We tested the hypothesis that inspiratory resistive loading (IRL) increases vagal-mediated complexity of heart rate variability (HRV) in older women. We recorded heart rate continually during 30 breaths with Sham or IRL (30 % of maximal inspiratory pressure) in sitting position. The normalized spectral power in the low (LFn) and high (HFn) frequency bands and the symbolic dynamics measures for 0 V, 2UV and 2 L V were obtained. HFn was higher and LFn was lower during IRL than Sham (p < 0.05). During IRL, 2UV component increased more than Sham (p < 0.05) while 0 V index remained unchanged (p> 0.05). In conclusion, acute IRL improved vagal modulation index of both linear (spectral analysis) and non-linear analysis (symbolic dynamics) in older women.
Keywords: Aging; Heart rate variability; Maximal inspiratory pressure; Respiratory muscles.
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