Effects of a brief Valsalva manoeuvre on hemodynamic response to strength exercises

Ocular rigidity and choroidal thickness changes in response to microgravity: A case study

Purpose

To evaluate ocular rigidity and choroidal thickness changes in response to microgravity and the Valsalva maneuver in a private astronaut.

Methods

Ophthalmological examination and Optical Coherence Tomography were performed before, during, and after space flight. Choroidal thickness was measured at all time points at rest and during the Valsalva maneuver. Ocular rigidity was obtained before and after flight using a non-invasive method enhanced with deep learning-based choroid segmentation.

Results

Ocular rigidity decreased after space flight compared to baseline. There was an increase in average choroidal thickness during the Valsalva maneuver compared to the resting condition before, during, and after space flight, and such increase was greater when the Valsalva maneuver was performed during space flight.

Conclusions and importance

The data indicates biomechanical changes to ocular tissues because of space flight and greater choroidal thickness increase. The findings could lead to a better understanding of space flight-associated neuro-ocular syndrome and may have repercussions for short duration missions in a nascent industry.

Is Exercise Blood Pressure Putting the Brake on Exercise Rehabilitation after Acute Type A Aortic Dissection Surgery?

(1) Background: Exercise is recommended to improve physical fitness in patients recovering from acute type A aortic dissection (ATAAD). However, surgery corrects the diseased blood vessels and reduces the risk of ATAAD, but it does not redefine a safe exercise blood pressure (BP) threshold. This review aimed to discuss whether the safe threshold of exercise BP can be upregulated after ATAAD surgery to increase exercise intensity with additional benefits. (2) Data sources: The PubMed databases were searched with the keywords “type A acute aortic dissection surgery”, “exercise”, “BP”, “stress”, and variations of these terms. (3) Study selection: Data from clinical trials, guidelines, and recent reviews were selected for review. (4) Results: Regular exercise can be considered a cardioprotective intervention for aortic dissection patients by attenuating hemodynamic responses at rest and during exercise. Previous studies have mainly focused on moderate-intensity aerobic exercise. In practice, the exercise systolic BP of some patients was higher than 160 mm Hg without adverse events, which indicates that the training intensity may be underestimated for patients after ATAAD surgery. Limited studies suggest a light-to-moderate resistance training for selected patients because it may cause a greater increase in BP. (5) Conclusions: Moderate-intensity continuous aerobic exercise supplemented by low-intensity resistance training is appropriate for cardiac rehabilitation after ATAAD surgery. The BP increase based on the normal exercise BP response, corresponding to the moderate-intensity is relatively safe. For high-risk post-ATAAD patients, considering the overall volume of training, personalizing the exercise regimen to remain within “safe” BP limits, and avoiding excessive fluctuations in BP should be the primary considerations for exercise training.

Rapid chest compression effects on intracranial pressure in patients with acute cerebral injury

BACKGROUND

Patients with acute brain injury often require invasive mechanical ventilation, increasing the risk of developing complications such as respiratory secretions retention. Rapid chest compression is a manual chest physiotherapy technique that aims to improve clearance of secretions in these patients. However, the rapid chest compression technique has been suggested to be associated with increased intracranial pressure in patients with acute brain injury. The aim of this work is to elucidate the effects of the technique on intracranial pressure in mechanically ventilated patients with acute brain injury. Furthermore, the effects of the technique in different volumes and flows recorded by the ventilator and the relationship between the pressure applied in the intervention group and the different variables will also be studied.

METHODS

Randomized clinical trial, double-blinded. Patients with acute brain injury on invasive mechanical ventilation > 48 h will be included and randomized in two groups. In the control group, a technique of passive hallux mobilization will be applied, and in the intervention group, it will be performed using the rapid chest compression technique. Intracranial pressure (main variable) will be collected with an intracranial pressure monitoring system placed at the lateral ventricles (Integra Camino).

DISCUSSION

The safety of chest physiotherapy techniques in patients at risk of intracranial hyperpressure is still uncertain. The aim of this study is to identify if the rapid manual chest compression technique is safe in ventilated patients with acute brain injury.

TRIAL REGISTRATION

NCT03609866 . Registered on 08/01/2018.

Exercise intensity assessment and prescription in cardiovascular rehabilitation and beyond: why and how: a position statement from the Secondary Prevention and Rehabilitation Section of the European Association of Preventive Cardiology

A proper determination of the exercise intensity is important for the rehabilitation of patients with cardiovascular disease (CVD) since it affects the effectiveness and medical safety of exercise training. In 2013, the European Association of Preventive Cardiology (EAPC), together with the American Association of Cardiovascular and Pulmonary Rehabilitation and the Canadian Association of Cardiac Rehabilitation, published a position statement on aerobic exercise intensity assessment and prescription in cardiovascular rehabilitation (CR). Since this publication, many subsequent papers were published concerning the determination of the exercise intensity in CR, in which some controversies were revealed and some of the commonly applied concepts were further refined. Moreover, how to determine the exercise intensity during resistance training was not covered in this position paper. In light of these new findings, an update on how to determine the exercise intensity for patients with CVD is mandatory, both for aerobic and resistance exercises. In this EAPC position paper, it will be explained in detail which objective and subjective methods for CR exercise intensity determination exist for aerobic and resistance training, together with their (dis)advantages and practical applications.

Cardiac Responses to Prenatal Resistance Exercise with and without the Valsalva Maneuver

PURPOSE

Exercise guidelines recommend incorporating resistance exercise (RE) into a regular aerobic training program during pregnancy. However, few women do so because of uncertainties about the safety of prenatal RE, particularly regarding the Valsalva maneuver (VM). The aim of this study was to determine the acute cardiovascular responses to prenatal RE at different intensities, with and without VM.

METHODS

Healthy pregnant (n = 15; 22.9 ± 5.9 wk of gestation) and nonpregnant women (n = 15) were recruited. Maximal strength over 10 repetitions (10RM) for semireclined leg press was determined. Women underwent standardized assessments of cardiac structure, function and mechanics (echocardiography), heart rate (ECG), and blood pressure (photoplethysmography) at baseline, during RE at 20%, 40%, and 60% 10RM while free-breathing, and at 40% 10RM with VM. Significant differences were identified between subjects at baseline (independent t-tests), between and within subjects during free-breathing RE (general linear model, baseline as a covariate), and between and within subjects for 40% 10RM free-breathing versus VM (mixed-effects model).

RESULTS

Resting cardiac output, heart rate, and stroke volume were greater in pregnant women, without differences in blood pressure, ejection fraction, or cardiac mechanics. During free-breathing RE, pregnant women had a greater ejection fraction compared with nonpregnant women; however, all other hemodynamic variables were not different between groups. Cardiac mechanics during free-breathing RE across all intensities were not different between groups, with the exception that pregnant women had a lower apical circumferential strain that did not affect global cardiac function. No differences were observed between groups during 40% 10RM RE with and without VM.

CONCLUSIONS

Pregnant women have proportionate cardiac responses to light-moderate RE, both with and without the VM. These findings reinforce the safety of RE in healthy pregnancy.

The Acute Cardiorespiratory and Cerebrovascular Response to Resistance Exercise

Resistance exercise (RE) is a popular modality for the general population and athletes alike, due to the numerous benefits of regular participation. The acute response to dynamic RE is characterised by temporary and bidirectional physiological extremes, not typically seen in continuous aerobic exercise (e.g. cycling) and headlined by phasic perturbations in blood pressure that challenge cerebral blood flow (CBF) regulation. Cerebral autoregulation has been heavily scrutinised over the last decade with new data challenging the effectiveness of this intrinsic flow regulating mechanism, particularly to abrupt changes in blood pressure over the course of seconds (i.e. dynamic cerebral autoregulation), like those observed during RE. Acutely, RE can challenge CBF regulation, resulting in adverse responses (e.g. syncope). Compared with aerobic exercise, RE is relatively understudied, particularly high-intensity dynamic RE with a concurrent Valsalva manoeuvre (VM). However, the VM alone challenges CBF regulation and generates additional complexity when trying to dissociate the mechanisms underpinning the circulatory response to RE. Given the disparate circulatory response between aerobic and RE, primarily the blood pressure profiles, regulation of CBF is ostensibly different. In this review, we summarise current literature and highlight the acute physiological responses to RE, with a focus on the cerebral circulation.

Acute impairment in respiratory muscle strength following a high-volume versus low-volume resistance exercise session

BACKGROUND

Diminished respiratory muscle has been shown following a strenuous bout of sit-ups however there is a paucity of evidence for this effect following a strenuous upper and lower body resistance training session. This study investigated the acute effect of a highvolume compared to a low-volume resistance exercise session on respiratory muscle strength.

METHODS

Twenty resistance-trained males (age 25.1 ± 7.4 y) participated in this randomised and cross-over design study. Participants completed two resistance training protocols (highand low-volume) and a control session (no exercise). Sessions involved 5 sets (high-volume) and 2 sets (low-volume) of 10 repetitions at 65% one-repetition maximum for each exercise (bench press, squat, seated shoulder press, and deadlift) with 90 s recovery between sets. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) was assessed pre-and post-session and respiratory gases were measured during the recovery between sets.

RESULTS

Following the high-volume session MIP and MEP decreased by a median of 10.0% (interquartile range, IQR = -15.2 to -2.6%) and 12.1% (IQR = -22.2 to -3.9%), respectively, which was significant compared to the low-volume (p<0.001) and control sessions (p≤ 0.001). At 20-min post high-volume session MEP returned to baseline whereas MIP returned to baseline values at 40-min. Greater metabolic stress was associated with the higher-volume session as demonstrated by a lower recovery end-tidal CO2 partial pressure across the majority of exercises (p≤0.008).

CONCLUSIONS

Findings suggest that respiratory muscle strength is impaired following a highvolume session resistance exercise session, however it appears to be restored within an hour post-exercise.

Lung Function and Respiratory Muscle Adaptations of Endurance- and Strength-Trained Males

Diverse exercise-induced adaptations following aerobic endurance compared to strength-training programs is well documented, however, there is paucity of research specifically focused on adaptations in the respiratory system. The aim of the study was to examine whether differences in lung function and respiratory muscle strength exist between trainers predominately engaged in endurance compared to strength-related exercise. A secondary aim was to investigate if lung function and respiratory muscle strength were associated with one-repetition maximum (1RM) in the strength trainers, and with VO2 max and fat-free mass in each respective group. Forty-six males participated in this study, consisting of 24 strength-trained (26.2 ± 6.4 years) and 22 endurance-trained (29.9 ± 7.6 years) participants. Testing involved measures of lung function, respiratory muscle strength, VO2 max, 1RM, and body composition. The endurance-trained compared to strength-trained participants had greater maximal voluntary ventilation (MVV) (11.3%, p = 0.02). The strength-trained compared to endurance-trained participants generated greater maximal inspiratory pressure (MIP) (14.3%, p = 0.02) and maximal expiratory pressure (MEP) (12.4%, p = 0.02). Moderate-strong relationships were found between strength-trained respiratory muscle strength (MIP and MEP) and squat and deadlift 1RM (r = 0.48-0.55, p ≤ 0.017). For the strength-trained participants, a strong relationship was found between MVV and VO2 max (mL·kg-1·min-1) (r = 0.63, p = 0.003) and a moderate relationship between MIP and fat-free mass (r = 0.42, p = 0.04). It appears that endurance compared to strength trainers have greater muscle endurance, while the latter group exhibits greater respiratory muscle strength. Differences in respiratory muscle strength in resistance trainers may be influenced by lower body strength.

Systematic review of intra-abdominal and intrathoracic pressures initiated by the Valsalva manoeuvre during high-intensity resistance exercises

The Valsalva manoeuvre, intra-abdominal pressure (IAP) and intrathoracic pressure (ITP) play important roles in resistance training and common daily activities. The purpose of this review is to summarize the ITP and IAP responses to resistance exercises and to determine which exercises elicit the highest or lowest body pressure values under high-intensity resistance exercise. The PubMed, Scopus and Web of Science databases were searched until November 1, 2018. A combination of the following search terms was used: Valsalva manoeuvre, hold breath, controlled breathing, controlled breath, abdominal pressure, intrathoracic pressure AND weight training, resistance exercise, power lifting. The search process yielded 1125 studies, of which 16 were accepted according to the selection criteria and methodological quality. The highest IAP was recorded during squats (over 200 mmHg) followed by deadlift, slide row and leg press (161–176 mmHg), and the lowest IAP was found during bench press (79±44 mmHg). The highest ITP was elicited by the leg press, deadlift and box lift (105–130 mmHg), which were higher than during the bench press (95±37 mmHg) and slide row (88±32 mmHg). We recommend the bench press and slide row as exercises useful for beginners and individuals with hypertension. Untrained individuals should not use heavy squats, deadlift, box lift and clean exercises until they have undergone progressive adaptation for lifting high loads resulting in high IAP and ITP. The values of IAP and ITP during high-intensity exercise seem to be determined mutually by the position of the human body and the external load.

Impaired hemodynamic response to tilt, handgrip and Valsalva manoeuvre in patients with takotsubo syndrome

PURPOSE

Long-term β-adrenolytics treatment in takotsubo syndrome (TTS) patients is based on the premise, that TTS is strongly associated with sympathetic nervous system overactivity. The aim of the study was to establish hemodynamic response to tilt, handgrip and Valsalva manoeuvre in patients with takotsubo syndrome compared to healthy subjects (CONTROL) and patients after ST Elevation Myocardial Infarction (STEMI).

MATERIAL AND METHOD

Echocardiographic examination was performed at rest, ECG and continuously non-invasively measured arterial blood pressure were used for evaluation of hemodynamic responses to Valsalva manoeuvre, static handgrip (HG) followed by post-exercise ischemia, and tilt. Ten healthy women, 20 with TTS and 20 after STEMI, mean age 64 ± 8.5 years, participated in the study.

RESULTS

Pressor response to Valsalva manoeuvre and tilt in TTS group was diminished in comparison to CONTROL and close to that of STEMI. During HG, increase of SBP was the lowest in TTS group. Data indirectly suggest that it was due to deficient stroke volume in TTS and STEMI patients during these manoeuvres; though echocardiographic findings at rest did not reveal any significant differences between groups.

CONCLUSIONS

Our data show that despite apparent resolution of the immediate effects of TTS, impaired response to cardiovascular challenge, similar to that in STEMI patients, persisted. As the manoeuvres applied mimic daily life situations, causes of impairment should be searched for and potential health risk evaluated.

Dynamic strength training intensity in cardiovascular rehabilitation: is it time to reconsider clinical practice? A systematic review

When added to endurance training, dynamic strength training leads to significantly greater improvements in peripheral muscle strength and power output in patients with cardiovascular disease, which may be relevant to enhance the patient’s prognosis. As a result, dynamic strength training is recommended in the rehabilitative treatment of many different cardiovascular diseases. However, what strength training intensity should be selected remains under intense debate. Evidence is nonetheless emerging that high-intensity strength training (≥70% of one-repetition maximum) is more effective to increase acutely myofibrillar protein synthesis, cause neural adaptations and, in the long term, increase muscle strength, when compared to low-intensity strength training. Moreover, multiple studies report that high-intensity strength training causes fewer increments in (intra-)arterial blood pressure and cardiac output, as opposed to low-intensity strength training, thus potentially pointing towards sufficient medical safety for the cardiovascular system. The aim of this systematic review is therefore to discuss this line of evidence, which is in contrast to current clinical practice, and to re-open the debate as to what dynamic strength training intensities should actually be applied.

Acute beetroot juice supplementation does not attenuate knee extensor exercise muscle fatigue in a healthy young population

[Purpose]

The effect of acute nitrate supplementation on muscle fatigue is largely unknown. This study aimed to evaluate the effect of acute nitrate supplementation on muscle fatigue.

[Methods]

Thirty-five recreationally active subjects consumed 140 ml of beetroot (BR) juice (nitrate: 8 mmol·d^-1) or placebo (PL) 12 and 2.5 hours before two exercise sessions. Peak torque was measured during 50 repetitions, at maximal effort, and during concentric knee extensions at 90°·s^-1. Blood pressure (BP) was recorded pre- and post-exercise.

[Results]

Peak torque, maximum work, rate of fatigue, and rate of work fatigue were similar between the BR and PL conditions. Post-exercise diastolic BP (BR: 67.2 ± 9.8 vs. PL: 64.5 ± 7.9 mmHg, p < 0.05) and mean arterial pressure (BR: 91.6 ± 9.3 vs. PL: 88.8 ± 8.2 mmHg, p < 0.05) were higher with BR supplementation.

[Conclusion]

These findings suggest that the acute intake of BR juice had no effect on knee extensor muscle strength or fatigue but increased BP in a healthy recreationally active population.

Exercise-based cardiac rehabilitation in surgically treated type-A aortic dissection patients

OBJECTIVES

Surgically treated type-A aortic dissection patients are often restricted from physical exercise due to a lack of knowledge about the blood pressure increase. Our aims were to evaluate the hemodynamic responses during exercise, and to assess changes in peak oxygen uptake, maximal workload, and quality-of-life after completion of an exercise-based cardiac rehabilitation program.

DESIGN

Three subgroups were retrospectively identified based on their different eligibility criteria. Group I (n = 10) had performed an exercise-based cardiac rehabilitation program including exercise tests. Group II (n = 9) had followed the program without the tests. Group III (n = 10) had neither been rehabilitated nor tested. For evaluation of hemodynamic parameters, we included a group of surgically treated patients with aortic valve stenosis, group IV (n = 32). Questionnaires were obtained to measure quality-of-life.

RESULTS

At baseline the group I and IV mean systolic blood pressure changed from 143 ± 16 mmHg and 150 ± 16 mmHg to 200 ± 32 mmHg and 213 ± 27 mmHg, respectively. The group I mean peak oxygen uptake changed from 23.5 ± 7.9 ml/min/kg before rehabilitation to 28.6 ± 8.4 ml/min/kg, p = .001, after rehabilitation. The mean maximal workload changed from 143 ± 80 W before rehabilitation to 178 ± 97 W, p = .003, after rehabilitation. At follow-up, the groups I-III physical quality-of-life score was 45.1 ± 15.0, 40.0 ± 9.0, and 30.0 ± 11.3, p < .025, respectively, and the mental quality-of-life score was 51.1 ± 6, 41.7 ± 6.7, and 32.5 ± 13.3, p < .001, respectively.

CONCLUSIONS

Our results suggest that type-A aortic dissection patients have hemodynamic responses to exercise that are comparable to other cardiovascular patients. Moreover, we found significant increases in peak oxygen uptake, maximal workload, and quality-of-life after ended ECR.

Marfan syndrome, inherited aortopathies and exercise: What is the right answer?

Exercise recommendations for those who have Marfan syndrome or other genetic predisposition for thoracic aortic disease remain controversial and at times ambiguous. There are no outcomes studies to help guide recommendations. In this review, we examine the guidelines regarding exercise and inherited aortic conditions, the theoretical reasoning and circumstantial evidence that support the guidelines, as well as the knowledge gaps that continue to exist.

Marfan syndrome, inherited aortopathies and exercise: what is the right answer?

Exercise recommendations for those who have Marfan syndrome or other genetic predisposition for thoracic aortic disease remain controversial and at times ambiguous. There are no outcomes studies to help guide recommendations. In this review, we examine the guidelines regarding exercise and inherited aortic conditions, the theoretical reasoning and circumstantial evidence that support the guidelines, as well as the knowledge gaps that continue to exist.

The cerebrovascular response to graded Valsalva maneuvers while standing

The Valsalva maneuver (VM) produces large and abrupt increases in mean arterial pressure (MAP) at the onset of strain (Phase I), however, hypotension, sufficient to induce syncope, occurs upon VM release (phase III). We examined the effect of VM intensity and duration on middle cerebral artery blood velocity (MCAv) responses. Healthy men (n =10; mean ± SD: 26 ± 4 years) completed 30%, 60%, and 90% of their maximal VM mouth pressure, for 5 and 10 sec (order randomized) while standing. Beat‐to‐beat MCAv and MAP during phase I (peak), at nadir (phase III), and recovery are reported as the change from standing baseline. During phase I, MCAv rose 15 ± 6 cm·s⁻¹ (P <0.001), which was not reliably different between intensities (P =0.11), despite graded increases in MAP (P <0.001; e.g., +12 ± 9 mmHg vs. +35 ± 14 for 5 sec 30% and 90% VM, respectively). During Phase III, the MCAv response was duration‐ (P = 0.045) and intensity dependent (P < 0.001), with the largest decrease observed following the 90% VM (e.g., −19 ± 13 and −15 ± 11 cm·s⁻¹ for 5 and 10 sec VM, respectively) with a concomitant decrease in MAP (P <0.001, −23 ± 11 and −23 ± 9 mmHg). This asymmetric response may be attributable to the differential modulators of MCAv throughout the VM. The mechanical effects of the elevated intrathoracic pressure during phase I may restrain increases in cerebral perfusion via related increases in intracranial pressure; however, during phase III the decrease in MCAv arises from an abrupt hypotension, the extent of which is dependent upon both the duration and intensity of the VM.

More intense Valsalva maneuvers when standing are associated with an increase blood pressure response during Phase I of the maneuver although this is not accompanied by changes in cerebral blood flow. However, following the maneuver (phase III) more intense straining is associated with a greater decrease in both blood pressure and cerebral blood flow and in some instances is sufficient to induce syncope.

In aged men, central vessel transmural pressure is reduced by brief Valsalva manoeuvre during strength exercise

A brief Valsalva manoeuvre, lasting 2-3 s, performed by young healthy men during strength exercise reduces transmural pressure acting on intrathoracic arteries. In this study, we sought to verify this finding in older men. Twenty normotensive, prehypertensive and moderately hypertensive otherwise healthy men 46-69 years old performed knee extensions combined with inspiration or with brief Valsalva manoeuvre performed at 10, 20 and 40 mmHg mouth pressure. Same respiratory manoeuvres were also performed at rest. Non-invasively measured blood pressure, knee angle, respiratory airflow and mouth pressure were continuously registered. In comparison to inspiration, estimated transmural pressure acting on thoracic arteries changed slightly and insignificantly during brief Valsalva manoeuvre at 10 and 20 mmHg mouth pressure. At 40 mmHg mouth pressure, transmural pressure declined at rest (-8·8 ± 11·4 mmHg) and during knee extension (-12·1 ± 11·9 mmHg). This decline ensued, as peak systolic pressure increase caused by this manoeuvre, was distinctly <40 mmHg. Only a main effect of mouth pressure was revealed (P<0·001) and neither exercise nor interaction between these factors, what suggests that transmural pressure decline, depended mainly on intrathoracic pressure developed during brief Valsalva manoeuvre. Resting blood pressure did not influence the effect of brief Valsalva manoeuvre on transmural pressure.