Abstract
We tested the hypotheses that prior aerobic (Study 1) or anaerobic (Study 2) exercise attenuates the increase in renal vascular resistance (RVR) during sympathetic stimulation. Ten healthy young adults (5 females) participated in both Study 1 (aerobic exercise) and Study 2 (anaerobic exercise). In Study 1, subjects completed three minutes of face cooling pre- and post- 30 min of moderate intensity aerobic exercise (68 ± 1% estimate maximal heart rate). In Study 2, subjects completed two minutes of the cold pressor test pre- and post- the completion of a 30 s maximal effort cycling test (Wingate Anaerobic Test). Both face cooling and the cold pressor test stimulate the sympathetic nervous system and elevate RVR. The primary dependent variable in both Studies was renal blood velocity, which was measured at baseline and every minute during sympathetic stimulation. Renal blood velocity was measured via the coronal approach at the distal segment of the right renal artery with pulsed wave Doppler ultrasound. RVR was calculated from the quotient of mean arterial pressure and renal blood velocity. In Study 1, renal blood velocity and RVR did not differ between pre- and post- aerobic exercise (P ≥ 0.24). Face cooling decreased renal blood velocity (P < 0.01) and the magnitude of this decrease did not differ between pre- and post- aerobic exercise (P = 0.52). RVR increased with face cooling (P < 0.01) and the extent of these increases did not differ between pre- and post- aerobic exercise (P = 0.74). In Study 2, renal blood velocity was 2 ± 2 cm/s lower post- anaerobic exercise (P = 0.02), but RVR did not differ (P = 0.08). The cold pressor test decreased renal blood velocity (P < 0.01) and the magnitude of this decrease did not differ between pre- and post- anaerobic exercise (P = 0.26). RVR increased with the cold pressor test (P < 0.01) and the extent of these increases did not differ between pre- and post- anaerobic exercise (P = 0.12). These data indicate that 30 min of moderate intensity aerobic exercise or 30 s of maximal effort anaerobic exercise does not affect the capacity to increase RVR during sympathetic stimulation following exercise.
Highlights
MATERIALS AND METHODSBlood pressure is often reduced for up to 60 min following an acute bout of dynamic exercise (Halliwill et al, 2013, 2014)
The purpose of this study was to test the hypothesis that prior aerobic exercise attenuates the increase in renal vascular resistance (RVR) during sympathetic stimulation
Peak systolic renal blood velocity, end diastolic renal blood velocity, and RVR did not differ between pre- and post-exercise (P ≥ 0.24, Table 1)
Summary
MATERIALS AND METHODSBlood pressure is often reduced for up to 60 min following an acute bout of dynamic exercise (Halliwill et al, 2013, 2014). Orthostatic tolerance, defined as the ability to maintain blood pressure during orthostasis (Schlader et al, 2016b), is often impaired following dynamic exercise (Halliwill et al, 2014) This is caused by a relative inability to maintain stroke volume during orthostasis, which is likely due to inadequate increases in resistance in the muscle vasculature, thereby promoting pooling of blood in this vascular bed (Halliwill et al, 2013, 2014). Despite resistance in these visceral vascular beds returning to pre-exercise levels shortly after exercise (Pricher et al, 2004), it may be that prior exercise attenuates the ability to increase vascular resistance during sympathetic activation If this were the case, the renal and/or splanchnic vasculatures could contribute to post-exercise orthostatic intolerance. The effect of prior exercise on the hemodynamic response to sympathetic stimulation in one of these visceral vasculatures is unknown
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