Muscle Damage following Maximal Eccentric Knee Extensions in Males and Females

Aim: To investigate whether there is a sex difference in exercise induced muscle damage. Materials and Method: Vastus Lateralis and patella tendon properties were measured in males and females using ultrasonography. During maximal voluntary eccentric knee extensions (12 reps x 6 sets), Vastus Lateralis fascicle lengthening and maximal voluntary eccentric knee extensions torque were recorded every 10° of knee joint angle (20–90°). Isometric torque, Creatine Kinase and muscle soreness were measured pre, post, 48, 96 and 168 hours post damage as markers of exercise induced muscle damage. Results: Patella tendon stiffness and Vastus Lateralis fascicle lengthening were significantly higher in males compared to females (p0.05). Creatine Kinase levels post exercise induced muscle damage were higher in males compared to females (p<0.05), and remained higher when maximal voluntary eccentric knee extension torque, relative to estimated quadriceps anatomical cross sectional area, was taken as a covariate (p<0.05). Conclusion: Based on isometric torque loss, there is no sex difference in exercise induced muscle damage. The higher Creatine Kinase in males could not be explained by differences in maximal voluntary eccentric knee extension torque, Vastus Lateralis fascicle lengthening and patella tendon stiffness. Further research is required to understand the significant sex differences in Creatine Kinase levels following exercise induced muscle damage

Misdiagnosis, Mistreatment, and Harm - When Medical Care Ignores Social Forces.

The Case Studies in Social Medicine demonstrate that when physicians use only biologic or individual behavioral interventions to treat diseases that stem from or are exacerbated by social factors, we risk harming the patients we seek to serve

Reliability and Validity of S3 Pressure Sensation as an Alternative to Deep Anal Pressure in Neurologic Classification of Persons With Spinal Cord Injury.

OBJECTIVE: To determine whether pressure sensation at the S3 dermatome (a new test) could be used in place of deep anal pressure (DAP) to determine completeness of injury as part of the International Standards for Neurological Classification of Spinal Cord Injury. DESIGN: Prospective, multicenter observational study. SETTING: U.S. Spinal Cord Injury Model Systems. PARTICIPANTS: Persons (N=125) with acute traumatic spinal cord injury (SCI), neurologic levels T12 and above, were serially examined at 1 month (baseline), 3, 6, and 12 months postinjury. There were 80 subjects with tetraplegia and 45 with paraplegia. INTERVENTIONS: S3 pressure sensation at all time points, with a retest at the 1-month time point. MAIN OUTCOME MEASURES: Test-retest reliability and agreement (κ), sensitivity, specificity, positive and negative predictive values. RESULTS: Test-retest reliability of S3 pressure at 1 month was almost perfect (κ=.98). Agreement of S3 pressure with DAP was substantial both at 1 month (κ=.73) and for all time points combined (κ=.76). The positive predictive value of S3 pressure for DAP was 89.3% at baseline and 90.3% for all time points. No pattern in outcomes was seen in those cases where S3 pressure and DAP differed at 1 month. CONCLUSIONS: S3 pressure sensation is reliable and has substantial agreement with DAP in persons with SCI at least 1 month postinjury. We suggest S3 pressure as an alternative test of sensory sacral sparing for supraconus SCI, at least in cases where DAP cannot be tested. Further research is needed to determine whether S3 pressure could replace DAP for classification of SCI

Muscle-tendon unit properties during eccentric exercise correlate with the creatine kinase response

© 2017 Hicks, Onambele-Pearson, Winwood and Morse. Aim: The aim of this paper was to determine whether; (1) patella tendon stiffness, (2) the magnitude of vastus lateralis fascicle lengthening, and (3) eccentric torque correlate with markers of exercise induced muscle damage. Method: Combining dynamometry and ultrasonography, patella tendon properties and vastus lateralis architectural properties were measured pre and during the first of six sets of 12 maximal voluntary eccentric knee extensions. Maximal isometric torque loss and creatine kinase activity were measured pre-damage (-48 h), 48, 96, and 168 h post-damage as markers of exercise-induced muscle damage. Results: A significant increase in creatine kinase (883 ± 667 UL) and a significant reduction in maximal isometric torque loss (21%) was reported post-eccentric contractions. Change in creatine kinase from pre to peak significantly correlated with the relative change in vastus lateralis fascicle length during eccentric contractions (r = 0.53, p = 0.02) and with eccentric torque (r = 0.50, p = 0.02). Additionally, creatine kinase tended to correlate with estimated patella tendon lengthening during eccentric contractions (p < 0.10). However, creatine kinase did not correlate with resting measures of patella tendon properties or vastus lateralis properties. Similarly, torque loss did not correlate with any patella tendon or vastus lateralis properties at rest or during eccentric contractions. Conclusion: The current study demonstrates that the extent of fascicle strain during eccentric contractions correlates with the magnitude of the creatine kinase response. Although at rest, there is no relationship between patella tendon properties and markers of muscle damage; during eccentric contractions however, the patella tendon may play a role in the creatine kinase response following EIMD

Using Multiple Sources of Knowledge to Investigate Northern Environmental Change: Regional Ecological Impacts of a Storm Surge in the Outer Mackenzie Delta, N.W.T.

Field data, remote sensing, and Inuvialuit knowledge were synthesized to document regional ecological change in the outer Mackenzie Delta and to explore the timing, causes, and implications of this phenomenon. In September 1999, a large magnitude storm surge inundated low-lying areas of the outer Mackenzie Delta. The storm was among the most intense on record and resulted in the highest water levels ever measured at the delta front. Synthesis of scientific and Inuvialuit knowledge indicates that flooding during the 1999 storm surge increased soil salinity and caused widespread vegetation death. Vegetation cover was significantly reduced in areas affected by the surge and was inversely related to soil salinity. Change detection analysis, using remotely sensed imagery bracketing the 1999 storm event, indicates severe impacts on at least 13 200 ha of terrestrial vegetation in the outer delta. Inuvialuit knowledge identifying the 1999 surge as anomalous is corroborated by geochemical profiles of permafrost and by a recently published paleo-environmental study, which indicates that storm surge impacts of this magnitude have not previously occurred during the last millennium. Almost a decade after the 1999 storm surge event, ecological recovery has been minimal. This broad-scale vegetation change is likely to have significant implications for wildlife and must be considered in regional ecosystem planning and in the assessment and monitoring of the cumulative impacts of development. Our investigations show that Inuvialuit were aware of the 1999 storm surge and the environmental impacts several years before the scientific and regulatory communities recognized their significance. This study highlights the need for multidisciplinary and locally informed approaches to identifying and understanding Arctic environmental change.La synthèse des données d’exploitation et de télédétection de même que des connaissances des Inuvialuit a été effectuée afin de répertorier les changements écologiques enregistrés dans la région extérieure du delta du Mackenzie et d’explorer la temporisation, les causes et les incidences de ce phénomène. En septembre 1999, une onde de tempête de grande magnitude a inondé les zones de faible élévation de l’extérieur du delta du Mackenzie. Il s’agit de la tempête la plus intense à n’avoir jamais été enregistrée, ce qui s’est traduit par les niveaux d’eau les plus élevés à n’avoir jamais été mesurés à la hauteur du delta. La synthèse des données scientifiques et des connaissances des Inuvialuit nous montre que l’inondation de 1999 a eu pour effet d’augmenter la salinité du sol et a entraîné la mort de la végétation à grande échelle. La couverture végétale a été réduite considérablement dans les zones visées par l’onde et était inversement reliée à la salinité du sol. L’analyse des détections de changement effectuée au moyen de l’imagerie télédétectée dans le cas de la tempête de 1999 laisse entrevoir de fortes incidences sur au moins 13 200 hectares de végétation terrestre dans l’extérieur du delta. Les connaissances des Inuvialuit, qui affirment que l’onde de 1999 était anormale, sont corroborées par les profils géochimiques du pergélisol ainsi que par une étude paléoenvironnementale qui indique que des incidences de cette ampleur découlant d’une onde de tempête ne se sont pas produites à un autre moment donné du dernier millénaire. Près d’une décennie après l’onde de tempête de 1999, le rétablissement écologique était minime. Ce changement de végétation à grande échelle aura vraisemblablement d’importantes incidences sur la faune et doit entrer en considération dans la planification de l’écosystème régional ainsi que dans l’évaluation et la surveillance des incidences cumulatives des travaux d’aménagement et de mise en valeur. Nos enquêtes nous ont permis de constater que les Inuvialuit étaient conscients des incidences environnementales de l’onde de tempête de 1999 plusieurs années avant que les scientifiques et le personnel s’occupant de la réglementation ne reconnaissent leur importance. Cette étude fait ressortir la nécessité d’avoir des méthodes multidisciplinaires et de faire appel aux gens de la région pour déterminer et comprendre les changements environnementaux dans l’Arctique

Rapid solidification morphologies in Ni3Ge: Spherulites, dendrites and dense-branched fractal structures

Single-phase β-Ni3Ge has been rapidly solidified via drop-tube processing. At low cooling rates (850–300 μm diameter particles, 700–2800 K s−1) the dominant solidification morphology, revealed after etching, is that of isolated spherulites in an otherwise featureless matrix. At higher cooling rates (300–75 μm diameter particles, 2800–25,000 K s−1) the dominant solidification morphology is that of dendrites, again imbedded within a featureless matrix. As the cooling rate increases towards the higher end of this range the dendrites display non-orthogonal side-branching and tip splitting. At the highest cooling rates studied (25,000 K s−1), dense-branched fractal structures are observed. Selected area diffraction analysis in the TEM reveals the spherulites and dendrites are a disordered variant of β-Ni3Ge, whilst the featureless matrix is the ordered variant of the same compound. We postulate that the spherulites and dendrites are the rapid solidification morphology and that the ordered, featureless matrix grew more slowly post-recalescence. Spherulites are most likely the result of kinetically limited growth, switching to thermal dendrites as the growth velocity increases. It is extremely uncommon to observe such a wide range of morphologies as a function of cooling rate in a single material

Scattering by coupled resonating elements in air

Scattering by (a) a single composite scatterer consisting of a concentric arrangement of an outer N-slit rigid cylinder and an inner cylinder which is either rigid or in the form of a thin elastic shell and (b) by a finite periodic array of these scatterers in air has been investigated analytically and through laboratory experiments. The composite scatterer forms a system of coupled resonators and gives rise to multiple low-frequency resonances. The corresponding analytical model employs polar angle dependent boundary conditions on the surface of the N-slit cylinder. The solution inside the slits assumes plane waves. It is shown also that in the low-frequency range the N-slit rigid cylinder can be replaced by an equivalent fluid layer. Further approximations suggest a simple square root dependence of the resonant frequencies on the number of slits and this is confirmed by data. The observed resonant phenomena are associated with Helmholtz-like behaviour of the resonator for which the radius and width of the openings are much smaller than the wavelength. The problem of scattering by a finite periodic array of such coupled resonators in air is solved using multiple scattering techniques. The resulting model predicts band-gap effects resulting from the resonances of the individual composite scatterers below the first Bragg frequency. Predictions and data confirm that use of coupled resonators results in substantial insertion loss peaks related to the resonances within the concentric configuration. In addition, for both scattering problems experimental data, predictions of the analytical approach and predictions of the equivalent fluid layer approximations are compared in the low-frequency interval

Circulating tumor necrosis factor alpha may modulate the short-term detraining induced muscle mass loss following prolonged resistance training

Copyright © 2019 McMahon, Morse, Winwood, Burden and Onambélé. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. Introduction: Tumor necrosis factor alpha (TNFα) is a pro-inflammatory cytokine that has been shown to modulate muscle mass, and is responsive to exercise training. The effects of resistance training (RT) followed by a short period of detraining on muscle size, architecture and function in combination with circulating TNFα levels have not been previously investigated in a young, healthy population. Methods: Sixteen participants (8 males and 8 females) were randomly assigned to a training group (TRA; age 20 ± 3 years, mass 76 ± 7 kg), whilst fourteen participants (7 males and 7 females) age 22 ± 2 years, mass 77 ± 6 kg were assigned to a control group (CON). Measures of vastus lateralis (VL) muscle size (normalized physiological cross-sectional area allometrically scaled to body mass; npCSA), architecture (fascicle length; LF, pennation angle Pθ), strength (knee extensor maximal voluntary contraction; KE MVC), specific force, subcutaneous fat (SF) and circulating TNFα were assessed at baseline (BL), post 8 weeks RT (PT), and at two (DT1) and four (DT2) weeks of detraining. Results: Pooled BL TNFα was 0.87 ± 0.28 pg/mL with no differences between groups. BL TNFα tended to be correlated with npCSA (p = 0.055) and KEMVC (p = 0.085) but not specific force (p = 0.671) or SF (p = 0.995). There were significant (p 0.05) changes in SF, specific force or TNFα at any time points. There was a significant correlation (p = 0.022, r = 0.57) between the relative changes in TNFα and npCSA at DT2 compared to PT. Discussion: Neither RT nor a period of short term detraining altered the quality of muscle (i.e., specific force) despite changes in morphology and function. TNFα does not appear to have any impact on RT-induced gains in muscle size or function, however, TNFα may play a role in inflammatory-status mediated muscle mass loss during subsequent detraining in healthy adults

Instability in clinical risk stratification models using deep learning

While it has been well known in the ML community that deep learning models suffer from instability, the consequences for healthcare deployments are under characterised. We study the stability of different model architectures trained on electronic health records, using a set of outpatient prediction tasks as a case study. We show that repeated training runs of the same deep learning model on the same training data can result in significantly different outcomes at a patient level even though global performance metrics remain stable. We propose two stability metrics for measuring the effect of randomness of model training, as well as mitigation strategies for improving model stability.Comment: Accepted for publication in Machine Learning for Health (ML4H) 202