10
4.2.1 Blood Pressure
In a meta-analysis of RCTs published up to February 2012 (105 aerobic, 29 dynamic
resistance, 14 combined, and 5 isometric training groups), systolic blood pressure
was reduced with aerobic, dynamic resistance, and isometric resistance training, but
not combined training [ 49 ]. Diastolic blood pressure was reduced with aerobic,
dynamic resistance, isometric resistance, and combined training. The authors tenta-
tively concluded that isometric handgrip and isometric leg training might result in
larger reductions in systolic and diastolic blood pressure than the other modes of
training, despite limited evidence currently available.
Although resting blood pressure is a widely used clinical measure of cardiovas-cular risk, it is well established that exercise causes a reduction in blood pressure
during the period immediately following a bout of exercise. Post-exercise hypoten-
sion (PEH), or the reduction in blood pressure following a bout of exercise, may last
up to 18 hours and may play an important role in the anti-hypertensive effects of
exercise. The optimal dose of exercise is not clear, however, Pescatello and col-
leagues [ 50 ] demonstrated that a light intensity (40% maximal oxygen consumption
[VO 2 max]) was as effective as a higher intensity bout of exercise (60% VO 2 max)
in eliciting significant PEH over the course of a nine-hour ambulatory monitoring
period. In contrast, Quinn [ 51 ] demonstrated more substantial and sustained PEH
over a 24 h period after a bout of higher intensity exercise (75% VO 2 max) com-
pared with lower intensity exercise (50% VO 2 max). There is also some evidence
that short bouts of moderate exercise produce more sustained PEH compared to
continuous sessions of the same total duration in prehypertensive adults [ 52 ].
4.2.2 Lipid Metabolism
Although observational studies suggest that regular activity is associated with
favourable lipid profiles, exercise interventions have yielded less consistent results.
In randomised, controlled trials of physical activity, the most commonly noted
change in blood lipid profiles is an increase in HDL-C concentration with less con-
sistent alterations in triglycerides (TG) and LDL-C concentrations. When HDL- C,
TG and LDL-C changes were noted, these were associated with interventions
involving weekly energy expenditure in excess of 900–1200 kcal but appear to be
independent of the exercise intensity used to achieve this energy expenditure [ 53 ,
54 ]. In a notable study that contained 492 sedentary adults, higher intensity (65–
70% of heart rate reserve) or more frequent walking (5–7 days per week) produced
more favourable changes in lipid profiles than moderate intensity (45–55% of heart
rate reserve) or low frequency (3–4 days per week) walking at 6 months, although
the effects were not sustained at 24 months [ 55 ]. Alterations in TG concentrations
appear to be more likely in men than in women and more likely to accompany
weight loss. There is also some evidence that less favourable lipid profiles at base-
line are more likely to alter in response to exercise [ 56 ]. In a meta-analysis of 13
M. Hamer et al.