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Contains fulltext : 238793.pdf (Publisher’s version ) (Closed access) PURPOSE: In this study, we examined whether the decrease in endothelial function associated with short-term exposure to elevated retrograde shear rate (SR), could be prevented when combined with a concurrent drop in transmural pressure in humans. METHODS: Twenty-five healthy individuals reported to our laboratory on three occasions to complete 30-min experimental conditions, preceded and followed by assessment of endothelial function using flow-mediated dilation (FMD). We used cuff inflation for 30-min to manipulate retrograde SR and transmural pressure in the brachial artery. Subjects underwent, in randomised order: (1) forearm cuff inflation to 60 mmHg (distal cuff; causing increase in retrograde SR), (2) upper arm cuff inflation to 60 mmHg (proximal cuff; causing increase in retrograde SR + decrease in transmural pressure), and (3) no cuff inflation (Control). RESULTS: The distal and proximal cuff conditions both increased brachial artery retrograde SR (p 0.05). A significant interaction-effect was found for FMD (p

Item does not contain fulltext Ischemic preconditioning (IPC) may enhance exercise performance. Cardioprotective effects of IPC are known to re-occur 24h after the stimulus. Whether the delayed effect of IPC has similar effects as IPC on exercise performance is unknown. OBJECTIVES: Examine whether IPC applied 24h (24-IPC) before exercise is equally effective as IPC in improving exercise performance. DESIGN: Randomized, cross-over study METHODS: 12 healthy participants were randomly exposed to SHAM-session, IPC or 24-IPC before a self-paced 5km running trial on a treadmill. Subjects were blinded for time, speed and heart rate. Furthermore, heart rate, BORG, and the local tissue saturation index were measured during exercise, while lactate levels were determined after running. Using a regression model, we explored whether these parameters predicted the change in running time after IPC and 24-IPC. RESULTS: We found no differences in finish time after IPC (SHAM: 1400+/-105s, IPC: 1381+/-112s, 24-IPC: 1385+/-113s; p=0.30). However, we observed a significant positive relation between the change in finish time after IPC and 24-IPC (p=0.016; r=0.677). Using stepwise linear regression, a lower post-exercise blood lactate level after IPC or 24-IPC was significantly related to an improvement in finish time (R2=0.47, beta=-0.687, p=0.007). CONCLUSIONS: Although no significant effect of IPC or 24-IPC on exercise performance was found, individual finish time after IPC and 24-IPC were strongly correlated. Therefore, our data suggest that, at the individual level, the effects of 24-IPC are closely related to the effects of IPC. 01 februari 2017

Item does not contain fulltext OBJECTIVE: Gradual local heating of the skin induces a largely NO-mediated vasodilatation. However, use of this assessment of microvascular health is limited because little is known about its reproducibility. METHODS: Healthy volunteers (n = 9) reported twice to the laboratory. CVC, derived from laser Doppler flux and mean arterial pressure, was examined in response to a standardized local heating protocol (0.5 degrees C per 150 second from 33 degrees C to 42 degrees C, followed by 20 minutes at 44 degrees C). Skin responses were examined at two locations on the forearm (between-site). Heating was repeated after a break of 24-72 hours (between-day). Reproducibility of skin responses at 33-42 degrees C is presented for absolute CVC and relative CVC responses corrected for maximal CVC at 44 degrees C (%CVCmax ). RESULTS: Between-day reproducibility of baseline CVC and %CVCmax for both sites was relatively poor (22-30%). At 42 degrees C, CVC and %CVCmax responses showed less variation (9-19%), whilst absolute CVC responses at 44 degrees C were 14-17%. Between-day variation for %CVCmax increased when using data from site 1 on day 1, but site 2 on the subsequent day (25%). CONCLUSION: Day-to-day reproducibility of baseline laser Doppler-derived skin perfusion responses is poor, but acceptable when absolute and relative skin perfusion to a local gradual heating protocol is utilized and site-to-site variation is minimized. 01 mei 2015

SPRUNG, V. S., D. J. CUTHBERTSON, C. J. A. PUGH, N. AZIZ, G. J. KEMP, C. DAOUSI, D. J. GREEN, N. T. CABLE, and H. JONES. Exercise Training in Polycystic Ovarian Syndrome Enhances Flow-Mediated Dilation in the Absence of Changes in Fatness. Med. Sci. Sports Exerc., Vol. 45, No. 12, pp. 2234–2242, 2013. Introduction: Polycystic ovarian syndrome (PCOS) is associated with an adverse cardiovascular disease (CVD) profile. A surrogate marker for CVD risk is endothelial dysfunction. Limited studies exist examining the cardiovascular and metabolic effects of exercise in PCOS and specifically its impact on endothelial function. Therefore, the aim of the current study was to investigate the impact of exercise on endothelial function, in parallel with body composition, insulin resistance, and cardiopulmonary fitness in PCOS. Methods: Ten women with PCOS (27 yr, 95% confidence interval [CI] = 23–32; 31 kgIm j2 , 95% CI = 28–34) completed a 16-wk exercise (EX) program, and seven women with PCOS (29 yr, 95% CI = 24–35; 35 kgIm j2 , 95% CI = 31–40) undertook conventional care (CC) following lifestyle advice. Brachial artery endothelial function was assessed pre- and postintervention using flow-mediated dilation adjusted for variability in baseline diameter. Visceral and abdominal subcutaneous adipose tissue was assessed using whole-body magnetic resonance imaging and 1 H magnetic resonance spectroscopy quantified liver fat. Cardiorespiratory fitness, glycemic control, hormone, and lipid profiles were also assessed. Data were analyzed using covariate-controlled generalized estimating equations. Results: At follow-up, EX improved flow-mediated dilation by 3.6% (95% CI = 0.5–6.7, P = 0.03) more than CC. There was a parallel improvement in cardiorespiratory fitness of 4.7 mLIkg j1 Imin j1 (95% CI = 1.4–7.9, P G 0.001) with EX versus CC. These changes were not explained by changes in visceral adipose tissue, subcutaneous adipose tissue, liver fat or insulin resistance. Conclusions: Supervised exercise in women with PCOS improves endothelial function, an adaptation associated with reduced CVD risk. This change occurs independent of changes in body weight or composition. The success of public health interventions in this

Glucagon-like peptide-1 receptor agonists (GLP-1 RA) are used for treatment in type 2 diabetes mellitus (T2DM). Little is known about their cardiovascular (CV) impact. We sought to determine the effects of chronic treatment on vascular function in T2DM. Brachial artery endothelial-dependent flow-mediated dilation (FMD) and endothelial-independent glyceryl trinitrate (GTN) function and carotid intima-medial thickness (cIMT) were assessed in 11 severely obese T2DMs (4 females, 7 males: 55 ± 8 years, diabetes duration 8.3 ± 4.7 years mean ± s.d.) before and after 6 months GLP-1 RA. Body weight (5.3 ± 1.2 kg; p < 0.05) and magnetic resonance imaging determined total and subcutaneous fat, but not visceral fat, decreased. Glycaemic control improved. There were no significant changes in FMD, GTN and cIMT (-1.1 ± 0.4%, 0.3 ± 3.0% and 0.00 ± 0.04 mm, respectively). Despite significant improvements in body composition and glycaemic control, 6 months GLP-1 RA treatment did not modulate vascular function. Alternative strategies may therefore be needed to reduce the burden of CV risk in severely obese patients with long-standing T2DM.

Polycystic ovary syndrome (PCOS) is associated with cardiovascular disease. The contribution of the nitric oxide (NO) dilator system to cutaneous endothelial dysfunction is currently unknown in PCOS. Our aim was to examine whether women with PCOS demonstrate impaired cutaneous microvascular NO function and whether exercise training can ameliorate any impairment. Eleven women with PCOS (age, 29 ± 7 years; body mass index, 34 ± 6 kg m(-2)) were compared with six healthy obese control women (age, 29 ± 7 years; body mass index, 34 ± 5 kg m(-2)). Six women with PCOS (30 ± 7 years; 31 ± 6 kg m(-2)) then completed 16 weeks of exercise training. Laser Doppler flowmetry, combined with intradermal microdialysis of l-N(G)-monomethyl-l-arginine, a nitric oxide antagonist, in response to incremental local heating of the forearm was assessed in women with PCOS and control women, and again in women with PCOS following exercise training. Cardiorespiratory fitness, homeostasis model assessment for insulin resistance, hormone and lipid profiles were also assessed. Differences between women with PCOS and control women and changes with exercise were analysed using Student's unpaired t tests. Differences in the contribution of NO to cutaneous blood flow [expressed as a percentage of maximal cutaneous vasodilatation (CVCmax)] were analysed using general linear models. At 42°C heating, cutaneous NO-mediated vasodilatation was attenuated by 17.5%CVCmax (95% confidence interval, 33.3, 1.7; P = 0.03) in women with PCOS vs. control women. Exercise training improved cardiorespiratory fitness by 5.0 ml kg(-1) min(-1) (95% confidence interval, 0.9, 9.2; P = 0.03) and NO-mediated cutaneous vasodilatation at 42°C heating by 19.6% CVCmax (95% confidence interval, 4.3, 34.9; P = 0.02). Cutaneous microvascular NO function is impaired in women with PCOS compared with obese matched control women but can be improved with exercise training.

The impact of manipulating shear stress on conduit artery vasodilation has not been comprehensively described in vivo. We hypothesized that manipulation of SR through the brachial and radial arteries would be associated with corresponding changes in diameter. We performed a series of studies involving the following: (1) leg cycle exercise at increasing intensities (≈70 and 85% maximum heart rate [HRmax]) with simultaneous bilateral measurement of SR in the radial arteries; (2) leg cycle exercise for 30 minutes at 80% HRmax with simultaneous bilateral measurement of velocity and diameter in the brachial arteries; and (3) bilateral forearm heating for 30 minutes with simultaneous bilateral measurement of brachial artery diameter and blood velocity. Cycling and forearm heating interventions were performed in the presence of unilateral cuff inflation throughout the experiment, or starting during the intervention (15 minutes), to manipulate SR responses. Cuff placement was associated with lower radial artery SR responses (cuffed versus uncuffed, 248±49 versus 349±105 L/s 85% HRmax; P P P P P

OBJECTIVE: The aim of this study was to examine the cutaneous vascular and sudomotor responses to combined moderate passive heat stress and normobaric hypoxia. METHOD: Thirteen healthy young males, dressed in a water-perfused suit, underwent passive heating (Δcore temperature ~0.7 °C) twice (NORMOXIA; 20.9% O2 and HYPOXIA; 13% O2 ). Chest and forearm skin blood flow (SkBF; laser Doppler flux), local sweat rate (SR; capacitance hygrometry) and core (intestinal pill) and skin temperatures, were recorded. RESULTS: HYPOXIA reduced baseline oxygen saturation (98±1 vs. 89±6%, P

AIMS: Supervised exercise reduces liver fat and improves endothelial function, a surrogate of cardiovascular disease risk, in non-alcoholic fatty liver disease (NAFLD). We hypothesised that after a 16-week supervised exercise program, patients would maintain longer-term improvements in cardiorespiratory fitness, liver fat and endothelial function. MATHERIALS AND METHODS: Ten NAFLD patients [5/5 males/females, age 51±13years, BMI 31±3 kg.m(2) (mean±s.d.)] underwent a 16-week supervised moderate-intensity exercise intervention. Biochemical markers, cardiorespiratory fitness (VO2peak), subcutaneous, visceral and liver fat (measured by magnetic resonance imaging and spectroscopy respectively) and brachial artery flow-mediated dilation (FMD) were assessed at baseline, after 16 weeks supervised training and 12-months after ending supervision. RESULTS: Despite no significant change in body weight, there were significant improvements in VO2peak [6.5 ml.kg(-1).min(-1) (95% CI 2.8, 10.1); P=0.003], FMD [2.9% (1.5, 4.2); P=0.001], liver transaminases (P0.05) and liver fat [1.4% (-13.0, 15.9); P=0.83] were not significantly different from baseline. CONCLUSIONS: Twelve months following cessation of supervision, exercise-mediated improvements in liver fat and other cardiometabolic variables had reversed with cardiorespiratory fitness at baseline levels. Maintenance of high cardiorespiratory fitness and stability of body weight are critical public health considerations for the treatment of NAFLD.International Journal of Obesity accepted article preview online, 21 July 2016. doi:10.1038/ijo.2016.123.

Childhood obesity is one of the most serious challenges of the 21st century and it is vital that evidence-based treatment approaches can be translated into practice to meet public health needs. Yet policy-makers cannot afford to wait for the results of lengthy trials before ‘probably efficacious’ interventions are made available to the public, and the need for a continuous improvement methodology has been highlighted. In this discussion paper, we draw on our experiences of developing and evaluating a family-based childhood obesity treatment intervention to discuss the challenges of meeting research appraisal standards, public health needs and delivery practicalities. Recommendations are made for a shift towards a translational approach that brings together the strengths of hypothesis-driven research and high-quality service evaluation to create reciprocal links between evidence, policy and practice.

Flow mediated dilation (FMD) is a surrogate marker of arterial function which can be improved by exercise training. To date, no study has assessed the magnitude of FMD changes in response to exercise training between groups of mono- (MZ) and di-zygotic (DZ) twins. The purpose of this study was therefore to compare FMD in MZ- and DZ twins before and after identical exercise training interventions. At baseline, FMD was assessed using high resolution Duplex ultrasound in 12 twin pairs (6 MZ pairs 13.5 ± 0.8 years, 6 DZ pairs 13.4 ± 0.8 years). Twins completed 8 weeks of exercise training (65-85% HR(max)), consisting of three 45-min sessions per week. Change (Δ) scores were entered into twin versus twin intraclass correlation analyses by group. Change in %body fat (r = 0.63, P = 0.05) was significantly correlated in the MZ, but not the DZ group (r = 0.31, P = 0.23). Change in FMD was also highly correlated in MZ (r = 0.74, P = 0.02) but not in the DZ group (r = 0.37, P = 0.18). Heritability of ΔFMD was estimated at 0.74. Exercise induced changes in FMD were similar within sets of monozygotic twins but not dizygotic twins. These data suggest that a significant portion of the arterial function response to exercise training may be genetically determined.

Aim: Recent studies found differences between groups in the rate of diameter increase following the flow-mediated dilation (FMD). Whilst exercise training alters the magnitude of the FMD, little is known about the impact of exercise training on the rate of diameter increase. The aim of this study is to examine post-cuff deflation changes in brachial artery diameter following 5 min forearm ischaemia every 2 weeks across 8-weeks of a handgrip exercise training regimen. Methods: Post-deflation changes in brachial artery diameter following 5-min of ischaemia were examined before, after and every 2-weeks across an 8-week handgrip training programme in healthy young men (n = 11) using echo-Doppler. Results: The magnitude of dilation increased at week 2‐4‐6, but returned towards baseline values at week 8 (anova: P = 0.001). The time-to-peak diameter (42 15 s) demonstrated a significant prolongation at week 4 (77 32 s), but returned towards baseline values at weeks 6 and 8 (anova: P < 0.001). The rate of diameter increase did not differ across the intervention. Conclusion: Exercise training in healthy subjects is initially characterized by a larger dilation. Since the rate of dilation did not change, a longer time-topeak dilation was necessary to achieve the increase in magnitude of dilation. As exercise training continues, the timing and magnitude of the peak

Aim: Alterations in the carotid baroreflex (CBR) control of arterial pressure may explain the reduction in arterial pressure and left ventricular (LV) function after prolonged exercise. We examined the CBR control of heart rate (HR) and mean arterial pressure (MAP), in addition to changes in LV function, pre- to post-exercise. Methods: Seven males (age, mean ± SEM; 29 ± 4 years) completed 4 h of ergometer rowing at a workload of 10–15% below the lactate threshold. The CBR control of HR and MAP was assessed via the rapid neck-suction/pressure protocol. LV systolic function was measured by echocardiography, where ejection fraction (EF), the ratio of systolic blood pressure to end systolic volume (SBP/ESV) and stroke volume (SV) were estimated. Results: Following exercise MAP was reduced (12 ± 3%) and HR was elevated (35 ± 5%; P

Arterial measurements are commonly undertaken to assess acute and chronic adaptations to exercise. Despite the widespread adoption of scaling practices in cardiac research, the relevance of scaling for body size and/or composition has not been addressed for arterial measures. We therefore investigated the relationships between brachial artery diameter and body composition in 129 children aged 9 to 10 yr (75 girls and 54 boys), and 50 men aged 16–49 yr. Body composition variables (total, lean, and fat mass in the whole body, arm, and forearm) were assessed by dual-energy X-ray absorptiometry, and brachial artery diameter was measured using high-resolution ultrasound. Bivariate correlations were performed, and arterial diameter was then scaled using simple ratios ( y/ x) and allometric approaches after log-log least squares linear regression and production of allometric exponents ( b) and construction of power function ratios ( y/ x b). Size independence was checked via bivariate correlations ( x: y/ x; x: y/ x b). As a result, significant correlations existed between brachial artery diameter and measures of body mass and lean mass in both cohorts ( r = 0.21–0.48, P < 0.05). There were no significant relationships between diameter and fat mass. All b exponents were significantly different from 1 (0.08–0.50), suggesting that simple ratio scaling approaches were likely to be flawed. This was confirmed when ratio scaling produced negative residual size correlations, whereas allometric scaling produced size-independent indexes ( r = 0.00 to 0.03, P > 0.05). In conclusion, when between- or within-group comparisons are performed under circumstances where it is important to control for differences in body size or composition, allometric scaling of artery diameter should be adopted rather than ratio scaling. Our data also suggest that scaling for lean or total mass may be more appropriate than scaling for indexes of fat mass.

The presence of axillary artery aneurysm and/or thrombus in overhead throwing athletes has been linked, theoretically, with the finding of compression by the humeral head induced by a diagnostic arm maneuver. However, whether this intermittent compression is incidental or of pathological significance has yet to be determined. Flow-mediated vasodilation (FMD), intima-media thickness (IMT) and maximum vasodilatory capacity were measured locally (3rd portion of the axillary artery) and downstream (brachial artery) in individuals previously tested for inducible axillary artery compression (compressor group [COMP]: n = 8, mean (SD) age: 23 (4) y; “noncompressor” control group [NONCOMP]: n = 8, 26 (4) y). A high-resolution ultrasound machine recorded arterial diameter and blood flow velocity. A rapid inflation/deflation pneumatic cuff placed distal to the site of measurement induced reactive hyperemia. Custom-designed wall tracking software with synchronized Doppler waveform analysis detected changes in arterial diameter, blood flow velocity and shear rate from baseline to 3 min after cuff deflation. Glyceryl trinitrate and/or ischemic hand grip exercises were administered to induce maximum vasodilation. No significant differences in FMD, IMT or maximum vasodilator capacity were observed between groups at the axillary artery. However, the downstream brachial FMD response was significantly diminished in the COMP group (6.38 [3.28]%) compared with the NONCOMP group (10.38 [2.74]%; p = 0.006) despite a comparable shear rate between groups (COMP: 81.92 (44.55) s −1 ; NONCOMP: 83.18 (40.02) s −1 ; p = 0.961). Pooled data revealed a significant negative relationship (r = −0.52, p = 0.038) between the FMD response and degree of arterial compression. These results suggest a chronic change in downstream vascular function in individuals demonstrating clinically significant inducible axillary artery compression. (E-mail: c.stapleton@2005.ljmu.ac.uk )

To investigate the regulation of blood pressure in response to an orthostatic challenge in athletes running a marathon.10 experienced male runners (mean (SD) age 29 (4) years) were tested on the day prior to the 2004 London Marathon, and again immediately postrace (race time 210 (36) min). In addition, 6 of the subjects were retested 24 h postrace. During each examination, beat-to-beat systolic arterial blood pressure (SBP) and heart rate (HR) were measured, and stroke volume (SV), cardiac output (CO) and total peripheral resistance (TPR) were estimated via arterial transmural pressure waveforms during 3 min in a supine position and then during 3 min of upright, unsupported standing. Data were averaged over 20 s epochs, and the final 20 s of each posture were compared prerace and postrace via repeated measures 2-way ANOVA.Prerace SBP in standing increased only moderately when compared with supine values (2 (9) mm Hg, NS). This was accompanied by an increase in HR (13 (7) beats/min, p0.05), as well as a decrease in SV (16 (9) ml, p0.05). However, there was little change in CO (-0.13 (0.97) litres/min, NS) or TPR (0.047 (0.280) medical units (MU), NS). Postrace SBP significantly decreased from supine to standing (-15 (20) mm Hg, p0.05). The change in SBP was accompanied by an increase in HR (19 (6) beats/min, p0.05) and a reduction in SV (26 (14) ml, p0.05) and CO (-1.02 (1.39) litres/min, p = 0.05). Postrace there was no change in TPR (0.366 (0.607) MU, NS) upon standing. The orthostatic adjustments in SBP, HR and CO were greater than at prerace (p0.05). The postrace orthostatic challenge resulted in only one subject experiencing presyncopal symptoms. At 24 h postrace, cardiovascular responses to an orthostatic challenge mirrored those at prerace.Following prolonged exercise, a fall in systolic blood pressure during orthostasis results from an inadequately compensated decrease in SV and resultant CO during standing.

Background: Guidelines recommend children and young people participate in at least 60 min of physical activity (PA) every day, however, findings from UK studies show PA levels of children vary across ethnic groups. Since parents play an instrumental role in determining children’s PA levels, this article aims to explore parental views of children’s PA in a multi-ethnic sample living in a large city in the North-West of England.\ud \ud Methods: Six single-ethnic focus groups were conducted with 36 parents of school-aged children (4 to 16 years) with a predominantly low socio-economic status (SES). Parents self-identified their ethnic background as Asian Bangladeshi (n = 5), Black African (n = 4), Black Somali (n = 7), Chinese (n = 6), White British (n = 8) and Yemeni (n = 6). Focus group topics included understanding of PA, awareness of PA guidelines, knowledge of benefits associated with PA and perceived influences on PA in childhood. Data were analysed thematically using QSR NVivo 9.0.\ud \ud \ud Results: Parents from all ethnic groups valued PA and were aware of its benefits, however they lacked awareness of PA recommendations, perceived school to be the main provider for children’s PA, and reported challenges in motivating children to be active. At the environmental level, barriers to PA included safety concerns, adverse weather, lack of resources and lack of access. Additional barriers were noted for ethnic groups from cultures that prioritised educational attainment over PA (Asian Bangladeshi, Chinese, Yemeni) and with a Muslim faith (Asian Bangladeshi, Black Somali, Yemeni), who reported a lack of culturally appropriate PA opportunities for girls.\ud \ud \ud Conclusion: Parents from multi-ethnic groups lacked awareness of children’s PA recommendations and faced barriers to promoting children’s PA out of school, with certain ethnic groups facing additional barriers due to cultural and religious factors. It is recommended children’s PA interventions address influences at all socio-ecological levels, and account for differences between ethnic groups.

The purpose of this study was to investigate the effects of supra-physiological changes in ovarian hormone levels on maximum force production in two conditions, one physiological (pregnancy) and one pseudo-physiological (in vitro fertilization (IVF) treatment). Forty IVF patients were tested at four distinct stages of treatment and 35 women were tested during each trimester of pregnancy and following parturition. Maximum voluntary isometric force per unit cross-sectional area of the first dorsal interosseus muscle was measured. Plasma concentrations of total and bioavailable oestradiol and testosterone were measured, in addition to the total concentrations of progesterone and human chorionic gonadotropin. Despite significant changes in the concentrations of total progesterone, 17β-oestradiol, bioavailable oestradiol and testosterone between phases, strength did not change significantly throughout IVF treatment (1.30 ± 0.29, 1.16 ± 0.38, 1.20 ± 0.29 and 1.26 ± 0.34 N mm−2, respectively, in the 4 phases of IVF treatment). Force production was significantly higher during the second trimester of pregnancy than following childbirth (1.33 ± 0.20 N mm−2 at week 12 of pregnancy, 1.51 ± 0.42 N mm−2 at week 20, 1.15 ± 0.26 N mm−2 at week 36 and 0.94 ± 0.31 N mm−2 at week 6 postnatal) but was not significantly correlated with any of the hormones measured. These data suggest that extreme changes in the concentrations of reproductive hormones do not affect the maximum force-generating capacity of young women.

To examine the effects of oral contraceptive use on maximum force production in young women.In the study, 21 female subjects (14 pill users and seven eumenorrheic controls) took part. All pill using subjects had been taking a combined, monophasic oral contraceptive pill for at least 6 months. Maximum dynamic and isometric leg strength, maximum isometric strength of the first dorsal interosseus (FDI) muscle, and plasma concentrations of oestradiol and progesterone were measured on days 7 and 14 of pill consumption and day 5 of pill withdrawal. The eumenorrheic group was tested (FDI strength and hormone concentrations) on days 2 and 21 of the menstrual cycle.There were no significant changes in the concentration of endogenous oestradiol or progesterone or any measure of muscle strength between pill phases (p0.05). The pill group did not significantly differ from the eumenorrheic group (p0.05), despite a significant increase in the concentration of progesterone and oestradiol on day 21 of the menstrual cycle compared with day 2 of the menstrual cycle and pill consumption and withdrawal (p0.05).These data suggest that oral contraceptive use does not significantly affect muscle strength. Moreover, oral contraceptive users were not stronger or weaker than their eumenorrheic counterparts.

Muscle strength has been investigated across the menstrual cycle, following the menopause, throughout pregnancy and during in vitro fertilisation treatment. In addition, amenorrheic females, oral contraceptive users and individuals that administer hormone replacement therapy have been used to explore different models of reproductive status. The results of such studies have clinical and athletic significance. If changes in the concentration of reproductive hormones affect muscle strength then functional capacity and exercise performance will change with advancing age. Despite documented changes in strength due to altered reproductive functioning, no consensus has been reached as to the absolute or directional effects of oestrogen and progesterone on muscle strength. Such inconsistencies may arise from differences in the definition and quantification of reproductive status and muscle strength. Future research should focus on measuring the concentration of reproductive hormones at the time of strength assess...

To determine the effects of pre-warming on the human metabolic and thermoregulatory responses to prolonged steady-rate exercise in moderate ambient temperatures and relative humidities [means (SD) 21.7 (2.1)° C and 36.7 (5.4)%, respectively], six healthy men each ran at a steady-rate (70% maximal oxygen uptake) on a treadmill until exhausted after being actively pre-warmed (AH), passively pre-warmed (PH), and rested (Cont). Exercise time to exhaustion was significantly reduced following both AH and PH compared to Cont [AH 47.8 (14.0) min, PH 39.6 (16.0) min, Cont 62.0 (8.8) min; P

Objective: This study examined the relationship between ethnic background and parental views of healthy body size, concerns surrounding overweight and attitudes to perceived causes of overweight in childhood. Method: A self-report questionnaire was designed to explore parental attitudes towards childhood weight. Sampling deliberately over-represented the views of parents from minority ethnic groups. Eight-hundred-and-eight parents of school-aged children completed the questionnaire. Parental data from Asian British, Black African, Black Somali, Chinese, South Asian, White British and Yemeni groups were included in the analysis. Results: Data showed that ethnic background was significantly associated with parental beliefs that overweight children will grow out of being overweight (X2[12, n = 773] = 59.25, p < 0.001) and that overweight children can still be healthy (X2[12, n = 780] = 25.17, p < 0.05). In both cases, agreement with the statements was highest among Black Somali parents. While the majority of parents believed that both dietary behaviours and physical activity played a role in the development of overweight in childhood, Yemeni parents were more likely to attribute overweight in childhood to dietary but not physical activity causes. Conclusion: Ethnic differences in parental perceptions of weight in childhood must be considered in the design of, and recruitment to, childhood obesity interventions aimed at minority ethnic groups.

1. To investigate the effect of the female reproductive hormones on muscle function, patients undergoing in vitro fertilization were tested during two phases of treatment. The first was following the downregulation of pituitary gonadotrophin releasing hormone (GnRH) receptors and the second after 9 days of gonadotrophin injections. 2. Maximal strength and fatiguability of the first dorsal interosseus muscle were assessed when oestrogen and progesterone were low, and less than 2 weeks later when oestrogen production reached supraphysiological levels. 3. There were no significant changes in either strength or fatigue resistance during acute, massive fluctuations in oestrogen. These results occurred at a time when progesterone levels remained relatively low. 4. Contrary to previous work, the present results suggest that oestrogen does not affect muscle strength.

Item does not contain fulltext Thickening of the carotid artery wall has been adopted as a surrogate marker of pre-clinical atherosclerosis, which is strongly related to increased cardiovascular risk. The cardioprotective effects of exercise training, including direct effects on vascular function and lumen dimension, have been consistently reported in asymptomatic subjects and those with cardiovascular risk factors and diseases. In the present review, we summarize evidence pertaining to the impact of exercise and physical activity on arterial wall remodelling of the carotid artery and peripheral arteries in the upper and lower limbs. We consider the potential role of exercise intensity, duration and modality in the context of putative mechanisms involved in wall remodelling, including haemodynamic forces. Finally, we discuss the impact of exercise training in terms of primary prevention of wall thickening in healthy subjects and remodelling of arteries in subjects with existing cardiovascular disease and risk factors. 01 april 2012

Item does not contain fulltext BACKGROUND: Although previous studies have reported age-related wall thickening in carotid arteries, it is not clear whether this is a systemic phenomenon which is also apparent in peripheral conduit arteries or whether conduit wall thickness (WT) changes occur to a similar degree in men and women. AIM: To determine whether sex modifies the impact of ageing on WT or wall-to-lumen ratio (W:L) in atherosclerosis-prone (i.e. carotid artery, femoral, superficial femoral, popliteal artery) and atherosclerosis-resistant (i.e. brachial artery) conduit arteries. METHODS: We included 30 young (23 +/- 2 year; 15M : 15F) and 31 older (70 +/- 5 year; 18M : 13F) healthy subjects. High-resolution ultrasound was used to measure diameter, WT and wall-to-lumen ratio (W/L) in all arteries. RESULTS: Older subjects had increased WT and W/L in the carotid, femoral, superficial femoral, popliteal and brachial arteries (all P < 0.05). Compared with women, men demonstrated larger diameter and WT (both P < 0.01) across all arteries. Sex did not impact upon age-related changes in WT or W/L (P = 0.39 and 0.43 respectively). CONCLUSION: Our data suggest that age-related wall thickening, evident in the carotid artery, is also apparent in the arteries of the upper and lower limbs. The impact of age on wall thickening did not differ between men and women. These data support the presence of systemic increases in WT and W/L with age in apparently healthy humans, independent of sex.

Flow-mediated dilation (FMD) assesses the health of the vascular endothelium. Despite widespread adoption of scaling practices in cardiac research, scaling for body size or composition has not been used for FMD. The present study investigated the relationships between brachial FMD and body composition in 129 children aged 9–10 (75♀, 54♂), and 50 men aged 16–49. Body composition variables (total, lean, fat mass in the whole body, arm, forearm) were assessed by dual-energy X-ray absorptiometry, FMD was measured in the brachial artery using high-resolution ultrasound. FMD was scaled using simple ratios (y/x) and allometric approaches (y/x b ) after log–log least squares linear regression produced allometric exponents (b). Size independence was confirmed via bivariate correlations (x:y/x; x:y/x b ). No relationships were evident between FMD and body composition variables in adults. Small correlations existed between FMD and measures of segmental fat mass in children (r = −0.18 to −0.19, p

Contains fulltext : 88295thijssen.pdf (Publisher’s version ) (Closed access) Coronary angiography and angioplasty are common invasive procedures in cardiovascular medicine, which involve placement of a sheath inside peripheral conduit arteries. Sheath placement and catheterization can be associated with arterial thrombosis, spasm and occlusion. In this paper we review the literature pertaining to the possible benefits of arterial 'prehabilitation'--the concept that interventions aimed at enhancing arterial function and size (i.e. remodelling) should be undertaken prior to cardiac catheterization or artery harvest during bypass graft surgery. The incidence of artery spasm, occlusion and damage is lower in larger arteries with preserved endothelial function. We conclude that the beneficial effects of exercise training on both artery size and function, which are particularly evident in individuals who possess cardiovascular diseases or risk factors, infer that exercise training may reduce complication rates following catheterization and enhance the success of arteries harvested as bypass grafts. Future research efforts should focus directly on examination of the 'prehabilitation' hypothesis and the efficacy of different interventions aimed at reducing clinical complications of common interventional procedures.

Contains fulltext : 80072thijssen.pdf (Publisher’s version ) (Closed access) It has been deemed important to normalize flow-mediated dilation (FMD), a marker of endothelial function, for between-subject differences in the eliciting shear rate (SR) stimulus. Conventionally, FMD is divided by the area under the curve of the SR stimulus. In the context of a cross-sectional comparison across different age cohorts, we examined whether this ratio approach adhered to established statistical assumptions necessary for reliable normalization. To quantify brachial artery FMD and area under the curve of SR, forearm cuff inflation to suprasystolic pressure was administered for 5 min to 16 boys aged 10.9 yr (SD 0.3), 48 young men aged 25.3 yr (SD 4.2), and 15 older men aged 57.5 yr (SD 4.3). Mean differences between age groups were statistically significant (P < 0.001) for nonnormalized FMD [children: 10.4% (SD 5.4), young adults: 7.5% (SD 2.9), older adults: 5.6% (SD 2.0)] but not for ratio-normalized FMD (P = 0.10). Moreover, all assumptions necessary for reliable use of ratio-normalization were violated, including regression slopes between SR and FMD that had y-intercepts greater than zero (P < 0.05), nonlinear and unstable relations between the normalized ratios and SR, skewed data distributions, and heteroscedastic variance. Logarithmic transformation of SR and FMD before ratio calculation improved adherence to these assumptions and resulted in age differences similar to the nonnormalized data (P = 0.03). In conclusion, although ratio normalization of FMD altered findings about age differences in endothelial function, this could be explained by violation of statistical assumptions. We recommend that exploration of these assumptions should be routine in future research. If the relationship between SR and FMD is generally found to be weak or nonlinear or variable between samples, then ratio normalization should not be applied.

Exercise-associated hyperthermia is routinely cited as the signal responsible for inducing an increased production of heat shock proteins (HSPs) following exercise. This hypothesis, however, has not been tested in human skeletal muscle. The aim of the present study was to therefore investigate the role of increased muscle and core temperature in contributing to the exercise-induced production of the major HSP families in human skeletal muscle.Seven physically active males underwent a passive heating protocol of 1 h duration during which the temperature of the core and vastus lateralis muscle were increased to similar levels to those typically occurring during moderately demanding aerobic exercise protocols. One limb was immersed in a tank containing water maintained at approximately 45 degrees C whilst the contra-lateral limb remained outside the tank and was not exposed to heat stress. Muscle biopsies were obtained from the vastus lateralis of both legs immediately prior to and at 48 h and 7 days post-heating.The heating protocol induced significant increases (P0.05) in rectal (1.5 +/- 0.2 degrees C) and muscle temperature of the heated leg (3.6 +/- 0.5 degrees C). Muscle temperature of the non-heated limb showed no significant change (P0.05) following heating (pre: 36.1 +/- 0.5, post: 35.7 +/- 0.2 degrees C). Heating failed to induce a significant increase (P0.05) in muscle content of HSP70, HSC70, HSP60, HSP27, alphaB-crystallin, MnSOD protein content or in the activity of superoxide dismutase and catalase.These data demonstrate that increases in both systemic and local muscle temperature per se do not appear to mediate the exercise-induced production of HSPs in human skeletal muscle and suggest that non-heat stress factors associated with contractile activity are of more importance in mediating this response.

To examine the influence of pre-warming on the physiological responses to prolonged intermittent exercise in ambient temperatures of 21.5 +/- 0.6 degrees C and relative humidities of 35.7 +/- 5.4% (mean +/- s), six healthy men performed intermittent treadmill running (30-s bouts at 90% of maximal oxygen uptake separated by 30-s static recovery periods) to exhaustion after active pre-warming, passive pre-warming and pre-exercise rest (control). Exercise time to exhaustion was significantly different between all conditions (active, 51.8 +/- 7.2 min; passive, 38.5 +/- 11.1 min; control, 72.0 +/- 17.2 min; P0.05). These changes in performance time were closely associated with a significant decline in both the rate of heat storage and heat storage capacity (P0.05). Rectal temperature, heart rate and ratings of perceived exertion were significantly higher during exercise in the two pre-warming conditions than in the control condition (P0.05). Ratings of perceived exertion were also significantly higher during exercise following passive pre-warming compared with active pre-warming (P0.05). During exercise there were no significant differences in serum prolactin, plasma norepinephrine and plasma free fatty acid concentrations between conditions. We conclude that both active and passive pre-warming promote a reduction in prolonged intermittent exercise capacity in environmental temperatures of 21 degrees C compared with pre-exercise rest. These performance decrements were dependent upon the mode of pre-warming and closely reflected alterations in body heat content.

The purpose of this study was to investigate the effects of supra-physiological changes in ovarian hormone levels on maximum force production in two conditions, one physiological (pregnancy) and one pseudo-physiological (in vitro fertilization (IVF) treatment). Forty IVF patients were tested at four distinct stages of treatment and 35 women were tested during each trimester of pregnancy and following parturition. Maximum voluntary isometric force per unit cross-sectional area of the first dorsal interosseus muscle was measured. Plasma concentrations of total and bioavailable oestradiol and testosterone were measured, in addition to the total concentrations of progesterone and human chorionic gonadotropin. Despite significant changes in the concentrations of total progesterone, 17beta-oestradiol, bioavailable oestradiol and testosterone between phases, strength did not change significantly throughout IVF treatment (1.30+/-0.29, 1.16+/-0.38, 1.20+/-0.29 and 1.26+/-0.34 N mm-2, respectively, in the 4 phases of IVF treatment). Force production was significantly higher during the second trimester of pregnancy than following childbirth (1.33+/-0.20 N mm-2 at week 12 of pregnancy, 1.51+/-0.42 N mm-2 at week 20, 1.15+/-0.26 N mm-2 at week 36 and 0.94+/-0.31 N mm-2 at week 6 postnatal) but was not significantly correlated with any of the hormones measured. These data suggest that extreme changes in the concentrations of reproductive hormones do not affect the maximum force-generating capacity of young women.

To investigate the effect of changes in sex hormone concentration on muscle strength and the bioavailability of 17-β oestradiol (oestradiol) and testosterone, seven eumenorrheic females were tested during two phases of the menstrual cycle. Maximum voluntary isometric strength of the first dorsal interosseus muscle was measured during the early follicular and mid-luteal phases of the menstrual cycle. These phases were chosen for testing as the concentration of total oestradiol is significantly different in these two phases. Total oestradiol has been repeatedly associated with changes in muscle strength in females, whereas the effects of bioavailable oestradiol are unknown. The concentrations of total and bioavailable oestradiol and testosterone were measured in addition to the concentration of total progesterone. Concentrations of total progesterone and oestradiol were significantly different between the early follicular and mid-luteal phases of the menstrual cycle (P

Purpose: Postexercise hypotension may be the result of an impaired vasoconstrictor response. This hypothesis was investigated by examining the central and peripheral hemodynamic responses during supine and seated recovery after maximal upright exercise. Methods: After supine or seated baseline measurements, seven normotensive male volunteers completed a graded upright cycling protocol to volitional exhaustion. This was immediately followed by either supine or seated recovery. Measurements of pulsatile arterial blood pressure and central and peripheral hemodynamic variables recorded 30 min before exercise were compared with those taken throughout 60 min of recovery. Results: Compared with baseline, mean arterial pressure (MAP) was reduced after exercise (P < 0.05) although the degree of change was not different between the supine (-9 ± 4 mm Hg) and seated positions (-6 ± 2 mm Hg). This change in MAP was associated with a reduction in diastolic blood pressure (DBP) (P < 0.05) and arterial pulse pressure (APP) (P < 0.01) for the supine and seated positions, respectively. The reduction in APP during seated recovery was accompanied by a decline in stroke volume (SV) (P < 0.05), not seen in the supine position, that limited the contribution of cardiac output (CO) to the maintenance of MAP. This effect of seated recovery was compensated by greater systemic (SVR) and regional vascular resistances in the forearm (FVR) and the forearm skin (SkVR A ). There was also evidence of an augmented return of FVR and SkVR A to resting levels in the seated position after exercise. Conclusion: The lower peripheral resistance in the supine compared with seated recovery position suggests there is potential for greater vasoconstriction, although this is not evoked to increase blood pressure. This further suggests that the arterial baroreceptor reflex is reset to a lower operating pressure after exercise.

Item does not contain fulltext PURPOSE: We performed two experiments to determine whether cutaneous microvascular adaptations in response to repeated core temperature (Tc) elevation are mediated by increases in skin blood flow (SkBF) and/or skin temperature. METHODS: Healthy subjects participated for 8 wk in thrice-weekly bouts of 30-min lower limb heating (40 degrees C). In study 1, both forearms were "clamped" at basal skin temperature throughout each heating bout (n = 9). Study 2 involved identical lower limb heating, with the forearms under ambient conditions (unclamped, n = 10). In both studies, a cuff was inflated around one forearm during the heating bouts to assess the contribution of SkBF and temperature responses. We assessed forearm SkBF responses to both lower limb (systemic reflex) heating and to local heating of the forearm skin, pre- and postintervention. RESULTS: Acutely, lower limb heating increased Tc (study 1, 0.63 degrees C +/- 0.15 degrees C; study 2, 0.69 degrees C +/- 0.19 degrees C; P < 0.001) and forearm SkBF (study 1, 0.13 +/- 0.03 vs 1.52 +/- 0.51; study 2, 0.14 +/- 0.01 vs 1.17 +/- 0.38 cutaneous vascular conductance (CVC); P < 0.001), with skin responses significantly attenuated in the cuffed forearm (P < 0.01). SkBF responses to local heating decreased in study 1 (clamped forearms; week 0 vs week 8, 1.46 +/- 0.52 vs 0.99 +/- 0.44 CVC; P < 0.05), whereas increases occurred in study 2 (unclamped; week 0 vs week 8, 1.89 +/- 0.57 vs 2.27 +/- 0.52 CVC; P < 0.05). Cuff placement abolished local adaptations in both studies. CONCLUSIONS: Our results indicate that repeated increases in SkBF and skin temperature result in increased skin flux responses to local heating, whereas repeated increases in SkBF in the absence of change in skin temperature induced the opposite response. Repeated increases in Tc induce intrinsic microvascular changes, the nature of which are dependent upon both SkBF and skin temperature. 01 november 2014

Whole-body cooling prior to activity has the potential to reduce thermal strain and fatigue during subsequent endurance exercise. Intermittent activity is associated with greater increases in rectal temperature compared with continuous exercise. Thus, the effect of pre-cooling on thermoregulatory responses was examined during an intermittent test under "normal" environmental conditions. Six male university soccer players [mean (SD) age 27 (2) years; height 1.77 (0.3) m; mass 72.2 (1.5) kg; maximal oxygen consumption 58.9 (3.5) ml x kg(-1) x min(-1)] completed a 90-minute soccer-specific intermittent exercise protocol on a non-motorized treadmill. The run was completed with and without pre-cooling under normal laboratory conditions (20 degrees C) and without pre-cooling in a heated laboratory (26 degrees C). The pre-cooling strategy involved exposure to a cold shower (26 degrees C) for 60 min. The pre-cooling manipulation lowered rectal temperature prior to exercise [-0.6 (0.6) degrees C, range -1.5 degrees C; P < 0.05]. The rectal temperature response to exercise was significantly lower following pre-cooling than in the heated condition [pre-cooled 38.1 (0.6) degrees C, heated 38.6 (0.3) degrees C]. The increase in rectal temperature during the second half of the protocol following pre-cooling was significantly greater than the increase observed under normal or heated conditions (P < 0.05). No significant differences were observed between the three conditions for oxygen consumption, heart rate, minute ventilation, rating of perceived exertion and plasma lactate, glucose or free fatty acid concentrations. Based on the current investigation, it can be concluded that there is no evidence for the beneficial effects of pre-cooling on the physiological responses to soccer-specific intermittent exercise under normal environmental conditions.