1,720,995 research outputs found
The acute effect of continuous and intermittent exercise on the exercise efficiency and physiological responses of ischemic heart disease
No full textThe effect of trial familiarisation on the validity and reproducibility of a field-based self-paced VO2MAX Test
No full textObjectives: The self-paced maximal oxygen uptake (V?O2max) test (SPV), which is based on the Borg 6-20 Ratings of Perceived Exertion (RPE) scale, allows participants to self-regulate their exercise intensity during a closed-loop incremental maximal exercise test. As previous research has assessed the utility of the SPV test within laboratory conditions, the purpose to this study was to assess the effect of trial familiarisation on the validity and reproducibility of a field-based, SPV test. Methods: In a cross-sectional study, fifteen men completed one laboratory-based graded exercise test (GXT) and three field-based SPV tests. The GXT was continuous and incremental until the attainment of VO2max. The SPV, which was completed on an outdoor 400m athletic track, consisted of five x 2 min perceptually-regulated (RPE11, 13, 15, 17 and 20) stages of incremental exercise. Results: There were no differences in the V?O2max reported between the GXT (63.5±10.1 ml?kg-1?min-1) and each SPV test (65.5±8.7, 65.4±7.0 and 66.7±7.7 ml?kg-1?min-1 for SPV1, SPV2 and SPV3, respectively; P>.05). Similar findings were observed when comparing V?O2max between SPV tests (P>.05). High intraclass correlation coefficients were reported between the GXT and the SPV, and between each SPV test (?.80). Although participants ran faster and further during SPV3, a similar pacing strategy was implemented during all tests. Conclusions: This study demonstrated that a field-based SPV is a valid and reliable V?O2max test. As trial familiarisation did not moderate V?O2max values from the SPV, the application of a single SPV test is an appropriate stand-alone protocol for gauging V?O2max
Effects of upright and recumbent cycling on executive function and prefrontal cortex oxygenation in young, healthy, men
Full text linkBackground: The purpose of this study was to assess the acute effects of posture (upright vs. recumbent) during moderate-intensity cycle exercise on executive function and prefrontal cortex oxygenation, in young healthy adults. Methods: Seventeen physically active men (24.6 ± 4.3y) completed two 30-minute submaximal, exercise tests (Conditions: upright and recumbent cycle ergometry). Executive function was assessed using the ‘colour’ and ‘word’ Stroop task, pre- (resting) and post-exercise. Regional oxygen saturation (rSO2) to the prefrontal cortex was continuously monitored using near-infrared spectroscopy. Results: Significant improvements in executive function (Stroop colour and word tasks) were observed following 30 minutes of exercise, for both upright and recumbent cycling (P < .05). However, there were no differences in executive function between cycling Conditions (P > .05). A significant increase in rSO2 was recorded immediately post-exercise compared to pre-exercise for both Conditions (P < .05), with a trend (P = .06) for higher peak rSO2 following recumbent cycling compared to upright cycling (81.9 ± 6.5 cf. 79.7 ± 9.3%, respectively). Conclusions: Although submaximal cycling exercise acutely improves cognitive performance and prefrontal oxygenation, changes in cognition are not perceived to be dependent on body posture in young, healthy men
Reliability of oscillometric central blood pressure responses to submaximal exercise
Full text linkCentral blood pressure responses to exercise may provide clinicians with a superior diagnostic and prognostic tool. However, in order to be of value in a clinical setting these assessments must be simple to conduct and reliable. Objective: Using oscillometric pulse wave analysis (PWA), determine the upper limit for between-day reliability of central systolic blood pressure (cSBP) and central pressure augmentation (AIx) responses to three progressive stages of submaximal exercise in cohort of young, healthy participants. Methods: Fifteen healthy males (25.8 y (SD 5.7), 23.9 kg/m2 (SD 2.5)) were tested on 3 different mornings in a fasted state, separated by a maximum of 14 days. Central hemodynamic variables were assessed on the left arm. Participants underwent three progressive stages of submaximal cycling at 50W (low), 100W (moderate) and 150W (moderate-hard). Results: During low- and moderate-intensity exercise the ICC values for cSBP (0.79-0.80) and AIx (0.81-0.85) indicated excellent reliability (ICC >0.75). For the moderate-hard intensity AIx could not be computed, and the ICC for cSBP was adequate (0.72). Conclusion: Findings from this study suggest that, at least in a young health cohort, oscillometric PWA can be used to reliably assess central blood pressure measurements during exercise, up to a moderate intensity. While further work is required to verify these findings in clinical cohorts, these measurements may potentially provide clinicians with a practical option for obtaining important hemodynamic information beyond that provided by resting peripheral blood pressure
Validation of oscillometric pulse wave analysis measurements in children
No full textBACKGROUND:Pulse wave analysis (PWA) has emerged as a noninvasive, valid, reliable, and widely used technique to investigate central blood pressures and systemic arterial wave reflection (augmentation index). The gold-standard technique is tonometry, but this technique can be challenging, especially when used on children. The purpose of this study was to validate oscillometric PWA for use in children.METHODS:Fifty-seven healthy children were recruited for participation. Central blood pressures and peripheral augmentation index (pAIx) were measured objectively using oscillometric (Pulsecor R7) and tonometric (SphygmaCor) devices. All measurements were made during the same visit under standardized conditions between the hours of 8 am and 10 am in the fasted state.RESULTS:Tonometric measurements were unsuccessful on 1 child. Comparisons were made on 56 children (mean age = 9.8±1.0 y; 57% male). A very strong relationship was found between devices for central systolic (r = 0.94; P < 0.001), diastolic (r = 0.99; P < 0.001) and mean (r = 0.96; P < 0.001) blood pressures. However, Bland-Altman analysis indicated a bias toward greater systolic blood pressures with the oscillometric monitor (mean difference = 4.5mm Hg; 95% confidence interval (CI) = -5.16 to -3.89). A good relationship was found for pAIx (r = 0.71; P < 0.001); the mean difference between devices was -1.70% (95% CI = -4.47% to 1.08%), which is not significantly different from zero.CONCLUSIONS:Findings from this study suggest that oscillometric PWA provides valid measures of central blood pressure and arterial wave reflection in children aged 8-10 years
The efficacy of a discontinuous graded exercise test in measuring peak oxygen uptake in children aged 8 to 10 years
Full text linkAs children’s natural activity patterns are highly intermittent in nature, and characterised by
rapid changes from rest to vigorous physical activity, discontinuous exercise tests may be considered ecologically
valid for this population group. This study compared the peak physiological responses from a discontinuous
and continuous graded exercise test (GXT_D, GXT_C, respectively) during treadmill exercise in children. Twentyone
healthy children (9.6 ± 0.6 y) completed GXT_D and GXT_C in a randomised order, separated by 72-hours.
Following each GXT, and after a 15-minute recovery, participants completed a verification test at 105% of the
velocity attained at peak oxygen consumption (VO2peak). There were no differences in VO2peak (55.3 ± 8.2
cf. 54.4 ± 7.6 mL·kg-1·min-1) or maximal heart rate (202 ± 10 cf. 204 ± 8 b·min-1) between GXT_C and GXT_D,
respectively (P>.05). Peak running speed (10.7 ± 0.9 cf. 12.1 ± 1.3 km·h-1) and respiratory exchange ratio
(1.04 ± 0.05 cf. 0.92 ± 0.05) were however different between tests (P<.001). Although similar peak physiological
values were revealed between GXT_C and the corresponding verification test (P>.05), VO2peak (53.3 ± 7.3
mL·kg-1·min-1) and heart rate (197 ± 13 b·min-1) were significantly lower in the GXT_D verification test (P<.05).
In conclusion, a discontinuous GXT is an accurate measure of VO2peak in children aged 8 to 10 years and may
be a valid alternative to a continuous GXT, despite its longer duration
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
The effect of a short-term exercise programme on haemodynamic adaptability; a randomised controlled trial with newly diagnosed transient ischaemic attack patients
No full textThis study assessed the effect of a short-term, 8-week exercise programme on resting and exercise blood pressure (systolic (SBP); diastolic (DBP)), and other haemodynamic responses (heart rate (HR), pulse pressure (PP), double product (DP)), of newly diagnosed transient ischaemic attack (TIA) patients. Sixty-eight TIA patients completed a continuous and incremental exercise test within 2 weeks of symptom diagnosis. HR, SBP and DBP were regularly measured at rest, during exercise and in recovery. Participants were then randomised to either an 8-week exercise programme or to a usual care control group prior to completing an identical post-intervention (PI) re-assessment. Individuals randomised to the exercise condition experienced a significantly greater reduction in resting HR (-5.4±10.2%), SBP (-6.7±8.1%) and DBP (-2.8±7.2%) than the control group at the PI assessment (all P<0.05). Similar findings were demonstrated at the PI assessment when comparing haemodynamic responses during exercise (P<0.05), with significantly larger decrements observed for SBP and HR (both 10-14%), PP (17-24%) and DP (26-32%) for those randomised to the exercise intervention (all P<0.05). This study demonstrates that structured physical activity soon after TIA diagnosis will improve haemodynamic responses. The early implementation of exercise following TIA diagnosis may be an important secondary prevention strategy for this population
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
- …
