors: L
authors: Bergfeldt
authors: Frieder
authors: F
authors: Braunschweig
mesh_terms: D001281:Atrial Fibrillation / Q000503:physiopathology; D004452:Echocardiography; D015716:Electrocardiography, Ambulatory; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009206:Myocardium / Q000378:metabolism*; D010807:Physical Endurance / Q000502:physiology*; D012420:Running / Q000502:physiology*; D013312:Stress, Physiological; D014336:Troponin / Q000097:blood*
chemical_list: D014336:Troponin