24 weeks of accumulative brisk walking differentially affects rate-pressure product & predicted VO2max

Physical activity (PA) is well known to reduce the risk of coronary heart disease (CHD), primarily mediated through adaptations in cardiovascular function. Aerobic fitness (VO2max) is often used to assess the outcome of PA interventions, however myocardial workload (MVO2) is a likely mechanism by which PA reduces the risk of CHD, but changes in VO2max and rate-pressure product (RPP), a non-invasive index of MVO2 may not be affected to the same extent. There are no known studies that have compared the effects of different types of walking programmes/interventions on maximum oxygen uptake VO2max versus MVO2.PURPOSE: The purpose of this randomised controlled trial was to compare the changes in VO2max and RPP after single (SBW) and accumulative (ABW) daily brisk walking sessions of equal volume.METHODS: 34 apparently healthy, non-medicated, non-smoking sedentary middle-aged males (54.1 ± 8.5 years), completed the study. Participants were randomly allocated to either: unchanged lifestyle (n= 15, CON); single bout of brisk walking (n= 16, SBW, one 30 minutes bout per day); or accumulative brisk walking (n= 22, ABW, 3 × 10 or 2 × 15 minute daily bouts) groups. Pre- and post-intervention SBP and HR were assessed, and RPP was calculated. VO2max was predicted from a submaximal treadmill test. Participants in the walking groups were instructed to walk >65% HRmax during the 24 week intervention. The data were analysed using ANCOVA with pre-walk values as the co-variateRESULTS: The main findings of this study were that ABW and SBW significantly decreased RPP compared to CON (P=0.012). RPP decreased by -0.80 ± 0.92 in SBW (P=0.036) and -0.92 ± 0.69 in ABW (P=0.028). Although SBW significantly increased VO2max (4.0 ± 3.1 mL·kg-1·min-1; P=0.005) compared to CON (0.0 ± 2.5 mL·kg-1·min-1), ABW did not significantly improve (0.8 ± 3.1 mL·kg-1·min-1; P=0.794)CONCLUSION: 24 weeks of brisk walking in single daily 30 minute sessions was sufficient to improve VO2max and decrease resting RPP values. Interestingly, although the data demonstrated that 24 weeks of accumulative brisk walking was insufficient to improve VO2max, resting RPP was indeed decreased. These findings suggest that despite the absence of adaptations in VO2max, favourable changes in cardiovascular function may still be evident, thereby reducing submaximal MVO2.