Perceptual Responses to High- and Moderate-Intensity Interval Exercise in Adolescents

This is the author accepted manuscript. The final version is available from Lippincott, Williams & Wilkins via the DOI in this record.PURPOSE: High-intensity continuous exercise is proposed to evoke unpleasant sensations as predicted by the dual mode theory (DMT), and may negatively impact on future exercise adherence. Previous studies support unpleasant sensations in affective responses during continuous high-intensity exercise, but the affect experience during high-intensity interval exercise (HIIE) involving brief bursts of high-intensity exercise separated by low-intensity activity is poorly understood in adolescents. We examined the acute affective, enjoyment and perceived exertion responses to HIIE compared to moderate-intensity interval exercise (MIIE) in adolescents. METHODS: Thirteen adolescent boys (mean±SD; age 14.0±0.5 years) performed two counterbalanced exercise conditions: 1) HIIE: 8 x 1-minute work intervals at 90% maximal aerobic speed; and 2) MIIE: between 9-12 x 1-minute work intervals at 90% ventilatory threshold where the number of intervals performed were distance-matched to HIIE. HIIE and MIIE intervals were interspersed with 75 s active recovery at 4 km·h. Affect, enjoyment and rating of perceived exertion (RPE) were recorded before, during and after exercise. RESULTS: Affect responses declined in both conditions but the fall was greater in HIIE than MIIE (P0.64). CONCLUSIONS: Despite elevated RPE, HIIE did not elicit prominent unpleasant feelings as predicted by DMT and was associated with greater post-exercise enjoyment responses than MIIE. This study demonstrates the feasibility of the application of HIIE as an alternative form of PA in adolescents.Adam Abdul Malik is financially supported by the Government of Malaysia for the funding under the academic staff training scheme (USM/PPSP(Pent)/L2/bJld.XV)

Validation and calibration for embedding rating of perceived exertion into high-intensity interval exercise in adolescents: a lab-based study

This is the author accepted manuscript. The final version is available from Human Kinetics via the DOI in this recordPURPOSE: Rating of perceived exertion (RPE) is a convenient and cost-effective tool that can be used to monitor high-intensity interval exercise (HIIE). However, no methodological study has demonstrated the validity of RPE in this context. Therefore, the aim of this study was to validate and calibrate RPE for monitoring HIIE in adolescents. METHODS: RPE, heart rate (HR), and oxygen uptake (V˙O2) data were retrospectively extracted from 3 lab-based crossover studies, with a pooled sample size of 45 adolescents, performing either cycling-based or running-based HIIE sessions. Within-participant correlations were calculated for RPE-HR and RPE-V˙O2, and receiver operator characteristic curve analysis was used to establish RPE cut points. RESULTS: The results showed that RPE-HR demonstrated acceptable criterion validity (r = .53-.74, P < .01), while RPE-V˙O2 had poor validity (r = .40-.48, P < .01), except for HIIE at 100% peak power (r = .59, P < .01). RPE cut points of 4 and 5 were established in corresponding to HR/V˙O2 based thresholds. CONCLUSION: RPE has some utility in evaluating intensity during lab-based running or cycling HIIE in adolescents. Future studies should expand the validation and calibration of RPE for prescribing and monitoring HIIE in children and adolescents in field-based contexts

Binary orbits as the driver of γ-ray emission and mass ejection in classical novae

Classical novae are the most common astrophysical thermonuclear explosions, occurring on the surfaces of white dwarf stars accreting gas from companions in binary star systems. Novae typically expel �10,000 solar masses of material at velocities exceeding 1,000 km/s. However, the mechanism of mass ejection in novae is poorly understood, and could be dominated by the impulsive flash of the thermonuclear runaway, prolonged optically thick winds, or binary interaction with the nova envelope. Classical novae are now routinely detected in GeV gamma-rays, suggesting that relativistic particles are accelerated by strong shocks in nova ejecta. Here we present high-resolution imaging of the gamma-ray-emitting nova V959 Mon at radio wavelengths, showing that its ejecta were shaped by binary motion: some gas was expelled rapidly along the poles as a wind from the white dwarf, while denser material drifted out along the equatorial plane, propelled by orbital motion. At the interface between the equatorial and polar regions, we observe synchrotron emission indicative of shocks and relativistic particle acceleration, thereby pinpointing the location of gamma-ray production. Binary shaping of the nova ejecta and associated internal shocks are expected to be widespread among novae, explaining why many novae are gamma-ray emitters

An ENU-induced mutation of miR-96 associated with progressive hearing loss in mice.

Progressive hearing loss is common in the human population, but little is known about the molecular basis. We report a new N-ethyl-N-nitrosurea (ENU)-induced mouse mutant, diminuendo, with a single base change in the seed region of Mirn96. Heterozygotes show progressive loss of hearing and hair cell anomalies, whereas homozygotes have no cochlear responses. Most microRNAs are believed to downregulate target genes by binding to specific sites on their mRNAs, so mutation of the seed should lead to target gene upregulation. Microarray analysis revealed 96 transcripts with significantly altered expression in homozygotes; notably, Slc26a5, Ocm, Gfi1, Ptprq and Pitpnm1 were downregulated. Hypergeometric P-value analysis showed that hundreds of genes were upregulated in mutants. Different genes, with target sites complementary to the mutant seed, were downregulated. This is the first microRNA found associated with deafness, and diminuendo represents a model for understanding and potentially moderating progressive hair cell degeneration in hearing loss more generally

Two Major Medicinal Honeys Have Different Mechanisms of Bactericidal Activity

Honey is increasingly valued for its antibacterial activity, but knowledge regarding the mechanism of action is still incomplete. We assessed the bactericidal activity and mechanism of action of Revamil® source (RS) honey and manuka honey, the sources of two major medical-grade honeys. RS honey killed Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa within 2 hours, whereas manuka honey had such rapid activity only against B. subtilis. After 24 hours of incubation, both honeys killed all tested bacteria, including methicillin-resistant Staphylococcus aureus, but manuka honey retained activity up to higher dilutions than RS honey. Bee defensin-1 and H2O2 were the major factors involved in rapid bactericidal activity of RS honey. These factors were absent in manuka honey, but this honey contained 44-fold higher concentrations of methylglyoxal than RS honey. Methylglyoxal was a major bactericidal factor in manuka honey, but after neutralization of this compound manuka honey retained bactericidal activity due to several unknown factors. RS and manuka honey have highly distinct compositions of bactericidal factors, resulting in large differences in bactericidal activity

Outbreak of Pneumonia in the Setting of Fatal Pneumococcal Meningitis among US Army Trainees: Potential Role of Chlamydia pneumoniae Infection

<p>Abstract</p> <p>Background</p> <p>Compared to the civilian population, military trainees are often at increased risk for respiratory infections. We investigated an outbreak of radiologically-confirmed pneumonia that was recognized after 2 fatal cases of serotype 7F pneumococcal meningitis were reported in a 303-person military trainee company (Alpha Company).</p> <p>Methods</p> <p>We reviewed surveillance data on pneumonia and febrile respiratory illness at the training facility; conducted chart reviews for cases of radiologically-confirmed pneumonia; and administered surveys and collected nasopharyngeal swabs from trainees in the outbreak battalion (Alpha and Hotel Companies), associated training staff, and trainees newly joining the battalion.</p> <p>Results</p> <p>Among Alpha and Hotel Company trainees, the average weekly attack rates of radiologically-confirmed pneumonia were 1.4% and 1.2% (most other companies at FLW: 0-0.4%). The pneumococcal carriage rate among all Alpha Company trainees was 15% with a predominance of serotypes 7F and 3. <it>Chlamydia pneumoniae </it>was identified from 31% of specimens collected from Alpha Company trainees with respiratory symptoms.</p> <p>Conclusion</p> <p>Although the etiology of the outbreak remains unclear, the identification of both <it>S. pneumoniae </it>and <it>C. pneumoniae </it>among trainees suggests that both pathogens may have contributed either independently or as cofactors to the observed increased incidence of pneumonia in the outbreak battalion and should be considered as possible etiologies in outbreaks of pneumonia in the military population.</p

High-Intensity Interval Training Interventions in Children and Adolescents: A Systematic Review

BackgroundWhilst there is increasing interest in the efficacy of high-intensity interval training in children and adolescents as a time-effective method of eliciting health benefits, there remains little consensus within the literature regarding the most effective means for delivering a high-intensity interval training intervention. Given the global health issues surrounding childhood obesity and associated health implications, the identification of effective intervention strategies is imperative.ObjectivesThe aim of this review was to examine high-intensity interval training as a means of influencing key health parameters and to elucidate the most effective high-intensity interval training protocol.MethodsStudies were included if they: (1) studied healthy children and/or adolescents (aged 5–18 years); (2) prescribed an intervention that was deemed high intensity; and (3) reported health-related outcome measures.ResultsA total of 2092 studies were initially retrieved from four databases. Studies that were deemed to meet the criteria were downloaded in their entirety and independently assessed for relevance by two authors using the pre-determined criteria. From this, 13 studies were deemed suitable. This review found that high-intensity interval training in children and adolescents is a time-effective method of improving cardiovascular disease biomarkers, but evidence regarding other health-related measures is more equivocal. Running-based sessions, at an intensity of >90% heart rate maximum/100–130% maximal aerobic velocity, two to three times a week and with a minimum intervention duration of 7 weeks, elicit the greatest improvements in participant health.ConclusionWhile high-intensity interval training improves cardiovascular disease biomarkers, and the evidence supports the effectiveness of running-based sessions, as outlined above, further recommendations as to optimal exercise duration and rest intervals remain ambiguous owing to the paucity of literature and the methodological limitations of studies presently available