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The purpose of this investigation was to characterize the arterial stiffness of male ultra-marathon runners (n = 9) using pulse wave velocity (cfPWV) and radial tonometry over the course of an ultra-marathon and during recovery. Measures were collected at rest, immediately following 45 km/75 km of running, then following 60 and 90 min of recovery. No statistical difference was found between baseline cfPWV and normative values. The cfPWV of ultra-endurance runners decreased at 45 km (3.4 ± 1.6 m/s, p = 0.006), followed by an increase (1.6 ± 1.8 m/s, p = 0.04) toward baseline levels at the 75 km mark. Radial tonometry measures also indicated small artery stiffness was transiently increased after 75 km. The amount of training time (r = 0.82, p = 0.007) and the duration of a typical training session (r = 0.73, p = 0.03) were correlated strongly with persisting decrements in large artery compliance at 60 min of recovery. The finding that arterial stiffness decreased at the 45 km distance and then reverted back toward baseline levels with prolonged running, may indicate a role of exercise duration or accumulated stress for affecting vascular compliance. At present, it is premature to suggest that athletes should alter training or racing practices to protect vascular health. [ABSTRACT FROM AUTHOR]

Study design:An investigation on large and small artery compliance in 36 able-bodied persons and persons with spinal cord injury (SCI).Objective:To evaluate the effect of various training states (endurance-trained vs untrained) on arterial compliance in individuals with chronic SCI of traumatic origin and in able-bodied individuals (matched for age, sex, height, and weight).Setting:Tertiary rehabilitation center in Canada.Methods:Large and small artery compliance were measured at the radial artery and physical activity was assessed via questionnaire.Results:There was no significant difference in large artery compliance between groups. Small artery compliance was reduced markedly (5.8±3.1 ml mm Hg−1 × 100) in untrained persons with SCI, in comparison to all other groups. Small artery compliance of endurance-trained individuals with SCI was slightly (4%) higher than that observed in the untrained able-bodied individuals (8.6±1.5 vs 8.2±1.4 ml mm Hg−1 × 100, respectively). Endurance-trained, able-bodied persons had greater small artery compliance (10.6±2.3 ml mm Hg−1 × 100) in comparison to the all other groups.Conclusion:Endurance training is related to increased small artery compliance in able-bodied individuals and persons with SCI (who are matched for age, sex, height and weight). Endurance training may attenuate the decline in small artery compliance seen with SCI. [ABSTRACT FROM AUTHOR]

There is a growing interest in training for and competing in race distances that exceed the marathon; however, little is known regarding the vascular effects of participation in such prolonged events, which last multiple consecutive hours. There exists some evidence that cardiovascular function may be impaired following extreme prolonged exercise, but at present, only cardiac function has been specifically examined following exposure to this nature of exercise. The primary purpose of this study was to characterize the acute effects of participation in an ultra-marathon on resting systemic arterial compliance. Arterial compliance and various resting cardiovascular indices were collected at rest from 26 healthy ultra-marathon competitors using applanation tonometry (HDI CR-2000) before and after participation in a mountain trail running foot race ranging from 120-195 km which required between 20-40 continuous hours (31.2 ± 6.8 h) to complete. There was no significant change in small artery compliance from baseline to post race follow-up (8.5 ± 3.4- 7.7 ± 8.2 mL/mmHgx100 , p = 0.65), but large artery compliance decreased from 16.1 ± 4.4 to 13.5 ± 3.8 mL/mmHgx10 ( p = 0.003). Participation in extreme endurance exercise of prolonged duration was associated with acute reductions in large artery compliance, but the time course of this effect remains to be elucidated. [ABSTRACT FROM AUTHOR]

We aimed to compare the Finapres system, which is designed for accurate intra-arterial amplitude measurement, to the Caretaker system, which is designed for temporal accuracy of intra-arterial measurement, in regard to measurement of pulse transit time (PTT) at baseline and following an endurance exercise session. Pulse transit time was evaluated between the R-wave of the ECG and the foot of the arterial waveform using either the Finapres (fpPTT) or Caretaker (ctPTT). 23 participants were measured before and after completion of endurance exercise. When comparing PTT values before and after an exercise intervention within devices, ctPTT was significantly different following exercise ( P = 0.03); however, the Finapres obtained values did not differ significantly. Before exercise, there was no significant relationship between devices, however, after exercise a significant moderate correlation was observed (r = 0.45, P = 0.02). Significant differences existed between ctPTT and fpPTT ( P < 0.001). The Caretaker system appears to be more accurate at detecting changes in PTT occurring as a result of a single aerobic exercise session. This may be due to the servo-controller feedback loop in the waveform contour predicting algorithm within the Finapres system, which is not present in the Caretaker unit. The Finapres system also appears to have an inherent delay in pulse contour reporting. [ABSTRACT FROM AUTHOR]

Introduction:Similarities between the clinical presentation of individuals living with spinal cord injury (SCI) and astronauts are remarkable, and may be of great interest to clinicians and scientists alike.Objectives:The primary purpose of this review is to outline the manner in which cardiovascular, musculoskeletal, renal, immune and sensory motor systems are affected by microgravity and SCI.Methods:A comprehensive review of the literature was conducted (using PubMed) to evaluate the hallmark symptoms seen after spaceflight and SCI. This literature was then examined critically to determine symptoms common to both populations.Results:Both SCI and prolonged microgravity exposure are associated with marked deteriorations in various physiological functions. Atrophy in muscle and bone, cardiovascular disturbances, and alterations in renal, immune and sensory motor systems are conditions commonly observed not only in individuals with SCI, but also in those who experience prolonged gravity unloading.Conclusion:The preponderance of data indicates that similar physiological changes occur in both SCI and prolonged space flight. These findings have important implications for future research in SCI and prolonged space flight. [ABSTRACT FROM AUTHOR]

Background: Schizophrenia is associated with poor cognitive function and elevated cardiometabolic disease risk. These health concerns may exacerbate neurocognitive dysfunction associated with hippocampal abnormalities, particularly hippocampal volume reductions. Regular exercise is thought to improve symptom severity, reduce depression, and improve cognition in schizophrenia, and may trigger exercise-mediated hippocampal growth. The potential for the benefits of exercise for treatment-resistant schizophrenia patients has not been clearly assessed. This study aims to assess the effect of exercise on hippocampal plasticity and clinical outcomes in chronic schizophrenia., Methods: Seventeen DSM-IV criteria schizophrenia or schizoaffective disorder patients completed a customized moderate intensity 12-week aerobic or weight-bearing exercise program. Adherence rates were 83% ± 9.4%) with 70% of participants completing the entire exercise program. Concomitant neuroimaging, clinical and cognitive assessments were obtained at baseline and 12-weeks., Results: At follow-up, symptom severity scores (t(16) = -16.8, p. ≤ 0.0001) and social functioning (t(16) = 4.4, p. = 0.0004) improved. A trend for improved depression scores (t(16) = -2.0, p. = 0.06) with no change in anxiety, or extrapyramidal symptoms were seen. Hippocampal volume increased (t(16) = -2.54, p. = 0.02), specifically in the left CA-1 field (F(16) = -2.33, p. = 0.03). Hippocampal vascular volume was unchanged. Change in hippocampal volume and vascular volume was not significantly correlated with change in symptom severity or affect scores., Conclusions: Adjunct exercise may accelerate symptom improvement in treatment-resistant psychosis patients. While the underlying mechanism remains unclear, these results indicate that chronic schizophrenia patients experience hippocampal plasticity in response to exercise., Study Registration: Clinical Trials.govNCT01392885., (Copyright © 2018 Elsevier B.V. All rights reserved.)

Background: Preclinical studies have reported that a single treadmill session performed 24h prior to doxorubicin provides cardio-protection. We aimed to characterize the acute change in cardiac function following an initial doxorubicin treatment in humans and determine whether an exercise session performed 24h prior to treatment changes this response., Methods: Breast cancer patients were randomized to either 30min of vigorous-intensity exercise 24h prior to the first doxorubicin treatment (n=13), or no vigorous exercise for 72h prior to treatment (control, n=11). Echocardiographically-derived left ventricular volumes, longitudinal strain, twist, E/A ratio, and circulating NT-proBNP, a marker of later cardiotoxicity, were measured before and 24-48h after the treatment., Results: Following treatment in the control group, NT-proBNP, end-diastolic and stroke volumes, cardiac output, E/A ratio, strain, diastolic strain rate, twist, and untwist velocity significantly increased (all p≤0.01). Whereas systemic vascular resistance (p<0.01) decreased, and ejection fraction (p=0.02) and systolic strain rate (p<0.01) increased in the exercise group only. Relative to control, the exercise group had a significantly lower NT-proBNP (p<0.01) and a 46% risk reduction of exceeding the cut-point used to exclude acute heart failure., Conclusion: The first doxorubicin treatment is associated with acutely increased NT-proBNP, echocardiographic parameters of myocardial relaxation, left ventricular volume overload, and changes in longitudinal strain and twist opposite in direction to documented longer-term changes. An exercise session performed 24h prior to treatment attenuated NT-proBNP release and increased systolic function. Future investigations should verify these findings in a larger cohort and across multiple courses of doxorubicin., (Copyright © 2017 Elsevier B.V. All rights reserved.)

We developed a multivariate prediction equation for estimating the highest obtainable pulmonary oxygen uptake (VO2p) during the 6-minute walk test (6-MWT) in 54 organ transplant recipients: heart/heart-double-lung (n=14), kidney/kidney-pancreas (n=16), liver (n=14), double lung (n=8), bone marrow (n=2). They were of age, 48+/-12 years. Participants performed a 6-MWT during which expired gases were collected and analyzed with a portable metabolic system interfaced with a wireless heart rate monitor. The following variables significantly contributed to the model for predicting the highest obtainable 6-MWT VO2p: 6-MWT distance (m), age (years), gender (male=0, female=1), resting heart rate, peak heart rate, weight (kg), and transplant type (kidney/kidney-pancreas=1, other=0), where: VO2p=1.253+0.022 (6-MWT distance)+0.112 (age) -3.192 (gender) -0.104 (resting heart rate)+0.127 (peak 6-MWT heart rate)-0.084 (weight)+2.116 (transplant type). The explanatory variables in our final model accounted for 78% of the variance in 6-MWT VO2p. In conclusion, the addition of an easily estimated 6-MWT VO2p will provide added clinical information of functional capacity following an exercise rehabilitation intervention or during routine follow-up for organ transplant recipients.

The objective of this review is to examine the effects of changes in the individual components of musculoskeletal fitness on indicators of health status. Available evidence regarding the impact of changes in musculoskeletal fitness on indicators of health status is summarized and evaluated. Intervention programs designed specifically to enhance musculoskeletal fitness have been effective in improving several indicators of health status including glucose metabolism, obesity, bone health, independent living, the incidence of falling and associated injuries, and/or psychological well-being. An enhanced musculoskeletal fitness is associated with an improvement in health status.

The purpose is to examine the relationship between musculoskeletal fitness and health status. Muscular strength is positively associated with independence and overall quality of life, and negatively associated with morbidity and potentially premature mortality. Muscular endurance is positively related to overall quality of life. Elevated muscular endurance may reduce the incidence of falling and its associated injuries. Muscular power is predictive of functional capacity, resultant disability, and potentially premature mortality. Flexibility is positively associated with mobility and independence. Women and the aged may be susceptible to musculoskeletal impairments leading to reduced health status and thus may represent primary target groups for intervention programs. High levels of musculoskeletal fitness are associated with positive health status, and low levels of musculoskeletal fitness are associated with lower health status.

Objective: Blood volume (BV) and hemoglobin concentration ([Hb]) play important roles in oxygen transport. Manipulation of both BV and [Hb] can markedly affect systemic oxygen transport and maximal aerobic capacity (VO2max). However, the role of BV in oxygen transport and aerobic performance is not well understood. It has recently been postulated that an acute expansion of BV using plasma volume (PV), independent of changes in [Hb], may represent a potential ergogenic property. Therefore, the primary objective of this review was to determine the potential ergogenic properties of volume loading., Data Sources: An extensive research of Medline and Sport-Discus along with cross-referencing was conducted. Articles were included on the basis of their relevancy to the purpose of this review. Only articles published in English were included in the analysis., Study Selection: All study designs using human participants were reviewed., Data Extraction: A systematic analysis of data regarding the effect of BV on the determination of oxygen transport, aerobic capacity, and endurance performance was conducted. Particular emphasis was given to articles that examined BV as the key independent variable. Articles relevant to the evaluation of the impact of BV on aerobic capacity and endurance performance were reviewed according to the strengths of the individual study designs., Results: Seven investigations evaluated the impact of acute changes in BV, independent of changes in [Hb], on VO2max. Of these investigations, three revealed that acute manipulations of BV result in no change or a slight reduction in VO2max. Three investigations revealed a significant improvement in VO2max after acute PV expansion. One investigation revealed a nonsignificant increase in VO2max after acute PV expansion. Seven investigations evaluated the impact of acute changes in BV, independent of changes in [Hb], on endurance performance: two revealed a significant improvement in endurance performance after acute PV expansion, and five revealed an unchanged or reduced endurance performance after acute PV expansion. The majority of investigations showing an improvement in VO2max and/or endurance performance after acute PV expansion were conducted using untrained individuals., Conclusion: Volume loading does not result in an improvement in VO2max and/or endurance performance in endurance athletes. Volume loading in untrained individuals may improve VO2max, but does not bring these individuals to the aerobic capacity of endurance-trained athletes. Also, volume loading generally does not lead to improvement in endurance performance, irrespective of its effects on VO2max.

Objective: To determine whether plasma volume expansion (PVexp) in elite endurance-trained (ET) cyclists, who already possess both a high blood volume (BV) and a high VO2max, leads to further enhancements in their cardiac function, VO2max, and endurance performance (time to exhaustion at 95% VO2max)., Methods: Nine male ET cyclists (V02max = 68.9 +/- 0.6 (SEM) mL x kg(-1) x min(-1)) were studied employing a double blind, cross-over design; i) before PVexp, ii) after sham PVexp (Sham), iii) after restoration of normocythemia, iv) after PVexp (6% dextran), and v) upon reestablishment of normocythemia., Results: PVexp resulted in a 547 +/- 61 mL increase in BV (P < 0.05). Maximal cardiac output and maximal stroke volume were higher (P < 0.05) after PVexp, but the magnitude of these increases was only sufficient to counter the hemodilution effect (lowered O2 content) of PVexp, such that O2 transport, VO2max, and endurance performance remained unchanged., Conclusions: Expansion of BV in elite ET cyclists, who already possess a high BV, does not improve their VO2max and endurance performance. Elite ET athletes may already be at an optimal BV, which is at or near the limits of their diastolic reserve capacity.

For exercise physiologists and sport cardiologists, one of the greatest challenges is to develop a valid, reliable, noninvasive and affordable measure of cardiac output (Q). There are several techniques available to measure Q during exercise conditions. These procedures generally provide accurate and reliable determinations of Q during submaximal exercise, but may be limited during maximal exercise conditions. The most commonly used noninvasive measures are the acetylene (C2H2) and carbon dioxide (CO2) rebreathe methods as reviewed in part I of this article. Only the foreign gas rebreathe method, using C2H2, meets all of the criteria of being noninvasive, easy to use, reliable and valid for use during maximal exercise. New methodologies have recently been developed to measure Q during exercise conditions. Although not as popular as the C2H2 and CO2 rebreathe methods, these methods have increasingly gained favour in exercise physiology and sport cardiology settings. The majority of these measures (if performed meticulously), with the exception of impedance cardiography, provide reasonably accurate and reliable determinations of Q. However, the cost of usage and technological limitations during maximal exercise have prevented these techniques from replacing the conventional measures of Q during exercise conditions. Doppler echocardiography and the modified C2H2 methods hold promise for the assessment of Q during maximal exercise. With further advances in these technologies their use in exercise physiology and sport cardiology setting may become more common.

The assessment of cardiac function, particularly cardiac output (Q) during heavy exercise is essential for the evaluation of cardiovascular factors that might limit oxygen transport. A series of invasive and noninvasive techniques has been developed for the assessment and monitoring of Q during resting and submaximal exercise conditions. However, very few techniques have been found to give accurate and reliable determinations of Q during vigorous to maximum exercise. For exercise physiologists and sport cardiologists, maximal exercise data are of primary importance. The 'gold standard' measures of cardiac function are considered to be the direct Fick and dye-dilution methods. These have been widely shown to give accurate and reliable determinations of Q during resting and submaximal exercise conditions; however, their use during maximal exercise conditions is debatable due to the inherent risks involved with each and their increasing inaccuracy during the later stages of vigorous exercise. Thermodilution has also been considered to be a relatively good method for the determination of Q during rest and exercise conditions, but recent authors have questioned its use due to the nature of the measure and its inaccuracy during strenuous exercise. Various noninvasive measures of cardiac function have been developed to overcome the problems associated with the 'gold standard' measures. The first part of this article discusses conventional techniques used in exercise physiology settings. The majority of these provide accurate and reliable determinations of Q during rest and submaximal exercise. However, very few techniques are suitable for maximal exercise conditions. Perhaps only the foreign gas rebreathe using acetylene (C2H2) meets all the criteria of being noninvasive, simple to use, reliable over repeated measurements, accurate and useful during maximal exercise.

Objective: To examine and compare the exercise cardiac function of endurance-trained (ET) women and men., Participants: Six ET women aged 20 to 29 years (mean VO2max = 64 ml.kg-1.min-1) and 9 ET men aged 20 to 29 years (mean VO2max = 69 ml.kg-1.min-1) were included in the study., Main Outcome Measures: Cardiac output (Q), stroke volume (SV), diastolic filling rate (DFR), and left ventricular ejection rate (LVER) were compared at rest and during exercise at heart rates (HRs) of 110, 130, 150, 170 bpm, and max. Resting blood volume (BV) and hemoglobin concentration ([Hb]) were also compared., Results: Compared to women, men had a higher BV and [Hb]. At HRmax, men had a higher Q (31.0 +/- 0.6 versus 24.1 +/- 0.9 l.min-1), SV, DFR, and LVER than women. When expressed relative to body mass (kg), there were no gender differences in SVmax, and women had a significantly higher a-v DO2max (approximately 19%) than men. The SV of the men and women did not plateau at a submaximal level but continued to increase progressively to HRmax. During maximal exercise, the DFR was significantly faster than the LVER in the men and the women., Conclusions: When ET men and women are matched for body mass, the gender difference in SVmax is reduced so that it is no longer statistically significant. However, there are still significant gender differences in Q, DFR, LVER, BV, and [Hb] that contribute to a higher VO2max (ml.kg-1.min-1) in ET men compared to women. To augment SVmax, women and men rely to a greater extent on diastolic filling than on left ventricular emptying.

Purpose: The acetylene rebreathe technique is a well established method for the determination of cardiac output (Q) at rest and during exercise. We sought to demonstrate that the acetylene rebreathe technique allows for highly reproducible determinations of Q., Methods: Nine elite male endurance cyclists (VO2max = 68.9 +/- 0.6 mL.kg-1.min-1) performed a modified acetylene rebreathe maneuver during incremental exercise on four repeat test days. A key modification to the method originally described by Grollman was the maintenance of a positive filling pressure during the inhalation portion of the procedure., Results: There were no significant differences in determinations of Q at the same submaximal heart rates on four separate test days. The coefficient of variation for repeat determinations of maximal Q during the same work rate, expressed as the standard deviation of the difference between duplicate measurements, is 4.8%. The coefficient of variation for determinations of maximal Q at the same heart rate on different days, expressed as the standard deviation of the difference between four test days, is 2.6%., Conclusion: These findings illustrate that the acetylene rebreathe technique can be used with confidence to assess Q across repeated experimental days.