Spontaneous cardiac baroreflex sensitivity is enhanced during post-exercise ischemia in men but not in women
Milena Samora1, André L Teixeira1, Jeann L Sabino-Carvalho1
1NeuroVASQ-Integrative Physiology Laboratory, Faculty of Physical Education, University of Brasília, Darcy Ribeiro Campus, Brasília, DF, Brazil.
Purpose:
To investigate the effect of isolated muscle metaboreflex activation on spontaneous cardiac baroreflex sensitivity (cBRS), and to characterize the potential sex-related differences in this interaction in young healthy subjects.
Methods:
40 volunteers (20 men and 20 women, age: 22 ± 0.4 year) were recruited. After 5-min rest period, the subjects performed 90 s of isometric handgrip exercise at 40% of maximal voluntary contraction followed by 3 min of post-exercise ischemia (PEI). Beat-to-beat heart rate and arterial blood pressure were continuously measured by finger photopletysmography. Spontaneous cBRS was assessed using the sequence technique and heart rate variability was measured in time (RMSSD-standard deviation of the RR intervals) and frequency domains (LF-low and HF-high frequency power).
Results:
Resting cBRS was similar between men and women. During PEI, cBRS was increased in men (Δ3.0 ± 1.1 ms mmHg- 1, P = 0.03) but was unchanged in women (Δ-0.04 ± 1.0 ms mmHg- 1, P = 0.97). In addition, RMSSD and HF power of heart rate variability increased in women (Δ7.4 ± 2.6 ms, P = 0.02; Δ373.4 ± 197.3 ms2; P = 0.04, respectively) and further increased in men (Δ26.4 ± 7.1 ms, P < 0.01; Δ1874.9 ± 756.2 ms2; P = 0.02, respectively). Arterial blood pressure increased from rest during handgrip exercise and remained elevated during PEI in both groups, however, these responses were attenuated in women.
Conclusions:
These findings allow us to suggest a sex-related difference in spontaneous cBRS elicited by isolated muscle metaboreflex activation in healthy humans.
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