title: Relation of Heart Rate and its Variability during Sleep with Age, Physical Activity, and Body Composition in Young Children.
abstract: Background:Recent studies have claimed a positive effect of physical activity and body composition on vagal tone. In pediatric populations, there is a pronounced decrease in heart rate with age. While this decrease is often interpreted as an age-related increase in vagal tone, there is some evidence that it may be related to a decrease in intrinsic heart rate. This factor has not been taken into account in most previous studies. The aim of the present study was to assess the association between physical activity and/or body composition and heart rate variability (HRV) independently of the decline in heart rate in young children.Methods:Anthropometric measurements were taken in 309 children aged 2-6 years. Ambulatory electrocardiograms were collected over 14-18 h comprising a full night and accelerometry over 7 days. HRV was determined of three different night segments: (1) over 5 min during deep sleep identified automatically based on HRV characteristics; (2) during a 20 min segment starting 15 min after sleep onset; (3) over a 4-h segment between midnight and 4 a.m. Linear models were computed for HRV parameters with anthropometric and physical activity variables adjusted for heart rate and other confounding variables (e.g., age for physical activity models).Results:We found a decline in heart rate with increasing physical activity and decreasing skinfold thickness. HRV parameters decreased with increasing age, height, and weight in HR-adjusted regression models. These relationships were only found in segments of deep sleep detected automatically based on HRV or manually 15 min after sleep onset, but not in the 4-h segment with random sleep phases.Conclusions:Contrary to most previous studies, we found no increase of standard HRV parameters with age, however, when adjusted for heart rate, there was a significant decrease of HRV parameters with increasing age. Without knowing intrinsic heart rate correct interpretation of HRV in growing children is impossible.
authors.affiliation: Preventive Cardiology and Sports Medicine, University Clinic for Cardiology, Inselspital, Bern University Hospital, University of Bern Bern, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Herzig
authors.affiliation: Preventive Cardiology and Sports Medicine, University Clinic for Cardiology, Inselspital, Bern University Hospital, University of Bern Bern, Switzerland.
authors.forename: Prisca
authors.initials: P
authors.lastname: Eser
authors.affiliation: Epidemiology, Biostatistics and Prevention Institute, University of Zurich Zurich, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Radtke
authors.affiliation: Epidemiology, Biostatistics and Prevention Institute, University of Zurich Zurich, Switzerland.
authors.forename: Alina
authors.initials: A
authors.lastname: Wenger
authors.affiliation: Institute of Pharmacology and Toxicology, University of ZurichZurich, Switzerland; University Hospital of Child and Adolescent Psychiatry and Psychotherapy, University of BernBern, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rusterholz
authors.affiliation: Preventive Cardiology and Sports Medicine, University Clinic for Cardiology, Inselspital, Bern University Hospital, University of Bern Bern, Switzerland.
authors.forename: Matthias
authors.initials: M
authors.lastname: Wilhelm
authors.affiliation: Institute of Pharmacology and Toxicology, University of ZurichZurich, Switzerland; Zurich Center for Integrative Human Physiology, University of ZurichZurich, Switzerland.
authors.forename: Peter
authors.initials: P
authors.lastname: Achermann
authors.affiliation: Endocrinology, Diabetes, and Metabolism Service, Centre Hospitalier Universitaire Vaudois (CHUV) Lausanne, Switzerland.
authors.forename: Amar
authors.initials: A
authors.lastname: Arhab
authors.affiliation: Child Development Center, University Children's Hospital ZurichZurich, Switzerland; Children's Research Center, University Children's Hospital ZurichZurich, Switzerland.
authors.forename: Oskar G
authors.initials: OG
authors.lastname: Jenni
authors.affiliation: Child Development Center, University Children's Hospital ZurichZurich, Switzerland; Children's Research Center, University Children's Hospital ZurichZurich, Switzerland.
authors.forename: Tanja H
authors.initials: TH
authors.lastname: Kakebeeke
authors.affiliation: Epidemiology, Biostatistics and Prevention Institute, University of Zurich Zurich, Switzerland.
authors.forename: Claudia S
authors.initials: CS
authors.lastname: Leeger-Aschmann
authors.affiliation: Endocrinology, Diabetes, and Metabolism Service, Centre Hospitalier Universitaire Vaudois (CHUV)Lausanne, Switzerland; Department of Clinical Psychology and Psychotherapy, University of FribourgFribourg, Switzerland.
authors.forename: Nadine
authors.initials: N
authors.lastname: Messerli-Bürgy
authors.affiliation: Department of Psychology, University of Basel Basel, Switzerland.
authors.forename: Andrea H
authors.initials: AH
authors.lastname: Meyer
authors.affiliation: Department of Clinical Psychology and Psychotherapy, University of Fribourg Fribourg, Switzerland.
authors.forename: Simone
authors.initials: S
authors.lastname: Munsch
authors.affiliation: Endocrinology, Diabetes, and Metabolism Service, Centre Hospitalier Universitaire Vaudois (CHUV)Lausanne, Switzerland; Division of Pediatric Endocrinology, Diabetology and Obesity, Centre Hospitalier Universitaire Vaudois (CHUV)Lausanne, Switzerland.
authors.forename: Jardena J
authors.initials: JJ
authors.lastname: Puder
authors.affiliation: Epidemiology, Biostatistics and Prevention Institute, University of Zurich Zurich, Switzerland.
authors.forename: Einat A
authors.initials: EA
authors.lastname: Schmutz
authors.affiliation: Department of Clinical Psychology and Psychotherapy, University of Fribourg Fribourg, Switzerland.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Stülb
authors.affiliation: Child Development Center, University Children's Hospital Zurich Zurich, Switzerland.
authors.forename: Annina E
authors.initials: AE
authors.lastname: Zysset
authors.affiliation: Epidemiology, Biostatistics and Prevention Institute, University of Zurich Zurich, Switzerland.
authors.forename: Susi
authors.initials: S
authors.lastname: Kriemler
keywords: SPLASHY; cardiac autonomic nervous system; cardiovascular health; children; growth; heart rate variability