The prevalence of pre-hypertension and hypertension in the elderly is very high. Apart from medication, physical exercise training is a potential strategy to reduce blood pressure, however, the ability to perform exercise can be limited in the elderly. Hence, alternative non-pharmacological strategies to reduce blood pressure are necessary. Two interventions that have been shown to positively influence blood pressure are respiratory muscle training (RMT) and intermittent hypoxia (IH). Whether a combination of RMT and IH yields even better effects is currently unknown. Therefore, in this study, the effect of a single session of RMT with and without IH on blood pressure and associated cardiovascular parameters will be investigated in elderly subjects with pre-hypertension.
Study Type
INTERVENTIONAL
Allocation
NA
Purpose
TREATMENT
Masking
NONE
Enrollment
14
RMT consists of six bouts of 5-min of volitional hyperpnoea . After each RMT bout, participants will breathe room air for 5 minutes.
RMT and IH consist of six bouts of 5-min of volitional hyperpnoea. After each RMT bout, participants will breathe a hypoxic gas mixture (10.5% O2 ) for 5 minutes.
No intervention
Exercise Physiology Lab, Institute of Human Movement Sciences and Sport, ETH Zurich
Zurich, Canton of Zurich, Switzerland
Change in blood pressure in mmHg
Blood pressure before, during, and after each intervention measured with an automated sphygmomanometer
Time frame: At baseline after 20 min of lying in a supine position, every 5 minutes during the 60 min intervention, and 20, 35 and 50 min after the end of the intervention
Change in pulse wave velocity in m/s
Carotid-femoral pulse wave velocity before and after each intervention, assessed with a device that simultaneously records (non-invasively) pressure signals from the carotid and femoral arteries
Time frame: At baseline after 25 min of lying in a supine position, and 25, 40 and 55 min after the end of the intervention
Change in cardiac output in L/min
Cardiac output before, during, and after each intervention measured with impedance cardiography
Time frame: At baseline after 15min of lying in a supine position, every 5 minutes during the 60 min intervention, and 15, 30 and 45 min after the end of the intervention
Change in total peripheral resistance in dyn x s/cm^5
Total peripheral resistance before, during, and after each intervention measured with impedance cardiography
Time frame: At baseline after 15min of lying in a supine position, every 5 minutes during the 60 min intervention, and 15, 30 and 45 min after the end of the intervention
Changes in baroreflex sensitivity in ms/mmHg
Baroreflex sensitivity before and after each intervention assessed with photo plethysmography
Time frame: At baseline after 15min of lying in a supine position, and 15, 30 and 45 min after the end of the intervention
Change in heart rate variability in ms
Heart rate variability measured before, during and after each intervention with impedance cardiography
Time frame: At baseline after 15min of lying in a supine position, every 5 minutes during the 60 min intervention, and 15, 30 and 45 min after the end of the intervention
Change in peripheral oxygenation during sleep in %Saturation
Peripheral oxygenation during sleep measured at home after each intervention with a finger pulse oxymeter
Time frame: Continuously during the night following each intervention, from time to bed until wake up time in the morning (i.e. on average approximately 8hours)
Change in sleep efficiency defined as the ratio of total sleep time and time in bed
Sleep efficiency measured at home after each intervention with an actigraph
Time frame: Continuously during the night following each intervention, from time to bed until wake up time in the morning (i.e. on average approximately 8hours)
Change in subjective sleep quality
Sleep quality (i.e. "How well did you sleep?" and "How recovered are you?") measured at home after each intervention with a visual analog scale (VAS). The two VAS consists each of a 10cm-horizontal line, with the left end of the lines representing low sleep quality ("slept very badly" and "not recovered at all", respectively) and the right end representing good sleep quality ("slept very well" and "completely recovered", respectively). Participants are asked to draw a vertical line in between the two ends on each of the two VAS.
Time frame: Within 5 minutes after waking-up following the night after each intervention
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