Association between objectively measured physical activity, chronic stress and leukocyte telomere length

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<.001) 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]. CONCLUSION: 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.