APPS November 2002 Meeting Abstract 2400

Kathryn Woolf-May¹, Andrew Owen², Deborah Ferrett¹, Steve Bird³, 1 Department of Sport and Exercise Science, Canterbury Christ Church University College, Canterbury, CT1 1QU, United Kingdom, 2 Department of Cardiology, Kent and Canterbury Hospital, Canterbury, CT1 3NG, United Kingdom, 3 Centre for Rehabilitation, Exercise and Sport Science, Victoria University, Melbourne, MC8001, Australia.

Left ventricular (LV) function deteriorates with age and until recently it was thought that only long-term vigorous exercise was capable of producing improvements in this parameter. However, a recent study on healthy sedentary middle-aged adults¹, showed increases in the rate of LV relaxation of 1.2 cm·s^-1 (95% confidence intervals 0.6 - 1.8 cm·s^-1) after only 18 weeks of brisk walking using single daily walking bouts of 20-40 minutes (min), for 150 min.week^-1 at 68% VO₂max. Therefore, in light of the recent guidelines advocating accumulative bouts of exercise, the aim of this study was to investigate the effect of accumulative short walking bouts upon LV diastolic function. Sixty four healthy men and women (31men and 33 women, aged 40-68 years) completed the study. Pre-intervention they were randomly divided into either a group of short walkers SW (n=27) or controls (n=37). Left Ventricular diastolic function was assessed using atrioventricular plane motion (AVPM) M mode echocardiography. The estimated weekly mean gross energy expenditure whilst walking for the SW was 4.0 ± 1.7 MJ, carried out for 150 ± 22 min, at an intensity of 73 ± 5% heart rate max and 61.3 ± 9.2 % VO₂max, which equated to walking 15.1 kilometres·week^-1. Post-intervention ANCOVA analysis revealed no significant increase in the rate of ventricular relaxation in the SW compared to the controls (mean difference post - pre-intervention for SW = 0.7 cm·s^-1, 95% confidence intervals 0.3 - 1.5 cm·s^-1 and controls = -0.1 cm·s^-1, 95% confidence intervals -1.0 - 0.7 cm·s^-1. These results indicate that accumulative short bouts may not be as effective as a longer single daily walking bout, of similar intensity and total weekly duration, at producing increases in the LV rate of relaxation. This should be a consideration when advocating the efficacy of accumulated short bouts of exercise.