Interaction between muscle metaboreflex and mechanoreflex modulation of arterial baroreflex sensitivity in exercise. |
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Authors: | C A Carrington C Ubolsakka M J White |
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Affiliation: | School of Sport and Exercise Sciences, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. C.A.Carrington@bham.ac.uk |
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Abstract: | The effect of external calf compression on baroreflex sensitivity (BRS) during electrically evoked plantar flexion and postexercise circulatory occlusion (PECO) was studied. Subjects took part in two experimental trials: control and compression. In both trials, electrically evoked isometric plantarflexion (Stim) was performed at 30% maximum voluntary contraction force for 2 min. During compression, a cuff (inflated to 250 mmHg) was applied to the active calf during exercise and PECO. Sequence analysis carried out on the systolic blood pressure responses, and R-wave-R-wave intervals revealed a rightward shift of the regression line along the pressure axis during Stim in both trials. In the control experiment, BRS was significantly (P < 0.01) increased from 10.37 +/- 1.87 ms/mmHg during Stim to 12.79 +/- 1.62 ms/mmHg during PECO. With external compression, BRS was unaltered between Stim (10.84 +/- 1.86 ms/mmHg) and PECO (11.40 +/- 1.54 ms/mmHg). Because the metabolic conditions were the same in both experiments, the results may best be explained by reactivation of muscle mechanoreceptor activity by external compression during PECO. |
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