title: Association between objectively measured physical activity, chronic stress and leukocyte telomere length.
abstract: BACKGROUND
  Physical activity (PA) attenuates chronic stress and age-related and cardiovascular disease risks, whereby potentially slowing telomere shortening. We aimed to study the association between seven-day objectively measured habitual PA, chronic stress and leukocyte telomere length.
  
  
  METHODS
  Study participants were African (N.=96) and Caucasian (N.=107) school teachers of the Sympathetic activity and Ambulatory Blood Pressure in Africans study. All lifestyle characteristics (including PA) were objectively measured. The general health questionnaire and serum cortisol were assessed as psychological and physical measures of chronic stress. Leukocyte telomere length was measured using the quantitative real-time polymerase chain reaction.
  
  
  RESULTS
  Africans had significantly shorter telomeres (P<.0001) and greater psychological distress (P=0.001) than Caucasians, whereas no group difference was seen for cortisol levels. Higher age (ß=-0.28 [-0.40, -0.16, P≤0.000), higher alcohol consumption (ß=-0.21 [-0.36, -0.08], P=0.003) and increased central obesity (ß=-0.17 [-0.30, -0.03], P=0.017) were all significantly associated with shorter telomeres. Habitual PA of different intensity was not significantly associated with markers of chronic stress or telomere length. However, more time spent with light intensity PA time was significantly and independently correlated with lower waist circumference (r=-0.21, P=0.004); in turn, greater waist circumference was significantly associated shorter telomeres (β=-0.17 [-0.30, -0.03], P=0.017).
  
  
  CONCLUSIONS
  Habitual PA of different intensity was not directly associated with markers of chronic stress and leukocyte telomere length in this biethnic cohort. However, our findings suggest that light intensity PA could contribute to lowered age-related disease risk and healthy ageing by facilitating maintenance of a normal waist circumference.
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa - roland.vonkaenel@barmelweid.ch.|Department of Neurology, Inselspital University Hospital, University of Bern, Bern, Switzerland - roland.vonkaenel@barmelweid.ch.|Department of Psychosomatic Medicine, Clinic Barmelweid, Barmelweid, Switzerland - roland.vonkaenel@barmelweid.ch.
authors.forename: Roland
authors.initials: R
authors.lastname: von Känel
authors.affiliation: Physical Activity, Sport and Recreation Research Group (PhASRec), North-West University, Potchefstroom, South Africa.
authors.forename: Erna J
authors.initials: EJ
authors.lastname: Bruwer
authors.affiliation: National Centre of Sport and Medicine, School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UK.
authors.forename: Mark
authors.initials: M
authors.lastname: Hamer
authors.affiliation: Physical Activity, Sport and Recreation Research Group (PhASRec), North-West University, Potchefstroom, South Africa.
authors.forename: J Hans
authors.initials: JH
authors.lastname: de Ridder
authors.affiliation: Hypertension in Africa Research Team (HART), North-West University, Potchefstroom, South Africa.
authors.forename: Leoné
authors.initials: L
authors.lastname: Malan
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000097:blood; D044383:Black People / Q000523:psychology; D015444:Exercise / Q000502:physiology*; D005260:Female; D006801:Humans; D007962:Leukocytes; D008297:Male; D008875:Middle Aged; D011446:Prospective Studies; D060888:Real-Time Polymerase Chain Reaction; D013315:Stress, Psychological; D011795:Surveys and Questionnaires; D059505:Telomere Homeostasis / Q000502:physiology*; D055105:Waist Circumference; D044465:White People / Q000523:psychology
chemical_list: D015415:Biomarkers