Reproducibility of the heart rate response to low-strain Valsalva manoeuvre in healthy subjects

To elucidate whether the intrastrain cardio-acceleration and cardio-deceleration responses to low-strain Valsalva manoeuvre at expiratory pressures 10 and 20 mmHg (VM10,VM20) are reproducible, a beat-to-beat heart rate study was undertaken in 46 subjects (40 male undergraduates aged 19-25 years and six laboratory workers (four females and two males aged 28-55 years). The intensity of the heart rate response (HRR) was assessed by a ratio of the mean value of the pre-strain heart rate (Valsalva means' ratio VMR). In each subject the HRR to VM10 and VM20 was measured by repeating each manoeuvre three times. Reproducibility was evaluated on a short-term (1 h), medium-term (1 and 6 months), and long-term (6 and 11 years) basis. With the individual differences the initial short-term reproducibility study revealed either an cardio-acceleration or cardio-deceleration response to VM10 and VM20, which persisted well in the repeated tests. On the ground of this result three individual modes of HRRs to VM10 and VM20 were distinguished: (i) Mode A, a deceleration response appeared both to VM10 and VM20; (ii) Mode B, a deceleration response appeared to VM10 and an acceleration response to VM20; (iii) Mode C, an acceleration response appeared both to VM10 and VM 20. All of these modes, as well as the separate acceleration and deceleration responses, were well reproducible at any cited time points. We suggest that the individual modes of HRR are induced by different states of autonomic cardiovascular reactivity: Mode A probably expresses a parasympathotonic (vagotonic), Mode C--a sympathotonic, and Mode B--an intermediate autonomic state. Thus, the individual modes of HRR to VM10 and to VM20 could be used as a method of non-invasive determination of cardiovascular autonomic reactivity.     

Mapping of the cerebral vascular response to hypoxia and hypercapnia using quantitative perfusion MRI at 3 T

Changes in breathing change the concentration of oxygen and carbon dioxide in arterial blood resulting in changes in cerebral blood flow (CBF). This mechanism can be described by the cerebral vascular response (CVR), which has been shown to be altered in different physiological and pathophysiological states. CBF maps of grey matter (GM) were determined with a pulsed arterial spin labelling technique at 3 T in a group of 19 subjects under baseline conditions, hypoxia, and hypercapnia. Experimental conditions allowed a change in either arterial oxygen (hypoxia) or carbon dioxide (hypercapnia) concentration compared with the baseline, leaving the other variable constant, in order to separate the effects of these two variables. From these results, maps were calculated showing the regional distribution of the CVR to hypoxia and hypercapnia in GM. Maps of CVR to hypoxia showed very high intra-subject variations, with some GM regions exhibiting a positive response and others a negative response. Per 10% decrease in arterial oxygen saturation, there was a statistically significant 7.0 +/- 2.9% (mean +/- SEM) increase in GM-CBF for the group. However, 70% of subjects showed an overall positive CVR (positive responders), and the remaining 30% an overall negative CVR (negative responders). Maps of CVR to hypercapnia showed less intra-subject variation. Per 1 mm Hg increase in partial pressure of end-tidal carbon dioxide, there was a statistically significant 5.8 +/- 0.9% increase in GM-CBF, all subjects showing an overall positive CVR. As the brain is particularly vulnerable to hypoxia, a condition associated with cardiorespiratory diseases, CVR maps may help in the clinic to identify the areas most prone to damage because of a reduced CVR.     

The Valsalva manoeuvre: physiology and clinical examples

The Valsalva manoeuvre (VM), a forced expiratory effort against a closed airway, has a wide range of applications in several medical disciplines, including diagnosing heart problems or autonomic nervous system deficiencies. The changes of the intrathoracic and intra‐abdominal pressure associated with the manoeuvre result in a complex cardiovascular response with a concomitant action of several regulatory mechanisms. As the main aim of the reflex mechanisms is to control the arterial blood pressure (BP), their action is based primarily on signals from baroreceptors, although they also reflect the activity of pulmonary stretch receptors and, to a lower degree, chemoreceptors, with different mechanisms acting either in synergism or in antagonism depending on the phase of the manoeuvre. A variety of abnormal responses to the VM can be seen in patients with different conditions. Based on the arterial BP and heart rate changes during and after the manoeuvre several dysfunctions can be hence diagnosed or confirmed. The nature of the cardiovascular response to the manoeuvre depends, however, not only on the shape of the cardiovascular system and the autonomic function of the given patient, but also on a number of technical factors related to the execution of the manoeuvre including the duration and level of strain, the body position or breathing pattern. This review of the literature provides a comprehensive analysis of the physiology and pathophysiology of the VM and an overview of its applications. A number of clinical examples of normal and abnormal haemodynamic response to the manoeuvre have been also provided.     

Systolic and diastolic changes in human coronary blood flow during Valsalva manoeuvre.

Valsalva manoeuvre is reported to be sometimes successful for the relief of angina pectoris. The present study investigated how haemodynamic changes produced by Valsalva manoeuvre can interact to improve the relationship between cardiac work and coronary blood flow. Ten male subjects aged 53 +/- 12 years (SD) were considered. Blood velocity in the internal mammary artery, previously anastomosed to the left descending coronary artery, was studied with Doppler technique. The subjects performed Valsalva manoeuvres by expiring into a tube connected to a mercury manometer, to develop a pressure of 40 mmHg. The arterial blood pressure curve was continuously monitored with a Finapres device from a finger of the left hand. During expiratory effort, an increase in heart rate and a decrease in arterial pulse pressure were followed by a more delayed and progressive increase in mean and diastolic pressures. Systolic blood velocity markedly decreased along with the reduction in pulse pressure and increase in heart rate. By contrast, diastolic and mean coronary blood velocities did not show any significant change. Since it is known that the Valsalva manoeuvre strongly reduces stroke volume and cardiac output, it is likely that a reduction in cardiac work also takes place. Since in diastole, i.e. when the myocardial wall is better perfused, coronary blood velocity did not show any significant reduction, it is likely that unchanged perfusion in the presence of reduced cardiac work is responsible for the relief from angina sometimes observed during Valsalva manoeuvre. It is also likely that the increase in heart rate prevents the diastolic and mean blood coronary velocity from decreasing during the expiratory strain, when an increased sympathetic discharge could cause vasoconstriction through the stimulation of the coronary alpha-receptors.     

Impedance cardiographic measurement of the physiological response to the Valsalva manoeuvre

The Valsalva manoeuvre was performed, with airway pressures of 10, 20, 30, 40 and 50 mmHg, on 11 healthy male subjects in both the standing and supine positions, and was evaluated with impedance cardiography using the Minnesota impedance cardiograph. Along with the impedance waveform, the output of a finger photoplethysmograph was recorded. The ratios of the amplitude of the finger and impedance pulses at the end of a 10s strain phase during the Valsalva manoeuvre were compared with those of the control period. The results in the standing position showed the impedance ratio changed from 0.81 to 0.61 as the airway pressure increased from 10 to 50 mmHg, whereas, over the same pressure range, the finger pulse ratio changed from 0.44 to 0.21. In the supine position, the response was similar to that for standing for most pressures. Upon release of the pressure, the impedance showed an immediate, large decrease, which suggests a significant rightheart and vena cava component in the impedance cardiographic signal. The results show that the impedance signals responded similarly to those of previous studies of central arterial pressure during the Valsalva manoeuvre, whereas the finger pulse decrease was approximately twice as much.     

Coronary reactive hyperaemia and arterial pressure in anaesthetized goats

To study the effects of arterial pressure on coronary reactive hyperaemia, left circumflex coronary artery flow was measured, and reactive hyperaemia was determined after 5, 10 or 20 s of occlusion of this artery in anaesthetized goats during normotension, hypertension and hypotension. During hypertension induced by aortic constriction (mean arterial pressure, MAP = 140 +/- 6 mmHg) coronary vascular resistance (CVR), reactive hyperaemia (ratio of peak in hyperaemic flow to control flow and ratio of repayment to debt) and the decrease in CVR during the peak in hyperaemic flow were comparable to those during normotension. During hypertension induced by noradrenaline (MAP = 144 +/- 6 mmHg) CVR was 16% lower (P < 0.05), reactive hyperaemia was reduced by 14-25% (P < 0.05) and the decrease in CVR during the peak in hyperaemic flow was lower than the values of these parameters during normotension. During hypotension induced by constriction of the caudal vena cava (MAP = 40 +/- 4 mmHg) CVR was 22% lower (P < 0.05), reactive hyperaemia was reduced by 25-65% (P < 0.05) and the decrease in CVR during the peak in hyperaemic flow was less compared to the values of these parameters during normotension. During hypotension induced by isoprenaline (MAP = 45 +/- 4 mmHg) CVR was 59% lower, reactive hyperaemia was reduced by 55-100% (P < 0.01) and the decrease in CVR during the peak in hyperaemic flow was less compared to the values of these parameters during normotension. Arterial pressure is a main determinant of coronary reactive hyperaemia after brief periods of ischaemia, and the relationship between arterial pressure and reactive hyperaemia may depend in part on changes in CVR after variations in arterial pressure. These changes in CVR may be related to the action on coronary vessels of myocardial factors and vascular myogenic mechanisms.     

Active regulation of cerebral venous tone: simultaneous arterial and venous transcranial Doppler sonography during a Valsalva manoeuvre

The aim of this study was to analyse the cerebral venous outflow in relation to the arterial inflow during a Valsalva manoeuvre (VM). In 19 healthy volunteers (mean age 24.1 ± 2.6 years), the middle cerebral artery (MCA) and the straight sinus (SRS) were insonated by transcranial Doppler sonography. Simultaneously the arterial blood pressure was recorded using a photoplethysmographic method. Two VM of 10 s length were performed per participant. Tracings of the variables were then transformed to equidistantly re-sampled data. Phases of the VM were analysed regarding the increase of the flow velocities and the latency to the peak. The typical four phases of the VM were also found in the SRS signal. The relative flow velocity (FV) increase was significantly higher in the SRS than in the MCA for all phases, particularly that of phase IV (p < 0.01). Comparison of the time latency of the VM phases of the MCA and SRS only showed a significant difference for phase I (p < 0.01). In particular, there was no significant difference for phase IV (15.8 ± 0.29 vs. 16.0 ± 0.28 s). Alterations in venous outflow in phase I are best explained by a cross-sectional change of the lumen of the SRS, while phases II and III are compatible with a Starling resistor. However, the significantly lager venous than the arterial overshoot in phase IV may be explained by the active regulation of the venous tone.     

Hybrid Cardiopulmonary Model for Analysis of Valsalva Maneuver with Radial Artery Pulse

A comprehensive model, which has the advantages of both lumped parameter and distributed parameter, has been developed with the objective of investigating the respiratory influences in radial artery pressure pulse as in photoplethysmography (PPG). It integrates lumped parameter cardiopulmonary (CP) model and transmission line arterial tree model from aorta to radial artery. The cardio-pulmonary interaction is realized by incorporating respiratory-induced variations in intrapleural pressure (Ppl) in circulatory system. The PPG signal of the model is considered as the radial artery pulse. To investigate the interaction Valsalva Maneuver (VM) condition has been simulated for different Ppl magnitude (10, 20, 30, and 40 mmHg) and for different time duration (5, 10, 15, and 20 s), and validated with PPG signal recorded in 10 normal subjects performing VM. The effects of test duration and VM pressure are studied in both the simulation and the experiments with specific focus on the maximal (%∆) changes in Heart Rate (HR), and Mean Arterial Pressure (MAP) during phases II and IV of VM. The correlation coefficients derived from model result have good agreement with experimental results. As radial artery pulse plays important role in both allopathy and alternate medicine systems, this model can serve to study its clinical importance in detecting cardiac and respiratory pathologies.     

Contribution of the inflow arteries to alterations cin total cerebrovascular resistance in the rabbit

The contribution made by the cerebral inflow arteries to total cerebrovascular resistance (CVR) and their importance in producing alterations in cerebral blood flow (CBF) (i.e., changes in CVR) were investigated. The arterial blood pressure at the circle of Willis was measured in 14 anesthetized rabbits via transorbital retrograde cannulation of the ophthalmic artery. CBF was measured in 21 rabbits under identical experimental conditions, using the hydrogen clearance technique. Inflow artery resistance was calculated from the measurements which were made at both normocapnia and hypercapnia throughout hemorrhagic hypotension. Under resting conditions, the inflow arteries made a relatively minor contribution to total CVR (7%). Hypercapnia resulted in a decrease in CVR and an increase in CBF; however, inflow artery resistance remained constant. Autoregulation and reductions in total CVR were observed as PP was reduced to 35 mm Hg. Inflow artery resistance remained constant at pressures greater than 45 mm Hg and increased slightly at PP less than 45 mm Hg. The relative contribution of inflow artery resistance to total CVR increased under the various conditions studied — increasing by a factor of 2 during hypercapnia, by a factor of 3 during hypotension, and by a factor of 4 during hypotension 4 hypercapnia. We concluded that the large inflow arteries do not participate in the autoregulatory or CO₂ responses of the cerebrovasculature of the rabbit.     

Cardiac responses to the Valsalva manoeuvre in different body positions

Summary A standardized Valsalva manoeuvre (VM) with a 15-s straining period was repeated in each of four postures by six male subjects. The postures were supine (SUP), sitting leaning back (LB), sitting leaning forward (LF) and standing (ST). During straining, the increase in heart rate (f _c) was different between LB and LF (+50% and +23%, respectively P<0.05). The decrease in stroke volume (SV), which was monitored by means of impedance cardiography, was different (63%, 68%, 39%, and 72%, P<0.001) as well as the decrease in cardiac output (CO) (55%, 53%, 26%, and 61%, P<0.001) in SUP, LB, LF, and ST, respectively. Accordingly, after pressure release the smallest changes of SV, f _c and CO were found in LF. In conclusion, cardiovascular stability during straining was increased during LF. Consequently, this posture would appear to be superior to other postures during unavoidable VM (weight lifting and defaecation). To perform tests on autonomic function LB would appear to be superior to the other postures because of the large autonomic responses, combined with minimum risk for the subject. The impedance method provided simple and reproducible determinations of SV changes during VM.     

Changes in muscle sympathetic nerve activity and calf blood flow during static handgrip exercise

Summary To test the function of sympathetic vascoconstrictor nerves on blood flow in resting limbs during static muscle contraction, muscle sympathetic nerve activity (MSNA) to the leg muscle was recorded from the tibial nerve microneurographically before, during and after 2 min of static handgrip (SHG). Simultaneously, calf blood flow (CBF) was measured by strain gauge plethysmography. An increase in MSNA, a decrease in CBF and an increase in calf vascular resistance (CVR) in the same resting limb occurred concomitantly during SHG. However, the increase in CVR was blunted in the second minute of handgrip when MSNA was still increasing. The results indicated that the decrease of CBF during SHG reflects the increase in MSNA, while the dissociation between MSNA and CVR at the later period of SHG may be related to metabolic change produced by the vasoconstriction.     

Intraocular pressure changes: the influence of psychological stress and the Valsalva maneuver

The effects of psychological stress and the Valsalva maneuver on short-term variations of intraocular pressure (IOP) were studied in 49 healthy adults. Psychological stress consisted of mental arithmetic tasks presented in counterbalanced order by computer and by the experimenter. Additionally, a standardized Valsalva maneuver was performed (in counterbalanced order with the psychological stressors). IOP was measured with a Goldmann tonometer before and after performance of each stressor. All three stressors transiently and highly significantly increased IOP, although the Valsalva maneuver produced changes of a greater magnitude (10.2 mmHg) than the psychological stressors (1.3 mmHg). Subjective stress ratings and heart rate increased in response to all stressors. There were no effects of task sequence, eye muscle tension, sex, smoking status (some smokers misreported their smoking status), or regular marijuana use, but regular physical exercise was associated with less IOP increase during psychological stress.     

Brady- and tachycardia in light of the Valsalva and the Mueller maneuver (apnea)

With a computerized impedance cardiograph we measured stroke volume (sv), cardiac output and heart rate (HR) in four men, during apnea with positive or negative intrapulmonic pressure (i.e., Valsalva and Mueller maneuver) in air. During Valsalva maneuvers the sv was reduced, and the compensatory rise in HR failed to keep the cardiac output at the control level before apnea. During both types of apnea, the diastolic pressure was increased as was the total peripheral resistance (TPR). The vasoconstriction and tachycardia during Valsalva maneuvers can be explained as a sino-aortic baroreceptor phenomenon in man. The smaller changes occurring during Mueller maneuvers result in no change in the transmural arterial pressure in the thorax, compared to the control level. Thus, without a stimulus there is no change in heart rate. The alveolar oxygen uptake and carbon dioxide elimination during apnea at total lung capacity was much larger than in the control phase before both types of apnea. The arteriolar vasoconstriction with increased TPR during the Valsalva apnea, was accompanied by a reduction in the stroke work of the left ventricle to approximately 50% of the work in the control phase.     

Comparison of sublingual isosorbide dinitrate and Valsalva maneuver for detection of obstruction in hypertrophic cardiomyopathy

Introduction

A left ventricular outflow tract (LVOT) obstruction assessment with a provoking test should be a routine part of the evaluation of patients with hypertrophic cardiomyopathy (HCM). The aim of this study was to compare the utility of the Valsalva maneuver (VM) and sublingual spray application of isosorbide dinitrate (ISDN) for detection of an obstruction.

Material and methods

We prospectively evaluated 81 consecutive HCM patients without severe rest LVOT obstruction (defined as peak rest pressure gradient (PG) ≥ 50 mm Hg). We measured PG at rest, during the VM, after sublingual ISDN spray, and during the VM after ISDN. An obstruction was defined as a PG ≥ 30 mm Hg.

Results

An obstruction was present in 15 patients (19%) at rest (median and interquartile range of PG 16 (7–26) mm Hg), in 38 patients (47%) during the VM (PG 28 (12–49) mm Hg), in 50 (62%) patients after ISDN (PG 50 (12–79) mm Hg), and in 55 patients (68%) during the VM after ISDN (PG 59 (20–87) mm Hg). The difference in occurrence of obstruction among different provoking tests was statistically significant for all comparisons (p < 0.001, except for the comparison of the ISDN test with the VM during ISDN, p = 0.025).

Conclusions

The ISDN test and the VM are useful screening methods for the detection of an HCM obstruction. Although ISDN appears to be more precise than the VM, the best option is a combination of both methods, which maximizes inducement of LVOT obstruction in patients with HCM.     

Neural, humoral, and metabolic control of coronary vascular resistance during exercise.

Neural, humoral, and metabolic effects on coronary vascular resistance were examined during exercise in conscious dogs, chronically instrumented for the measurement of aortic pressure, heart rate, and left circumflex coronary blood flow. Exercise significantly decreased coronary vascular resistance (CVR) in intact (INT) group, in which CVR was controlled by neural, humoral, and metabolic factors. In cardiac denervated (CD) group with pretreatment of alpha blocker (phentolamine, 2 mg/kg), in which CVR was controlled only by metabolic factor, exercise significantly decreased CVR. To eliminate metabolic effect on CVR, CVR was normalized by the product of CVR and double product (DP = mean aortic pressure x heart rate). CVR.DP did not change throughout the exercise in dogs with CD with alpha blocker. Thus, metabolic effect on CVR during exercise can be excluded by the product of CVR and DP. This calculation was applied to INT group with alpha blocker and CD group without blockers. The 12 km/h exercise significantly increased CVR.DP from 4.1 +/- 0.3 x 10(4) to 6.4 +/- 0.9 x 10(4) in INT group with alpha blocker, in which CVR was controlled only by neural factor, and from 2.8 +/- 0.2 x 10(4) to 4.5 +/- 0.5 x 10(4) in CD group, in which CVR was controlled only by humoral factor. These data suggest that 1) neural and humoral coronary vasoconstriction occurs during exercise, 2) neural and humoral vasoconstriction is overwhelmed by metabolic vasodilation, and 3) CVR.DP is a beneficial calculation for excluding metabolic effect on CVR during exercise.     

Alterations of postural and Valsalva responses in coronary heart disease

Patients in congestive heart failure are known to have altered autonomic responses to circulatory stress. In this study, two different age groups of male coronary heart disease (CHD) patients, not in failure, as well as normal male subjects, underwent standard 20-min 70 degrees head-up tilt and Valsalva tests. Responses were monitored by noninvasive methods and cardiac output was estamated with a transthoracic impedance method. During tilt, the CHD patients and control subjects had similar heart rate and diastolic pressure responses. However, the CHD patients had a greater decline in pulse pressure during tilt, mainly due to a decrease in systolic pressure. CHD patients had lesser declines in stroke volume and cardiac index and lesser increases in total vascular resistance than did control subjects. In the Valsalva, the heart rate phase increments (and decrements) from control and rate increments (and decrements) between successive phases were less in the coronary patients. The results indicate that coronary patients, not in failure, have diminished circulatory responses to the tilt and Valsalva maneuver and suggest that these tests may be useful functional indices of cardiovascular capability in coronary disease.     

Influence of microgravity on astronauts' sympathetic and vagal responses to Valsalva's manoeuvre

When astronauts return to Earth and stand, their heart rates may speed inordinately, their blood pressures may fall, and some may experience frank syncope. We studied brief autonomic and haemodynamic transients provoked by graded Valsalva manoeuvres in astronauts on Earth and in space, and tested the hypothesis that exposure to microgravity impairs sympathetic as well as vagal baroreflex responses. We recorded the electrocardiogram, finger photoplethysmographic arterial pressure, respiration and peroneal nerve muscle sympathetic activity in four healthy male astronauts (aged 38–44 years) before, during and after the 16 day Neurolab space shuttle mission. Astronauts performed two 15 s Valsalva manoeuvres at each pressure, 15 and 30 mmHg, in random order. Although no astronaut experienced presyncope after the mission, microgravity provoked major changes. For example, the average systolic pressure reduction during 30 mmHg straining was 27 mmHg pre-flight and 49 mmHg in flight. Increases in muscle sympathetic nerve activity during straining were also much greater in space than on Earth. For example, mean normalized sympathetic activity increased 445 % during 30 mmHg straining on earth and 792 % in space. However, sympathetic baroreflex gain, taken as the integrated sympathetic response divided by the maximum diastolic pressure reduction during straining, was the same in space and on Earth. In contrast, vagal baroreflex gain, particularly during arterial pressure reductions, was diminished in space. This and earlier research suggest that exposure of healthy humans to microgravity augments arterial pressure and sympathetic responses to Valsalva straining and differentially reduces vagal, but not sympathetic baroreflex gain.     

Wavelet analysis of autonomic outflow of normal subjects on head-up tilt, cold pressor test, Valsalva manoeuvre and deep breathing

Non-invasive autonomic evaluation has used fast Fourier transform (FFT) to assign a range of low (LF) and high frequencies (HF) as markers of sympathetic and parasympathetic influences, respectively. However, FFT cannot be applied to brief transient phenomena, such as those observed on performing autonomic tests where the acute changes of cardiovascular signals (blood pressure and heart rate) that represent the first and most important stage of the autonomic performance towards a new state of equilibrium occur. Wavelet analysis has been proposed as a method to overcome and complement information taken exclusively in the frequency domain. With discrete wavelet transform (DWT), a time-frequency analysis can be done, allowing the visualization in time of the contribution of LF and HF to the observed changes of a particular signal. In this study, we evaluate with wavelets the acute changes in R-R intervals and systolic blood pressure that are observed in normal subjects during four classical autonomic tests: head-up tilt (HUT), cold pressor test (CPT), deep breathing (DB) and Valsalva manoeuvre (VM). Continuous monitoring of ECG and blood presure was performed. Also LF, HF and LF/HF were calculated. Consistent with previous interpretations, data showed an increase of sympathetic activity in HUT, CPT and VM. On DB, results reflected an increase in parasympathetic activity and frequencies. In conclusion, when compared with FFT, wavelet analysis allows the evaluation of autonomic variability during short and non-stationary periods of time and may constitute a useful advance in the assessment of autonomic function in both physiological and pathological conditions.     

Cardiovascular reactivity during public speaking as a function of personality variables.

An experiment was conducted to assess the effects of a real-life stressor (public speaking) upon cardiovascular reactivity (CVR). Changes in blood pressure and heart rate from baseline to task were measured in a sample of 86 men and women. The purpose was to examine the effects of individual differences (Type A personality, hostility and gender) on CVR. Participants gave a 6-min oral presentation during which they were evaluated by their professor and with classmates as the audience. Results indicated that all participants had marked CVR during public speaking. There were differences in reactivity patterns between men and women, but personality did not play a role except for high hostile men. It is suggested that intense stressors may result in high levels of CVR independent of personality variables that moderate reactivity at lower levels of stress.     

Hemodynamic responses during and after multiple sets of stretching exercises performed with and without the Valsalva maneuver

OBJECTIVE:

This study investigated the acute hemodynamic responses to multiple sets of passive stretching exercises performed with and without the Valsalva maneuver.

METHODS:

Fifteen healthy men aged 21 to 29 years with poor flexibility performed stretching protocols comprising 10 sets of maximal passive unilateral hip flexion, sustained for 30 seconds with equal intervals between sets. Protocols without and with the Valsalva maneuver were applied in a random counterbalanced order, separated by 48-hour intervals. Hemodynamic responses were measured by photoplethysmography pre-exercise, during the stretching sets, and post-exercise.

RESULTS:

The effects of stretching sets on systolic and diastolic blood pressure were cumulative until the fourth set in protocols performed with and without the Valsalva maneuver. The heart rate and rate pressure product increased in both protocols, but no additive effect was observed due to the number of sets. Hemodynamic responses were always higher when stretching was performed with the Valsalva maneuver, causing an additional elevation in the rate pressure product.

CONCLUSIONS:

Multiple sets of unilateral hip flexion stretching significantly increased blood pressure, heart rate, and rate pressure product values. A cumulative effect of the number of sets occurred only for systolic and diastolic blood pressure, at least in the initial sets of the stretching protocols. The performance of the Valsalva maneuver intensified all hemodynamic responses, which resulted in significant increases in cardiac work during stretching exercises.