932 research outputs found
Sort by
An applied paradigm for simple analysis of the lower limb kinematic chain in explosive movements: an example using the fencing foil attacking lunge
Get PDFA simple method to quantify the kinematic chain in a propulsive task would facilitate assessment of athlete effectiveness. The study’s aim was to assess if the kinematic chain distinguishes between skill levels. Fencers were separated into two groups based on attacking lunge ability (7 skilled; 8 novices). Rear leg 3D joint angular extension velocity magnitudes and timings, sword kinematics and rear leg kinetics were obtained in the propulsion phase of the attacking lunge. Skilled fencers obtained greater sword velocity (3.24 ± 0.24 m∙s−1 vs. 2.69 ± 0.29 m∙s−1; p = 0.02). The skilled group had a greater sequential kinematic chain of the hip, knee and ankle, demonstrated by significantly greater ankle angular velocity (9.1 ± 2.1 rad·s−1 skilled; 5.4 ± 2.9 rad·s−1 novice). Ankle plantarflexion velocity showed a strong positive correlation with horizontal peak force (r = 0.81; p < 0.01). The skilled group demonstrated greater horizontal impulse (1.85 ± 0.29 N·s·kg−1 skilled; 1.45 ± 0.32 N·s·kg−1 novice), suggesting greater effectiveness in applying the kinematic chain towards horizontal propulsion. Analysis of the kinematic chain, which was able to distinguish between skill levels in a propulsive task, is an effective and simple paradigm to assess whole limb contributions to propulsive movements
Social tourism & older people: the IMSERSO initiative
Get PDFExtant demand-perspective social tourism studies have generally focused on children, families and the disabled whilst older people remain an under-researched group in relation to the personal and social benefits of social tourism initiatives. This study discusses the lack of research on social tourism and older people and takes a demand-side perspective to examine one of the world’s most developed and large-scale social tourism schemes for older people, the Spanish Government’s IMSERSO programme. A qualitative approach explores the nature of older people’s engagement with the scheme and its impact on their wellbeing, through individual in-depth interviews with twenty-seven IMSERSO participants in Benidorm, Spain – a popular IMSERSO destination. The thematic analysis is structured around five themes: social connectivity, the impact of caring responsibilities, a new beginning, escape and practical support. The findings for these IMSERSO participants suggest that, as factors such as caring obligations and hardship experienced in early life are reduced in later life, they have the capacity for increased holiday-taking and social activity and consequently for participation in the IMSERSO scheme. The scheme is found to have a positive impact on their wellbeing by providing opportunities for meeting and interacting with new people, acting as a distraction from ill-health and thus reducing stress, depression and anxiety. However, the article raises questions over the ability of those without strong social networks, including no partner, and those with ongoing caring responsibilities (those who, it could be argued, are most in need of a holiday) to participate in the scheme
The independent effects of hypovolemia and pulmonary vasoconstriction on ventricular function and exercise capacity during acclimatisation to 3800 m
Get PDFWe aimed to determine the isolated and combined contribution of hypovolemia and hypoxic pulmonary vasoconstriction in limiting left ventricular (LV) function and exercise capacity under chronic hypoxemia at high altitude. In a double‐blinded, randomized and placebo‐controlled design, twelve healthy participants underwent echocardiography at rest and during submaximal exercise before completing a maximal test to exhaustion at sea level (SL; 344 m) and after 5–10 days at 3800 m. Plasma volume was normalised to SL values, and hypoxic pulmonary vasoconstriction was reversed by administration of Sildenafil (50 mg) to create four unique experimental conditions that were compared with SL values; high altitude (HA), Plasma Volume Expansion (HA‐PVX), Sildenafil (HA‐SIL) and Plasma Volume Expansion with Sildenafil (HA‐PVX‐SIL). High altitude exposure reduced plasma volume by 11% (P < 0.01) and increased pulmonary artery systolic pressure (19.6 ± 4.3 vs. 26.0 ± 5.4, P < 0.001); these differences were abolished by PVX and SIL respectively. LV end‐diastolic volume (EDV) and stroke volume (SV) were decreased upon ascent to high altitude, but were comparable to sea level in the HA‐PVX. LV EDV and SV were also elevated in the HA‐SIL and HA‐PVX‐SIL trials compared to HA, but to a lesser extent. Neither PVX or SIL had a significant effect on the LV EDV and SV response to exercise, or the maximal oxygen consumption or peak power output. In summary, at 3800 m both hypovolemia and hypoxic pulmonary vasoconstriction contribute to the decrease in LV filling, however, restoring LV filling does not confer an improvement in maximal exercise performance
Integrating models of long-term athletic development to maximize the physical development of youth
Get PDFLong-term athletic development is important to prepare youth for sport and an active lifestyle. Several models have provided general frameworks for long-term athletic development from different perspectives that consider factors such as when to sample and specialize and what physical qualities to train and when. More recently, more specific models of long-term athletic development have emerged that focus on both specific modes of training and specific fitness qualities. This includes models focused on the development of speed, agility, power, and endurance as well as models devoted to resistance training, plyometric training, and weightlifting. These models incorporate factors such as technical competency, developmental stage, maturation, and training age to describe the long-term progression of athletic development. A challenge for the coach is to understand how these models inform one another and how they integrate into practice to allow the use of multiple modes of training to develop multiple components of fitness simultaneously throughout childhood and adolescence. This review will examine how information from various models can be integrated to maximize the physical long-term athletic development of youth
Carotid artery wall mechanics in young males with high cardiorespiratory fitness
Get PDFThe influence of cardiorespiratory fitness (CRF) on arterial stiffness in young adults remains equivocal. Beyond conventional measures of arterial stiffness, 2D strain imaging of the common carotid artery (CCA) provides novel information related to the intrinsic properties of the arterial wall. Therefore, this study aimed to assess the effect of CRF on both conventional indices of CCA stiffness and 2D strain parameters, at rest and following a bout of aerobic exercise in young healthy males. Short‐axis ultrasound images of the CCA were recorded in 34 healthy men [22 years (95%CI, 19–22)] before, and immediately after 5‐minutes of aerobic exercise (40% VO2max). Images were analysed for arterial diameter, peak circumferential strain (PCS), and peak systolic and diastolic strain rates (S‐SR, D‐SR). Heart rate (HR), systolic and diastolic blood pressure (SBP, DBP) were simultaneously assessed and Petersons' elastic modulus (Ep) and Beta stiffness (β1) were calculated. Participants were separated post hoc into moderate and high fitness groups [VO2max: 48.9 ml.kg‐1 min‐1 (95%CI, 44.7–53.2) vs. 65.6 ml.kg‐1 min‐1 (95%CI, 63.1–68.1); P 0.13) but were elevated in the moderate‐fitness group post‐exercise (P 0.05). High‐fit individuals exhibit elevated CCA PCS and S‐SR, which may reflect training‐induced adaptations that help to buffer the rise in pulse‐pressure and stroke volume during exercise
Pre-season injury and illness associations with perceptual wellness, neuromuscular fatigue, sleep and training load in elite rugby union
No full textThe aim of this study was to investigate injury and illness associations with perceptual wellness, neuromuscular fatigue, sleep and training load in an elite rugby union team during pre-season. During an 11-wk pre-season, 51 elite rugby union athletes were monitored twice-a-week for physiological (sleep quality, energy, muscle soreness) and psychological perceptual wellness (mood), self-reported sleep hours and counter-movement jump height. Training load was estimated via h/athlete/wk. for all training activities. Risk ratios were used to assess weekly injury and illness risk, with effect sizes comparing differences in injury and illness severity above and below thresholds of group mean fatigue and training load measures. Probability of effects were assessed using clinical chances and qualitative inferences. Day 1 perceptual sleep quality and energy were associated with increased illness incidence (Risk ratio = 8.5; Very likely) and severity (Effect sizes = 1.15-1.71; Likely-Very likely) but not injury. Sleeping 8.8-h/athlete/wk.) and resistance training (>3.4-h/athlete/wk.) thresholds were associated with increased injury and injury/illness combined incidence (Risk ratios = 1.8-5.2; Likely-Very likely) and severity (Effect sizes = 0.40-1.12; Possibly-Likely) but not for illness alone. Decreases in day 1 counter-movement jump height preceded spikes in injury in weeks 4 and 7. Simple fatigue and load measures showed potential for informing management of training to minimise injury/illness during an intense rugby union pre-season
Prevalence of subclinical cardiac abnormalities in patients with metal-on-metal hip replacements
Get PDFBackground
Metal-on-metal (MOM) hip prostheses have a higher failure rate than conventional prostheses and leaching of cobalt and chromium has been linked to cardiomyopathy. We screened MOM subjects to evaluate if cobalt and chromium are related to subclinical cardiac dysfunction.
Methods
A single centre, non-randomised, observational study using echocardiography in 95 patients who had undergone MOM hip prostheses, and 15 age matched controls with non-MOM hip replacement. Serial plasma cobalt and chromium levels were recorded, and data compared by tertiles of cobalt exposure.
Results
Indexed left ventricular (LV) end-diastolic and end-systolic volumes (EDVi and ESVi) increased with tertile of cobalt (omnibus p = 0.003 for EDVi and ESVi), as did indexed left atrial (LA) volumes (p = 0.003). MOM subjects had 25% larger EDVi than controls, 32% larger ESVi (40 ml vs. 32 ml, and 15 ml vs. 11 ml, p = 0.003 for both) and 28% larger indexed LA (23 ml vs. 18 ml, p = 0.002). There were no differences in LV systolic or diastolic function, including ejection fraction, tissue velocity and mitral E/e′. Estimated glomerular filtration rate was 18% lower in the highest tertile compared with the lowest (p = 0.01) and correlated inversely with LA volume (r = −0.36, p < 0.001) and LV EDV (r = −0.24, p = 0.02).
Conclusions
No correlations between sensitive measures of systolic or diastolic cardiac function or serum cobalt/chromium levels were observed in this study. However, there was a relationship between increasing left ventricular and left atrial volumes and declining renal function with high cobalt levels which requires further evaluation in MOM patients
Whole body vibration of different frequencies inhibits H-reflex but does not affect voluntary activation
Get PDFThis study aimed to investigate the effects of whole-body vibration (WBV) at a frequency spectrum from 20 to 50 Hz on the Hoffmann (H) reflex and the voluntary motor output of ankle plantar-flexor muscles. A single-group (n: 8), repeated measures design was adopted with four conditions: standing (no vibration), 20, 35 and 50 Hz, each lasting one minute. H-reflex of the soleus muscle, maximal voluntary contraction (MVC) and central activation ratio (CAR) of the plantar-flexors were evaluated before, 1 and 5 min after each frequency condition. H-reflex decreased by 36.7% at 20 Hz, by 28% at 35 Hz, and by 34.8% at 50 Hz after one minute from WBV compared to baseline. Neither MVC nor CAR changed after WBV at all frequency conditions. The short-term, acute inhibition of the H-reflex after WBV at 20, 35 and 50 Hz suggested that decreased excitability of spinal motoneurons is not frequency dependent. On the other hand, the lack of vibration induced effects on MVC and CAR indicated that a 1-min WBV stimulus is not sufficient to affect the voluntary motor output
Different Effects of Vascular Aging on Ischemic Predisposition in Healthy Men and Women
Get PDFInvasive studies of the twentieth century showed the value of aortic pressure-time integrals as markers of myocardial oxygen demand and supply. More recent studies have used these concepts to evaluate the mechanisms of ischemic predisposition using noninvasive arterial tonometry in cardiology outpatients. We sought to evaluate the spectrum of myocardial oxygen demand and supply in a large cross-sectional community sample of healthy volunteers and identify the roles of age, sex, and wave reflection. Arterial tonometry was performed in 3682 healthy volunteers. Measures of systolic and diastolic pressure-time integrals and their ratio in addition to cardiac ejection duration were determined and analyzed by age and sex. Multiple regression analyses were performed to identify the mechanisms underlying observations, while controlling for confounders (heart rate, height, weight, and mean pressure). In a healthy cohort, older women more than men (P<0.001) had unfavorable myocardial oxygen supply:demand ratios because of differing effects of vascular aging
Probabilistic models comparing Fast4 and traditional tennis
No full textTennis matches are hierarchies made up of sets containing games which, in turn, contain points. Traditional tennis games and tiebreakers could theoretically be infinite in length because a player needs to be at least 2 points ahead of the opponent to win. Fast4 tennis is a newer format of tennis that has been used at a number of levels of the sport including professional tennis where it has been used in Next Generation Finals events since 2017. The purpose of the current investigation is to compare the traditional tennis format to Fast4 tennis in terms of the probability of different players winning matches and the duration of matches. Probabilistic models of Fast4 tennis games and tiebreakers were developed. These models allowed the probability of winning games and tiebreakers to be compared between the two formats of tennis for a range of probabilities of players winning points. The models were then used within a series of simulations to determine the probability of winning sets and matches as well as the durations of games, tiebreakers, sets and matches in the two formats. Each component of the two formats of tennis was simulated 100,000 times revealing a reduced impact of serve, greater chance of upsets and shorter matches in Fast 4 tennis than in traditional tennis. The probability of players of differing abilities winning matches as well as the duration of tennis matches should be considered by those making decisions on the format of matches to be applied in tennis tournaments as well as by those preparing to compete in such tournaments