Predicting critical power in elite cyclists: questioning validity of the 3-min All-out test

Purpose: New applications of the critical power concept, such as the modelling of intermittent work capabilities, are exciting prospects for elite cycling. However, accurate calculation of the required parameters is traditionally time invasive and somewhat impractical. An alternative single test protocol (3-min All-out) has recently been proposed, but validation in an elite population is lacking. The traditional approach for parameter establishment, but with fewer tests, could also prove an acceptable compromise. Methods: Six senior Australian endurance track cycling representatives completed six efforts to exhaustion on two separate days over a three week period. These included 1, 4, 6, 8 and 10 minute self-paced efforts, plus the 3-min All-out protocol. Traditional work versus time calculations of CP and W’ using the five self-paced efforts were compared to calculations from the 3-min All-out protocol. The impact of using just two or three self-paced efforts for traditional CP and W’ estimation were also explored using thresholds of agreement (8W, 2.0kJ respectively). Results: CP estimated from the 3-min All-out approach was significantly higher than from the traditional approach (402±33W, 351±27W, p<0.001), whilst W’ was lower (15.5±3.0kJ, 24.3±4.0kJ, p=0.02). Five different combinations of two or three self-paced efforts led to CP estimates within the threshold of agreement, with only one combination deemed accurate for W’. Conclusions: In elite cyclists the 3-min All-out approach is not suitable to estimate CP when compared to the traditional method. However, reducing the number of tests used in the traditional method lessens testing burden whilst maintaining appropriate parameter accuracy.Jason C Bartram, Dominic Thewlis, David T Martin, Kevin I Norto

The long-term effect of minimalist shoes on running performance and injury: design of a randomised controlled trial

INTRODUCTION: The outcome of the effects of transitioning to minimalist running shoes is a topic of interest for runners and scientists. However, few studies have investigated the longer term effects of running in minimalist shoes. The purpose of this randomised controlled trial (RCT) is to investigate the effects of a 26 week transition to minimalist shoes on running performance and injury risk in trained runners unaccustomed to minimalist footwear. METHODS AND ANALYSIS: A randomised parallel intervention design will be used. Seventy-six trained male runners will be recruited. To be eligible, runners must be aged 18-40 years, run with a habitual rearfoot footfall pattern, train with conventional shoes and have no prior experience with minimalist shoes. Runners will complete a standardised transition to either minimalist or control shoes and undergo assessments at baseline, 6 and 26 weeks. 5 km time-trial performance (5TT), running economy, running biomechanics, triceps surae muscle strength and lower limb bone mineral density will be assessed at each time point. Pain and injury will be recorded weekly. Training will be standardised during the first 6 weeks. Primary statistical analysis will compare 5TT between shoe groups at the 6-week time point and injury incidence across the entire 26-week study period. ETHICS AND DISSEMINATION: This RCT has been approved by the Human Research Ethics Committee of the University of South Australia. Participants will be required to provide their written informed consent prior to participation in the study. Study findings will be disseminated in the form of journal publications and conference presentations after completion of planned data analysis. TRIAL REGISTRATION NUMBER: This RCT has been registered with the Australian New Zealand Clinical Trials Registry (ACTRN12613000642785).Joel T Fuller, Dominic Thewlis, Margarita D Tsiros, Nicholas A T Brown, Jonathan D Buckle

Simulating time-series data for improved deep neural network performance

Deep learning algorithms have shown remarkable performance in classification tasks, however, they typically perform poorly with small training datasets due to overfitting. Overfitting occurs for all data types, although for the purposes of this study we are interested in time-based signals. This study introduces a novel technique to simulate time series signals from a dataset of categorically labeled data which can be used to train a deep neural network. The objective is to improve the predictive accuracy of a deep neural network on a separate validation dataset. To demonstrate the simulation methodology and improvements to the model's performance, a small dataset of ground reaction forces was used with the goal of identifying a person based on the raw signal. Our results show that the simulation method presented improves validation accuracy and reduces model training time for each of the three signal types.Jordan Yeomans, Simon Thwaites, William S. P. Robertson, David Booth, Brian Ng, Dominic Thewli

Hand function is altered in individuals with a history of illicit stimulant use

Published: December 29, 2014Use of illicit stimulant drugs such as methamphetamine, cocaine, and ecstasy are a significant worldwide problem. However, little is known about the effect of these drugs on movement. The aim of the current study was to investigate hand function in adults with a history of illicit stimulant use. We hypothesized that prior use of illicit stimulant drugs is associated with abnormal manipulation of objects. The study involved 22 subjects with a history of illicit stimulant use (aged 29±8 yrs; time since last use: 1.8±4.0 yrs) and two control groups comprising 27 non-drug users (aged 25±8 yrs) and 17 cannabis users with no history of stimulant use (aged 22±5 yrs). Each subject completed screening tests (neuropsychological assessment, medical history questionnaire, lifetime drug history questionnaire, and urine drug screen) prior to gripping and lifting a light-weight object with the dominant right hand. Horizontal grip force, vertical lift force, acceleration, and first dorsal interosseus electromyographic (EMG) activity were recorded during three trials. In trial one, peak grip force was significantly greater in the stimulant group (12.8±3.9 N) than in the control groups (non-drug: 10.3±4.6 N; cannabis: 9.4±2.9 N, P<0.022). However, peak grip force did not differ between groups in trials two and three. The results suggest that individuals with a history of stimulant use overestimate the grip force required to manipulate a novel object but, are able to adapt grip force in subsequent lifts. The results suggest that movement dysfunction may be an unrecognized consequence of illicit stimulant use.Verity Pearson-Dennett, Stanley C. Flavel, Robert A. Wilcox, Dominic Thewlis, Adam P. Vogel, Jason M. White, Gabrielle Tod

Biomechanical changes and recovery of gait function after total hip arthroplasty for osteoarthritis: a systematic review and meta-analysis

© 2018 Elsevier. This manuscript version is made available under the CC-BY-NC-ND 4.0 license: http://creativecommons.org/licenses/by-nc-nd/4.0/ This author accepted manuscript is made available following 12 month embargo from date of publication (February 2018) in accordance with the publisher’s archiving policyObjective To determine the change in walking gait biomechanics after total hip arthroplasty (THA) for osteoarthritis (OA) compared to the pre-operative gait status, and to compare the recovery of gait following THA with healthy individuals. Methods Systematic review with meta-analysis of studies investigating changes in gait biomechanics after THA compared to (1) preoperative levels and (2) healthy individuals. Data were pooled at commonly reported time points and standardised mean differences (SMDs) were calculated in meta-analyses for spatiotemporal, kinematic and kinetic parameters. Results Seventy-four studies with a total of 2,477 patients were included. At 6 weeks postoperative, increases were evident for walking speed (SMD: 0.32, 95% confidence intervals (CI) 0.14, 0.50), stride length (SMD: 0.40, 95% CI 0.19, 0.61), step length (SMD: 0.41, 95% CI 0.23, 0.59), and transverse plane hip range of motion (ROM) (SMD: 0.36, 95% CI 0.05, 0.67) compared to pre-operative gait. Sagittal, coronal and transverse hip ROM was significantly increased at 3 months (SMDs: 0.50 to 1.07). At 12 months postoperative, patients demonstrated deficits compared with healthy individuals for walking speed (SMD: −0.59, 95% CI −1.08 to −0.11), stride length (SMD: −1.27, 95% CI -1.63, −0.91), single limb support time (SMD: −0.82, 95% CI −1.23, −0.41) and sagittal plane hip ROM (SMD: −1.16, 95% CI −1.83, −0.49). Risk of bias scores ranged from seven to 24 out of 26. Conclusions Following THA for OA, early improvements were demonstrated for spatiotemporal and kinematic gait patterns compared to the pre-operative levels. Deficits were still observed in THA patients compared to healthy individuals at 12 months

Magnetoelectric ordering of BiFeO3 from the perspective of crystal chemistry

In this paper we examine the role of crystal chemistry factors in creating conditions for formation of magnetoelectric ordering in BiFeO3. It is generally accepted that the main reason of the ferroelectric distortion in BiFeO3 is concerned with a stereochemical activity of the Bi lone pair. However, the lone pair is stereochemically active in the paraelectric orthorhombic beta-phase as well. We demonstrate that a crucial role in emerging of phase transitions of the metal-insulator, paraelectric-ferroelectric and magnetic disorder-order types belongs to the change of the degree of the lone pair stereochemical activity - its consecutive increase with the temperature decrease. Using the structural data, we calculated the sign and strength of magnetic couplings in BiFeO3 in the range from 945 C down to 25 C and found the couplings, which undergo the antiferromagnetic-ferromagnetic transition with the temperature decrease and give rise to the antiferromagnetic ordering and its delay in regard to temperature, as compared to the ferroelectric ordering. We discuss the reasons of emerging of the spatially modulated spin structure and its suppression by doping with La3+.Comment: 18 pages, 5 figures, 3 table

Vibrational properties of the one-component σ\sigma phase

A structural model of a one-component $\sigma$-phase crystal has been constructed by means of molecular dynamics simulation. The phonon dispersion curves and the vibrational density of states were computed for this model. The dependence of the vibrational properties on the thermodynamical parameters was investigated. The vibrational density of states of the $\sigma$-phase structure is found to be similar to that of a one-component glass with icosahedral local order. On the basis of this comparison it is concluded that the $\sigma$ phase can be considered to be a good crystalline reference structure for this glass