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Polygenic Modeling of Muscle Fibers Composition
Abstract and Figures
The present study investigated the genetic architecture of muscle fibers composition by means of the genome-wide association study and polygenic score modeling. Hundred thousands of single genetic variants and aggregated signal from multiple genetic variants were tested for an association with a proportion of the type I muscle fibers. We found several suggestively associated genetic variants (p-value < 0.00001) that can be potentially replicated with a larger cohort. The polygenic scores for 165 individuals using 49,105 genetic variants identified a significant association between the polygenic component and muscle fibers ratio (linear regression p-value = 0.00012). The present work provides new insights into the complex genetic structure of the muscle fibers.
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In order to gain insight into skiing performance, it is necessary to determine the point where each turn begins. Recent developments in sensor technology have made it possible to develop simpler automatic turn detection methodologies, however they are not feasible for regular use. The aim of this study was to develop a sensor set up and an algorithm to precisely detect turns during alpine ski, which is feasible for a daily use. An IMU was attached to the posterior upper cuff of each ski boot. Turn movements were reproduced on a ski-ergometer at different turn durations and slopes. Algorithms were developed to analyze vertical, medio-lateral, anterior-posterior axes, and resultant accelerometer and gyroscope signals. Raw signals, and signals filtered with 3, 6, 9, and 12 Hz cut-offs were used to identify turn switch points. Video recordings were assessed to establish a reference turn-switch and precision (mean bias = 5.2, LoA = 51.4 ms). Precision was adjusted based on reference and the best signals were selected. The z-axis and resultant gyroscope signals, filtered at 3Hz are the most precise signals (0.056 and 0.063 s, respectively) to automatically detect turn switches during alpine skiing using this simple system.
Background: Alzheimer's disease (AD) and dementia are chronic diseases with progressive deterioration of cognition, function, and behavior leading to severe disability and death. The prevalence of AD and dementia is constantly increasing because of the progressive aging of the population. These conditions represent a considerable challenge to patients, their family and caregivers, and the health system, because of the considerable need for resources allocation. There is no disease modifying intervention for AD and dementia, and the symptomatic pharmacological treatments has limited efficacy and considerable side effects. Non-pharmacological treatment (NPT), which includes a wide range of approaches and techniques, may play a role in the treatment of AD and dementia.
Aim: To review, with a narrative approach, current evidence on main NPTs for AD and dementia.
Methods: PubMed and the Cochrane database of systematic reviews were searched for studies written in English and published from 2000 to 2018. The bibliography of the main articles was checked to detect other relevant papers.
Results: The role of NPT has been largely explored in AD and dementia. The main NPT types, which were reviewed here, include exercise and motor rehabilitation, cognitive rehabilitation, NPT for behavioral and psychological symptoms of dementia, occupational therapy, psychological therapy, complementary and alternative medicine, and new technologies, including information and communication technologies, assistive technology and domotics, virtual reality, gaming, and telemedicine. We also summarized the role of NPT to address caregivers' burden.
Conclusions: Although NPT is often applied in the multidisciplinary approach to AD and dementia, supporting evidence for their use is still preliminary. Some studies showed statistically significant effect of NPT on some outcomes, but their clinical significance is uncertain. Well-designed randomized controlled trials with innovative designs are needed to explore the efficacy of NPT in AD and dementia. Further studies are required to offer robust neurobiological grounds for the effect of NPT, and to examine its cost-efficacy profile in patients with dementia.
This thesis creates a new method for assessing player performance in Australian
football, specifically for an application to the Australian Football League
(AFL).
Data have been captured by Champion Data as the official statistics provider
to the AFL since 1999. More than 100 event types are recorded for each game,
such as possessions, disposals, tackles and goals. Up to 50 variables are available
to describe the context, quality and location of such events.
A full investigation of this information was performed to extract relevant
traits of the data, and to improve on existing methods of analysis and available
knowledge within the industry. Two outcomes of this exploratory analysis
were a visual representation of data through the use of heatmaps, and a new
measure for kicking ability called ’kick rating’. Heatmaps have been used by
AFL clubs since 2008 as a way of communicating information to players and
extracting information about team and player tactical traits. Kick ratings
have been used by AFL clubs since 2011 as a development tool for their own
players, and for scouting of opposition players.
The data were also compiled into a player performance measure (‘Equity
Ratings’), where the spatial locations of each event acted as a basis for
evaluation. For each event, the rating system calculates the equity of the
player’s team before and after the event to measure the objective contribution
that the event made to a team’s position.
i
Players who consistently improve the position of their team are rewarded
with a large positive rating. Worsening the position of the team results in a
negative rating. In this manner, the quality of a player’s involvements will be
considered more important than previous rating systems which placed more
emphasis on the quantity of a player’s involvements in a game.
Equity Ratings proved to be the most comprehensive measure of player
performance that has been applied to AFL - showing decreased bias towards
midfield players and a higher correlation to match results. A cross-season
evaluation of player performance was then compiled to assess long-range performance.
This combined measure has been adopted by the league as the
‘Official AFL Player Ratings’, hosted on the official website of the league
(afl.com.au) and through the League’s official mobile and tablet apps.
Background:
It is important for highly active individuals to accurately assess their hydration level. Bioelectrical impedance (BIA) can potentially meet these needs but its validity in active individuals is not well established.
Methods:
We compared whole-body bioimpedance measurements obtained from multi-frequency bioelectrical impedance spectroscopy (BIS, Xitron 4200) at a 50 kHz frequency with those determined by a phase-sensitive single-frequency device (SF-BIA, BIA-101, RJL/Akern Systems) in two populations: active adults and elite athletes.
Results:
One hundred twenty-six participants, including active males involved in recreational sports (N = 25, 20-39 yr) and elite athletes (females: N = 26, 18-35 yr; males: N = 75, 18-38 yr) participated in this study. Reactance (Xc), Resistance (R), Impedance (Z), and phase angle (PhA) were obtained by BIS and SF-BIA. Small but significant differences (R: -9.91 ± 15.09 Ω; Xc: -0.97 ± 2.56 Ω; Z: -9.96 ± 15.18 Ω; PhA: 0.12 ± 0.2°) were observed between the bioimpedance equipment in all measured variables (p < 0.05) though differences were within the devices' technical error of measurements. Device-specific values were highly (p < 0.0001) correlated [R2 ranged from 0.881 (Xc) to 0.833 (R)], but slopes and intercepts were different (p < 0.0001) from 1 and 0, respectively. Relatively large limits of agreement were observed for R (-40 to 21 Ω), Xc (-6 to 4 Ω), PhA (-0.4 to 0.5°), and impedance (-40 to 20 Ω).
Conclusion:
Bioimpedance measurements from the current single- and multi-frequency devices should not be used interchangeably. The of lack of agreement between devices was observed in determining individual values of R, Xc, Z and PhA of highly active populations possibly due to methodological and biological factors.
Advances in body composition assessment enable a detailed body composition analyses and the respective organization at
different levels. Sports-related professionals are interested in understanding how and which body components are relevant
for improving performance, prevent injury risk, and monitor athletic health. The aim of this review is to propose an integrative model that links performance, injury risk, and athletic health with body components, and to report their cross-sectional and longitudinal associations. Cross-sectional studies reveal that endurance athletes with higher fat mass (FM) show a longer race time, whereas a higher fat-free mass benefits power and strength-related tasks. Longitudinal studies indicated that increases in intracellular water, assessed through dilution techniques, were associated with power and strength improvements, independently of weight and lean-soft-tissue changes. There is evidence that athletes involved in weight sensitive sports restrict energy intake, thus reducing energy availability (EA) and compromising bone health (Female Athlete Triad). To counteract the low EA and related negative energy balance, metabolic adaption (MA) occurs to promote energy conservation. Currently, reference values for body composition assessment using anthropometry and DXA are available for a few sports, according to sex. More research is needed to develop a functional body composition profile according to sports-specific
requirements.
Purpose:
The exercise-induced increase in skin and body temperature, cutaneous blood flow and electrolyte accumulation on the skin affects the validity of bioimpedance analysis (BIA) to assess post-exercise changes in hydration. This study aimed to assess the influence of a 10-min cold (22°C) shower on the time course of impedance measurements after controlled exercise.
Methods:
Ten male athletes (26.2±4.1 yr and BMI 23.9±1.7 kg/m2) were tested on two different days. During both trials, athletes ran for 30 min on a treadmill in a room at 22°C. In a randomized cross-over trial, the participants underwent a 10-min cold shower in the trial occasion and did not shower in the control trial. BIA variables were measured before running (i.e. baseline (T0)), immediately after exercising (T1), then at 20 (T2), 40 (T3) and 60 min (T4) after the exercise. The shower was performed after T1 in the shower trial.
Results:
Body weight decreased similarly after running (-0.4±0.1%, p<0.001 and -0.4±0.1%, p<0.001). Resistance and vector length returned to baseline at T2 in the shower trial, whereas baseline values were achieved at T3 in the control trial (p>0.05). In the control trial, reactance remained at a lower level for the entire testing period (38.1±6.9 vs. 37.3±6.7, p<0.001). Forehead skin temperature returned to baseline values at T2 with shower, while it was still high at T4 without shower (p<0.001).
Conclusions:
The present data show that a 10-min cold shower enables the stabilization of BIA measurements within 20 min after exercise, which might facilitate the assessment of hydration change after exercise.
Representative learning design provides a framework for the extent to which practice simulates key elements of a performance setting. Improving both the measurement and analysis of representative learning design would allow for the refinement of sports training environments that seek to replicate competition conditions and provide additional context to the evaluation of athlete performance. Using rule induction, this study aimed to develop working models for the determination of high frequency, representative events in Australian Rules football kicking. A sample of 9005 kicks from the 2015 Australian Football League season were categorised and analysed according to the following constraints: type of pressure, kick distance, possession source, time in possession, velocity and kick target. The Apriori algorithm was used to develop two models. The first consisted of 10 rules containing the most commonly occurring constraint sets occurring during the kick in AF, with support values ranging from 0.15 to 0.22. None of the rules contained more than three constraints and confidence values ranged from 0.63 to 0.84. The second model considered ineffective and effective kick outcomes and displayed 70% classification accuracy. This research provides a measurement approach to determine the degree of representativeness of sports practice and is directly applicable to various team sports.
Background:
The polygenic risk score (PRS) for schizophrenia, derived from very large numbers of weakly associated genetic markers, has been repeatedly shown to be robustly associated with schizophrenia in independent samples and also with other diseases and traits.
Aim:
This study aims to explore the distribution of the schizophrenia PRS in subjects of different ancestry.
Methods:
The schizophrenia PRS derived from the large genome-wide association study carried out by the Psychiatric Genetics Consortium was calculated using the downloaded genotypes of HapMap subjects from 11 different ancestral groups. It was also calculated using downloaded genotypes of European schizophrenia cases and controls from the CommonMind Consortium.
Results:
The PRS for schizophrenia varied significantly between ancestral groups (P<2×10) and was much higher in African than European HapMap subjects. The mean difference between these groups was 10 times as high as the mean difference between European schizophrenia cases and controls. The distributions of scores for African and European subjects hardly overlapped.
Conclusion:
The PRS cannot be regarded as simply a measure of the polygenic contribution to risk of schizophrenia and clearly contains a strong ancestry component. It is possible that this could be controlled to some extent by incorporating principal components as covariates, but doubts remain as to how it should be interpreted. The PRS derived from European subjects cannot be applied to non-Europeans, limiting its potential usefulness in clinical settings and raising issues of inequity in health provision. Previous studies that have used the PRS should be re-examined in the light of these findings.
