Comparison Of Contraction Versus Compression On Arterial Stiffness

Le résumé fourni par la source

Increased arterial stiffness is associated with cardiovascular risk. Central and peripheral arterial stiffness measured with pulse wave velocity (PWV) are reduced 5 min after a single bout of dynamic exercise. Peripheral arterial stiffness is also reduced after a single bout of passive compressions on the legs. We reasoned that comparing contraction versus compression would allow determination of the mechanical contribution to exercise-induced reduction in peripheral arterial stiffness. PURPOSE: Examine whether exercise produces a larger reduction in peripheral arterial stiffness compared to passive compressions. METHODS: Ten healthy young volunteers participated in this study (7 females, 28 ± 4 yrs, mean ± SD). Two tonometers were placed simultaneously on the brachial and radial arteries of the exercising arm for measurement of peripheral arterial stiffness. Beat-by-beat arterial pressure was obtained by a photoplethysmographic sensor on the middle finger of the contralateral hand. Brachial-radial PWV and mean arterial pressure (MAP) were recorded before exercise/compressions then at 5-, 15-, and 30-min post-exercise/compressions. The exercise consisted of 5-min rhythmic handgrip exercise (2 sec contraction/2 sec relaxation) at 50% of maximal voluntary contraction. Passive compressions were performed using a large blood pressure cuff placed on the right forearm for 5-min at ~200 mmHg (2-sec inflation/2-sec deflation). RESULTS: Handgrip exercise reduced brachial-radial PWV from 12.9 ± 3.4 m/sec at baseline to 8.8 ± 3.4 m/sec at 5 min, 8.6 ± 1.9 m/sec at 15 min, and 10.1 ± 3.2 m/sec at 30 min post-exercise. For passive compressions brachial-radial PWV decreased from 11.4 ± 2.7 m/sec to 9.5 ± 4 m/sec at 5 min, 10.2 ± 3.1 m/sec at 15 min, and 11.4 ± 4 m/sec at 30 min. ANOVA revealed a significant time effect (p = 0.001) but no time x condition interaction (p > 0.05). MAP was not statistically significantly different across all time points (p > 0.05). CONCLUSIONS: These results show that peripheral arterial stiffness measured as brachial-radial PWV was reduced similarly after 5-min of rhythmic handgrip exercise and passive compressions. Thus, the primary stimulus to the reduction in peripheral arterial stiffness after exercise may be a mechanical effect rather than a metabolic effect.

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