4,694 research outputs found
Intermittent hypoxic resistance training: Does it provide added benefit?
Methods to enhance the adaptive responses to resistance training are of great interest to clinical and athletic populations alike. Altering the muscular environment by restricting oxygen availability during resistance exercise has been shown to induce favorable physiological adaptations. An acute hypoxic stimulus during exercise essentially increases reliance on anaerobic pathways, augmenting metabolic stress responses, and subsequent hypertrophic processes (Scott et al., 2014). Hypoxic strategies during resistance exercise were originally investigated using blood flow restriction (BFR) methods (Takarada et al., 2000), whereby a cuff is applied proximally to a limb to partially limit arterial inflow while occluding venous outflow from the working muscles. Another method that has been investigated more recently is performing resistance exercise in systemic hypoxia, by means of participants breathing a hypoxic air mixture. The addition of systemic hypoxia to resistance training has previously resulted in significantly enhanced hypertrophic and strength responses to both low-load (20% 1-repetition maximum; 1RM) (Manimmanakorn et al., 2013a,b) and moderate-load (70% 1RM) (Nishimura et al., 2010) resistance training. While research into intermittent hypoxic resistance training (IHRT) is in its infancy, some studies have reported conflicting results, which is likely due to differing research methodologies. In a recent review, it has been suggested that many of the potential mechanisms underpinning muscle adaptations to BFR training and IHRT are linked to the muscular oxygenation status and degree of metabolic stress associated with exercise (Scott et al., 2014). The purpose of this paper is to briefly summarize the adaptive responses that have been reported following both low- and moderate-load IHRT and to highlight key areas of concern for IHRT methodology, including the level of hypoxia used and the degree of metabolic stress imposed during exercise
Training Monitoring for Resistance Exercise: Theory and Applications
Resistance exercise is difficult to quantify owing to its inherent complexity with numerous training variables contributing to the training dose (type of exercise, load lifted, training volume, inter-set rest periods, and repetition velocity). In addition, the intensity of resistance training is often inadequately determined as the relative load lifted (% 1-repetition maximum), which does not account for the effects of inter-set recovery periods, repetition velocity, or the number of repetitions performed in each set at a given load. Methods to calculate the volume load associated with resistance training, as well as the perceived intensity of individual sets and entire training sessions have been shown to provide useful information regarding the actual training stimulus. In addition, questionnaires to subjectively assess how athletes are coping with the stressors of training and portable technologies to quantify performance variables such as concentric velocity may also be valuable. However, while several methods have been proposed to quantify resistance training, there is not yet a consensus regarding how these methods can be best implemented and integrated to complement each other. Therefore, the purpose of this review is to provide practical information for strength coaches to highlight effective methods to assess resistance training, and how they can be integrated into a comprehensive monitoring program
Challenges and Benefits of Standardising Early Warning Systems: A Case Study of New Zealand’s Volcanic Alert Level System
Volcano early warning systems are used globally to communicate volcano-related information to diverse stakeholders ranging from specific user groups to the general public, or both. Within the framework of a volcano early warning system, Volcano Alert Level (VAL) systems are commonly used as a simple communication tool to inform society about the status of activity at a specific volcano. Establishing a VAL system that is effective for multiple volcanoes can be challenging, given that each volcano has specific behavioural characteristics. New Zealand has a wide range of volcano types and geological settings, including rhyolitic calderas capable of very large eruptions (>500 km3) and frequent unrest episodes, explosive andesitic stratovolcanoes, and effusive basaltic eruptions at both caldera and volcanic field settings. There is also a range in eruption frequency, requiring the VAL system to be used for both frequently active ‘open-vent’ volcanoes, and reawakening ‘closed-vent’ volcanoes. Furthermore, New Zealand’s volcanoes are situated in a variety of risk settings ranging from the Auckland Volcanic Field, which lies beneath a city of 1.4 million people; to Mt. Ruapehu, the location of popular ski fields that are occasionally impacted by ballistics and lahars, and produces tephra that falls in distant cities. These wide-ranging characteristics and their impact on society provide opportunities to learn from New Zealand’s experience with VAL systems, and the adoption of a standardised single VAL system for all of New Zealand’s volcanoes following a review in 2014. This chapter outlines the results of qualitative research conducted in 2010–2014 with key stakeholders and scientists, including from the volcano observatory at GNS Science, to ensure that the resulting standardised VAL system is an effective communication tool. A number of difficulties were faced in revising the VAL system so that it remains effective for all of the volcanic settings that exist in New Zealand. If warning products are standardised too much, end-user decision making and action can be limited when unusual situations occur, e.g., there may be loss of specific relevance in the alert message. Specific decision-making should be based on more specific parameters than the VAL alone, however wider VAL system standardisation can increase credibility, a known requirement for effective warning, by ensuring that warning sources are clear, trusted and widely understood. With a credible source, user groups are less likely to look for alternatives or confirmation, leading to faster action. Here we consider volcanic warnings within the wider concept of end-to-end multi-hazard early warning systems including detection, evaluation, notification, decision-making and action elements (based on Carsell et al. 2004)
Acceleration-Based Running Intensities of Professional Rugby League Match-Play
Purpose: To quantify the energetic cost of running and acceleration efforts during rugby league competition to aid in prescription and monitoring of training. Methods: Global positioning system (GPS) data were collected from 37 professional rugby league players across 2 seasons. Peak values for relative distance, average acceleration/deceleration, and metabolic power (P<sub>met</sub>) were calculated for 10 different moving-average durations (1–10 min) for each position. A mixed-effects model was used to assess the effect of position for each duration, and individual comparisons were made using a magnitude-based-inference network. Results: There were almost certainly large differences in relative distance and P<sub>met</sub> between the 10-min window and all moving averages <5 min in duration (ES = 1.21–1.88). Fullbacks, halves, and hookers covered greater relative distances than outside backs, edge forwards, and middle forwards for moving averages lasting 2–10 min. Acceleration/deceleration demands were greatest in hookers and halves compared with fullbacks, middle forwards, and outside backs. P<sub>met</sub> was greatest in hookers, halves, and fullbacks compared with middle forwards and outside backs. Conclusions: Competition running intensities varied by both position and moving-average duration. Hookers exhibited the greatest P<sub>met</sub> of all positions, due to high involvement in both attack and defense. Fullbacks also reached high P<sub>met</sub>, possibly due to a greater absolute volume of running. This study provides coaches with match data that can be used for the prescription and monitoring of specific training drills
Positional group significantly influences the offensive and defensive skill involvements of junior representative rugby league players during match play
© 2015 Taylor & Francis. This study examined the skill involvements of three positional groups across a junior representative rugby league season. Data were collected from 45 rugby league players (mean ± SD; age = 16.5 ± 1.0 years) currently participating in the Harold Matthews and SG Ball Cup. Players were subdivided into hit-up forwards, adjustables and outside backs. The frequency (n · min−1) of offensive, defensive and overall involvements was coded for each group using a notation system and a practical coach skill analysis tool. Multivariate analysis of variance (MANOVA) revealed a significant effect of playing position on skill involvements (F = 9.06; P < 0.001; ES = 0.41). Hit-up forwards performed a significantly greater frequency of offensive (0.31 ± 0.10), defensive (0.42 ± 0.15) and overall involvements (0.74 ± 0.19) when compared to adjustables (0.20 ± 0.08, 0.28 ± 0.08 and 0.52 ± 0.15, respectively) and outside backs (0.20 ± 0.12, 0.11 ± 0.07 and ± 0.31 ± 0.17, respectively). Further, adjustables performed a significantly greater number of defensive (0.28 ± 0.08) and overall involvements (0.52 ± 0.15) when compared to outside backs (0.11 ± 0.07 and 0.31 ± 0.17, respectively). The findings of this study suggest that it is important to consider a junior player’s positional group when analysing their skill involvements. Information gained from this study could assist in the design of specific training methodologies for junior rugby league players in high-level talent development programmes
Efficacy of nonselective optogenetic control of the medial septum over hippocampal oscillations: the influence of speed and implications for cognitive enhancement
Optogenetics holds great promise for both the dissection of neural circuits and the evaluation of theories centered on the temporal organizing properties of oscillations that underpin cognition. To date, no studies have examined the efficacy of optogenetic stimulation for altering hippocampal oscillations in freely moving wild-type rats, or how these alterations would affect performance on behavioral tasks. Here, we used an AAV virus to express ChR2 in the medial septum (MS) of wild-type rats, and optically stimulated septal neurons at 6Â Hz and 30Â Hz. We measured the corresponding effects of these stimulations on the oscillations of the MS and hippocampal subfields CA1 and CA3 in three different contexts: (1) With minimal movement while the rats sat in a confined chamber; (2) Explored a novel open field; and (3) Learned and performed a T-maze behavioral task. While control yellow light stimulation did not affect oscillations, 6-Hz blue light septal stimulations altered hippocampal theta oscillations in a manner that depended on the animal's mobility and speed. While the 30 Hz blue light septal stimulations only altered theta frequency in CA1 while the rat had limited mobility, it robustly increased the amplitude of hippocampal signals at 30Â Hz in both regions in all three recording contexts. We found that animals were more likely to make a correct choice during Day 1 of T-maze training during both MS stimulation protocols than during control stimulation, and that improved performance was independent of theta frequency alterations
The incidence and clinical burden of respiratory syncytial virus disease identified through hospital outpatient presentations in Kenyan children
There is little information that describe the burden of respiratory syncytial virus (RSV) associated disease in the tropical African outpatient setting.
Methods
We studied a systematic sample of children aged <5 years presenting to a rural district hospital in Kenya with acute respiratory infection (ARI) between May 2002 and April 2004. We collected clinical data and screened nasal wash samples for RSV antigen by immunofluorescence. We used a linked demographic surveillance system to estimate disease incidence.
Results
Among 2143 children tested, 166 (8%) were RSV positive (6% among children with upper respiratory tract infection and 12% among children with lower respiratory tract infection (LRTI). RSV was more likely in LRTI than URTI (p<0.001). 51% of RSV cases were aged 1 year or over. RSV cases represented 3.4% of hospital outpatient presentations. Relative to RSV negative cases, RSV positive cases were more likely to have crackles (RR = 1.63; 95% CI 1.34–1.97), nasal flaring (RR = 2.66; 95% CI 1.40–5.04), in-drawing (RR = 2.24; 95% CI 1.47–3.40), fast breathing for age (RR = 1.34; 95% CI 1.03–1.75) and fever (RR = 1.54; 95% CI 1.33–1.80). The estimated incidence of RSV-ARI and RSV-LRTI, per 100,000 child years, among those aged <5 years was 767 and 283, respectively.
Conclusion
The burden of childhood RSV-associated URTI and LRTI presenting to outpatients in this setting is considerable. The clinical features of cases associated with an RSV infection were more severe than cases without an RSV diagnosis
Knowledge of the signs and symptoms and risk factors of lung cancer in Australia: Mixed methods study
© 2016 Crane et al. Background: Lung cancer is the leading cause of cancer death in Australia. There is potential that health promotion about the risks and warning signs of lung cancer could be used to reduce delays in symptom presentation when symptoms are first detected. This study investigated knowledge, attitudes and beliefs which might impact help-seeking behaviour and could provide insight into possible public health interventions in New South Wales (NSW). Methods: A convergent mixed method study design was used wherein data from 16 qualitative focus groups of residents (40+ years), purposefully recruited and stratified by smoking status, age and geography (metropolitan/regional), were compared with a CATI administered population-wide telephone survey (n = 1,000) using the Cancer Research UK cancer awareness measure (LungCAM). Qualitative findings were analysed thematically using NVIVO. Logistic regression analysis was used to investigate predictors of symptom knowledge in STATA. Findings were integrated using triangulation techniques. Results: Across focus groups, haemoptysis was the only symptom creating a sense of medical urgency. Life experiences evoked a 'wait and see' attitude to any health deterioration. Perceived risk was low amongst those at risk with current smokers preferring to deny their risk while former smokers were generally unaware of any ongoing risk. The quantitative sample consisted of females (62 %), 40-65 years (53 %), low SES (53 %), former (46 %) and current smokers (14 %). In quantitative findings, haemoptysis and dyspnoea were the most recognised symptoms across the sample population. Age (<65 years), sex (female) and high socio-economic status contributed to a higher recognition of symptoms. Smoking was recognised as a cause of lung cancer, yet ever-smokers were less likely to recognise the risk of lung cancer due to second-hand smoke (OR 0.7 95 % CI 0.5-0.9). Conclusion: While there was some recognition of risk factors and symptoms indicative of lung cancer, there was disparity across the sample population. The qualitative findings also suggest that knowledge may not lead to earlier presentation; a lack of urgency about symptoms considered trivial, and smoking-related barriers such as stigma may also contribute to time delays in presentation. Public health interventions may be required to increase awareness of risk and emphasise the importance of seeking medical attention for ongoing symptoms
At risk of being risky: The relationship between "brain age" under emotional states and risk preference.
Developmental differences regarding decision making are often reported in the absence of emotional stimuli and without context, failing to explain why some individuals are more likely to have a greater inclination toward risk. The current study (N=212; 10-25y) examined the influence of emotional context on underlying functional brain connectivity over development and its impact on risk preference. Using functional imaging data in a neutral brain-state we first identify the "brain age" of a given individual then validate it with an independent measure of cortical thickness. We then show, on average, that "brain age" across the group during the teen years has the propensity to look younger in emotional contexts. Further, we show this phenotype (i.e. a younger brain age in emotional contexts) relates to a group mean difference in risk perception - a pattern exemplified greatest in young-adults (ages 18-21). The results are suggestive of a specified functional brain phenotype that relates to being at "risk to be risky.
Enforced expression of PPP1R13L increases tumorigenesis and invasion through p53-dependent and p53-independent mechanisms.
PPP1R13L was initially identified as a protein that binds to the NF-[kappa]B subunit p65/RelA and inhibits its transcriptional activity. It also binds p53 and inhibits its action. One set of experimental findings based on over-expression of PPP1R13L indicates that PPP1R13L blocks apoptosis. Another set of experiments, based on endogenous production of PPP1R13L, suggests that the protein may sometimes be pro-apoptotic. We have used primary mouse embryonic fibroblasts (MEFs), dually transformed by H-ras and Adenovirus E1A and differing in their p53 status, to explore the effects of PPP1R13L over-expression, thus examining the ability of PPP1R13L to act as an oncoprotein. We found that over-expression of PPP1R13L strongly accelerated tumor formation by ras/E1A and also resulted in an increased metastatic potential of the tumors. PPP1R13L over-expressing cells were depleted for both p53 and active p65/RelA and we found that both p53 dependent and independent apoptosis pathways were regulated by PPP1R13L. Finally, studies with the proteasome inhibitor MG132 revealed that over-expression of PPP1R13L causes faster p53 degradation, a likely explanation for the depletion of p53. Taken together, our results show that increased levels of PPP1R13L can increase tumorigenesis and furthermore pinpoint PPP1R13L as a gene that influences metastasis
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