Heart rate variability in adults with chronic musculoskeletal pain: A systematic review.

PURPOSE: The aim of this review was to compare the heart rate variability (HRV) responses at rest of adults with chronic musculoskeletal pain against healthy controls. METHODS: The PubMed, Scopus, Web of Science (Science and Social Science Citation Index), and CINAHL databases were searched, with no date restrictions. Two independent reviewers selected observational studies that characterized the HRV responses at rest in adults with chronic musculoskeletal pain compared with those of healthy controls. Methodological quality was assessed using the Downs and Black checklist. RESULTS: This study followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses statement. HRV in adults with chronic musculoskeletal pain was evaluated systematically. Of the 4893 studies screened, 20 of poor-to-moderate quality met the inclusion criteria. Most studies used electrocardiography and at least one time and/or frequency domain index. Studies were found that investigated HRV in adults with temporomandibular disorders, neck pain, whiplash, low back pain, and fibromyalgia. The heterogeneity of the studies in relation to painful conditions, parameters or position for HRV analysis precluded a meta-analysis. In general, these studies seem to show increased sympathetic and decreased parasympathetic modulation in adults with musculoskeletal pain when compared to controls. CONCLUSIONS: Adults with musculoskeletal pain exhibited a decline in HRV compared to controls. However, definitive conclusions cannot be drawn since the evidence is heterogeneous and of moderate quality. Further high-quality research with standardized measurements is needed.

Changes of the cardiac baroreflex bandwidth during postural challenges.

Baroreflex is commonly typified from heart period (HP) and systolic arterial pressure (SAP) spontaneous variations in the frequency domain mainly by estimating its sensitivity. However, an informative parameter linked to the rapidity of the HP response to SAP changes, such as the baroreflex bandwidth, remains unquantified. We propose a model-based parametric approach for estimating the baroreflex bandwidth from the impulse response function (IRF) of the HP-SAP transfer function (TF). The approach accounts explicitly for the action of mechanisms modifying HP regardless of SAP changes. The method was tested during graded baroreceptor unloading induced by head-up tilt (HUT) at 15°, 30°, 45°, 60°, and 75° (T15, T30, T45, T60, and T75) in 17 healthy individuals (age: 21-36 yr; 9 females and 8 males) and during baroreceptor loading obtained via head-down tilt (HDT) at -25° in 13 healthy men (age: 41-71 yr). The bandwidth was estimated as the decay constant of the monoexponential IRF fitting. The method was robust because the monoexponential fitting described adequately the HP dynamics following an impulse of SAP. We observed that 1) baroreflex bandwidth is reduced during graded HUT and this narrowing is accompanied by the reduction of the bandwidth of mechanisms that modify HP regardless of SAP changes and 2) baroreflex bandwidth is not affected by HDT but that of SAP-unrelated mechanisms becomes wider. This study provides a method for estimating a baroreflex feature that provides different information compared with the more usual baroreflex sensitivity while accounting explicitly for the action of mechanisms changing HP irrespective of SAP.

Insights into the Serum Metabolic Adaptations in Response to Inspiratory Muscle Training: A Metabolomic Approach Based on 1H NMR and UHPLC-HRMS/MS.

Inspiratory muscle training (IMT) is known to promote physiological benefits and improve physical performance in endurance sports activities. However, the metabolic adaptations promoted by different IMT prescribing strategies remain unclear. In this work, a longitudinal, randomized, double-blind, sham-controlled, parallel trial was performed to investigate the effects of 11 weeks (3 days·week-1) of IMT at different exercise intensities on the serum metabolomics profile and its main regulated metabolic pathways. Twenty-eight healthy male recreational cyclists (30.4 ± 6.5 years) were randomized into three groups: sham (6 cm·H2O of inspiratory pressure, n = 7), moderate-intensity (MI group, 60% maximal inspiratory pressure (MIP), n = 11) and high-intensity (HI group, 85-90% MIP, n = 10). Blood serum samples were collected before and after 11 weeks of IMT and analyzed by 1H NMR and UHPLC-HRMS/MS. Data were analyzed using linear mixed models and metabolite set enrichment analysis. The 1H NMR and UHPLC-HRMS/MS techniques resulted in 46 and 200 compounds, respectively. These results showed that ketone body metabolism, fatty acid biosynthesis, and aminoacyl-tRNA biosynthesis were upregulated after IMT, while alpha linolenic acid and linoleic acid metabolism as well as biosynthesis of unsaturated fatty acids were downregulated. The MI group presented higher MIP, Tryptophan, and Valine levels but decreased 2-Hydroxybutyrate levels when compared to the other two studied groups. These results suggest an increase in the oxidative metabolic processes after IMT at different intensities with additional evidence for the upregulation of essential amino acid metabolism in the MI group accompanied by greater improvement in respiratory muscle strength.

The Aging Process: A Metabolomics Perspective.

Aging process is characterized by a progressive decline of several organic, physiological, and metabolic functions whose precise mechanism remains unclear. Metabolomics allows the identification of several metabolites and may contribute to clarifying the aging-regulated metabolic pathways. We aimed to investigate aging-related serum metabolic changes using a metabolomics approach. Fasting blood serum samples from 138 apparently healthy individuals (20−70 years old, 56% men) were analyzed by Proton Nuclear Magnetic Resonance spectroscopy (1H NMR) and Liquid Chromatography-High-Resolution Mass Spectrometry (LC-HRMS), and for clinical markers. Associations of the metabolic profile with age were explored via Correlations (r); Metabolite Set Enrichment Analysis; Multiple Linear Regression; and Aging Metabolism Breakpoint. The age increase was positively correlated (0.212 ≤ r ≤ 0.370, p < 0.05) with the clinical markers (total cholesterol, HDL, LDL, VLDL, triacylglyceride, and glucose levels); negatively correlated (−0.285 ≤ r ≤ −0.214, p < 0.05) with tryptophan, 3-hydroxyisobutyrate, asparagine, isoleucine, leucine, and valine levels, but positively (0.237 ≤ r ≤ 0.269, p < 0.05) with aspartate and ornithine levels. These metabolites resulted in three enriched pathways: valine, leucine, and isoleucine degradation, urea cycle, and ammonia recycling. Additionally, serum metabolic levels of 3-hydroxyisobutyrate, isoleucine, aspartate, and ornithine explained 27.3% of the age variation, with the aging metabolism breakpoint occurring after the third decade of life. These results indicate that the aging process is potentially associated with reduced serum branched-chain amino acid levels (especially after the third decade of life) and progressively increased levels of serum metabolites indicative of the urea cycle.

Can respiratory muscle training change the blood pressure levels in hypertension? A systematic review with meta-analysis.

The aim was to systematically review randomized controlled trials investigating the effects of respiratory training on blood pressure control in hypertensive individuals. Systematic review with meta-analysis was coducted following the guidelines from PRISMA statement. Searches for randomized controlled trials were performed in four electronic databases (PubMed, Cochrane Library, SCOPUS, and PEDro). Studies were included if they were randomized controlled trials that examined the impact of respiratory training on blood pressure of individuals with systemic arterial hypertension and the patients had no other associated disease. Eight studies were included for final analysis (total of 270 participants; 18-85 years) and presented an average score of 6.25 in the PEDro scale, being considered of high methodological quality. The meta-analysis showed a reduction in systolic and diastolic blood pressure for respiratory training when the load was applied [-15.72 (-18.63; -12.81) and -7.08 (-9.03; -5.13) mmHg, respectively]. There was also a reduction in systolic, but not in diastolic blood pressure when the training was performed without load [-5.08 (-7.49; -2.66) and -1.04 (-2.55; +0.46) mmHg, respectively]. The respiratory training has a positive effect in BP in hypertensive patients, however, only when performed with load seems to be able to promote some beneficial effect on diastolic blood pressure reduction.

Is pelvic floor muscle training able to alter the response of cardiovascular autonomic modulation and provide a possible cardiovascular benefit to pregnant women?

AIMS: To evaluate the acute and chronic effect of an exercise protocol of pelvic floor muscles (PFMs) contraction on the heart period (HP) and systolic arterial pressure (SAP) variabilities and baroreflex sensitivity (BRS) at rest in pregnant women; and to evaluate if this progressive exercise protocol was well-tolerated by the pregnant women studied. METHODS: We evaluated 48 women at 18 weeks of pregnancy by vaginal palpation, vaginal manometry, and cardiopulmonary exercise test. They were divided in control (CG; 31.75 ± 3.91 years) and training groups (TG; 30.71 ± 3.94 years). At 19 and 36 weeks of pregnancy, electrocardiogram and noninvasive peripheral SAP data were collected at rest before and after 10 PFM contractions. TG performed PFMT from the 20th to the 36th week. HP and SAP variabilities were analyzed by spectral and symbolic analysis. The baroreflex was evaluated by cross-spectral analysis between the HP and SAP series. RESULTS: The groups did not differ in relation to VO2 , HP and SAP variabilities, and BRS at the beginning of the protocol. TG increased the endurance of the PFM after training. PFM contraction did not change the HP and SAP variabilities, and BRS at the 18th week. After the training, the TG presented lower SAP mean, lower BF of SAP variability, and higher BRS than CG. CONCLUSIONS: Acute PFM contractions did not alter HP and SAP variabilities and BRS, but PFMT resulted in a lower SAP mean and higher BRS in trained pregnant when compared to the untrained.

Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p < 0.001). Peak torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p < 0.001). Eccentric knee extension torque was the only exercise tested that showed an interaction effect between age and muscle length (p < 0.001), which suggested different torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

Use of Heart Rate Variability to Estimate Lactate Threshold in Coronary Artery Disease Patients during Resistance Exercise.

The aim of this study was to investigate whether it is possible to identify the first turn point of blood lactate (BL) concentration (1st lactate threshold - LT1) during a discontinuous resistance exercise protocol in coronary artery disease (CAD) patients and verify if heart rate variability (HRV) responses are consistent with BL responses. A total of 22 elderly men, 12 with CAD and 10 apparently healthy (control group = CG), underwent one-repetition maximum (1RM) testing on an inclined leg press. Discontinuous resistance exercise testing (DRET) was initiated at 10% of the 1RM with subsequent increases of 10% until 30% and after this percentage, 5% increments of 1RM was carried out. The load corresponding to LT1 was approximately 30% 1RM in both groups; and the LT1 estimate by HRV was associated with BL responses. HRV indices representing parasympathetic modulation decreased with increasing loads until LT1 and stabilized thereafter in both groups, and HRV indices representing sympathetic and parasympathetic modulations only increased in the CAD group from 30% 1RM with higher values after this load in relation to the CG. We conclude HRV appears to be an effective tool to estimate the LT1 during discontinuous resistance exercise in patients with CAD. In addition, these results may have an impact on the prescription of endurance resistance exercise in the CAD population, as cardiac vagal modulation is an important indicator of cardiovascular protection and the over-activity of sympathetic modulation is related to cardiovascular risk.

Cardiac autonomic response to acute painful stimulus in individuals with chronic neck pain: A case-control study.

PURPOSE: Characterize heart rate and cardiac autonomic response to painful stimulus on neck pain. METHODS: Twenty-five individuals with neck pain and 25 healthy subjects were included. Heart rate variability and heart rate were assessed in the conditioned pain modulation test at pretest rest, during testing and in recovery. Heart rate variability indices were obtained using linear and nonlinear methods. RESULTS: No significant differences were observed between groups regarding heart rate and the linear methods (p > 0.05). However, significant difference was observed between groups regarding nonlinear methods (standard deviation of the instantaneous variability of beat-to-beat interval variability, p = 0.005) CONCLUSIONS: Individuals with chronic neck pain showed autonomic responses similar to those of their healthy counterparts during the conditioning stimulus.

On the Validity of Single Regression Strategy for Granger Causality Assessment in Cardiovascular and Cardiorespiratory Control Studies.

Granger causality (GC) analysis is based on the comparison between prediction error variances computed over the full and restricted models after identifying the coefficients of appropriate vector regressions. GC markers can be computed via a double regression (DR) approach identifying two separate, independent models and a single regression (SR) strategy optimizing the description of the dynamics of the target over the full model and, then, reusing some parts of it in the restricted model. The present study compares the SR and DR strategies over heart period (HP), systolic arterial pressure (SAP) and respiration (R) beat-to-beat series collected during a graded orthostatic challenge induced by head-up tilt in 17 healthy individuals (age: 21-36 yrs; median: 29 yrs; 9 females and 8 males). We found that the DR approach was more powerful than the SR one in detecting the expected stronger involvement of the baroreflex during the challenge, while the expected weaker cardiorespiratory coupling was identified by both SR and DR strategies. The less powerful ability of the SR approach was the result of the greater variance of GC markers compared to the DR strategy. We conclude that, contrary to the suggestions present in literature, the SR approach is not necessarily associated with a smaller dispersion of GC markers. Moreover, we suggest that additional factors, such as the strategy utilized to build embedding spaces and metric utilized to compare prediction error variances, might play an important role in differentiating SR and DR approaches.

Characterization of Multiple Regimes of Cardiorespiratory Phase Synchronization in Athletes Undergoing Inspiratory Muscle Training.

Cardiorespiratory phase synchronization (CRPS) is defined as the stable occurrence of n heartbeats within m respiratory cycles according to the n:m phase locking ratio (PLR). Since CRPS is an intermittent phenomenon where different phase synchronization regimes and epochs of phase unlocking can alternate within the same recording, an index of CRPS ideally should assess all potential PLRs present in the recording. However, traditional approaches compute the synchronization index (SYNC%) over a single n:m PLR, namely the one that maximizes CRPS. In the present work, we tested a synchronization index assessing the total percentage of heartbeats coupled to the inspiratory onset regardless of phase locking regimes (SYNC%sum) and we compared its efficacy to the more traditional SYNC%. Analysis was carried out in a cohort of 25 male amateur cyclists (age: 20-40 yrs) undergoing inspiratory muscle training (IMT) at different intensities. CRPS was assessed before and after the IMT protocol, during an experimental condition known to modify CRPS, namely active standing (STAND). We found that after a moderate intensity IMT at 60% of the maximal inspiratory pressure, SYNC%sum could detect the decrease in CRPS following STAND. This result was not visible using the more traditional SYNC%. Therefore, we stress the significant presence of different phase locking regimes in athletes and the importance of accounting for multiple PLRs in CRPS analysis.Clinical Relevance- Multiple phase locking regimes contribute significantly to cardiorespiratory control in amateur cyclists especially after inspiratory muscle training of moderate intensity.

Effects of a cardiopulmonary telerehabilitation using functional exercises in individuals after COVID-19 hospital discharge: A randomized controlled trial.

INTRODUCTION: Individuals with severe coronavirus disease 2019 (COVID-19) may present respiratory and motor complications, requiring rehabilitation programs (RP) for long periods. However, access to cardiopulmonary rehabilitation is poor. Cardiopulmonary telerehabilitation is an alternative for cardiopulmonary dysfunction, improving functional capacity, dyspnea, and quality of life. Moreover, few clinical trials verified the effectiveness of telerehabilitation using functional exercise for post-COVID symptoms. Thus, the present study aimed to verify the effects of cardiopulmonary telerehabilitation using functional and accessible exercises in individuals after COVID-19 hospital discharge. METHODS: This blinded, randomized, and controlled clinical trial and included 67 adult individuals after COVID-19 hospital discharge. Participants were randomized into the groups of telerehabilitation (TG; n = 33) and control (CG; n = 34). TG underwent an individualized exercise program (functional and accessible exercises) supervised by a physical therapist (videoconference), and CG received guidance on general care and self-monitoring of vital signs (videoconference). The primary outcome was performance and physiological responses on the 6-minute step test (6MST). Secondary outcomes were performance on the 2-minute stationary walk test (2MSWT), 30-second chair stand test (30CST), and quality of life using the 36-Item Short Form Health Survey (SF-36) questionnaire physical functioning concept (PF). RESULTS: Functional capacity (6MST) improved by 28 ± 17 steps in TG and 15 ± 26 in CG (p = 0.04). For secondary outcomes, performance on 2MSWT increased by 39 ± 6 steps in TG and 10 ± 6 in CG (p = 0.00); 30CST by 3 ± 1 repetitions in TG and 1.5 ± 0.5 in CG (p = 0.05); and PF (SF-36) by 17 ± 4 points in TG and 12 ± 4 in CG (p = 0.00). Also, peak oxygen uptake VO2peak (6MST) improved by 3.8 ± 1 mL min-1 kg-1 in TG and 4.1 ± 1 in CG (p = 0.6), and heart rate demand (6MST) by 11 ± 37% in TG and -4 ± 19% in CG (p = 0.04). CONCLUSIONS: Cardiopulmonary telerehabilitation using functional exercises improved the exercise and functional capacity assessed using 6MST, 30CST, and 2MSWT and the quality of life of individuals after COVID-19 hospital discharge.

Causal relationships between heart period and systolic arterial pressure during graded head-up tilt.

In physiological conditions, heart period (HP) affects systolic arterial pressure (SAP) through diastolic runoff and Starling's law, but, the reverse relation also holds as a result of the continuous action of baroreflex control. The prevailing mechanism sets the dominant temporal direction in the HP-SAP interactions (i.e., causality). We exploited cross-conditional entropy to assess HP-SAP causality. A traditional approach based on phases was applied for comparison. The ability of the approach to detect the lack of causal link from SAP to HP was assessed on 8 short-term (STHT) and 11 long-term heart transplant (LTHT) recipients (i.e., less than and more than 2 yr after transplantation, respectively). In addition, spontaneous HP and SAP variabilities were extracted from 17 healthy humans (ages 21-36 yr, median age 29 yr; 9 females) at rest and during graded head-up tilt. The tilt table inclinations ranged from 15 to 75° and were changed in steps of 15°. All subjects underwent recordings at every step in random order. The approach detected the lack of causal relation from SAP to HP in STHT recipients and the gradual restoration of the causal link from SAP to HP with time after transplantation in the LTHT recipients. The head-up tilt protocol induced the progressive shift from the prevalent causal direction from HP to SAP to the reverse causality (i.e., from SAP to HP) with tilt table inclination in healthy subjects. Transformation of phases into time shifts and comparison with baroreflex latency supported this conclusion. The proposed approach is highly efficient because it does not require the knowledge of baroreflex latency. The dependence of causality on tilt table inclination suggests that "spontaneous" baroreflex sensitivity estimated using noncausal methods (e.g., spectral and cross-spectral approaches) is more reliable at the highest tilt table inclinations.

Moderate- and High-Intensity Inspiratory Muscle Training Equally Improves Inspiratory Muscle Strength and Endurance-A Double-Blind Randomized Controlled Trial.

BACKGROUND AND OBJECTIVE: Inspiratory muscle training (IMT) produced outstanding results in the physical performance of active subjects; however, little is known about the best training intensity for this population. The objective was to investigate the impact of an IMT of high intensity, using the critical inspiratory pressure (CIP), on inspiratory muscle strength (IMS), inspiratory muscle endurance (IME), peak power, and oxygen uptake of recreational cyclists; and to compare these results with moderate-intensity IMT (60% of maximal inspiratory pressure [MIP]). METHODS: Thirty apparently healthy male recreational cyclists, 20-40 years old, underwent 11 weeks of IMT (3 times per week; 55 min per session). Participants were randomized into 3 groups: sham group (6 cmH2O; n = 8); 60% MIP (MIP60; n = 10) and CIP (n = 12). All participants performed the IMS test and incremental IME test at the first, fifth, ninth, and 13th weeks of the experimental protocol. Cardiopulmonary exercise testing was performed on an electromagnetic braking cycle ergometer pre-IMT and post-IMT. Data were analyzed using a 2-way repeated measures ANOVA (group and period factors). RESULTS: IMS increased in CIP and MIP60 groups at the ninth and 13th weeks compared with the sham group (P < .001; ß = 0.99). Regarding IME, there was an interaction between the CIP and MIP60 groups in all periods, except in the initial evaluation (P < .001; ß = 1.00). Peak power (in watts) increased after IMT in CIP and MIP60 groups (P = .01; ß = 0.67). Absolute oxygen uptake did not increase after IMT (P = .49; ß = 0.05). Relative oxygen uptake to lean mass values did not change significantly (P = .48; ß = 0.05). CONCLUSION: High-intensity IMT is beneficial on IMS, IME, and peak power, but does not provide additional gain to moderate intensity in recreational cyclists.

Heart-rate variability and blood-lactate threshold interaction during progressive resistance exercise in healthy older men.

The objective of this study was to (a) evaluate the impact of the leg press, at variable percentages of 1 repetition maximum (1RM), on heart rate variability (HRV) and blood lactate and (b) determine the relationship between HRV with blood lactate in a healthy elderly cohort. Ten healthy men (64 +/- 4 years) participated in a progressive leg-press protocol to maximal exertion. Initially, 1RM for the leg press was determined for all subjects. The protocol then began at 10% of 1RM, with subsequent increases of 10% until 30% of 1RM, followed by incremental adjustments of 5% until exhaustion. The measurement of instantaneous R-R interval variability from Poincare plots (SD1 and SD2) and time domain indexes (RMSSD and RMSM), blood pressure, and blood lactate were obtained at rest and all leg-press loads. Significant alterations of HRV and blood lactate were observed from 30% of 1RM leg press (p < 0.05). Additionally, significant correlations were found between the lactate threshold (LT) and the RMSSD threshold (r = 0.78; p < 0.01), and between the LT and SD1 threshold (r = 0.81, p < 0.01). We conclude that metabolic and cardiovascular alterations are apparent during relatively low resistance exercise (RE) loads in apparently healthy subjects. In addition, HRV indexes were associated with blood-lactate levels during RE. The practical applications is the possibility of using HRV as a noninvasive measure obtained at a relatively low cost may be used to identify neural and metabolic alterations during RE in older subjects.

Oxylipin Response to Acute and Chronic Exercise: A Systematic Review.

Oxylipins are oxidized compounds of polyunsaturated fatty acids that play important roles in the body. Recently, metabololipidomic-based studies using advanced mass spectrometry have measured the oxylipins generated during acute and chronic physical exercise and described the related physiological effects. The objective of this systematic review was to provide a panel of the primary exercise-related oxylipins and their respective functions in healthy individuals. Searches were performed in five databases (Cochrane, PubMed, Science Direct, Scopus and Web of Science) using combinations of the Medical Subject Headings (MeSH) terms: "Humans", "Exercise", "Physical Activity", "Sports", "Oxylipins", and "Lipid Mediators". An adapted scoring system created in a previous study from our group was used to rate the quality of the studies. Nine studies were included after examining 1749 documents. Seven studies focused on the acute effect of physical exercise while two studies determined the effects of exercise training on the oxylipin profile. Numerous oxylipins are mobilized during intensive and prolonged exercise, with most related to the inflammatory process, immune function, tissue repair, cardiovascular and renal functions, and oxidative stress.

Cardiovascular responses to pelvic floor muscle contraction in healthy women: Prospective study.

OBJECTIVE: Analyze the acute heart rate and blood pressure responses to two protocols of pelvic floor muscles contractions in premenopausal and postmenopausal women. METHODS: Fifty-four women without pelvic floor muscles disorders were eligible and allocated into two groups: premenopausal and postmenopausal. The groups underwent two protocols and the pelvic floor muscle endurance, heart rate, and blood pressure values were monitored. Both protocols included 10 pelvic floor muscles contractions; one series contained contractions lasting 5 s with 5 s of rest between each contraction and the other series contained contractions lasting 10 s with 10 s of rest. RESULTS: In both groups, there was a significant increase in the heart rate during pelvic floor muscles contractions (premenopausal: 71.0 ± 7.3 and 80.3 ± 7.7; postmenopausal: 65.4 ± 6.6 and 73.6 ± 6.6, at rest and contractions peak, respectively) and in systolic blood pressure immediately after the contractions. The observed values during exercise returned to basal values seconds after the contractions. A positive correlation between heart rate and vaginal squeeze pressure (r = 0.45, p = 0.0007 and r = 0.48, p = 0.0003, 5- and 10-s series, respectively) was observed. CONCLUSION: The proposed protocol of isometric pelvic floor muscles contractions caused an increase in heart rate and blood pressure within the normal range and might not represent a cardiovascular risk for healthy postmenopausal women without urinary incontinence and without cardiovascular dysfunctions.

Chronic Influence of Inspiratory Muscle Training at Different Intensities on the Serum Metabolome.

This study investigated the chronic effect of inspiratory muscle training (IMT) on the human serum metabolome in healthy male recreational cyclists. Using a randomized, parallel group design, twenty-eight participants were randomized to three IMT groups: low intensity (LI, n = 7); moderate intensity (MI, n = 10); and high intensity (HI, n = 11). The IMT was performed for 11 weeks. Another group of participants under the same conditions, who did not perform the IMT but participated in all procedures, was included as controls (CG, n = 6). Blood samples were collected one week before and after 11 weeks of IMT and analyzed for metabolite shifts using 1H NMR. Statistical analysis included a 4 (group) × 2 (time) repeated measures ANOVA using the general linear model (GLM), and multivariate principal component analysis (PCA). Untargeted metabolomics analysis of serum samples identified 22 metabolites, including amino acids, lipids, and tricarboxylic acid cycle intermediates. Metabolites shifts did not differ between groups, indicating that IMT at three intensity levels did not alter the serum metabolome relative to the control group. These results reveal novel insights into the metabolic effects of the IMT and are consistent with the results from other studies showing negligible chronic alterations in the serum metabolome in response to physical training.

Metabolomics-Based Studies Assessing Exercise-Induced Alterations of the Human Metabolome: A Systematic Review.

This systematic review provides a qualitative appraisal of 24 high-quality metabolomics-based studies published over the past decade exploring exercise-induced alterations of the human metabolome. Of these papers, 63% focused on acute metabolite changes following intense and prolonged exercise. The best studies utilized liquid chromatography mass spectrometry (LC-MS/MS) analytical platforms with large chemical standard libraries and strong, multivariate bioinformatics support. These studies reported large-fold changes in diverse lipid-related metabolites, with more than 100 increasing two-fold or greater within a few hours post-exercise. Metabolite shifts, even after strenuous exercise, typically return to near pre-exercise levels after one day of recovery. Few studies investigated metabolite changes following acute exercise bouts of shorter durations (< 60 min) and workload volumes. Plasma metabolite shifts in these types of studies are modest in comparison. More cross-sectional and exercise training studies are needed to improve scientific understanding of the human system's response to varying, chronic exercise workloads. The findings derived from this review provide direction for future investigations focused on the body's metabolome response to exercise.

Assessment of the Coupling Strength of Cardiovascular Control via Joint Symbolic Analysis during Postural Challenge in Recreational Athletes.

Short-term cardiovascular control, comprising cardiac baroreflex and mechanisms governing cardiac contractility and vascular properties, links heart period (HP) and systolic arterial pressure (SAP) fluctuations. It is activated during postural challenge and this activation is traditionally quantified via linear tools such as HP-SAP squared coherence function. In this study the ability of a nonlinear bivariate tool based on joint symbolic analysis (JSA) approach was tested against HP-SAP coherence function during orthostatic challenge in recreational athletes. We studied 9 men healthy cycling practitioners (age: 20-40 yrs) at rest in supine condition (REST) and during active standing (STAND). The JSA method is based on the definition of symbolic HP and SAP patterns and on the evaluation of the rate of their simultaneous occurrence in both HP and SAP series. HP-SAP squared coherence was computed in the low frequency band (LF, from 0.04 to 0.15 Hz). We found the expected response to the postural stimulus, namely the increase of sympathetic modulation and the contemporaneous vagal withdrawal. However, only JSA was able to detect the expected increase of association between HP and SAP variability series over slow time scales. This result suggests that recreational athletes have more relevant nonlinear interactions between HP and SAP that might be missed by traditional linear tools and might require nonlinear tools to be efficiently described.