Post-exercise effects on aortic wave reflection derived from wave separation analysis in young- to middle-aged pre-hypertensives and hypertensives

Pulsatile load and wasted pressure effort are reduced following an acute bout of aerobic exercise

Following aerobic exercise, sustained vasodilation and concomitant reductions in total peripheral resistance (TPR) result in a reduction in blood pressure that is maintained for two or more hours. However, the time course for postexercise changes in reflected wave amplitude and other indices of pulsatile load on the left ventricle have not been thoroughly described. Therefore, we tested the hypothesis that reflected wave amplitude is reduced beyond an hour after cycling at 60% V̇o_2peak for 60 min. Aortic pressure waveforms were derived in 14 healthy adults (7 men, 7 women; 26 ± 3 yr) from radial pulse waves acquired via high-fidelity applanation tonometry at baseline and every 20 min for 120 min postexercise. Concurrently, left ventricle outflow velocities were acquired via Doppler echocardiography and pressure-flow analyses were performed. Aortic characteristic impedance (Zc), forward (Pf) and backward (Pb) pulse wave amplitude, reflected wave travel time (RWTT), and wasted pressure effort (WPE) were derived. Reductions in aortic blood pressure, Zc, Pf, and Pb were all sustained postexercise whereas increases in RWTT emerged from 60 to 100 min post exercise (all P < 0.05). WPE was reduced by ∼40% from 40 to 100 min post exercise (all P < 0.02). Stepwise multiple regression analysis revealed that the peak ΔWPE was associated with ΔRWTT (β = -0.57, P = 0.003) and ΔPb (β = 0.52, P = 0.006), but not Δcardiac output, ΔTPR, ΔZc, or ΔPf. These results suggest that changes in pulsatile hemodynamics are sustained for ≥100 min following moderate intensity aerobic exercise. Moreover, decreased and delayed reflected pressure waves are associated with decreased left ventricular wasted effort after exercise.NEW & NOTEWORTHY We demonstrate that pulsatile load on the left ventricle is diminished following 60 min of moderate intensity aerobic exercise. During recovery from exercise, the amplitude of the forward and backward traveling pressure waves are attenuated and the arrival of reflected waves is delayed. Thus, the work imposed upon the left ventricle by reflected pressure waves, wasted pressure effort, is decreased after exercise.

Effects of cycling bouts performed with different intensities and amounts of energy expended on central pressure and pulse wave reflection in normotensive and hypertensive men

OBJECTIVE

This study investigated pulse wave analysis in normotensive and hypertensive men after cycling bouts with different intensities and amounts of energy expended.

METHODS

Twenty-four men were assigned into normotensive (n = 14; age: 40.7 ± 2.8 years; 24-h ambulatory SBP/DBP:121 ± 2/74 ± 1 mmHg) and hypertensive (n = 10; age: 39.2 ± 2.3 years; 24-h ambulatory SBP/DBP:139 ± 3/86 ± 2 mmHg) groups. Participants undertook a maximal cardiopulmonary exercise test, a nonexercise control session (CTL) and three cycling bouts [two prolonged bouts expending 300 kcal at 50% (i.e. P-MOD) and 70% (i.e. P-VIG) oxygen uptake reserve (VO2R) and one short bout expending 150 kcal at 50% VO2R (i.e. S-MOD)] performed in a randomized order. Central SBP (cSBP), pulse pressure (cPP), augmentation pressure, augmentation index (AIx), heart rate (HR) and AIx adjusted for HR (AIx@75) were determined 10 min before, and 30- and 70-min postintervention.

RESULTS

Compared to CTL, only the P-VIG changed the cSBP [70-min (Δ -11.7 mmHg)], cPP [70-min (Δ:-7.4 mmHg)], augmentation pressure [30-min (Δ:-5.7 mmHg); 70-min (Δ:-7.3 mmHg)], AIx [30-min (Δ:-15.3 %); 70-min (Δ:-16.4 %)], AIx@75 [30-min (Δ:-12.8 %); 70-min (Δ:-13.9 %)] and HR [70-min (Δ: 9.9 bpm)] in the hypertensive group. However, all exercise bouts mitigated the increased cSBP responses post-CTL in the hypertensive group.

CONCLUSION

The present study provides evidence that vigorous-intensity aerobic exercise reduces acute central pressure and pulse wave reflection in hypertensive men.

Central aortic hemodynamics following acute lower and upper-body exercise in a cold environment among patients with coronary artery disease

Exercise is beneficial to cardiovascular health, evidenced by reduced post-exercise central aortic blood pressure (BP) and wave reflection. We assessed if post-exercise central hemodynamics are modified due to an altered thermal state related to exercise in the cold in patients with coronary artery disease (CAD). CAD patients (n = 11) performed moderate-intensity lower-body exercise (walking at 65–70% of HR_max) and rested in neutral (+ 22 °C) and cold (− 15 °C) conditions. In another protocol, CAD patients (n = 15) performed static (five 1.5 min work cycles, 10–30% of maximal voluntary contraction) and dynamic (three 5 min workloads, 56–80% of HR_max) upper-body exercise at the same temperatures. Both datasets consisted of four 30-min exposures administered in random order. Central aortic BP and augmentation index (AI) were noninvasively assessed via pulse wave analyses prior to and 25 min after these interventions. Lower-body dynamic exercise decreased post-exercise central systolic BP (6–10 mmHg, p < 0.001) and AI (1–6%, p < 0.001) both after cold and neutral and conditions. Dynamic upper-body exercise lowered central systolic BP (2–4 mmHg, p < 0.001) after exposure to both temperatures. In contrast, static upper-body exercise increased central systolic BP after exposure to cold (7 ± 6 mmHg, p < 0.001). Acute dynamic lower and upper-body exercise mainly lowers post-exercise central BP in CAD patients irrespective of the environmental temperature. In contrast, central systolic BP was elevated after static exercise in cold. CAD patients likely benefit from year-round dynamic exercise, but hemodynamic responses following static exercise in a cold environment should be examined further.

Clinical trials.gov: NCT02855905 04/08/2016.

Effects of aerobic, resistance and concurrent exercise on pulse wave reflection and autonomic modulation in men with elevated blood pressure

The acute effects of exercise modes on pulse wave reflection (PWR) and their relationship with autonomic control remain undefined, particularly in individuals with elevated blood pressure (BP). We compared PWR and autonomic modulation after acute aerobic (AE), resistance (RE), and concurrent exercise (CE) in 15 men with stage-1 hypertension (mean ± SE: 34.7 ± 2.5 years, 28.4 ± 0.6 kg/m², 133 ± 1/82 ± 2 mmHg). Participants underwent AE, RE, and CE on different days in counterbalanced order. Applanation tonometry and heart rate variability assessments were performed before and 30-min postexercise. Aortic pressure decreased after AE (− 2.4 ± 0.7 mmHg; P = 0.01), RE (− 2.2 ± 0.6 mmHg; P = 0.03), and CE (− 3.1 ± 0.5 mmHg; P = 0.003). Augmentation index remained stable after RE, but lowered after AE (− 5.1 ± 1.7%; P = 0.03) and CE (− 7.6 ± 2.4% P = 0.002). Systolic BP reduction occurred after CE (− 5.3 ± 1.9 mmHg). RR-intervals and parasympathetic modulation lowered after all conditions (~ 30–40%; P < 0.05), while the sympathovagal balance increased after RE (1.2 ± 0.3–1.3 ± 0.3 n.u., P < 0.05). Changes in PWR correlated inversely with sympathetic and directly with vagal modulation in CE. In conclusion, AE, RE, and CE lowered central aortic pressure, but only AE and CE reduced PWR. Overall, those reductions related to decreased parasympathetic and increased sympathetic outflows. Autonomic fluctuations seemed to represent more a consequence than a cause of reduced PWR.

Caffeine ingestion alters central hemodynamics following aerobic exercise in middle-aged men

PURPOSE

To examine the acute influence of caffeine on post-exercise central blood pressures, arterial stiffness, and wave reflection properties.

METHODS

In a double-blind randomized placebo-controlled crossover study design, ten middle-aged males (55 ± 5 year) completed two exercise trials after ingestion of caffeine (400 mg) or placebo. Measurements were taken before and 30 min post-ingestion via cuff-based pulse wave analysis (PWA) and carotid-femoral pulse wave velocity (PWV). Participants performed a 40-min cycling bout at 70% HRmax with matched workloads between trials. PWA and PWV were reassessed 30 min post-exercise.

RESULTS

Prior to exercise, compared to placebo, caffeine increased brachial systolic blood pressure (bSBP) (+ 12.3 ± 2.4 mmHg; p = 0.004), brachial diastolic blood pressure (bDBP) (+ 7.7 ± 0.9 mmHg; p = 0.011), central systolic blood pressure (cSBP) (+ 11.1 ± 2.1 mmHg; p = 0.005) and central diastolic blood pressure (cDBP) (+ 7.6 ± 1.0 mmHg; p = 0.012). PWV was higher 30 min after pill ingestion (p = 0.021 for time) with a trend for a greater increase in caffeine (p = 0.074 for interaction). bSBP (p = 0.036) and cSBP (p = 0.007) were lower after exercise but remained higher (both p < 0.001) in caffeine compared to placebo. PWV remained higher (p = 0.023) after exercise in caffeine compared to placebo but was not influenced by exercise. At rest, augmentation pressure (AP) and index (AIx) were not influenced by caffeine ingestion. Conversely, AIx was lower (p = 0.009) after exercise in placebo only.

CONCLUSION

In healthy and active middle-aged men, pre-exercise caffeine ingestion led to higher central and peripheral systolic blood pressures, PWV and AIx at 30 min post-exercise, indicating an increased left ventricular workload which may have implications for cardiovascular event risk.

Post-exercise Response of Arterial Parameters for Arterial Health Assessment Using a Microfluidic Tactile Sensor and Vibration-Model-Based Analysis: A Proof-of-Concept Study

OBJECTIVE

Arterial stiffness and endothelial function are two established surrogate markers of subclinical atherosclerosis and are quantified by three arterial parameters: elasticity, viscosity and radius of the arterial wall. Yet, the current methods for their assessment are unsuitable for routine use. Post-exercise response of the cardiovascular (CV) system serves as a more sensitive detection of subclinical arterial abnormalities that are not apparent at-rest. The objective of this study is to propose a novel method that can measure post-exercise response of arterial parameters and is also suitable for routine use.

APPROACH

A microfluidic tactile sensor with a location-insensitive configuration was used for arterial pulse signal measurements on six asymptomatic male subjects, offering measurement reliability, ease use by a layperson, and affordability. By treating the arterial pulse signal as a vibration signal of the arterial wall, vibration-model-based analysis of only one measured pulse signal with no calibration was conducted for simultaneous estimation of three arterial parameters. Exercise-intensity-normalized percent changes in arterial parameters were utilized to remove the influence of variation in exercise intensity on post-exercise response, and then their measured values were compared for difference in post-exercise response between the subjects.

MAIN RESULTS

One subject who was obese, on subject who had insomnia, and the oldest subject in the study demonstrated differences in post-exercise response at the radial artery (RA), as compared with the three subjects free of those three factors. Despite a lack of statistical significance, the observed difference at the RA between subjects was supported by (i) their consistency with the related findings in the literature, and (ii) their consistency with the measured values at the carotid artery (CA) and superficial temporal artery (STA) and the anatomical difference between the three arteries.

SIGNIFICANCE

The proposed method has the potential of offering an affordable and convenient diagnosis tool for routine arterial health assessment.

The potential role of testosterone in hypertension and target organ damage in hypertensive postmenopausal women

Objective: The aim of this study was to confirm the potential role of testosterone in hypertension and target organ damage (TOD) in hypertensive postmenopausal women.

Methods: A matched group study was conducted. One hundred sixty-one hypertensive postmenopausal women between 45 and 65 years of age were enrolled as group 1. Another 161 age-matched hypertensive men were enrolled as group 2. Ambulatory blood pressure monitoring, echocardiographic imaging, vascular function, sex hormones and clinical characteristics were evaluated. Quantitative data were analyzed using independent Student’s t-test and multiple regression analysis.

Results: The mean and load level of blood pressure were lower in women than in men (P<0.05), except for the mean level and load of the nocturnal systolic blood pressure (SBP) (123.77±15.72 mmHg vs 126.35±15.64 mmHg, and 50.43±30.31% vs 55.35±28.51%, P>0.05). However, the carotid-femoral pulse wave velocity (cf-PWV) in women was higher than that in men (9.68±2.23 m/s vs 8.03±2.82 m/s, P<0.05). The ratio of the early diastolic mitral peak flow velocity to early diastolic mitral annular velocity (E/Em) was obviously impaired (13.06±3.53 vs 12.05±3.68, P<0.05) in women. Furthermore, in women, a positive correlation was found between testosterone and cf-PWV (γ=0.157, P=0.046), and Cf-PWV was positively related to the mean level of nighttime SBP (γ=0.210, P=0.008). Moreover, nocturnal SBP was a risk factor for E/Em (γ=0.156, P=0.048, P<0.05).

Conclusion: Testosterone may play a role in the correlation between hypertension and TOD in hypertensive postmenopausal women.

Clinical Trial number: This research study was registered under the ClinicalTrials.gov PRS Website (NCT03451747).

Influence of Exercise Mode on Post-exercise Arterial Stiffness and Pressure Wave Measures in Healthy Adult Males

Background: Exercise mode has been reported to be an important determinant of arterial stiffness and wave reflection changes following a brief bout of exercise with inconsistent results to date. This study examined the impact of exercise mode on arterial stiffness and pressure wave measures following acute aerobic exercise (AER), resistance exercise (RES), and a control (CON) condition with no exercise. Methods: In a randomized, cross-over, repeated measures design, 21 healthy adult males (26.7 ± 7.2 years) undertook three experimental intervention sessions: AER (30-min cycle ergometry at 70-75% maximum heart rate), RES (3 × 10 repetitions of six upper and lower body exercises at 80-90% of 10-repetition maximum) and CON (30-min seated rest). Measures of arterial stiffness and pressure waves, such as carotid-femoral pulse wave velocity (cf-PWV), augmentation index (AIx), AIx corrected for heart rate of 75 (AIx75), and forward wave (Pf), backward wave (Pb) and reflection magnitude, were assessed at Rest and at 10-min intervals for 60 min after the intervention sessions. Comparisons between interventions and over time were assessed via repeated measures ANOVA and post-hoc Tukey's tests. Results: No significant differences in cf-PWV were noted between the three interventions at rest or post-intervention. However, RES led to significantly greater post-intervention AIx, AIx75, Pf, and Pb compared to AER and CON with AIx75 also remaining significantly elevated throughout the post-intervention period. In contrast, AER resulted in a brief, significant elevation of AIx75 and no change in cf-PWV, Pf, Pb, and reflection magnitude. Conclusions: Exercise mode, specifically RES and AER, significantly influenced the time course of pressure wave reflection responses following a brief bout of exercise in healthy adult males. Distinct adjustments during exercise including changes in blood pressure and vasomotor tone may be key modulators of post-exercise arterial function. Identification of modal differences may assist in understanding the impact of exercise on cardiovascular function and the mechanisms by which exercise benefits vascular health.

Postexercise hypotension in central aortic pressures following walking and its relation to cardiorespiratory fitness

BACKGROUND

Central aortic blood pressure (BP) is reduced after exercise. The aim of this study was to determine whether cardiorespiratory fitness relates to postexercise reductions in aortic BP.

METHODS

Sixteen young adults completed maximal exercise testing for peak oxygen uptake (VO2). Participants walked at a slow (80 steps/min, ~47% maxHR) and fast (125 steps/min, ~65% maxHR) stepping cadence for 3000 steps on two nonconsecutive days. Before and after each walking condition, radial tonometry was used to derive aortic pressures. Measurements after walking were taken after 30 and 60 min of supine recovery.

RESULTS

The change in aortic BP was similar between walking cadences. Aortic systolic BP (-2.3 mmHg, P=0.03) and pulse pressure (-3.2 mmHg, P<0.001) were significantly reduced after 60 min of recovery as compared to baseline. The reduction in aortic pulse pressure was associated with decreased forward (r=0.69, P<0.001) and backward wave pressure (r=0.70, P<0.001). Peak VO2 was not associated (P>0.05) with these changes, but was strongly associated with non-significant changes in aortic systolic BP (30min: r=-0.54, P=0.03) and diastolic BP (30 min: r=-0.64, 60 min: r=-0.77; both P<0.01) after slow walking only.

CONCLUSIONS

These results indicate that cardiorespiratory fitness associates with aortic pressure reductions after walking dependent on exercise intensity.

Reliability of arterial stiffness indices at rest and following a single bout of moderate-intensity exercise in older adults

Short-term changes in arterial stiffness with exercise are proposed to better reflect vascular impairments than resting measures alone and are suggested as a prognostic indicator of cardiovascular risk in older adults. Arterial stiffness indices are reliable at rest, but the time-course and reliability of postexercise changes in arterial stiffness in older adults are unknown. The precision of postexercise changes in arterial stiffness should be determined prior to their use in large prospective trials. This study assessed the between-day reliability of the changes in pulse wave velocity (PWV), augmentation index (AIx75) and reflection magnitude (RM) following an exercise bout in older adults. Ten older adults (71 ± 5 years) were tested on three separate days, 7 days apart. PWV, AIx75 and RM were assessed at rest, immediately post and at 20, 40 and 60 min during recovery after moderate-intensity cycling. Intraclass correlation coefficient (ICC) and reliability coefficient (RC) were used to assess the relative and absolute reliability of arterial stiffness responses. PWV increased, and RM decreased immediately after exercise (P<0·05), and returned to baseline during recovery. AIx decreased during recovery (P<0·001). Resting ICC values were 0·91 (PWV), 0·72 (AIx75) and 0·40 (RM). Reliability of the immediate changes following exercise was high for PWV (ICC:0·87, RC:1·9 m s^-1 ) and moderate for AIx75 (ICC:0·64, RC:7%) and RM (ICC:0·59, RC:9%). Reliability of the postexercise responses was similar to that at rest for all measures of arterial stiffness. These findings indicate that postexercise changes in arterial stiffness indices are reliable in healthy older adults and supports further investigation of the prognostic value of these responses.

Effects of exercise intensity and cardiorespiratory fitness on the acute response of arterial stiffness to exercise in older adults

PURPOSE

Increased arterial stiffness is observed with ageing and in individuals with low cardiorespiratory fitness ([Formula: see text]O_2peak), and associated with cardiovascular risk. Following an exercise bout, transient arterial stiffness reductions offer short-term benefit, but may depend on exercise intensity. This study assessed the effects of exercise intensity on post-exercise arterial stiffness in older adults with varying fitness levels.

METHODS

Fifty-one older adults (72 ± 5 years) were stratified into fitness tertiles ([Formula: see text]O_2peak: low-, 22.3 ± 3.1; mid-, 27.5 ± 2.4 and high-fit 36.3 ± 6.5 mL kg^-1 min^-1). In a randomised order, participants underwent control (no-exercise), moderate-intensity continuous exercise (40% of peak power output; PPO), and higher-intensity interval exercise (70% of PPO) protocols. Pulse wave velocity (PWV), augmentation index (AIx75) and reflection magnitude (RM) were assessed at rest and during 90 min of recovery following each protocol.

RESULTS

After control, delta PWV increased over time (P < 0.001) and delta RM was unchanged. After higher-intensity interval exercise, delta PWV (P < 0.001) and delta RM (P < 0.001) were lower to control in all fitness groups. After moderate-intensity continuous exercise, delta PWV was not different from control in low-fit adults (P = 0.057), but was lower in the mid- and higher-fit older adults. Post-exercise AIx75 was higher to control in all fitness groups (P = 0.001).

CONCLUSIONS

In older adults, PWV increases during seated rest and this response is attenuated after higher-intensity interval exercise, regardless of fitness level. This attenuation was also observed after moderate-intensity continuous exercise in adults with higher, but not lower fitness levels. Submaximal exercise reveals differences in the arterial stiffness responses between older adults with higher and lower cardiorespiratory fitness.