title: Resting autonomic modulations and the heart rate response to exercise.
abstract: OBJECTIVE
  Identify the underlying role of resting heart rate variability (HRV) in the hearts response to graded exercise testing (GXT).
  
  
  METHODS
  Resting 5-min HRV and heart rate (HR) measurements were made in 33 volunteers (19 males, median age 34, range 25-63 years and 14 females median age 48, range 21-63 years). Measures of VO2 peak and HR obtained during a maximal GXT and heart rate recovery (HRR) post-GXT were assessed for associations with resting HRV. Differences and effect size (d) for measures of HRV were assessed between groups based on established risk cut-points for resting, exercise and recovery HR responses.
  
  
  RESULTS
  Small associations were observed for the majority of resting HRV and GXT HR responses (best r value = -0.27, P > 0.05). Measures of HRV demonstrated moderate associations with HRR (best r value = 0.46, P < 0.05) and were able to predict a negative risk HRR. In contrast to other dependent variables, measures of HRV were consistently able to demonstrate significant and moderate to large (d = 0.9-2.0) differences between groups based on literature defined prognostic HR cut-points.
  
  
  CONCLUSIONS
  Small associations with HR responses to exercise prevent their accurate prediction from resting HRV. Data support the use of vagally mediated resting HRV in predicting better HRR. Lower resting autonomic modulations underlined high risk resting and exercise HR responses. Resting short-term HRV measurements should be considered when assessing cardiac autonomic health from the HR response before, during and/or after exercise.
authors.affiliation: Research Centre for Society and Health, Buckinghamshire New University, Chalfont St Giles, UK. david.nunan@dphpc.ox.ac.uk
authors.forename: David
authors.initials: D
authors.lastname: Nunan
authors.forename: Djordje G
authors.initials: DG
authors.lastname: Jakovljevic
authors.forename: Gay
authors.initials: G
authors.lastname: Donovan
authors.forename: Lynette D
authors.initials: LD
authors.lastname: Singleton
authors.forename: Gavin R H
authors.initials: GR
authors.lastname: Sandercock
authors.forename: David A
authors.initials: DA
authors.lastname: Brodie
mesh_terms: D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005080:Exercise Test; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male; D008875:Middle Aged