The effects of aerobic exercise on metabolic risk, insulin sensitivity and intrahepatic lipid in healthy older people from the Hertfordshire Cohort Study: a randomised controlled trial

AIMS/HYPOTHESIS: We sought to determine the effect of an aerobic exercise intervention on clustered metabolic risk and related outcomes in healthy older adults in a single-centre, explanatory randomised controlled trial. METHODS: Participants from the Hertfordshire Cohort Study (born 1931-1939) were randomly assigned to 36 supervised 1 h sessions on a cycle ergometer over 12 weeks or to a non-intervention control group. Randomisation and group allocation were conducted by the study co-ordinator, using a software programme. Those with prevalent diabetes, unstable ischaemic heart disease or poor mobility were excluded. All data were collected at our clinical research facility in Cambridge. Components of the metabolic syndrome were used to derive a standardised composite metabolic risk score (zMS) as the primary outcome. Trial status: closed to follow-up. RESULTS: We randomised 100 participants (50 to the intervention, 50 to the control group). Mean age was 71.4 (range 67.4-76.3) years. Overall, 96% of participants attended for follow-up measures. There were no serious adverse events. Using an intention-to-treat analysis, we saw a non-significant reduction in zMS in the exercise group compared with controls (0.07 [95% CI -0.03, 0.17], p = 0.19). However, the exercise group had significantly decreased weight, waist circumference and intrahepatic lipid, with increased aerobic fitness and a 68% reduction in prevalence of abnormal glucose metabolism (OR 0.32 [95% CI 0.11-0.92], p = 0.035) compared with controls. Results were similar in per-protocol analyses. CONCLUSIONS/INTERPRETATION: Enrolment in a supervised aerobic exercise intervention led to weight loss, increased fitness and improvements in some but not all metabolic outcomes. In appropriately screened older individuals, such interventions appear to be safe. TRIAL REGISTRATION: Controlled-trials.com ISRCTN60986572 FUNDING: Medical Research Council.