Physiological adaptations of active postmenopausal women and matched men to the multi-day Sardinia Selvaggio Blu wild trek: a gender-comparative pilot study.

PURPOSE: To evaluate the effects of wild trekking by examining, in postmenopausal women, the physiological adaptations to an intensive 5-day wild trek and comparing their responses to those displayed by a group of men of comparable age, training status and mountaineering skills. METHODS: Six healthy, active postmenopausal women in their sixth decade of life participated in the study. Six men of comparable age and training status were also enrolled for gender-based comparisons. The participants traversed the Selvaggio Blu wild trek (Sardinia, Italy) completing a total of 56 km, for an overall height differential of 14,301 m. During all 5-day trek, subjects were supervised by two alpine guides. Changes in body composition, cardiorespiratory fitness, and metabolic patterns of energy expenditure were evaluated before and after the intervention. RESULTS: Total energy expenditure during the trek was significantly higher (p = 0.03) in women (12.88 ± 3.37 kcal/h/kg) than men (9.27 ± 0.89 kcal/h/kg). Extracellular (ECW) and intracellular water (ICW) increased significantly following the trek only in women (ECW: - 3.8%; p = 0.01; ICW: + 3.4%; p = 0.01). The same applied to fat-free mass (+ 5.6%; p = 0.006), fat mass (- 20.4%; p = 0.006), skeletal muscle mass (+ 9.5%; p = 0.007), and appendicular muscle mass (+ 7.3%; p = 0.002). Peak VO2/kg (+ 9.4%; p = 0.05) and fat oxidation (at 80 W: + 26.96%; p = 0.04; at 100 W: + 40.95%; p = 0.02; at 120 W: + 83.02%; p = 0.01) were found increased only in women, although no concurrent changes in partial pressure of end-tidal CO2 (PETCO2) was observed. CONCLUSIONS: In postmenopausal women, a 5-day, intensive and physically/technically demanding outdoor trekking activity led to significant and potentially relevant changes in body composition, energy balance and metabolism that are generally attained following quite longer periods of training.

Ischemic preconditioning of the muscle reduces the metaboreflex response of the knee extensors.

PURPOSE: This study investigated the effect of ischemic preconditioning (IP) on metaboreflex activation following dynamic leg extension exercise in a group of healthy participants. METHOD: Seventeen healthy participants were recruited. IP and SHAM treatments (3 × 5 min cuff occlusion at 220 mmHg or 20 mmHg, respectively) were administered in a randomized order to the upper part of exercising leg's thigh only. Muscle pain intensity (MP) and pain pressure threshold (PPT) were monitored while administrating IP and SHAM treatments. After 3 min of leg extension exercise at 70% of the maximal workload, a post-exercise muscle ischemia (PEMI) was performed to monitor the discharge group III/IV muscle afferents via metaboreflex activation. Hemodynamics were continuously recorded. MP was monitored during exercise and PEMI. RESULTS: IP significantly reduced mean arterial pressure compared to SHAM during metaboreflex activation (mean ± SD, 109.52 ± 7.25 vs. 102.36 ± 7.89 mmHg) which was probably the consequence of a reduced end diastolic volume (mean ± SD, 113.09 ± 14.25 vs. 102.42 ± 9.38 ml). MP was significantly higher during the IP compared to SHAM treatment, while no significant differences in PPT were found. MP did not change during exercise, but it was significantly lower during the PEMI following IP (5.10 ± 1.29 vs. 4.00 ± 1.54). CONCLUSION: Our study demonstrated that IP reduces hemodynamic response during metaboreflex activation, while no effect on MP and PPT were found. The reduction in hemodynamic response was likely the consequence of a blunted venous return.

Combined mental task and metaboreflex impair cerebral oxygenation in patients with type 2 diabetes mellitus.

Cardiovascular regulation is altered by type 2 diabetes mellitus (DM2), producing an abnormal response to muscle metaboreflex. During physical exercise, cerebral blood flow is impaired in patients with DM2, and this phenomenon may reduce cerebral oxygenation (COX). We hypothesized that the simultaneous execution of a mental task (MT) and metaboreflex activation would reduce COX in patients with DM2. Thirteen individuals suffering from DM2 (6 women) and 13 normal age-matched controls (CTL, 6 women) participated in this study. They underwent five different tests, each lasting 12 min: postexercise muscle ischemia (PEMI) to activate the metaboreflex, control exercise recovery (CER), PEMI + MT, CER + MT, and MT alone. COX was evaluated using near-infrared spectroscopy with sensors applied to the forehead. Central hemodynamics was assessed using impedance cardiography. We found that when MT was superimposed on the PEMI-induced metaboreflex, patients with DM2 could not increase COX to the same extent reached by the CTL group (101.13% ± 1.08% vs. 104.23% ± 2.51%, P < 0.05). Moreover, patients with DM2 had higher mean blood pressure and systemic vascular resistance as well as lower stroke volume and cardiac output levels compared with the CTL group, throughout our experiments. It was concluded that patients with DM2 had reduced capacity to enhance COX when undertaking an MT during metaboreflex. Results also confirm that patients with DM2 had dysregulated hemodynamics during metaboreflex, with exaggerated blood pressure response and vasoconstriction. This may have implications for these patients' lack of inclination to exercise.

Muscle metaboreflex adaptations to exercise training in health and disease.

Abnormalities in the muscle metaboreflex concur to exercise intolerance and greater cardiovascular risk. Exercise training benefits neurocardiovascular function at rest and during exercise, but its role in favoring muscle metaboreflex in health and disease remains controversial. While some authors demonstrated that exercise training enhanced the sensitization of muscle metabolically afferents and improved neurocardiovascular responses to muscle metaboreflex activation, others reported unaltered responses. This narrative review aimed to: (a) highlight the current evidence on the effects of exercise training upon cardiovascular and autonomic responses to muscle metaboreflex activation; (b) analyze the role of training components and indicate potential mechanisms of metaboreflex adaptations; and (c) address key methodological features for future research. Though limited, accumulated evidence suggests that muscle metaboreflex adaptations depend on the individual clinical status, exercise modality, and training duration. In healthy populations, most trials negated the hypothesis of metaboreflex improvement due to chronic exercise, irrespective of the training duration. Favorable changes in patients with impaired metaboreflex, particularly chronic heart failure, mostly resulted from long-term interventions (> 16 weeks) including aerobic exercise of moderate to high intensity, performed in isolation or within multimodal training. Potential mechanisms of metaboreflex improvements include enhanced sensitivity of channels and receptors, greater antioxidant capacity, lower metabolite accumulation, increased functional sympatholysis, and muscle perfusion. Future research should investigate: (1) the dose-response relationship of training components within different exercise modalities to elicit improvements in individuals showing intact or impaired muscle metaboreflex; and (2) potential and specific underlying mechanisms of metaboreflex improvements in individuals with different medical conditions.

Blood Pressure Response to Muscle Metaboreflex Activation is Impaired in Men Living with HIV.

We investigated the muscle metaboreflex contribution to blood pressure response during dynamic handgrip exercise in men living with HIV (MLHIV) vs. without HIV (Controls). Pressor and heart rate responses were evaluated during metaboreflex activation through post-exercise muscle ischemia (PEMI) method and control exercise session (CER) in 17 MLHIV and 21 Controls. Protocols were performed randomly on the same day, being both sessions composed of 12 min, as follows: a) 3 min at rest, b) 3 min of dynamic handgrip exercise at 30% of maximal voluntary contraction, c) 3 min of recovery post-exercise with vascular occlusion (occlusion only in PEMI), and d) 3 min of recovery post-exercise without vascular occlusion. To assess metaboreflex response, differences between PEMI and CER in recovery post-exercise were calculated for blood pressure and heart rate. Systolic and mean blood pressure (P<0.01) were superior in the last 2 min of recovery with vascular occlusion at PEMI in relation to CER for both groups. No difference was found between groups for blood pressure and heart rate (P>0.05). However, metaboreflex response for systolic blood pressure was lower in MLHIV vs. Controls (4.05±4.63 vs. 7.61±3.99 mmHg; P=0.01). In conclusion, pressor response during metaboreceptor stimulation was attenuated in men living with HIV, which may suggest loss of muscle metaboreflex sensibility.

Moderate Exercise Improves Cognitive Function in Healthy Elderly People: Results of a Randomized Controlled Trial.

BACKGROUND: Physical activity in the elderly is recommended by international guidelines to protect against cognitive decline and functional impairment. OBJECTIVE: This Randomized Controlled Trial (RCT) was set up to verify whether medium-intensity physical activity in elderly people living in the community is effective in improving cognitive performance. DESIGN: RCT with parallel and balanced large groups. SETTING: Academic university hospital and Olympic gyms. SUBJECTS: People aged 65 years old and older of both genders living at home holding a medical certificate for suitability in non-competitive physical activity. METHODS: Participants were randomized to a 12-week, 3 sessions per week moderate physical activity program or to a control condition focused on cultural and recreational activities in groups of the same size and timing as the active intervention group. The active phase integrated a mixture of aerobic and anaerobic exercises, including drills of "life movements", strength and balance. The primary outcome was: any change in Addenbrooke's Cognitive Examination Revised (ACE-R) and its subscales. RESULTS: At the end of the trial, 52 people completed the active intervention, and 53 people completed the control condition. People in the active intervention improved on the ACE-R (ANOVA: F(1;102)=4.32, p=0.040), and also showed better performances on the memory (F(1;102)=5.40 p=0.022) and visual-space skills subscales of the ACE-R (F(1;102)=4.09 p=0.046). CONCLUSION: A moderate-intensity exercise administered for a relatively short period of 12 weeks is capable of improving cognitive performance in a sample of elderly people who live independently in their homes.Clinical Trials Registration No: NCT03858114.

A brief bout of exercise in hypoxia reduces ventricular filling rate and stroke volume response during muscle metaboreflex activation.

PURPOSE: The hemodynamic consequences of exercise in hypoxia have not been completely investigated. The present investigation aimed at studying the hemodynamic effects of contemporary normobaric hypoxia and metaboreflex activation. METHODS: Eleven physically active, healthy males (age 32.7 ± 7.2 years) completed a cardiopulmonary test on an electromagnetically braked cycle-ergometer to determine their maximum workload (Wmax). On separate days, participants performed two randomly assigned exercise sessions (3 minutes pedalling at 30% of Wmax): (1) one in normoxia (NORMO), and (2) one in normobaric hypoxia with FiO2 set to 13.5% (HYPO). After each session, the following protocol was randomly assigned: either (1) post-exercise muscle ischemia (PEMI) to study the metaboreflex, or (2) a control exercise recovery session, i.e., without metaboreflex activation. Hemodynamics were assessed with impedance cardiography. RESULTS: The main result was that the HYPO session impaired the ventricular filling rate (measured as stroke volume/diastolic time) response during PEMI versus control condition in comparison to the NORMO test (31.33 ± 68.03 vs. 81.52 ± 49.23 ml·s-1,respectively, p = 0.003). This caused a reduction in the stroke volume response (1.45 ± 9.49 vs. 10.68 ± 8.21 ml, p = 0.020). As a consequence, cardiac output response was impaired during the HYPO test. CONCLUSIONS: The present investigation suggests that a brief exercise bout in hypoxia is capable of impairing cardiac filling rate as well as stroke volume during the metaboreflex. These results are in good accordance with recent findings showing that among hemodynamic modulators, ventricular filling is the most sensible variable to hypoxic stimuli.

Diabetic Cardiomyopathy and Ischemic Heart Disease: Prevention and Therapy by Exercise and Conditioning.

Metabolic syndrome, diabetes, and ischemic heart disease are among the leading causes of death and disability in Western countries. Diabetic cardiomyopathy is responsible for the most severe signs and symptoms. An important strategy for reducing the incidence of cardiovascular disease is regular exercise. Remote ischemic conditioning has some similarity with exercise and can be induced by short periods of ischemia and reperfusion of a limb, and it can be performed in people who cannot exercise. There is abundant evidence that exercise is beneficial in diabetes and ischemic heart disease, but there is a need to elucidate the specific cardiovascular effects of emerging and unconventional forms of exercise in people with diabetes. In addition, remote ischemic conditioning may be considered among the options to induce beneficial effects in these patients. The characteristics and interactions of diabetes and ischemic heart disease, and the known effects of exercise and remote ischemic conditioning in the presence of metabolic syndrome and diabetes, are analyzed in this brief review.

Effects of exercise in normobaric hypoxia on hemodynamics during muscle metaboreflex activation in normoxia.

PURPOSE: Little is known about the cardiovascular effects of the transition from exercise in hypoxia (EH) to normoxia. This investigation aimed to assess hemodynamics during the metaboreflex elicited in normoxia after EH. METHODS: Ten trained athletes (four females and six males, age 35.6 ± 8.4 years) completed a cardiopulmonary test to determine the workload at anaerobic threshold (AT). On separate days, participants performed three randomly assigned exercise sessions (10 min pedalling at 80% of AT): (1) one in normoxia (EN); (2) one in normobaric hypoxia with FiO2 15.5% (EH15.5%); and (3) one in normobaric hypoxia with FiO2 13.5% (EH13.5%). After each session, the following protocol was randomly assigned: either (1) post-exercise muscle ischemia after cycling for 3 min, to study the metaboreflex, or (2) a control exercise recovery (CER) session, without any metaboreflex stimulation. RESULTS: The main result were that both EH15.5% and EH13.5% impaired (p < 0.05) the ventricular filling rate response during the metaboreflex (- 18 ± 32 and - 20 ± 27 ml s-1), when compared to EN (+ 29 ± 32 ml s-1), thereby causing a reduction in stroke volume response (- 9.1 ± 3.2, - 10.6 ± 8.7, and + 5 ± 5.7 ml for EH15.5%, EH13.5% and EN test, respectively, p < 0.05). Moreover, systemic vascular resistance was increased after the EH15.5% and the EH13.5% in comparison with the EN test. CONCLUSIONS: These data demonstrate that moderate exercise in hypoxia impairs the capacity to enhance venous return during the metaboreflex stimulated in normoxia. Overall, there is a functional shift from a flow to vasoconstriction-mediated mechanism for maintaining the target blood pressure during the metaboreflex.

Metaboreflex-mediated hemodynamic abnormalities in individuals with coronary artery disease without overt signs or symptoms of heart failure.

This study was devised to investigate the effect of coronary artery disease (CAD) without overt signs of heart failure on the cardiovascular responses to muscle metaboreflex activation. We hypothesized that any CAD-induced preclinical systolic and/or diastolic dysfunction could impair hemodynamic response to the metaboreflex test. Twelve men diagnosed with CAD without any sign or symptoms of heart failure and 11 age-matched healthy control (CTL) subjects participated in the study. Subjects performed a postexercise muscle ischemia (PEMI) test to activate the metaboreflex. They also performed a control exercise recovery test to compare data from the PEMI test. The main results were that the CAD group reached a similar mean arterial blood pressure response as the CTL group during PEMI. However, the mechanism by which this response was achieved was different between groups. In particular, CAD achieved the target mean arterial blood pressure by increasing systemic vascular resistance (+383.8 ± 256.6 vs. +91.2 ± 293.5 dyn·s-1·cm-5 for the CAD and CTL groups, respectively), the CTL group by increasing cardiac preload (-0.92 ± 8.53 vs. 5.34 ± 4.29 ml in end-diastolic volume for the CAD and CTL groups, respectively), which led to an enhanced stroke volume and cardiac output. Furthermore, the ventricular filling rate response was higher in the CTL group than in the CAD group during PEMI ( P < 0.05 for all comparisons). This study confirms that diastolic function is pivotal for normal hemodynamics during the metaboreflex. Moreover, it provides evidence that early signs of diastolic impairment attributable to CAD can be detected by the metaboreflex test. NEW & NOTEWORTHY Individuals suffering from coronary artery disease without overt signs of heart failure may show early signs of diastolic dysfunction, which can be detected by the metaboreflex test. During the metaboreflex, these subjects show impaired preload and stroke volume responses and exaggerated vasoconstriction compared with controls.

Cardiorespiratory responses and myocardial function within incremental exercise in healthy unmedicated older vs. young men and women.

BACKGROUND: Age-related differences concerning cardiorespiratory responses and myocardial function during exercise have not been extensively investigated in healthy populations. AIMS: To compare cardiorespiratory performance and myocardial function during maximal exercise in healthy/unmedicated men (older, n = 24, 63-75 years; young, n = 22, 19-25 years) and women (older, n = 18, age = 63-74 years; young, n = 23, 19-25 years). METHODS: Oxygen uptake (VO2), ventilation minute (V E), heart rate (HR), stroke volume (SV), cardiac output (Q), O2 pulse (O2p), preejection period (PEP), and left ventricular ejection time (LVET) were assessed during cycle incremental exercise. RESULTS: HR and SV remained equivalent between age groups until 75 and 50% peak workload, respectively. Q increased by 2.5 and 4.5 times in older and young groups, respectively. However, Q/VO2 ratio was always similar across age and sex groups (∼0.50). The energetic efficiency ratio (W/VO2) was also alike in older and young men, but slightly lower in women. At maximal exercise, cardiorespiratory responses were lower in older than young men and women: VO2 (-40 to 50%), V E (-35 to 37%), HR (-23%), SV (-26 to 29%), Q (-43 to 45%), and O2p (-15 to 20%). Cardiac and SV indices were lower in older than young groups by approximately 42 and 25%, respectively. LVET was longer in the older individuals, while PEP was similar across age groups. Hence, PEP/LVET was lowered among older vs. young men and women. CONCLUSION: Submaximal work capacity was preserved in healthy and unmedicated older individuals. Age-related lessening of maximal performance in both sexes was due to poor chronotropic and, particularly, inotropic properties of the heart.

Case Study: Physical Capacity and Nutritional Status Before and After a Single-Handed Yacht Race.

During solitary sailing, the sailor is exposed to sleep deprivation and difficulties in consuming regular meals. Sailor weight loss is often reported. In the present case study, we describe changes in the physical capacity and nutritional status of an athlete attempting a single-handed yacht race around the globe. An Italian male ocean racer (Gaetano Mura) asked for our help to reach an optimum level of physical and nutritional preparation. We planned his diet after assessing his anthropometric parameters and body composition, as well as his usual energy intake and nutritional expenditure. The diet consisted of 120 meals stored in sealed plastic bags. Before his departure, GM performed two incremental exercise tests (cycle ergometry and arm crank ergometry) to assess his physical capacity. Cardiac functions were also estimated by Doppler echocardiography. All measures and exercise tests were repeated 10 days after GM finished the race, which lasted 64 days. Anthropometric measures did not change significantly, with the exception of arm fat area and thigh muscle area, which decreased. There were evident increments in maximum oxygen intake and maximum workload during arm cranking after the race. On the contrary, maximum oxygen uptake and maximum workload decreased during cycling. Finally, end-diastolic and stroke volume decreased after the race. It was concluded that nutritional counseling was useful to avoid excessive changes in nutritional status and body composition due to 64 days of solitary navigation. However, a reduction in physical leg capacity and cardiovascular functions secondary to leg disuse were present.

Ischemic preconditioning reduces hemodynamic response during metaboreflex activation.

Ischemic preconditioning (IP) has been shown to improve exercise performance and to delay fatigue. However, the precise mechanisms through which IP operates remain elusive. It has been hypothesized that IP lowers the sensation of fatigue by reducing the discharge of group III and IV nerve endings, which also regulate hemodynamics during the metaboreflex. We hypothesized that IP reduces the blood pressure response during the metaboreflex. Fourteen healthy males (age between 25 and 48 yr) participated in this study. They underwent the following randomly assigned protocol: postexercise muscle ischemia (PEMI) test, during which the metaboreflex was elicited after dynamic handgrip; control exercise recovery session (CER) test; and PEMI after IP (IP-PEMI) test. IP was obtained by occluding forearm circulation for three cycles of 5 min spaced by 5 min of reperfusion. Hemodynamics were evaluated by echocardiography and impedance cardiography. The main results were that after IP the mean arterial pressure response was reduced compared with the PEMI test (means ± SD +3.37 ± 6.41 vs. +9.16 ± 7.09 mmHg, respectively). This was the consequence of an impaired venous return that impaired the stroke volume during the IP-PEMI more than during the PEMI test (-1.43 ± 15.35 vs. +10.28 ± 10.479 ml, respectively). It was concluded that during the metaboreflex, IP affects hemodynamics mainly because it impairs the capacity to augment venous return and to recruit the cardiac preload reserve. It was hypothesized that this is the consequence of an increased nitric oxide production, which reduces the possibility to constrict venous capacity vessels.

Cardio-metabolic responses during horse riding at three different speeds.

PURPOSE: The purpose of the present investigation was to study the metabolic demand and cardiovascular response during a typical horse riding session. METHODS: To this aim, 19 (9 male, 10 female) riders, regularly participating in competitions, were enrolled. They underwent a preliminary, incremental exercise test on a cycle-ergometer to assess their anaerobic threshold (AT) and VO2max. Then, participants underwent a riding training session, which comprised periods of walking, trotting, and cantering for a total of 20 min. Oxygen uptake (VO2), carbon dioxide production (VCO2), and heart rate (HR) were obtained throughout the preliminary and riding test by means of a portable metabolic system. Moreover, excess of CO2 production (CO2excess) and oxygen pulse (OP) were also calculated to obtain an estimate of anaerobic glycolysis and stroke volume. RESULTS: The main result was that all collected parameters remained below the AT level throughout the riding session, with the exception of HR that approached the AT level only during cantering. In detail, during cantering, average VO2, VCO2, HR, CO2excess, and OP values were 1289 ± 331 mL min(-1), 1326 ± 266 mL min(-1), 158 ± 22 bpm, 215 ± 119 mL min(-1), and 7.8 ± 1.6 mL/bpm, respectively. CONCLUSIONS: It was concluded that riding imposes only light to moderate stress on the aerobic and anaerobic energy systems. Moreover, cardiovascular reserve is only moderately recruited in terms of inotropism, while chronotropism can be stimulated more.

Mean Blood Pressure Assessment during Post-Exercise: Result from Two Different Methods of Calculation.

At rest the proportion between systolic and diastolic periods of the cardiac cycle is about 1/3 and 2/3 respectively. Therefore, mean blood pressure (MBP) is usually calculated with a standard formula (SF) as follows: MBP = diastolic blood pressure (DBP) + 1/3 [systolic blood pressure (SBP) - DBP]. However, during exercise this proportion is lost because of tachycardia, which shortens diastole more than systole. We analysed the difference in MBP calculation between the SF and a corrected formula (CF) which takes into account changes in the diastolic and systolic periods caused by exercise-induced tachycardia. Our hypothesis was that the SF potentially induce a systematic error in MBP assessment during recovery after exercise. Ten healthy males underwent two exercise-recovery tests on a cycle-ergometer at mild-moderate and moderate-heavy workloads. Hemodynamics and MBP were monitored for 30 minutes after exercise bouts. The main result was that the SF on average underestimated MBP by -4.1 mmHg with respect to the CF. Moreover, in the period immediately after exercise, when sustained tachycardia occurred, the difference between SF and CF was large (in the order of -20-30 mmHg). Likewise, a systematic error in systemic vascular resistance assessment was present. It was concluded that the SF introduces a substantial error in MBP estimation in the period immediately following effort. This equation should not be used in this situation.

Differences in hemodynamic response to metaboreflex activation between obese patients with metabolic syndrome and healthy subjects with obese phenotype.

Patients suffering from obesity and metabolic syndrome (OMS) manifest a dysregulation in hemodynamic response during exercise, with an exaggerated systemic vascular increase. However, it is not clear whether this is the consequence of metabolic syndrome per se or whether it is due to concomitant obesity. The aim of the present investigation was to discover whether OMS and noncomplicated obesity resulted in different hemodynamic responses during the metaboreflex. Twelve metabolically healthy but obese subjects (MHO; 7 women), 13 OMS patients (5 women), and 12 normal age-matched controls (CTL; 6 women) took part in this study. All participants underwent a postexercise muscle ischemia protocol to evaluate the metaboreflex activity. Central hemodynamics were evaluated by impedance cardiography. The main result shows an exaggerated increase in systemic vascular resistance from baseline during the metaboreflex in the OMS patients as compared with the other groups (481.6 ± 180.3, -0.52 ± 177.6, and -60.5 ± 58.6 dynes·s(-1)·cm(-5) for the OMS, the MHO, and the CTL groups, respectively; P < 0.05). Moreover, the MHO subjects and the CTL group showed an increase in cardiac output during the metaboreflex (288.7 ± 325.8 and 703.8 ± 276.2 ml/m increase with respect to baseline), whereas this parameter tended to decrease in the OMS group (-350 ± 236.5 ml/m). However, the blood pressure response, which tended to be higher in the OMS patients, was not statistically different between groups. The results of the present investigation suggest that OMS patients have an exaggerated vasoconstriction in response to metaboreflex activation and that this fact is not due to obesity per se.

Effect of aging on hemodynamic response to metaboreflex activation.

PURPOSE: The aim of the present investigation was to assess the role of aging on the contribution of diastolic function during metaboreflex activation. In particular, it aimed to determine whether age-related impairment in diastolic function would produce a different hemodynamic response in elderly subjects (EG) as compared to young controls (CTL). METHODS: Hemodynamic response to metaboreflex activation obtained by post-exercise muscle ischemia (PEMI) was gathered in 22 EG and 20 healthy CTL. Subjects also performed a control exercise recovery (CER) test to compare data from the PEMI test. RESULTS: The main results showed that the EG group reached higher mean arterial blood pressure (MAP) increment than the CTL group during the PEMI test (+11.2 ± 8.6 vs 6.1 ± 6.4 mmHg in the EG and CTL group, respectively). Moreover, the mechanism by which this response was achieved was different between the two groups. In detail, EG reached the target MAP by increasing systemic vascular resistance (+235.2 ± 315.1 vs -44.4 ± 167.7 dynes s(-1) cm(-5) for the EG and the CTL group, respectively), whereas MAP response in the CTL was the result of an increase in cardiac pre-load (-1.5 ± 11.2 vs 14 ± 13.7 ml in end-diastolic volume for the EG and the CTL group, respectively), which led to a rise in stroke volume and cardiac output. Moreover, early filling peak velocities showed a higher response in the CTL than EG group. CONCLUSIONS: This study demonstrates that diastolic function is important for normal hemodynamic adjustment during the metaboreflex and to avoid excessive vasoconstriction.

Metaboreflex activity in multiple sclerosis patients.

PURPOSE: The muscle metaboreflex activation has been shown essential to reach normal hemodynamic response during exercise. It has been demonstrated that patients with multiple sclerosis (MS) have impaired autonomic functions and cardiovascular regulation during exercise. However, to the best of our knowledge, no previous research to date has studied the metaboreflex in MS patients. The purpose of this study was to investigate the hemodynamic response to metaboreflex activation in patients with MS (n = 43) compared to an age-matched, control group (CTL, n = 21). METHODS: Cardiovascular response during the metaboreflex was evaluated using the post-exercise muscle ischemia (PEMI) method and during a control exercise recovery (CER) test. The difference in hemodynamics between the PEMI and the CER test was calculated and this procedure allowed for the assessment of the metaboreflex response. Hemodynamics was estimated by impedance cardiography. RESULTS: The MS group showed a normal mean blood pressure (MBP) response as compared to the CTL group (+6.5 ± 6.9 vs. +8 ± 6.8 mmHg, respectively), but this response was achieved with an increase in systemic vascular resistance, that was higher in the MS with respect to the CTL group (+137.6 ± 300.5 vs. -14.3 ± 240 dyne · s(-1) cm(-5), respectively). This was the main consequence of the MS group's incapacity to raise the stroke volume (-0.65 ± 10.6 vs. +6.2 ± 12.8 ml, respectively). CONCLUSION: It was concluded that MS patients have an impaired capacity to increase stroke volume (SV) in response to low level metaboreflex, even if they could sustain the MBP response by vasoconstriction. This was probably a consequence of their chronic physical de-conditioning.

Nervous Facilitation in Cardiodynamic Response of Exercising Athletes to Superimposed Mental Tasks: Implications in Depressive Disorder.

INTRODUCTION: Motor commands to perform exercise tasks may also induce activation of cardiovascular centres to supply the energy needs of the contracting muscles. Mental stressors per se may also influence cardiovascular homeostasis. We investigated the cardiovascular response of trained runners simultaneously engaged in mental and physical tasks to establish if aerobically trained subjects could develop, differently from untrained ones, nervous facilitation in the brain cardiovascular centre. Methods : Cardiovascular responses of 8 male middle-distance runners (MDR), simultaneously engaged in mental (colour-word interference test) and physical (cycle ergometer exercise) tasks, were compared with those of 8 untrained subjects. Heart rate, cardiac (CI) and stroke indexes were assessed by impedance cardiography while arterial blood pressures were assessed with a brachial sphygmomanometer. Results : Only in MDR simultaneous engagement in mental and physical tasks induced a significant CI increase which was higher (p<0.05) than that obtained on summing CI values from each task separately performed. Conclusion : Aerobic training, when performed together with a mental effort, induced a CI oversupply which allowed a redundant oxygen delivery to satisfy a sudden fuel demand from exercising muscles by utilizing aerobic sources of ATP, thus shifting the anaerobic threshold towards a higher work load. From data of this study it may also be indirectly stated that, in patients with major depressive disorder, the promotion of regular low-intensity exercise together with mental engagement could ameliorate the perceived physical quality of life, thus reducing their heart risk associated with physical stress.