In patients with severe autonomic dysfunction, water ingestion elicits an acute pressor response. Hypertension may be associated with changes in cardiovascular autonomic modulation, but there is no information on the acute effects of water ingestion in patients with hypertension. In this study, we compared the effect of acute water ingestion on haemodynamic and autonomic responses of hypertensive and normotensive individuals. Eight patients with mild hypertension were compared to 10 normotensive individuals. After 30 min resting in the supine position all subjects ingested 500 ml of water. At baseline and after water ingestion, venous blood samples for plasma volume determination were collected, and electrocardiographic tracings, finger blood pressure, forearm blood flow and muscle sympathetic nerve activity (MSNA) were obtained. Water ingestion resulted in similar and minor reduction in plasma volume. Systolic and diastolic blood pressure increased in both hypertensive (mean7s.d.: 19/1476/ 3 mm Hg) and normotensive subjects (17/1476/3 mm Hg). There was an increase in forearm vascular resistance and in MSNA. Heart rate was reduced (hypertensive: 571 beats/min, normotensive: 576 beats/min) and the high-frequency component of heart rate and systolic blood pressure variability was increased. In hypertensive and normotensive individuals, acute water ingestion elicits a pressor response, an effect that is most likely determined by an increased vasoconstrictor sympathetic activity, and is counterbalanced by an increase in blood pressure and heart rate vagal modulation.

We explored whether interval walking with blood flow restriction (BFR) increases net metabolic cost of locomotion in healthy young men at their optimal walking speed. We also determined whether decreased walking economy resulting from BFR might be accompanied by an increase in ventilation relative to VO2 and VCO2 . Finally, we examined possible relationships between the changes in ratings of perceived exertion (RPE) and those obtained in minute ventilation (VE ) during walking with BFR. Eighteen healthy men (age: 22·5 ± 3·4 years) performed graded treadmill exercise to assess VO2max . In a randomized fashion, participants also performed five bouts of 3-min treadmill exercise with and without BFR at their optimal walking speed. Walking with BFR elicited an overall increase in net VO2 (10·4%) compared with that seen in the non-BFR condition (P<0·05). The participants also demonstrated greater VE and VE /VO2 values while walking with BFR (P<0·05). Conversely, VE /VCO2 was similar between conditions at each walking bout. We found no significant correlation between the changes in VE and RPE induced by walking with BFR (r = 0·38, P>0·05). Our results indicate that (i) BFR decreases net walking economy in healthy young men, even at their optimal walking speed; (ii) heightened ventilatory drive may explain a small proportion of BFR effects on walking economy; and (iii) the ventilatory responses to BFR walking may be largely independent of changes in perceived exertion and are likely matched to the flux of CO2 between muscles and respiratory centres.

This preliminary investigation aimed to assess beta (β) oscillation, a marker of the brain GABAergic signaling, as a potential objective pain marker, hence contributing at the same time to the mechanistic approach of pain management. This case–control observational study measured β electroencephalographic (EEG) oscillation in 12 right-handed adult male with chronic neuropathic pain and 10 matched controls (∼55 years). Participants were submitted to clinical evaluation (pain visual analog scale, Hospital Anxiety, and Depression scale) and a 24-min high-density EEG recording (BIOSEMI). Data were analyzed using the EEGlab toolbox (MATLAB), SPSS, and R. The global power spectrum computed within the low (Lβ, 13–20 Hz) and the high (Hβ, 20–30 Hz) β frequency sub-bands was significantly lower in patients than in controls, and accordingly, Lβ was negatively correlated to the pain visual analog scale (R = −0.931, p = 0.007), whereas Hβ correlation was at the edge of significance (R = −0.805; p = 0.053). Patients’ anxiety was correlated to pain intensity (R = 0.755; p = 0.003). Normalization of the low and high β global power spectrum (GPS) to the GPS of the full frequency range, while confirming the significant Lβ power decrease in chronic neuropathic pain patients, vanished the significance of the Hβ decrease, as well as the correlation between Lβ power and pain intensity. Our results suggest that the GABAergic Lβ EEG oscillation is affected by chronic neuropathic pain. Confirming the Lβ GPS decrease and the correlation with pain intensity in larger studies would open new opportunities for the clinical application of gamma-aminobutyric acid-modifying therapies.

New Findings r What is the central question of this study?The effects of water ingestion on the chronotropic response to dynamic exercise, performed below and above the ventilatory threshold, have not been previously explored. r What is the main finding and its importance? Drinking 500 ml of water before exercise reduces the chronotropic response to submaximal exercise performed below and above the ventilatory threshold, but not at maximal exercise intensities.Ingestion of water attenuates the chronotropic response to submaximal exercise. However, it is not known whether this effect is equally manifested during dynamic exercise below and above the ventilatory threshold (VT). We explored the effects of water ingestion on the heart rate response to an incremental cycle-ergometer protocol. In a randomized fashion, 19 healthy adults (10 men and nine women, age 20.9 ± 1.8 years) ingested 50 and 500 ml of water before completing a cycle-ergometer protocol on two separate days. The heart rate and oxygen uptake (V O 2 ) responses to water ingestion were analysed both at rest and during exercise performed below and above the VT. The effects of water intake on brachial blood pressure were measured only at rest. Resting mean arterial pressure increased and resting heart rate decreased, but only after 500 ml of water (P < 0.05). Compared with that seen after 50 ml of water, the 500 ml volume elicited an overall decrease in submaximal heart rate (P < 0.05). In contrast, drinking 500 ml of water did not affect submaximalV O 2 . The participants' maximal heart rate, maximalV O 2 and VT were similar between conditions. Our results therefore indicate that, owing to its effects on submaximal heart rate over a broad spectrum of intensities, the drinking of water should be recognized as a potential confounder in cardiovascular exercise studies. However, by showing no differences between conditions for submaximalV O 2 , they also suggest that the magnitude of heart rate reduction after drinking 500 ml of water may be of minimal physiological significance for exercise cardiorespiratory capacity.