The increase in blood pressure during training is a disadvantage of strength training in the elderly. To reduce this effect it is generally recommended to apply lower levels of relative muscle strength with longer contraction durations or higher number of repetitions (continuous mode (CM), e. g. 50% of maximal strength, 10 to 15 repetitions without pauses). Alternatively, higher contraction forces could be combined with frequent periods of muscle relaxation and fewer repetitions (intermittent mode (IM), e. g. 80% of maximal strength, 8 repetitions consisting of 1.5 s concentric contraction, 1.5 s eccentric contraction and 3 s pause). We compared the blood pressure effects of both approaches during leg press exercise in two age groups (10 subjects aged 22 to 42 y, 9 subjects aged 60 to 72 y). Blood pressure was measured continuously by a non-invasive method (FINAPRES, Ohmeda 2300, Englewood USA).
Results: 1. The age of the subjects had no significant influence on the slopes of blood pressure increase during the different exercise modes. 2. The frequent insertion of short (3 s) periods of muscle relaxation (IM) decreased the blood pressure response more effectively than a reduction in contraction strength alone (CM). Short muscle relaxations have an immediate, mechanical effect on blood pressure and they allow a metabolic recovery which attenuates the trend of blood pressure increase.