The effects of brisk walking on endurance fitness, lipoprotein metabolism and other risk factors for coronary heart disease

This thesis examines the potential of a one year programme of brisk walking to influence endurance fitness, lipoprotein metabolism and other risk factors for coronary heart disease (CHD) in previously sedentary, middle-aged men. Seventy-two asymptomatic males were recruited into the study and randomly allocated on a two to one basis into either a walking group (n = 48) or a control group (n = 24). Walkers were asked to build up to an average of 45 minutes of brisk walking per day and maintain this level thereafter. Control subjects continued with their habitual lifestyle. Both groups undertook not to change their dietary habits. Maximum oxygen uptake (V0₂max) was predicted at base line, three, six and 12 months from submaximal heart rate and oxygen uptake data during treadmill walking. Endurance fitness was assessed at similar intervals by measuring heart rate and blood lactate concentration during standardised submaximal treadmill walking. Serum concentrations of total cholesterol, high density lipoprotein cholesterol, apoproteins A-I and B, triglycerides and lipoprotein(a) were measured at each observation point. Additionally, plasma fibrinogen, resting arterial blood pressure and indices of pulmonary function were determined. Differences in the response of walkers and controls over time were examined using two way analysis of variance for repeated measures employing the 5% level of significance. Adherence to the walking programme was high and 42 of the walkers (88%) remained in the study for the year completing an average of 28 ± 9 (mean ± SD) minutes of brisk walking each day (self-report). The response of the walkers over time was significantly different to that of the controls for predicted V0₂max and for heart rate and blood lactate concentration during standardised submaximal exercise indicating that brisk walking favourably influenced endurance fitness. No significant differences were observed between groups for any of the lipoprotein variables or other CHD risk factors monitored during the study. It was concluded that brisk walking did not influence established CHD risk factors in this group of previously sedentary middle-aged men despite the evidence of improved endurance fitness.