Geometric View of Measurement Errors

The slope of the best fit line from minimizing the sum of the squared oblique errors is the root of a polynomial of degree four. This geometric view of measurement errors is used to give insight into the performance of various slope estimators for the measurement error model including an adjusted fourth moment estimator introduced by Gillard and Iles (2005) to remove the jump discontinuity in the estimator of Copas (1972). The polynomial of degree four is associated with a minimun deviation estimator. A simulation study compares these estimators showing improvement in bias and mean squared error

Structure variation and evolution in microphase-separated grafted diblock copolymer films

The phase behavior of grafted d-polystyrene-block-poly(methyl methacrylate) diblock copolymer films is examined, with particular focus on the effect of solvent and annealing time. It was observed that the films undergo a two-step transformation from an initially disordered state, through an ordered metastable state, to the final equilibrium configuration. It was also found that altering the solvent used to wash the films, or complete removal of the solvent prior to thermal annealing using supercritical CO2, could influence the structure of the films in the metastable state, though the final equilibrium state was unaffected. To aid in the understanding to these experimental results, a series of self-consistent field theory calculations were done on a model diblock copolymer brush containing solvent. Of the different models examined, those which contained a solvent selective for the grafted polymer block most accurately matched the observed experimental behavior. We hypothesize that the structure of the films in the metastable state results from solvent enrichment of the film near the film/substrate interface in the case of films washed with solvent or faster relaxation of the nongrafted block for supercritical CO2 treated (solvent free) films. The persistence of the metastable structures was attributed to the slow reorganization of the polymer chains in the absence of solvent

Validity and reliability of RPE as a measure of intensity during isometric wall squat exercise

Background and Aims: Isometric exercise (IE), including wall squat training, has been shown to be effective at reducing resting blood pressure (BP). Rating of perceived exertion (RPE) is also widely used as an accessible additional measure of IE intensity. Despite this, no RPE scales have been specifically designed for use with IE and it is not clear whether RPE is sensitive enough to distinguish between different lower limb IE workloads. Therefore, the aims of this study were to assess the validity and reliability of RPE as a measure of IE intensity (workload) and physiological exertion (Heart rate and BP), and to examine whether RPE is able to discern differences in wall squat workload (knee angle) at a resolution of 10-degrees, as was previous shown for heart rate (HR) and BP. Methods: Twenty-nine male participants completed 8 separate isometric wall squat testing sessions, separated by a minimum of 5-hours. Each session consisted of a single 2-minute isometric wall squat test, at one of five randomised workloads (knee joint angles). Three of the knee angles were repeated, a second time, to allow measurements of reliability. Throughout the exercise protocol, HR and BP were recorded continuously; values for each 30-second time-point were calculated as the mean of the proceeding 5-seconds, peak values for the 2-minute bout were taken as the mean results for the final 5- seconds of the bout. Additionally, mean results for the full 2-minute period were calculated. RPE was collected every 30 seconds. Concurrent validity was assessed by correlating RPE results with the criterion measures: Knee joint angle, HR and BP. Differences in RPE were assessed across consecutive workloads and time-points. Results: There were significant increases in RPE at each consecutive wall squat workload (p < 0.001) and between each consecutive 30-second time point (p < 0.001). Additionally, the RPE results produced a significant inverse relationship with knee angle (r = -0.79; p < 0.001) and significant positive relationships with HR (r = 0.53, p < 0.001) and BP (systolic: r = 0.77; diastolic: r = 0.62; mean arterial pressure: r = 0.70, p < 0.001). Conclusion: RPE provides a valid and reliable measure of isometric wall squat intensity, physiological exertion, and can discern between knee angles with a resolution of 10°. Relevance for patients: Patients and practitioners implementing isometric exercise training for arterial blood pressure reduction can use RPE to accurately monitor the intensity of the exercise and the physiological responses

Strongman training – Needs analysis and integration into strength and conditioning programming: part 2.

The article aims to evaluate the integration of strongman based exercises within the practice of strength and conditioning. It should give the reader a clear understanding of the specific physiological and biomechanical traits of each of the exercises discussed in the previous article. This information will then be used to discuss its amalgamation within traditional based exercises within the planning of a periodised programme for strength and conditioning practitioners

Strongman training – a rationale for its inclusion in strength & conditioning: part 1

This article, the first in a two-part series, aims to introduce the concepts of strongman-type training relative to some of the exercises adopted. It should give the reader a detailed background into the evolution of strongman training with a strong rationale for its inclusion within the practice of strength and conditioning

Validity and reliability of the ‘Isometric Exercise Scale’ (IES) for measuring ratings of perceived exertion during continuous isometric exercise

Purpose: Isometric exercise (IE) interventions have been shown to be effective at reducing resting arterial blood pressure (BP). IE intensity is generally determined using force, electromyography (EMG), heart rate (HR), or knee joint angle. However, ratings of perceived exertion (RPE) may provide a more accessible means of determining exercise intensity. Therefore, the aim of this study was to assess the validity of a specific Isometric Exercise Scale (IES) during a continuous incremental isometric wall squat test. Methods: Twenty-nine male participants completed 4 incremental IE tests. Each test consisted of 5 isometric wall squat intensities, determined by knee joint angles from 135° to 95°, each held for up to 2 minutes. The tests were continuous until volitional fatigue or completion of the 5 work stages. Throughout the exercise protocol, RPE (IES and Borg’s CR-10), HR and blood pressure were recorded. Results: The IES produced a strong positive linear relationship with the CR-10 (r = 0.967) . Additionally, strong positive relationships between the IES and wall squat duration (r = 0.849), HR (r = 0.819) and BP (r = 0.841) were seen. Intra-class correlation coefficients and coefficients of variations for the IES ranged from r = 0.81 to 0.91 and 4.5% to 54% respectively, with greater reliability seen at the higher workloads. Conclusions: The IES is a valid and reliable measure of RPE, exercise intensity, and it accurately represents the changes in physiological measures of exertion during IE; as such, the IES can be used as a useful additional measure of exercise intensity during IET interventions

Characteristics of torque production of the lower limb are significantly altered after 2 hours of treadmill load carriage

Load carriage is seldom completed in isolation, meaning load bearers need to be physically capable of physical activity after the load carriage task. This study aims to examine changes in lower limb muscle strength, as measured by torque production across a range of joint angles as a result of prolonged load carriage. Thirty-four healthy participants underwent two hours of loaded or unloaded treadmill load carriage, with lower limb muscle function variables assessed pre and post activity. The loaded group had a mass of (Mean(range)) 76.45 (27.12)kg, stature: 178.56 (17.63)cm, age: 23(6)yrs, and comprised of 13 males and 3 females. While the unloaded group had a body mass of 73.69(24.19)kg, stature: 178.89(18.49)cm, age: 22(5)yrs and comprised of 14 males and 4 females. Significant reductions across a range of parameters were observed. Characterised by reductions at the optimum muscle length for torque output, with all aspects demonstrating large (knee extension at 180˚·s-1: 0.51 Standardised SD, knee extnsion at 60˚·s-1: 0.98 standardised SD) or extremely large individual differences (knee flexion at 180˚·s-1: 2.17 standardised SD). These findings suggest after the completion of the load carriage task participants are in a significantly reduced physical state, which may have implications for secondary tasks