8,964 research outputs found
Effect of expiratory muscle fatigue on exercise tolerance and locomotor muscle fatigue in healthy humans
High-intensity exercise (> or =90% of maximal O(2) uptake) sustained to the limit of tolerance elicits expiratory muscle fatigue (EMF). We asked whether prior EMF affects subsequent exercise tolerance. Eight male subjects (means +/- SD; maximal O(2) uptake = 53.5 +/- 5.2 ml.kg(-1).min(-1)) cycled at 90% of peak power output to the limit of tolerance with (EMF-EX) and without (CON-EX) prior induction of EMF and for a time equal to that achieved in EMF-EX but without prior induction of EMF (ISO-EX). To induce EMF, subjects breathed against an expiratory flow resistor until task failure (15 breaths/min, 0.7 expiratory duty cycle, 40% of maximal expiratory gastric pressure). Fatigue of abdominal and quadriceps muscles was assessed by measuring the reduction relative to prior baseline values in magnetically evoked gastric twitch pressure (Pga(tw)) and quadriceps twitch force (Q(tw)), respectively. The reduction in Pga(tw) was not different after resistive breathing vs. after CON-EX (-27 +/- 5 vs. -26 +/- 6%; P = 0.127). Exercise time was reduced by 33 +/- 10% in EMF-EX vs. CON-EX (6.85 +/- 2.88 vs. 9.90 +/- 2.94 min; P < 0.001). Exercise-induced abdominal and quadriceps muscle fatigue was greater after EMF-EX than after ISO-EX (-28 +/- 9 vs. -12 +/- 5% for Pga(tw), P = 0.001; -28 +/- 7 vs. -14 +/- 6% for Q(tw), P = 0.015). Perceptual ratings of dyspnea and leg discomfort (Borg CR10) were higher at 1 and 3 min and at end exercise during EMF-EX vs. during ISO-EX (P < 0.05). Percent changes in limb fatigue and leg discomfort (EMF-EX vs. ISO-EX) correlated significantly with the change in exercise time. We propose that EMF impaired subsequent exercise tolerance primarily through an increased severity of limb locomotor muscle fatigue and a heightened perception of leg discomfort
Effect of expiratory muscle fatigue on exercise tolerance and locomotor muscle fatigue in healthy humans
High-intensity exercise (> or =90% of maximal O(2) uptake) sustained to the limit of tolerance elicits expiratory muscle fatigue (EMF). We asked whether prior EMF affects subsequent exercise tolerance. Eight male subjects (means +/- SD; maximal O(2) uptake = 53.5 +/- 5.2 ml.kg(-1).min(-1)) cycled at 90% of peak power output to the limit of tolerance with (EMF-EX) and without (CON-EX) prior induction of EMF and for a time equal to that achieved in EMF-EX but without prior induction of EMF (ISO-EX). To induce EMF, subjects breathed against an expiratory flow resistor until task failure (15 breaths/min, 0.7 expiratory duty cycle, 40% of maximal expiratory gastric pressure). Fatigue of abdominal and quadriceps muscles was assessed by measuring the reduction relative to prior baseline values in magnetically evoked gastric twitch pressure (Pga(tw)) and quadriceps twitch force (Q(tw)), respectively. The reduction in Pga(tw) was not different after resistive breathing vs. after CON-EX (-27 +/- 5 vs. -26 +/- 6%; P = 0.127). Exercise time was reduced by 33 +/- 10% in EMF-EX vs. CON-EX (6.85 +/- 2.88 vs. 9.90 +/- 2.94 min; P < 0.001). Exercise-induced abdominal and quadriceps muscle fatigue was greater after EMF-EX than after ISO-EX (-28 +/- 9 vs. -12 +/- 5% for Pga(tw), P = 0.001; -28 +/- 7 vs. -14 +/- 6% for Q(tw), P = 0.015). Perceptual ratings of dyspnea and leg discomfort (Borg CR10) were higher at 1 and 3 min and at end exercise during EMF-EX vs. during ISO-EX (P < 0.05). Percent changes in limb fatigue and leg discomfort (EMF-EX vs. ISO-EX) correlated significantly with the change in exercise time. We propose that EMF impaired subsequent exercise tolerance primarily through an increased severity of limb locomotor muscle fatigue and a heightened perception of leg discomfort
Exercise-induced abdominal muscle fatigue in healthy humans
Exercise-induced abdominal muscle fatigue in healthy humans. J Appl
Physiol 100: 1554â1562, 2006. First published January 19, 2006;
doi:10.1152/japplphysiol.01389.2005.âThe abdominal muscles have
been shown to fatigue in response to voluntary isocapnic hyperpnea
using direct nerve stimulation techniques. We investigated whether
the abdominal muscles fatigue in response to dynamic lower limb
exercise using such techniques. Eleven male subjects [peak oxygen
uptake (VË O2 peak) 50.0 1.9 (SE) ml kg 1 min 1] cycled at
90% VË O2 peak to exhaustion (14.2 4.2 min). Abdominal muscle
function was assessed before and up to 30 min after exercise by
measuring the changes in gastric pressure (Pga) after the nerve roots
supplying the abdominal muscles were magnetically stimulated at
1â25 Hz. Immediately after exercise there was a decrease in Pga at all
stimulation frequencies (mean 25 4%; P 0.001) that persisted
up to 30 min postexercise ( 12 4%; P 0.001). These reductions
were unlikely due to changes in membrane excitability because
amplitude, duration, and area of the rectus abdominis M wave were
unaffected. Declines in the Pga response to maximal voluntary expiratory
efforts occurred after exercise (158 13 before vs. 145 10
cmH2O after exercise; P 0.005). Voluntary activation, assessed
using twitch interpolation, did not change (67 6 before vs. 64 2%
after exercise; P 0.20), and electromyographic activity of the rectus
abdominis and external oblique increased during these volitional
maneuvers. These data provide new evidence that the abdominal
muscles fatigue after sustained, high-intensity exercise and that the
fatigue is primarily due to peripheral mechanisms
Understanding the notion of accessible spaces and places: Sydney CBD Visitor Accessibility Web portal www.sydneyforall.com
The paper presents an approach to understanding the accessibility of spaces and places for people with disabilities and seniors. For these groups, the challenges associated with recreational access are compounded by the cultural context, fragmented approaches to wayfinding and a lack of collaboration by providers to promote accessible experiences. The paper presents the outcome of the research project that sought to collaboratively promote accessible experiences within the Sydney CBD and Sydney Harbour environs. The Sydney for All web portal was developed in conjunction with three industry partners: Tourism NSW; Tourism and Transport Forum; and NSW Dept of Environment and Climate Change. The research engaged in participatory action research with the major stakeholders, attractions and the destination experience providers. The Web portal complies with the highest W3C web accessibility standards as evidenced through the compliance testing by Vision Australia. The paper outlines the research approach, underlying philosophy and the major accessibility features of the portal through a case study of the North Head Lookout. As will be demonstrated, the portal is a starting point to understanding accessible experiences through focusing on universal design, destination experience and management frameworks rather than using constraints based approaches that dominate mainstream access auditing
Average acceleration and intensity gradient of primary school children and associations with indicators of health and wellbeing
Average acceleration (AvAcc) and intensity gradient (IG) have been proposed as standardised metrics describing physical activity (PA) volume and intensity, respectively. We examined hypothesised between-group PA differences in AvAcc and IG, and their associations with health and wellbeing indicators in children. ActiGraph GT9X wrist accelerometers were worn for 24-h·dâ1 over seven days by 145 children aged 9-10. Raw accelerations were averaged per 5-s epoch to represent AvAcc over 24-h. IG represented the relationship between log values for intensity and time. Moderate-to-vigorous PA (MVPA) was estimated using youth cutpoints. BMI z-scores, waist-to-height ratio (WHtR), peak oxygen uptake (VO2peak), Metabolic Syndrome risk (MetS score), and wellbeing were assessed cross-sectionally, and 8-weeks later. Hypothesised between-group differences were consistently observed for IG only (p<.001). AvAcc was strongly correlated with MVPA (r=0.96), while moderate correlations were observed between IG and MVPA (r=0.50) and AvAcc (r=0.54). IG was significantly associated with health indicators, independent of AvAcc (p<.001). AvAcc was associated with wellbeing, independent of IG (p<.05). IG was significantly associated with WHtR (p<.01) and MetS score (p<.05) at 8-weeks follow-up. IG is sensitive as a gauge of PA intensity that is independent of total PA volume, and which relates to important health indicators in children
Experiences of Improving Access to Psychological Therapy Services for Perinatal Mental Health Difficulties: a Qualitative Study of Women's and Therapists' Views
BACKGROUND: Perinatal mental health difficulties are highly prevalent. In England, the Improving Access to Psychological Therapy (IAPT) programme provides evidence-based psychological treatment, predominantly in the form of brief manualized cognitive behavioural therapy (CBT), to people with mild to moderate depression or anxiety. Yet little is known about the experiences of women referred to IAPT with perinatal mental health difficulties. AIMS: The aim of this qualitative study was to investigate how women view IAPT support for perinatal mental health. We also gained the perspective of IAPT therapists. METHOD: Semi-structured interviews were conducted with twelve women who had been referred to and/or received therapy from IAPT during the perinatal period. Additionally, fourteen IAPT therapists participated in two focus groups. Thematic analysis was used. RESULTS: Key themes centred on barriers to access and the need to tailor support to (expectant) mothers. Women and therapists suggested that experiences could be improved by supporting healthcare professionals to provide women with more help with referrals, better tailoring support to the perinatal context, improving perinatal-specific training, supervision and resources, and offering a more individualized treatment environment. CONCLUSIONS: Overall, women reported positive experiences of support offered by IAPT for perinatal mental health difficulties. However, services should seek to facilitate access to support and to enable therapists to better tailor treatment
A national qualitative investigation of the impact of service change on doctors' training during Covid-19
BACKGROUND: The Covid-19 crisis sparked service reconfigurations in healthcare systems worldwide. With postgraduate medical education sitting within these systems, service reconfigurations substantially impact trainees and their training environment. This study aims to provide an in-depth qualitative understanding of the impact of service reconfiguration on doctors' training during the pandemic, identifying opportunities for the future as well as factors that pose risks to education and training and how these might be mitigated. METHODS: Qualitative parallel multi-centre case studies examined three Trusts/Health Boards in two countries in the United Kingdom. Data were collected from online focus groups and interviews with trainees and supervisors using semi-structured interview guides (September to December 2020). A socio-cultural model of workplace learning, the expansive-restrictive continuum, informed data gathering, analysis of focus groups and coding. RESULTS: Sixty-six doctors participated, representing 25 specialties/subspecialties. Thirty-four participants were male, 26 were supervisors, 17 were specialty trainees and 23 were foundation doctors. Four themes described the impact of pandemic-related service reconfigurations on training: (1) Development of skills and job design, (2) Supervision and assessments, (3) Teamwork and communication, and (4) Workload and wellbeing. Service changes were found to both facilitate and hinder education and training, varying across sites, specialties, and trainees' grades. Trainees' jobs were redesigned extensively, and many trainees were redeployed to specialties requiring extra workforce during the pandemic. CONCLUSIONS: The rapid and unplanned service reconfigurations during the pandemic caused unique challenges and opportunities to doctors' training. This impaired trainees' development in their specialty of interest, but also presented new opportunities such as cross-boundary working and networking
Laser Ultrasonic Thermoelastic/Ablation Generation with Laser Interferometric Detection in Graphite/Polymer Composites
Ultrasonic signals have been generated and detected in graphite/polymer composites by optical methods. A Doppler interferometric technique was used for detection. The output voltage of this type of interferometer is proportional to the surface velocity of a sample area which is illuminated by cw laser light. Ultrasonic signals were generated by thermoelastic and ablation processes which occur as a consequence of laser pulses incident on the opposite surface of the sample. The evolution of the magnitude and shape of the detected signals was measured as a function of the pulse energy of the generating laser. Low-energy laser pulses generated ultrasound without causing obvious surface damage. At higher energies surface damage was observable in post inspection but could also be detected by observing (through protective goggles) bright flashes near the illuminated area. The energy at which these processes first occur is qualitatively referred to as the ablation threshold. Changes in the observed waveform were evident at energies above the ablation threshold. The higher-energy waveforms were found to consist of a superposition of a thermoelastic component and an ablatic component, whose relative magnitudes changed with laser power. A delay in the initiation of the ablatic wave relative to the thermoelastic wave was observed to be of the order of 0.3 ÎŒs, consistent with observations in pure polymer. [1] Photoelectric detection measurements of the ablation plume also showed a clear threshold and a time scale for growth of the ablation products with a characteristic time scale on the order of 0.3 ÎŒs
Seroprevalence of HTLV-1 and HTLV-2 amongst mothers and children in Malawi within the context of a systematic review and meta-analysis of HTLV seroprevalence in Africa
OBJECTIVES: Human Tâlymphotropic virus (HTLV)â1 causes Tâcell leukaemia and myelopathy. Together with HTLVâ2, it is endemic in some African nations. Seroprevalence data from Malawi are scarce, with no reports on associated disease incidence. HTLV seroprevalence and type were tested in 418 healthy mothers from Malawi. In addition, we tested the sera of 534 children to investigate motherâtoâchild transmission. To provide context, we conducted a systematic review and metaâanalysis of HTLV seroprevalence in African women and children. METHODS: Stored samples from a previous childhood cancer and BBV study were analysed. ELISA was used for HTLV screening followed by immunoblot for confirmation and typing. Standard methods were used for the systematic review. RESULTS: HTLV seroprevalence was 2.6% (11/418) in mothers and 2.2% (12/534) in children. Three mothers carried HTLVâ1 alone, seven had HTLVâ2 and one was dually infected. Three children carried HTLVâ1 alone, seven had HTLVâ2 and two were dually infected. Only two corresponding mothers of the 12 HTLVâpositive children were HTLV positive. The systematic review included 66 studies of women and 13 of children conducted in 25 African countries. Seroprevalence of HTLVâ1 varied from 0 to 17% and of HTLVâ2 from 0 to 4%. CONCLUSIONS: In contrast to findings from other studies in Africa, the seroprevalence of HTLVâ2 was higher than that of HTLVâ1 in Malawi and one of the highest for the African region. The lack of motherâchild concordance suggests alternative sources of infection among children. Our data and analyses contribute to HTLV prevalence mapping in Africa
Religious Participation and DSM IV Major Depressive Disorder Among Black Caribbeans in the United States
This study examines the relationship between religious involvement and 12-month and lifetime DSM-IV major depressive disorder (MDD) within a nationally rep- resentative sample of Black Caribbean adults. MDD was assessed using the DSM-IV World Mental Health Com- posite International Diagnostic Interview (WMH-CIDI). Religious involvement included measures of religious coping, organizational and nonorganizational involvement, and subjective religiosity. Study findings indicate that religious involvement is associated with 12-month and lifetime prevalence of MDD. Multivariate relationships between religious involvement and MDD indicate lower prevalence of 12-month and lifetime MDD among persons who use religious coping and characterize themselves as being religious (for lifetime prevalence only); persons who frequently listen to religious radio programs report higher lifetime MDD. Lower rates of 12-month and lifetime MDD are noted for persons who attend religious services at least once a week (as compared to both higher and lower levels of attendance), indicating a curvilinear relationship. The findings are discussed in relation to previous research on religion and mental health concerns, conceptual models of the role of religion in mental health (e.g., prevention, resource mobilization) that specify multiple and often divergent pathways and mechanisms of religious effects on health outcomes, and the role of religion among Caribbean Blacks.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/107411/1/Religious Participation and DSM IV Major Depressive Disorder Among Black Caribbeans in the United States.pdfDescription of Religious Participation and DSM IV Major Depressive Disorder Among Black Caribbeans in the United States.pdf : Main articl
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