Comprehensive cardiopulmonary profile of individuals with Down syndrome.

BACKGROUND: Individuals with Down syndrome (DS) have low levels of cardiorespiratory fitness and previous studies have shown that these low levels of fitness have a physiological cause. During exercise, the cardiovascular, ventilatory and muscular systems are simultaneously active. While individual parameters of these systems have been investigated in DS before, the interaction between these parameters and systems have not been discussed in detail. Doing so may provide important insight regarding the aetiology of low cardiorespiratory fitness and which parameters of the cardiovascular, pulmonary and muscular systems are altered in individuals with DS compared with their peers without DS. METHODS: Cardiopulmonary exercise tests were performed in healthy adults with and without DS. Parameters related to the cardiovascular, ventilatory and muscular systems were collected until VO2peak . In total, 51 participants were included in analysis, of which 21 had DS. RESULTS: Individuals with DS showed lower peak values for all collected outcomes (P ≤ 0.001) compared with those without DS, except for ventilatory threshold as a percentage of maximal oxygen uptake and VE /VCO2 slope, which were similar. CONCLUSIONS: Our results show that individuals with DS present impairments across the cardiovascular, ventilatory and muscular aspects of the cardiopulmonary system.

Training responsiveness of cardiorespiratory fitness and arterial stiffness following moderate-intensity continuous training and high-intensity interval training in adults with intellectual and developmental disabilities.

BACKGROUND: Cardiorespiratory fitness (CRF) prompts antiatherogenic adaptations in vascular function and structure. However, there is an extraordinary interindividual variability in response to a standard dose of exercise, wherein a substantial number of adults with intellectual and developmental disabilities (IDD) do not improve CRF. We (1) evaluated the effects of 12-month of moderate-intensity continuous training (MICT) on CRF and arterial stiffness and (2) tested whether an additional 3-month of high-intensity interval training (HIIT) would add to improvements in CRF responsiveness and arterial stiffness. METHODS: Fifteen adults with mild-to-moderate IDD (male adults = 9, 30.1 ± 7.5 years old) met 3 days per week for 30 min MICT for 12 months, after which the incidence of CRF responsiveness was calculated (≥5.0% change in absolute peak VO2 ). Thereafter, responders and non-responders started HIIT for 3 months with identical daily training load/frequency. Peak VO2 , local and regional indices of arterial stiffness were assessed prior to and after each period. RESULTS: Sixty per cent of the participants were non-responders following MICT, but the incidence dropped to 20% following HIIT (P = 0.03). Absolute peak VO2 values reached significant difference from pre-intervention (+0.38 ± 0.08 L min-1 , P = 0.001) only when HIIT was added. Lower limb pulse wave velocity (PWV) decreased following MICT (-0.8 ± 1.1 m s-1 , P = 0.049), whereas central PWV only decreased following HIIT (-0.8 ± 0.9 m s-1 , P = 0.013). CONCLUSIONS: Cardiorespiratory fitness responsiveness and reductions in PWV to a 12-month MICT period in adults with IDD improved following a period of HIIT programme inducing higher metabolic stress.

Anthropometry does not fully explain low fitness among adults with Down syndrome.

BACKGROUND: Cardiorespiratory fitness, expressed as peak oxygen uptake during exercise (VO2 peak), is an important predictor of cardiovascular health and is related to anthropometry in the general population. Individuals with Down syndrome (DS) have reduced cardiorespiratory fitness and often exhibit different anthropometrics compared with the general population. Interestingly, the relation between anthropometry and cardiorespiratory fitness found in the general population is not apparent in individuals with DS. However, accurate measures with dual energy X-ray absorptiometry (DEXA) scan have not been used to investigate this relationship in this population. The purpose of this paper was to investigate the relationship between accurate measures of anthropometry and cardiorespiratory fitness in adults with DS compared with an age-matched and sex-matched control group. METHODS: Anthropometrics (height, weight, waist and hip circumference, body composition via DEXA) and cardiorespiratory fitness (VO2 peak, measured during a graded maximal exercise test) were assessed in adults with (n = 9; 25 ± 3 years; 6 male patients) and without DS (n = 10, 24 ± 4 years; 5 male patients). RESULTS: Participants with DS were shorter (P < 0.01) than without DS and had a higher body mass index (P < 0.01), waist circumference (WC) (P = 0.026) and waist/height ratio (WHtR) (P < 0.01), but similar weight, body surface area (BSA), waist/hip ratio and body composition (P > 0.05). Participants with DS had significantly lower relative VO2 peak and VO2 peak corrected for total lean mass (TLM), but similar absolute VO2 peak, compared with without DS. In participants with DS, only WC and WHtR were associated with VO2 peak, whereas in participants without DS, height, weight, BSA, TLM, leg lean mass and body fat percentage were associated with VO2 peak. CONCLUSIONS: These results suggest that the relation between anthropometry and cardiorespiratory fitness found in the general population is not the same in adults with DS and that anthropometrics do not fully explain cardiorespiratory fitness in adults with DS. Further research into potential alternative explanations is required.

Central and Peripheral Postexercise Blood Pressure and Vascular Responses in Young Adults with Obesity.

INTRODUCTION: Adults with obesity are at an increased risk of incident hypertension. Regular aerobic exercise is recommended for the prevention and treatment of hypertension, but whether young adults with obesity exhibit impaired postexercise blood pressure (BP) and vascular responses remains unclear. PURPOSE: We tested the hypothesis that young adults with obesity exhibit attenuated postexercise hypotension (PEH) and postexercise peripheral vasodilation compared with young adults without obesity. METHODS: Thirty-six normotensive adults without and with obesity (11 men and 7 women per group) underwent measurements of brachial and central BP, and leg blood flow (Doppler ultrasound) at baseline and at 30, 60, and 90 min after acute 1-h moderate-intensity cycling. Leg vascular conductance (LVC) was calculated as flow/mean arterial pressure. RESULTS: Both groups exhibited similar brachial and central PEH (peak change from baseline, -2 and -4 mm Hg for brachial and central systolic BPs, respectively, for both groups; time effect, P < 0.05). Both groups also exhibited postexercise peripheral vasodilation, assessed via LVC (time effect, P < 0.05), but its overall magnitude was smaller in young adults with obesity (LVC change from baseline, +47% ± 37%, +29% ± 36%, and +20% ± 29%) compared with young adults without obesity (LVC change from baseline, +88% ± 58%, +59% ± 54%, and +42% ± 51%; group effect, P < 0.05). CONCLUSIONS: Although obesity did not impair PEH after acute moderate-intensity exercise, young adults with obesity exhibited smaller postexercise peripheral vasodilation compared with young adults without obesity. Collectively, these findings have identified evidence for obesity-induced alterations in the peripheral vasculature after exercise.

Hemodynamic Response to Isometric Handgrip Exercise in Adults with Intellectual Disability.

INTRODUCTION: Individuals with intellectual disability (ID) have an increased risk of cardiovascular disease and reduced work capacity, which could partly be explained by alterations to autonomic and hemodynamic regulation. The measurement of heart rate and blood pressure during isometric handgrip (HG) exercise, a sympathoexcitatory stimulus, is a noninvasive method to investigate autonomic and hemodynamic alterations. The purpose of this study was to assess alterations to autonomic and associated hemodynamic regulation between individuals with ID and a matched control group during isometric HG exercise. METHODS: Individuals with ID (n = 13; 31 ± 2 yr, 27.6 ± 7.7 kg·m-2) and without ID (n = 16; 29 ± 7 yr, 24.2 ± 2.8 kg·m-2) performed 2 min of isometric HG exercise at 30% of maximal voluntary contraction (MVC) in the seated position. Blood pressure was averaged for 2 min before, during, and after HG exercise (mean arterial pressure [MAP], systolic blood pressure, and diastolic blood pressure). Heart rate variability, blood pressure variability, and baroreflex sensitivity were calculated from the continuous blood pressure and heart rate recordings. RESULTS: Isometric HG elicited a blunted response in systolic blood pressure, diastolic blood pressure, and MAP among individuals with ID compared with individuals without ID, even after controlling for strength (MAP: rest, HG, recovery; ID: 103 ± 7, 108 ± 9, 103 ± 7; without ID: 102 ± 7, 116 ± 10, 104 ± 10 mm Hg; interaction P < 0.05). Individuals with ID also had an attenuated baroreflex sensitivity response to HG exercise compared with individuals without ID (interaction P = 0.041), but these effects were no longer significant after controlling for maximal voluntary contraction. Indices of heart rate variability and blood pressure variability were not different between groups overall or in response to HG exercise (P > 0.05). CONCLUSIONS: Individuals with ID have a blunted hemodynamic and autonomic response to isometric HG exercise compared with individuals without ID.

Cardiopulmonary Profile of Individuals with Intellectual Disability.

INTRODUCTION: Individuals with intellectual disabilities (ID) are often sedentary and have low fitness levels. Current knowledge supports the existence of physiological barriers resulting in low fitness and exercise intolerance in individuals with Down syndrome, which might be applicable to other ID etiologies. If physiological barriers exist in ID, this would require adaptation of the physical activity guidelines. PURPOSE: The aim of this study was to assess differences in cardiopulmonary profiles, including maximal oxygen uptake, during a cardiopulmonary exercise test in individuals with ID without Down syndrome and healthy controls. METHODS: Participants performed an incremental cardiopulmonary exercise test on a treadmill until exhaustion. Outcomes were peak heart rate (HRpeak), absolute peak oxygen uptake (V˙O2peak), relative V˙O2peak, peak minute ventilation, peak CO2 expenditure, oxygen uptake efficiency slope, V˙E/V˙CO2 slope, absolute O2 pulse, relative O2 pulse, difference from predicted HRpeak, HR reserve, RERpeak, ventilatory threshold (VT), and VT as a percentage of V˙O2peak. Differences between groups were analyzed with Student's t-tests and multiple linear regression after adjusting for potential confounders (sex, age, body mass index, and activity level). RESULTS: Individuals with ID had worse outcomes on all of the cardiopulmonary outcomes, except for VT expressed as a percentage of V˙O2peak and V˙E/V˙CO2 slope (P < 0.05). Having ID was an independent predictor of reduced physiologic function during exercise (P < 0.05). CONCLUSION: These results demonstrate that individuals with ID present exercise intolerance potentially related to lower HRpeak and impairments in ventilatory function, and these results also suggest the possibility of peripheral muscle hypoperfusion. Existing physical activity guidelines likely underestimate the actual intensity of activity performed by individuals with ID and need to be adapted.

Acute High-Intensity Interval Exercise in Multiple Sclerosis with Mobility Disability.

INTRODUCTION: Multiple sclerosis (MS) is an immune-mediated, neurological disease that results in physiological deconditioning with increasing disability. High-intensity interval training (HIIT) exercise has induced significant improvements in physiological conditioning in healthy and clinical populations and might be appropriate for persons with MS who have mobility disability. The feasibility and acute effects of HIIT using recumbent stepping in persons with MS who have mobility disability are relatively unknown. METHODS: The physiological effects of single sessions of HIIT and continuous (CON), steady-state aerobic exercise using recumbent stepping were compared in 20 persons with MS with mobility disability (i.e., Expanded Disability Status Scale of 4.0-6.5). The HIIT bout included 10 cycles of 1-min intervals at the work rate associated with 90% peak aerobic capacity (V˙O2peak) followed by 1-min recovery intervals at 15 W, totaling 20 min in length. The CON bout consisted of 20 min at the work rate associated with 50% to 60% V˙O2peak. Physiological (i.e., power output, oxygen consumption, carbon dioxide expiration, respiratory exchange ratio, ventilation, HR, and core temperature) and perceptual (i.e., ratings of perceived exertion) measures were collected across the acute sessions. RESULTS: There were statistically significant condition-time interactions for all physiological measures and ratings of perceived exertion expressing differential patterns of change over time for HIIT versus CON (P < 0.05). The main effect of condition was significant for all physiological outcomes, except core temperature, with the HIIT condition inducing significantly higher values than CON (P < 0.05). CONCLUSIONS: High-intensity interval training exercise taxes the cardiorespiratory system significantly more than CON, yet without deleterious effects on core temperature in persons with MS. This has important implications for informing an evidence-based exercise prescription that is appropriate for improving physiological conditioning in persons with MS who have mobility disabilities.

Single and combined effects of body composition phenotypes on carotid intima-media thickness.

BACKGROUND: Central fatness might be a more sensitive predictor of atherosclerotic changes in children than are total body fat measures. However, it is unclear whether a total body fat measure coupled with an estimate of a more central pattern of fat accumulation predicts increased carotid intima-media-thickness (cIMT) better than either measure alone. OBJECTIVE: The objective of the study is to identify the ability of a combination of simple anthropometric screening tools or a combination of objective measures of body composition to predict cIMT. METHODS: cIMT was assessed on the common carotid artery in 349 children aged 11-12 years old (183 girls). Body mass index (BMI), waist circumference (WC) and waist-to-height ratio (WHtR) were dichotomized according to established criteria and indices of total body (TBFI) and abdominal (ABFMI) fat were assessed by dual-energy X-ray absorptiometry and categorized (increased risk ≥85%). Single and combined associations among anthropometric and laboratorial measures with the risk of having increased cIMT (≥85%) and discriminatory performance were tested with logistic regression analysis and Receiver Operator Curve analysis. RESULTS: Children with higher total fatness (BMI and TBFI) or higher central pattern of fat accumulation (WC, WHtR and BFMI) were in higher risk for increased cIMT [odds ratio (OR): 2.08-3.24). The risk for increased cIMT was not higher among children who coupled high total and high central fatness (OR: 2.27-3.10). CONCLUSIONS: Combination of total and central measures of fat does not improve the prediction of increased cIMT in children. Simple surrogate measures of fatness can be used to predict increased cIMT urging special attention to those children who exhibit increased abdominal fat.

The role of fatness on physical fitness in adolescents with and without Down syndrome: The UP&DOWN study.

BACKGROUND/OBJECTIVES: Adolescents with Down syndrome (DS) exhibit higher levels of fatness and low levels of physical fitness compared with those without DS. In adolescents without DS, fatness is tightly associated with physical fitness, but this association is unclear in adolescents with DS. The aim of this study was to examine the association between several markers of fatness and physical fitness in a relative large sample of adolescents with and without DS. SUBJECTS/METHODS: A total of 111 adolescents with DS (41 females) aged 11-20 years participated in this cross-sectional study. We also included a sex-matched control group (ratio 1:2) of 222 adolescents without DS aged 12-18 years, participating in the UP&DOWN Study. The Assessing Level of Physical Activity (ALPHA) health-related fitness test battery for adolescents was used to assess fatness and physical fitness. RESULTS: Our results show that fatness is not associated with low levels of physical fitness in adolescents with DS (that is, 3 of the 16 analyses identified differences in physical fitness variables by groups of fatness). In contrast, fatness, as expected, is associated with levels of physical fitness in adolescents without DS (that is, 13 of the 16 analyses identified differences in physical fitness variables by groups of fatness). CONCLUSIONS: The present finding contributes to new knowledge by suggesting that the role of fatness on physical fitness is different in adolescents with and without DS, and consequently, the poor levels of physical fitness in adolescents with DS may be due to the syndrome rather than the high prevalence of obesity from this population.

Aerobic Exercise Training and Arterial Changes in African Americans versus Caucasians.

UNLABELLED: African Americans (AA) have increased carotid artery intima-media thickness and decreased vascular function compared with their Caucasian (CA) peers. Aerobic exercise prevents and potentially reverses arterial dysfunction. PURPOSE: The purpose of this study was to examine the effect of 8 wk of moderate- to high-intensity aerobic training in young healthy sedentary AA and CA men and women. METHODS: Sixty-four healthy volunteers (men, 28; women, 36) with mean age 24 yr underwent measures of arterial structure, function, and blood pressure (BP) variables at baseline, after the 4-wk control period, and 8 wk after training. RESULTS: There was a significant increase in VO2peak among both groups after exercise training. Brachial systolic BP decreased significantly after the control period in both groups but not after exercise training. Carotid pulse pressure decreased significantly in both groups after exercise training as compared with that in baseline. There was no change in any of the other BP variables. AA had higher intima-media thickness at baseline and after the control period but it significantly decreased after exercise training compared with that of CA. AA had significantly lower baseline forearm blood flow and reactive hyperemia compared with those of CA, but exercise training had no effect on these variables. There was no significant difference in arterial stiffness (central pulse wave velocity) and wave-reflection (augmentation index) between the two groups at any time point. CONCLUSIONS: This is the first study to show that 8 wk of aerobic exercise training causes significant improvement in the arterial structure in young, healthy AA, making it comparable with the CA and with minimal effects on BP variables.

Effect of Aspirin Supplementation on Hemodynamics in Older Firefighters.

PURPOSE: Cardiovascular events are the leading cause of line-of-duty fatality for firefighters. Aspirin reduces the risk of cardiovascular events in men and may reduce fatalities in older (>40 yr) firefighters. We hypothesized that both chronic and acute aspirin supplementation would improve vascular function after live firefighting but that chronic supplementation would also improve resting hemodynamics. METHODS: Twenty-four firefighters (40-60 yr) were randomly assigned to acute or chronic aspirin supplementation or placebo in a balanced, crossover design. Arterial stiffness, brachial and central blood pressures, as well as forearm vasodilatory capacity and blood flow were measured at rest and immediately after live firefighting. RESULTS: Total hyperemic blood flow (area under the curve (AUC)) was increased (P < 0.001) after firefighting with no effects for aspirin supplementation or acute versus chronic administration (AUC, from 107 ± 5 to 223 ± 9 in aspirin condition and from 97 ± 5 to 216 ± 7 mL·min⁻¹ per 100-mL forearm tissue for placebo; P < 0.05 for main, and P > 0.05 for interaction). Arterial stiffness/central blood pressure increased (P < 0.04) with no effect of aspirin (from 0.0811 ± 0.001 to 0.0844 ± 0.003 m·s·mm⁻¹ Hg⁻¹ in aspirin condition versus 0.0802 ± 0.002 to 0.0858 ± 0.002 m·s⁻¹·mm Hg⁻¹ in placebo condition), whereas peripheral and central systolic and pulse pressures decreased after firefighting across conditions (P < 0.05). CONCLUSIONS: Live firefighting resulted in increased AUC and pressure-controlled arterial stiffness and decreased blood pressure in older firefighters, but aspirin supplementation did not affect macro- or microvascular responsiveness at rest or after firefighting.

Independent Association of Muscular Strength and Carotid Intima-Media Thickness in Children.

The aim of this cross-sectional study was to examine the influence of muscular strength on carotid intima-media thickness (cIMT) in children, controlling for the effect of cardiorespiratory fitness (CRF) and central adiposity and to examine if differences among muscular strength tertiles translate to physiological differences. We assessed cIMT of the common carotid artery in 366 children between 11-12 years of age (191 girls). Measures included cIMT assessed with high-resolution ultrasonography, a maximal handgrip strength test, body fat mass and lean mass from DXA and CRF determined using a maximal cycle ergometer test. Association between muscular strength and cIMT adjusted for CRF and central adiposity, as measured by trunk fat, was tested with multiple linear regression analysis. Differences in risk factors among muscular strength groups were tested with ANOVA. The Muscular Strength Index (MSI) was inversely associated with cIMT independently of CRF and central adiposity (p<0.05). The low MSI group had the highest values of cIMT, waist circumference and systolic blood pressure and the lowest CRF (p<0.05). There was an inverse and independent association between muscular strength and cIMT. Low muscular strength was associated with higher levels of cardiovascular disease risk factors in children.

Effects of Walking with Blood Flow Restriction on Excess Post-exercise Oxygen Consumption.

This study determined the influence of walking with blood flow restriction (BFR) on the excess post-exercise oxygen consumption (EPOC) of healthy young men. 17 healthy young men (22.1±2.9 years) performed graded treadmill exercise to assess VO2peak. In a randomized fashion, each participant performed 5 sets of 3-min treadmill exercise at their optimal walking speed with 1-min interval either with or without BFR. Participants were then seated in a chair and remained there for 30 min of recovery. Expired gases were continuously monitored during exercise and recovery. BFR increased the O2 cost of walking as well as its relative intensity and cumulative O2 deficit (p<0.05). The EPOC magnitude after walking with BFR was greater than in the non-BFR condition (p<0.05). No differences between conditions were seen for the duration of EPOC. The EPOC magnitude was no longer different between conditions after controlling for the differences in relative intensity and in the cumulative O2 deficit (p>0.05). These data indicate that walking with BFR increases the magnitude of EPOC. Moreover, they also demonstrate that such increment in EPOC is likely explained by the effects of BFR on walking relative intensity and cumulative O2 deficit.

Blood pressure changes following aerobic exercise in Caucasian and Chinese descendants.

Acute aerobic exercise produces post-exercise hypotension (PEH). Chinese populations have lower prevalence of cardiovascular disease compared to Caucasians. PEH may be associated cardiovascular disease through its influence on hypertension. The purpose of this study was to compare PEH between Caucasian and Chinese subjects following acute aerobic exercise. 62 (30 Caucasian and 32 Chinese, 50% male) subjects underwent measurement of peripheral and central hemodynamics as well as arterial and cardiac evaluations, 30 min and 60 min after 45 min of treadmill exercise. Caucasians exhibited significantly higher baseline BP than the Chinese. While the reduction in brachial artery systolic BP was greater in Caucasian than in the Chinese, there was no difference in changes in carotid systolic BP between the groups. The increase in cardiac output and heart rate was greater in the Chinese than Caucasians, but total peripheral resistance and leg pulse wave velocity decreased by a similar magnitude in the Chinese and Caucasian subjects. We conclude that acute aerobic exercise produces a greater magnitude of PEH in peripheral systolic BP in Caucasian compared to Chinese subjects. The different magnitude in PEH was caused by the greater increase in cardiac output mediated by heart rate, with no change in stroke volume. It is possible that initial BP differences between races influenced the findings.

A novel and personalized rehabilitation program for obese kidney transplant recipients.

INTRODUCTION: Physical rehabilitation programs for kidney transplant recipients are not routinely personalized to patients' physical and emotional health, which could result in a potentially limited health impact, shorter-term participation, and an overall low success rate. MATERIALS AND METHODS: We conducted an internal review board-approved randomized prospective study involving a 12-month supervised multidisciplinary rehabilitation program (GH method) initiated after kidney transplantation in obese recipients (body mass index >30). The new method incorporates 3 major components: physical exercise, behavioral interventions, and nutritional guidance. We compared 9 patients who underwent supervised rehabilitation with 8 patients who underwent standard care. Patients were followed up after the start of the intervention, and multiple assessments were performed. RESULTS: The adherence to training and follow-up was 100% in the intervention group, compared with 25% at 12 months in the control group. There was a trend for a higher glomerular filtration rate in the intervention group compared with the control group (55.5 ± 18.6 mL/min/1.73 m(2) vs 38.8 ± 18.9 mL/min/1.73 m(2), P = .06). The quality of life (SF-36) mean score improved more in the intervention group compared with the control group (583 ± 13 vs 436 ± 22, P = .008). There was a significantly higher employment rate in the intervention group, 77.7% at 12 months compared with 12.5% in the control group (P = .02). CONCLUSIONS: Our preliminary results suggest that this comprehensive approach to physical rehabilitation can improve adherence, kidney function, quality of life, and employment rate for obese patients after kidney transplantation.

Sex differences in ventricular-vascular coupling following endurance training.

INTRODUCTION: Ventricular and vascular coupling is defined as the ratio of arterial elastance (Ea) to ventricular elastance (Elv) and describes the interaction between the heart and arterial system. There are sex differences in both arterial and ventricular function in response to both acute exercise and aerobic exercise training. PURPOSE: To examine the effects of aerobic exercise training on elastances and the coupling ratio in young adult men and women. We hypothesized a reduction in the coupling ratio in both sexes due to a decrease in Ea that would be more pronounced in men and an increase in Elv that would be larger in women. METHODS: Fifty-three healthy, young adults completed the study. Central pulse wave velocity and heart volumes were measured before and after an 8-week aerobic training intervention. Elastances were calculated as Ea = end-systolic pressure/stroke volume and Elv = end-systolic pressure/end-systolic volume and indexed to body surface area. RESULTS: After the intervention, women augmented indexed and un-indexed Elv from 2.09 ± 0.61 to 2.52 ± 0.80 mmHg/ml, p < 0.05, and reduced the coupling ratio from 0.72 ± 18 to 0.62 ± 15, p < 0.05, while men maintained their pre-training ratio (from 0.66 ± 0.20 to 0.74 ± 0.21, p > 0.05). Women also reduced end-systolic pressure (from 91 ± 10 to 87 ± 10 mmHg), and both groups reduced central pulse wave velocity (from 6.0 ± 1.0 to 5.6 ± 0.6 m/s, p < 0.05). CONCLUSION: We conclude that after 8 weeks of aerobic training, only women reduced their coupling ratio due to an increase in Elv. This suggests that aerobic exercise training elicits sex-dependent changes in the coupling ratio in young, healthy individuals.

Body composition and body fat distribution are related to cardiac autonomic control in non-alcoholic fatty liver disease patients.

BACKGROUND/OBJECTIVES: Heart rate recovery (HRR), a cardiac autonomic control marker, was shown to be related to body composition (BC), yet this was not tested in non-alcoholic fatty liver disease (NAFLD) patients. The aim of this study was to determine if, and to what extent, markers of BC and body fat (BF) distribution are related to cardiac autonomic control in NAFLD patients. SUBJECTS/METHODS: BC was assessed with dual-energy X-ray absorptiometry in 28 NAFLD patients (19 men, 51±13 years, and 9 women, 47±13 years). BF depots ratios were calculated to assess BF distribution. Subjects' HRR was recorded 1 (HRR1) and 2 min (HRR2) immediately after a maximum graded exercise test. RESULTS: BC and BF distribution were related to HRR; particularly weight, trunk BF and trunk BF-to-appendicular BF ratio showed a negative relation with HRR1 (r=-0.613, r=-0.597 and r=-0.547, respectively, P<0.01) and HRR2 (r=-0.484, r=-0.446, P<0.05, and r=-0.590, P<0.01, respectively). Age seems to be related to both HRR1 and HRR2 except when controlled for BF distribution. The preferred model in multiple regression should include trunk BF-to-appendicular BF ratio and BF to predict HRR1 (r2=0.549; P<0.05), and trunk BF-to-appendicular BF ratio alone to predict HRR2 (r2=0.430; P<0.001). CONCLUSIONS: BC and BF distribution were related to HRR in NAFLD patients. Trunk BF-to-appendicular BF ratio was the best independent predictor of HRR and therefore may be best related to cardiovascular increased risk, and possibly act as a mediator in age-related cardiac autonomic control variation.

Effect of sex on wasted left ventricular effort following maximal exercise.

Wasted left ventricular effort (∆Ew) refers to work required of the left ventricle to eject blood that does not result in increased stroke volume and is related to left ventricular hypertrophy. Literature shows that men and women have differing ventricular and vascular responses to and following exercise. Our purpose was to determine how ∆Ew changes post-exercise in men and women and examine potential mechanisms. We hypothesized a reduction in ∆Ew that would be greater in men and that central pulse wave velocity and wave intensity (WIA) would be related to ∆Ew. Blood pressures, central pulse wave velocity (cPWV), and WIA were obtained at rest, 15 and 30 min after maximal exercise. Both sexes reduced ∆Ew post-maximal exercise (p>0.05 for interaction), but women had higher ∆Ew at each time point (p<0.05). The first peak of WIA increased 15 min post-exercise only in women (p<0.05). cPWV was attenuated (p<0.05) in women at 15 min and men at 30 min (p<0.05) post-exercise with a significant time by sex interaction (p<0.05). WIA (1st peak) was correlated (p<0.05) to ∆Ew in both sexes before and 15 min post-exercise, but cPWV was only associated with ∆Ew in men at 30 min post-exercise. We conclude that both sexes decrease ∆Ew after maximal exercise, but vascular and ventricular changes associated with the attenuation of ∆Ew are not uniform between sexes.

Resting and post exercise arterial-ventricular coupling in endurance-trained men and women.

The relationship between effective arterial elastance (EA) and left ventricular end-systolic elastance (ELV) is a determinant of cardiac performance, known as arterial-ventricular coupling (AVC). The purpose of this study was to examine the acute effects of high-intensity interval (HI) and low-intensity steady state (SS) exercise on AVC. Twenty-three (13 men, 10 women) young (26 years), endurance-trained individuals completed a VO2 peak test followed by an acute SS and HI exercise bout on separate visits. Before (Pre) and 30- and 60-min after each bout, measures of aortic end-systolic pressure (ESP), left ventricular end-systolic volume and stroke volume were obtained. Across both conditions (HI and SS) and both sexes, at 30 and 60 min post exercise, ESP and ELV were reduced from Pre 30 and 60-min exercise (ESP: 86±7, 77±8 and 73±8 mm Hg; ELV: 4.93±1.53, 4.19±1.38 and 4.10±1.53 mm Hg ml(-1) m(-2)). EA was only reduced at 60 min post exercise (1.90±0.36, 1.78±0.50 and 1.57±0.36). Both EA and ELV were reduced following acute SS and HI exercise. This is likely because of similar reductions in total peripheral resistance following both exercise bouts. These results suggest that endurance-trained individuals are able to match peripheral vascular changes with changes in left ventricular function following dynamic exercise of different intensities.

Symptomatic correlates of six-minute walk performance in persons with multiple sclerosis.

BACKGROUND: The six-minute walk (6MW) test has been identified as a valid, reliable, and reproducible measure of endurance walking performance that differentiates persons with multiple sclerosis (MS) and controls and correlates with disability and walking impairment. AIM: This study examined symptoms of fatigue, pain, and depression as correlates of 6MW performance and the possibility that such symptoms would account for the difference in 6MW distance between persons with MS and controls. DESIGN: Observational. SETTING: Research laboratory. POPULATION: Sixty-six persons, 33 with MS and 33 controls matched on age, sex, height, and weight. METHODS. Participants completed the fatigue severity scale (FSS), short-form of the McGill pain questionnaire (SF-MPQ), and depression items of the hospital anxiety and depression scale (HADS-D) and then performed the six-minute walk (6MW) in a rectangular corridor. RESULTS: There were statistically significant differences between groups in 6MW distance (p = 0.0001) and FSS (P=0.0001) and SF-MPQ (P=0.025), but not HADS-D (P>0.05), scores. 6MW distance was significantly correlated with FSS (P=-0.66), SF-MPQ (P=-0.38), and HADS-D (P=-0.33) scores in the overall sample, but 6MW distance was significantly correlated with only FSS scores in the separate samples of those with MS (P=-0.46) and controls (P=-0.46). Only group (ß=0.32) and FSS scores (ß=-0.53) explained variance in overall 6MW distance in a hierarchical, linear regression analysis. CONCLUSION: This study provides new insight into the symptomatic correlates of 6MW performance and identifies fatigue as a possible target of interventions designed to improve walking endurance in MS. CLINICAL REHABILITATION IMPACT: Clinicians and practitioners might consider targeting fatigue as a method of managing compromised endurance walking in persons with MS.