title: Telemetry-derived heart rate variability responses to a physical stressor.
abstract: Analysis of heart rate variability (HRV) responses to an orthostatic challenge can be used to investigate autonomic control of heart rate, an index of cardiovascular function. HRV is typically assessed using the electrocardiogram (ECG), which can be impractical for use with large population-based studies.
  
  
  OBJECTIVE
  To assess the validity and reliability of telemetry-derived HRV responses to an orthostatic challenge.
  
  
  METHODS
  Twenty healthy adults (26 + 5 years, 45% male) were tested on three separate mornings. Following 20-min supine rest, R-R intervals were recorded using a telemetric device during three conditions: BASE, TILT and RECOVERY. ECG was simultaneously used on 1 day for validity comparison. Measures of HRV included the following: standard deviation of normal-to-normal intervals (SDNN), the root-mean-square of successive differences (RMSSD) and the low-frequency (LF) and high-frequency (HF) spectral power.
  
  
  RESULTS
  For all parameters, there was excellent agreement between devices for BASE (r = 0·96-0·99), TILT (r = 0·89-1·00) and RECOVERY (r = 0·96-1·00). For the telemetric device, between-day intraclass coefficient values for RMSDD, SDNN and HF were all above the 0·75 criterion for each condition, indicating excellent between-day reliability. For each condition, the reliability coefficient, expressed as a percentage of the mean (RC%), was marginally lower (greater reliability) for RMSDD (RC% 11-13) and SDNN (RC% 10-12) compared to HF (RC% 12-17). However, SDNN did not significantly respond to the orthostatic challenge.
  
  
  CONCLUSIONS
  Telemetric HRV, particularly RMSDD and HF, can be used to provide a sensitive, valid and reliable assessment of autonomic control of heart rate.
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Montaño
authors.affiliation: School of Sport and Exercise, Massey University, Wellington, New Zealand.
authors.forename: Freddy
authors.initials: F
authors.lastname: Brown
authors.affiliation: School of Human Performance and Recreation, University of Southern Mississippi, Hattiesburg, MS, USA.
authors.forename: Daniel P
authors.initials: DP
authors.lastname: Credeur
authors.affiliation: Department of Epidemiology, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
authors.forename: Michelle A
authors.initials: MA
authors.lastname: Williams
authors.affiliation: School of Sport and Exercise, Massey University, Wellington, New Zealand.
authors.forename: Lee
authors.initials: L
authors.lastname: Stoner
mesh_terms: D000328:Adult; D004244:Dizziness / Q000175:diagnosis* / Q000503:physiopathology; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate; D006801:Humans; D008297:Male; D056888:Patient Positioning; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D013312:Stress, Physiological; D013686:Telemetry / Q000379:methods*; D018667:Tilt-Table Test; D013997:Time Factors; D055815:Young Adult
keywords: autonomic nervous system; cardiovascular function; concurrent validity; orthostatic challenge; reliability; reproducibility