title: Autonomic cardiac regulation, blood pressure and cardiorespiratory fitness responses to different training doses over a 12 week group program in the elderly.
abstract: OBJECTIVE
  The study assessed the effects of different weekly training frequencies performed over a 12 week exercise programme (strength, endurance, balance) on autonomic cardiac activity, blood pressure and cardiorespiratory fitness (CRF) in elderly individuals.
  
  
  METHODS
  Fifty-eight individuals participated in the study: 2TG (N=24, 71.1±6.4 yrs; 19 females, 5 males) performing two, 60min sessions/week; and 3TG (N=34, 72.3±7.9 yrs; 25 females, 9 males) performing three, 60min sessions/week. Time domain and spectral analysis of heart rate variability (HRV) quantified autonomic cardiac regulation.
  
  
  RESULTS
  Natural logarithm (Ln) transformation was applied to all HRV parameters. There were significant reductions in total power (Ln TP) (p=0.006), low frequency (Ln LF) (p=0.013), high frequency (Ln HF) (p=0.013) and root mean square of successive differences (Ln rMSSD) (p=0.014) post training in 3TG after intervention. Diastolic BP (DBP) decreased significantly in both groups (2TG: P<0.001; 3TG: P<0.001). Both groups showed significant improvements in six-minute walk distance (2TG: P=0.003, 3TG: P=0.001). However, there were significant HRV differences between 2TG and 3TG for Ln TP (P=0.018), Ln LF (P=0.049), Ln HF (P=0.039) and Ln rMSSD (P=0.049).
  
  
  CONCLUSIONS
  A combined exercise programme resulted in improved DBP and CRF irrespective of training two or three 60min sessions/week. However, training three, sessions/week induced negative health-related changes in autonomic cardiac activity through reducing HRV parasympathetic function, while HRV was maintained in the group training twice a week.
authors.affiliation: Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa; Discipline of Sport and Exercise Science, UC-Research Institute for Sport and Exercise, Faculty of Health, University of Canberra, ACT, Australia. Electronic address: mckunea@ukzn.ac.za.
authors.forename: A J
authors.initials: AJ
authors.lastname: McKune
authors.affiliation: Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: B
authors.initials: B
authors.lastname: Peters
authors.affiliation: School of Clinical Medicine, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: S S
authors.initials: SS
authors.lastname: Ramklass
authors.affiliation: Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa.
authors.forename: J
authors.initials: J
authors.lastname: van Heerden
authors.affiliation: Discipline of Biokinetics, Exercise and Leisure Sciences, School of Health Sciences, University of KwaZulu-Natal, Durban, South Africa; AFC Bournemouth, Bournemouth, United Kingdom.
authors.forename: C
authors.initials: C
authors.lastname: Roberts
authors.affiliation: Faculty of Physical Culture, Palacký University, Olomouc, Czech Republic.
authors.forename: J
authors.initials: J
authors.lastname: Krejčí
authors.affiliation: Faculty of Physical Culture, Palacký University, Olomouc, Czech Republic.
authors.forename: M
authors.initials: M
authors.lastname: Botek
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D000072599:Cardiorespiratory Fitness / Q000502:physiology*; D015444:Exercise / Q000502:physiology*; D005260:Female; D006339:Heart Rate / Q000502:physiology*; D006801:Humans; D008297:Male
keywords: Aerobic fitness; Aging; Fatigue; Heart rate variability; Training frequency