bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Added Mass on Lead-Zirconate-Titanate Thin-Film Microactuators in Aqueous Environments
Authors: Luo Chuan , Tai W. C. , Yang Cheng-Wei , Cao G. Z. , Shen I. Y.
Published: September 2016

In this paper, we conduct experimental, theoretical, and numerical studies of a lead-zirconate-titanate (PZT) thin-film microactuator probe submerged in water. The major component of the actuator is a PZT diaphragm anchored on four silicon sidewalls. There is also silicon residue at the juncture of the diaphragm and the sidewalls due to imperfect etching processes. In the experimental study, frequency response functions of actuator displacement are measured via a laser Doppler vibrometer and a spectrum analyzer. The measurements show that the first natural frequency of the microactuator reduces from 80 kHz in air to 20 kHz when the microactuator is submerged in water. A viable explanation is that the surrounding water induces significant added mass to the microactuator. Estimation of the added mass based on theories in fluid mechanics successfully reconciles the predicted frequency to the vicinity of 20 kHz confirming the effects of added mass. Finite element models are also created to study how the silicon sidewalls and residue affect the added mass. Simulations show that presence of the sidewalls or residue would modify the fluid flow thus altering the added mass and natural frequency. In general, the finite element predictions agree well with the experimental measurements within 10% difference.
Uncertainty Analysis of a Tilting-Pad Journal Bearing Using Fuzzy Logic Techniques
Authors: Cavalini A. A. , Dourado A. G. S. , Lara-Molina F. A. , Steffen V.
Published: September 2016

This paper is dedicated to the analysis of uncertainties affecting the load capability of a 4-pad tilting-pad journal bearing in which the load is applied on a given pad load on pad configuration (LOP). A well-known stochastic method has been used extensively to model uncertain parameters by using the so-called Monte Carlo simulation. However, in the present contribution, the inherent uncertainties of the bearing parameters (i.e., the pad radius, the oil viscosity, and the radial clearance; bearing assembly clearance) are modeled by using a fuzzy dynamic analysis. This alternative methodology seems to be more appropriate when the stochastic process that characterizes the uncertainties is unknown. The analysis procedure is confined to the load capability of the bearing, being generated by the envelopes of the pressure fields developed on each pad. The hydrodynamic supporting forces are determined by considering a nonlinear model, which is obtained from the solution of the Reynolds equation. The most significant results are associated to the changes in the steady-state condition of the bearing due to the reaction forces that are modified according to the uncertainties introduced in the system. Finally, it is worth mentioning that the uncertainty analysis in this case provides relevant information both for design and maintenance of tilting-pad hydrodynamic bearings.
Design Optimization of Gas Foil Thrust Bearings for Maximum Load Capacity1
Authors: Kim Tae Ho , Park Moonsung , Lee Tae Won
Published: September 2016

The aim of the present study is to develop a design guideline to improve the load capacity of gas foil thrust bearings (GFTBs). The Reynolds equation for an isothermal isoviscous ideal gas calculates the gas film pressure. The film pressure averaged in the radial direction determines the ultimate load capacity. The load capacity, film pressure profile, and film thickness profile are predicted for a GFTB with an outer radius of 55 mm, inner radius of 30 mm, and eight foils each of arc length 45 deg. The predictions show that the load capacity of the GFTB increases with increasing rotor speed and decreasing minimum film thickness. A parametric study, in which the ramp extent (or inclined angle) is increased from 5 deg to 40 deg, and the ramp height from 0 to 320 μm, reveals that GFTBs have an optimal ramp extent of ∼22.5 deg and ramp height of 30 μm for maximum load capacity. A series of maximum load capacity measurements are conducted on four test GFTBs with ramp heights of 50, 150, 250, and 350 μm at the speeds of 12, 15, and 18 krpm. To estimate the maximum load capacity, the applied load is increased until the drag torque rises suddenly with a sharp peak. The test results show that the maximum load capacity generally increases for decreasing ramp height and for increasing rotor speed. The GFTB with a ramp height of 50 μm shows the largest maximum load capacity of 510 N, for example. Test results are in good agreement with model predictions.
Investigations on Wave Propagation of the Pressure Pulsation in a Helmholtz-Type Hydraulic Silencer With a Hemispherical Vessel
Authors: Ichiyanagi Takayoshi , Kuribayashi Tetsuya , Nishiumi Takao
Published: September 2016

The Helmholtz-type hydraulic silencer is one of the most practical silencers for attenuating pressure pulsations in hydraulic systems owing to its simple structure and reasonable cost. Maximum attenuation performance can be attained at the resonance frequency in accordance with the principle of Helmholtz resonance. Therefore, it is extremely important to precisely determine the resonance frequency at the design stage. It was clarified in our previous study that the shape of the volume vessel affects the resonance frequency of the silencer because of the wave propagation of pressure pulsation inside the volume vessel. In this study, the attenuation characteristics and wave propagation in a silencer with a hemispherical vessel are investigated. A mathematical model that takes into account the propagation of a one-dimensional wave in the radial direction of the hemispherical vessel is proposed and compared with the step section approximation model and the classic lumped parameter model. Furthermore, the effectiveness of the theoretical analysis is verified by experiments wherein the dimensional specifications of the vessel and neck are adjusted.
Surface Strains of Porcine Tricuspid Valve Septal Leaflets Measured in Ex Vivo Beating Hearts
Authors: Amini Khoiy Keyvan , Biswas Dipankar , Decker Thomas N. , Asgarian Kourosh T. , Loth Francis , Amini Rouzbeh
Published: September 2016

Quantification of the tricuspid valve (TV) leaflets mechanical strain is important in order to understand valve pathophysiology and to develop effective treatment strategies. Many of the traditional methods used to dynamically open and close the cardiac valves in vitro via flow simulators require valve dissection. Recent studies, however, have shown that restriction of the atrioventricular valve annuli could significantly change their in vivo deformation. For the first time, the porcine valve leaflets deformation was measured in a passive ex vivo beating heart without isolating and remounting the valve annuli. In particular, the right ventricular apexes of porcine hearts (n = 8) were connected to a pulse-duplicator pump that maintained a pulsatile flow from and to a reservoir connected to the right atrium and the pulmonary arteries. This pump provided a right ventricular pressure (RVP) waveform that closely matched physiological values, leading to opening and closure of the tricuspid and pulmonary valves (PVs). At the midsection of the valve leaflets, the peak areal strain was 9.8 ± 2.0% (mean±standard error). The peak strain was 5.6 ± 1.1% and 4.3 ± 1.0% in the circumferential and radial directions, respectively. Although the right ventricle was beating passively, the leaflet peak areal strains closely matched the values measured in other atrioventricular valves (i.e., the mitral valve (MV)) in vivo. This technique can be used to measure leaflet strains with and without the presence of valve lesions to help develop/evaluate treatment strategies to restore normal valve deformation.
On Parametric Stability of a Nonconstant Axially Moving String Near Resonances
Authors: Malookani Rajab A. , van Horssen Wim T.
Published: September 2016

The stability of an axially moving string system subjected to parametric excitation resulting from speed fluctuations has been examined in this paper. The time-dependent velocity is assumed to be a harmonically varying function around a (low) constant mean speed. The method of characteristic coordinates in combination with the two timescales perturbation method is used to compute the first-order approximation of the solutions of the equations of motion that governs the transverse vibrations of an axially moving string. It turns out that the system can give rise to resonances when the velocity fluctuation frequency is equal (or close) to an odd multiple of the natural frequency of the system. The stability conditions are investigated analytically in terms of the displacement-response and the energy of the system near the resonances. The effects of the detuning parameter on the amplitudes of vibrations and on the energy of the system are also presented through numerical simulations.
A Study on the Correlation Between Dynamic Transmission Error and Dynamic Tooth Loads in Spur and Helical Gears
Authors: Sainte-Marie N. , Velex P. , Roulois G. , Caillet J.
Published: September 2016

A three-dimensional (3D) dynamic gear model is presented which combines classic shaft, lumped parameter, and specific two-node gear elements. The mesh excitation model is based on transmission errors (TEs), and its mathematical grounding is briefly described. The validity of the proposed methodology is assessed for both spur and helical gears by comparison with experimental evidence. The model is then employed to analyze the relationship between dynamic transmission errors (DTE) and dynamic tooth loads (DF) or root stresses. It is shown that a linear dependency can be found as long as the system behavior is dominated by shaft torsion but that this linear relationship tends to disappear when bending cannot be neglected.
Improved First-Order Approximate Models of Temperature and Thermal Stresses for Online Fatigue Monitoring
Authors: Zhang Hengliang , Xie Danmei , Jiang Jin
Published: September 2016

Online monitoring of temperature and thermal stresses is an important way to ensure the safety of power plants considering fatigue and creep damages. The effect of online monitoring is determined by the accuracy and calculating time of monitoring models. In this paper, the improved first-order analytical models of temperature and thermal stresses considering temperature-dependent material properties have been derived by using homotopy analysis method (HAM) and superposition principle. The optimal convergence control parameters are obtained by calculating the mean-square residual errors. The validity and accuracy of the proposed models were proved by results comparisons with finite element method (FEM) and artificial parameter method.
Intake Flow Analysis of a Pulsed Detonation Engine
Authors: Strafaccia Joshua A. , Ölçmen Semih M. , Hoke John L. , Paxson Daniel E.
Published: September 2016

Unsteady flow within the intake system of a hydrogen–air pulse detonation engine (PDE) has been analyzed using a quasi-one-dimensional (Q1D) computational fluid dynamic (CFD) code. The analysis provides insight into the unsteady nature of localized equivalence ratios and their effects on PDE performance. For this purpose, a code originally configured to model the PDE tube proper was modified to include a 6.1 m long intake with a single fuel injector located approximately 3.05 m upstream of the primary intake valve. The results show that constant fuel mass flow rate injection from the injector creates large local variations in equivalence ratio throughout the PDE within a cycle. The effect of fill fraction on the engine performance is better described with the presence of the inlet model. However, the effect of ignition delay is shown to be better predicted with a model without the inlet.
Fiber Bragg gratings‐based sensing for real‐time needle tracking during MR‐guided brachytherapy
Authors: Borot de Battisti Maxence , Denis de Senneville Baudouin , Maenhout Metha , Lagendijk Jan J. W. , van Vulpen Marco , Hautvast Gilion , Binnekamp Dirk , Moerland Marinus A.
Published: September 2016

Purpose

The development of MR‐guided high dose rate (HDR) brachytherapy is under investigation due to the excellent tumor and organs at risk visualization of MRI. However, MR‐based localization of needles (including catheters or tubes) has inherently a low update rate and the required image interpretation can be hampered by signal voids arising from blood vessels or calcifications limiting the precision of the needle guidance and reconstruction. In this paper, a new needle tracking prototype is investigated using fiber Bragg gratings (FBG)‐based sensing: this prototype involves a MR‐compatible stylet composed of three optic fibers with nine sets of embedded FBG sensors each. This stylet can be inserted into brachytherapy needles and allows a fast measurement of the needle deflection. This study aims to assess the potential of FBG‐based sensing for real‐time needle (including catheter or tube) tracking during MR‐guided intervention.

Methods

First, the MR compatibility of FBG‐based sensing and its accuracy was evaluated. Different known needle deflections were measured using FBG‐based sensing during simultaneous MR‐imaging. Then, a needle tracking procedure using FBG‐based sensing was proposed. This procedure involved a MR‐based calibration of the FBG‐based system performed prior to the interventional procedure. The needle tracking system was assessed in an experiment with a moving phantom during MR imaging. The FBG‐based system was quantified by comparing the gold‐standard shapes, the shape manually segmented on MRI and the FBG‐based measurements.

Results

The evaluation of the MR compatibility of FBG‐based sensing and its accuracy shows that the needle deflection could be measured with an accuracy of 0.27 mm on average. Besides, the FBG‐based measurements were comparable to the uncertainty of MR‐based measurements estimated at half the voxel size in the MR image. Finally, the mean(standard deviation) Euclidean distance between MR‐ and FBG‐based needle position measurements was equal to 0.79 mm(0.37 mm). The update rate and latency of the FBG‐based needle position measurement were 100 and 300 ms, respectively.

Conclusions

The FBG‐based needle tracking procedure proposed in this paper is able to determine the position of the complete needle, under MR‐imaging, with better accuracy and precision, higher update rate, and lower latency compared to current MR‐based needle localization methods. This system would be eligible for MR‐guided brachytherapy, in particular, for an improved needle guidance and reconstruction.
Use of regularized principal component analysis to model anatomical changes during head and neck radiation therapy for treatment adaptation and response assessment
Authors: Chetvertkov Mikhail A. , Siddiqui Farzan , Kim Jinkoo , Chetty Indrin , Kumarasiri Akila , Liu Chang , Gordon J. James
Published: September 2016

Purpose

To develop standard (SPCA) and regularized (RPCA) principal component analysis models of anatomical changes from daily cone beam CTs (CBCTs) of head and neck (H&N) patients and assess their potential use in adaptive radiation therapy, and for extracting quantitative information for treatment response assessment.

Methods

Planning CT images of ten H&N patients were artificially deformed to create “digital phantom” images, which modeled systematic anatomical changes during radiation therapy. Artificial deformations closely mirrored patients’ actual deformations and were interpolated to generate 35 synthetic CBCTs, representing evolving anatomy over 35 fractions. Deformation vector fields (DVFs) were acquired between pCT and synthetic CBCTs (i.e., digital phantoms) and between pCT and clinical CBCTs. Patient‐specific SPCA and RPCA models were built from these synthetic and clinical DVF sets. EigenDVFs (EDVFs) having the largest eigenvalues were hypothesized to capture the major anatomical deformations during treatment.

Results

Principal component analysis (PCA) models achieve variable results, depending on the size and location of anatomical change. Random changes prevent or degrade PCA's ability to detect underlying systematic change. RPCA is able to detect smaller systematic changes against the background of random fraction‐to‐fraction changes and is therefore more successful than SPCA at capturing systematic changes early in treatment. SPCA models were less successful at modeling systematic changes in clinical patient images, which contain a wider range of random motion than synthetic CBCTs, while the regularized approach was able to extract major modes of motion.

Conclusions

Leading EDVFs from the both PCA approaches have the potential to capture systematic anatomical change during H&N radiotherapy when systematic changes are large enough with respect to random fraction‐to‐fraction changes. In all cases the RPCA approach appears to be more reliable at capturing systematic changes, enabling dosimetric consequences to be projected once trends are established early in a treatment course, or based on population models.
A gate evaluation of the sources of error in quantitative90Y PET
Authors: Strydhorst Jared , Carlier Thomas , Dieudonné Arnaud , Conti Maurizio , Buvat Irène
Published: September 2016

Purpose

Accurate reconstruction of the dose delivered by 90Y microspheres using a postembolization PET scan would permit the establishment of more accurate dose–response relationships for treatment of hepatocellular carcinoma with 90Y. However, the quality of the PET data obtained is compromised by several factors, including poor count statistics and a very high random fraction. This work uses Monte Carlo simulations to investigate what impact factors other than low count statistics have on the quantification of90Y PET.

Methods

PET acquisitions of two phantoms—a NEMA PET phantom and the NEMA IEC PET body phantom‐containing either 90Y or 18F were simulated using gate. Simulated projections were created with subsets of the simulation data allowing the contributions of random, scatter, and LSO background to be independently evaluated. The simulated projections were reconstructed using the commercial software for the simulated scanner, and the quantitative accuracy of the reconstruction and the contrast recovery of the reconstructed images were evaluated.

Results

The quantitative accuracy of the 90Y reconstructions were not strongly influenced by the high random fraction present in the projection data, and the activity concentration was recovered to within 5% of the known value. The contrast recovery measured for simulated 90Y data was slightly poorer than that for simulated 18F data with similar count statistics. However, the degradation was not strongly linked to any particular factor. Using a more restricted energy range to reduce the random fraction in the projections had no significant effect.

Conclusions

Simulations of 90Y PET confirm that quantitative 90Y is achievable with the same approach as that used for 18F, and that there is likely very little margin for improvement by attempting to model aspects unique to 90Y, such as the much higher random fraction or the presence of bremsstrahlung in the singles data.
Technical Note: scuda: A software platform for cumulative dose assessment
Authors: Park Seyoun , McNutt Todd , Plishker William , Quon Harry , Wong John , Shekhar Raj , Lee Junghoon
Published: September 2016

Purpose

Accurate tracking of anatomical changes and computation of actually delivered dose to the patient are critical for successful adaptive radiation therapy (ART). Additionally, efficient data management and fast processing are practically important for the adoption in clinic as ART involves a large amount of image and treatment data. The purpose of this study was to develop an accurate and efficient Software platform for CUmulative Dose Assessment (scuda) that can be seamlessly integrated into the clinical workflow.

Methods

scuda consists of deformable image registration (DIR), segmentation, dose computation modules, and a graphical user interface. It is connected to our image PACS and radiotherapy informatics databases from which it automatically queries/retrieves patient images, radiotherapy plan, beam data, and daily treatment information, thus providing an efficient and unified workflow. For accurate registration of the planning CT and daily CBCTs, the authors iteratively correct CBCT intensities by matching local intensity histograms during the DIR process. Contours of the target tumor and critical structures are then propagated from the planning CT to daily CBCTs using the computed deformations. The actual delivered daily dose is computed using the registered CT and patient setup information by a superposition/convolution algorithm, and accumulated using the computed deformation fields. Both DIR and dose computation modules are accelerated by a graphics processing unit.

Results

The cumulative dose computation process has been validated on 30 head and neck (HN) cancer cases, showing 3.5 ± 5.0 Gy (mean±STD) absolute mean dose differences between the planned and the actually delivered doses in the parotid glands. On average, DIR, dose computation, and segmentation take 20 s/fraction and 17 min for a 35‐fraction treatment including additional computation for dose accumulation.

Conclusions

The authors developed a unified software platform that provides accurate and efficient monitoring of anatomical changes and computation of actually delivered dose to the patient, thus realizing an efficient cumulative dose computation workflow. Evaluation on HN cases demonstrated the utility of our platform for monitoring the treatment quality and detecting significant dosimetric variations that are keys to successful ART.
Reference‐based MRI
Authors: Weizman Lior , Eldar Yonina C. , Ben Bashat Dafna
Published: September 2016

Purpose

In many clinical MRI scenarios, existing imaging information can be used to significantly shorten acquisition time or to improve Signal to Noise Ratio (SNR). In this paper the authors present a framework, referred to as FASTMER, for fast MRI by exploiting a reference image.

Methods

The proposed approach utilizes the possible similarity of the reference image to the acquired image, which exists in many clinical MRI imaging scenarios. Examples include similarity between adjacent slices in high resolution MRI, similarity between various contrasts in the same scan and similarity between different scans of the same patient. To account for the fact that the reference image may exhibit low similarity with the acquired image the authors develop an iterative weighted reconstruction approach, which tunes the weights according to the degree of similarity.

Results

Experimental results demonstrate the performance of the method in three different clinical MRI scenarios: The first example demonstrates SNR improvement in high resolution brain MRI, the second scenario exploits similarity between T2‐weighted and fluid‐attenuated inversion recovery (FLAIR) for fast FLAIR scanning and the last application utilizes similarity between baseline and follow‐up scans for fast follow‐up acquisition. The results show that FASTMER outperforms image reconstruction of existing state‐of‐the‐art methods.

Conclusions

The authors present a framework for fast MRI by exploiting a reference image. Recovery is based on an iterative algorithm that supports cases in which similarity to the reference scan is not guaranteed. This extends the applicability of the FASTMER to different MRI scanning scenarios. Thanks to the existence of reference images in various clinical imaging tasks, the proposed framework can play a major role in improving reconstruction in many MR applications.
A Comparison of Frontal Plane Projection Angle Across Landing Tasks in Female Gymnasts
Authors: Comfort Paul , Colclough Aideen , Herrington Lee
Published: September 2016

The aim of this study was to compare FPPA between three landing tasks and determine the reliability of FPPA in 15 competitive female gymnasts (age 13.5 ± 2.07 years). Reliability of FPPA was highest in the drop landing task, with no learning effect present. The backaway task showed the greatest FFPA (right: 26.75 ± 9.57°; left: 19.67 ± 9.03°), which was greater than the drop landing task (right: 19.07 ± 7.42°; left: 12.18 ± 4.83°). Individuals involved in training young female gymnasts are encouraged to screen for injury risk using FPPA during the drop landing task.
The Effect of Storing Temperature and Duration on Urinary Hydration Markers
Authors: Adams J.D. , Kavouras Stavros A. , Johnson Evan C. , Jansen Lisa T. , Capitan-Jimenez Catalina , Robillard Joseph I. , Mauromoustakos Andy
Published: September 2016

The purpose of this investigation was to quantify the effects of storage temperature, duration, and the urinary sediment on urinary hydration markers. Thirty-six human urine samples were analyzed fresh and then the remaining sample was separated into 24 separate vials, six in each of the following four temperatures: 22 °C, 7 °C, -20 °C, and -80 °C. Two of each sample stored in any given temperature, were analyzed after 1, 2, and 7 days either following vortexing or centrifugation. Each urine sample was analyzed for osmolality (UOsm), urine specific gravity (USG), and urine color (UC). UOsm was stable at 22 °C, for 1 day (+5–9 mmol∙kg-1, p > .05) and at 7 °C, UOsm up to 7 days (+8–8 mmol∙kg-1, p > .05). At -20 and -80 °C, UOsm decreased after 1, 2, and 7 days (9–61 mmol∙kg-1, p < .05). Vortexing the sample before analysis further decreased only UOsm in the -20 °C and -80 °C storage. USG remained stable up to 7 days when samples were stored in 22 °C or 7 °C (p > .05) but declined significantly when stored in -20 °C, and -80 °C (p < .001). UC was not stable in any of the storing conditions for 1, 2, and 7 days. In conclusion, these data indicate that urine specimens analyzed for UOsm or USG remained stable in refrigerated (7 °C) environment for up to 7 days, and in room temperature for 1 day. However, freezing (-20 and -80 °C) samples significantly decreased the values of hydration markers.
No Dose Response Effect of Carbohydrate Mouth Rinse on Cycling Time-Trial Performance
Authors: James Ruth M. , Ritchie Sarah , Rollo Ian , James Lewis J.
Published: September 2016

The aim of the current study was to investigate the influence of mouth rinsing carbohydrate at increasing concentrations on ~1 hr cycle time trial performance. Eleven male cyclists completed three experimental trials, following an overnight fast. Cyclists performed a ~1 hr time trial on a cycle ergometer, while rinsing their mouth for 5 s with either a 7% maltodextrin solution (CHO), 14% CHO or a taste-matched placebo (PLA) after every 12.5% of the set amount of work. Heart rate was recorded every 12.5% of the time trial, while RPE and GI comfort were determined every 25% of the time trial. The mouth rinse protocol influenced the time to complete the time trial (p < .001), with cyclists completing the time trial faster during 7% CHO (57.3 ± 4.5 min; p = .004) and 14% CHO (57.4 ± 4.1 min; p = .007), compared with PLA (59.5 ± 4.9 min). There was no difference between the two carbohydrate trials (p = .737). There was a main effect of time (P<0.001) for both heart rate and RPE, but no main effect of trial (p = .107 and p = .849, respectively). Scores for GI comfort ranged from 0–2 during trials, indicating very little GI discomfort during exercise. In conclusion, mouth rinsing and expectorating a 7% maltodextrin solution, for 5 s routinely during exercise was associated with improved cycle time trial performance approximately 1 h in duration. Increasing the carbohydrate concentration of the rinsed solution from 7% to 14% resulted in no further performance improvement.
Assessing Overreaching With Heart-Rate Recovery: What Is the Minimal Exercise Intensity Required?
Authors: Le Meur Yann , Buchheit Martin , Aubry Anaël , Coutts Aaron J , Hausswirth Christophe
Published: September 2016

Purpose:

Faster heart-rate recovery (HRR) after high to maximal exercise (≥90% of maximal heart rate) has been reported in athletes suspected of functional overreaching (f-OR). This study investigated whether this response would also occur at lower exercise intensity.

Methods:

Responses of HRR and rating of perceived exertion (RPE) were compared during an incremental intermittent running protocol to exhaustion in 20 experienced male triathletes (8 control subjects and 13 overload subjects led to f-OR) before and immediately after an overload training period and after a 1-wk taper.

Results:

Both groups demonstrated an increase in HRR values immediately after the training period, but this change was very likely to almost certainly larger in the f-OR group at all running intensities (large to very large differences, eg, +16 ± 7 vs +3 ± 5 beats/min, in the f-OR and control groups at 11 km/h, respectively). The highest between-groups differences in changes in HRR were reported at 11 km/h (13 ± 4 beats/min) and 12 km/h (10 ± 6 beats/min). A concomitant increase in RPE at all intensities was reported only in the f-OR group (large to extremely large differences, +2.1 ± 1.5 to +0.7 ± 1.5 arbitrary units).

Conclusion:

These findings confirm that faster HRR does not systematically predict better physical performance. However, when interpreted in the context of the athletes’ fatigue state and training phase, HRR after submaximal exercise may be more discriminant than HRR measures taken after maximal exercise for monitoring f-OR. These findings may be applied in practice by regularly assessing HRR after submaximal exercise (ie, warm-up) for monitoring endurance athletes’ responses to training.
A Comparison of Physical and Technical Performance Profiles Between Successful and Less-Successful Professional Rugby League Teams
Authors: Kempton Thomas , Sirotic Anita C. , Coutts Aaron J.
Published: September 2016

Purpose:

To examine differences in physical and technical performance profiles using a large sample of match observations drawn from successful and less-successful professional rugby league teams.

Methods:

Match activity profiles were collected using global positioning satellite (GPS) technology from 29 players from a successful rugby league team during 24 games and 25 players from a less-successful team during 18 games throughout 2 separate competition seasons. Technical performance data were obtained from a commercial statistics provider. A progressive magnitude-based statistical approach was used to compare differences in physical and technical performance variables between the reference teams.

Results:

There were no clear differences in playing time, absolute and relative total distances, or low-speed running distances between successful and less-successful teams. The successful team possibly to very likely had lower higher-speed running demands and likely had fewer physical collisions than the less-successful team, although they likely to most likely demonstrated more accelerations and decelerations and likely had higher average metabolic power. The successful team very likely gained more territory in attack, very likely had more possessions, and likely committed fewer errors. In contrast, the less-successful team was likely required to attempt more tackles, most likely missed more tackles, and very likely had a lower effective tackle percentage.

Conclusions:

In the current study, successful match performance was not contingent on higher match running outputs or more physical collisions; rather, proficiency in technical performance components better differentiated successful and less-successful teams.
The High-Pull Exercise: A Comparison Between a VersaPulley Flywheel Device and the Free Weight
Authors: Núñez F. Javier , Suarez-Arrones Luis J. , Cater Paul , Mendez-Villanueva Alberto
Published: September 2016

The aim of this study was to examine the kinematics and kinetics (force, velocity, and acceleration) and blood lactate concentration with the VersaPulley (VP) device in comparison with free-weight (FW) exercise at a similar external load. Fifteen rugby players randomly performed 2 training sessions of 6 sets of 6 repetitions with 20 s of recovery between sets of the high-pull exercise with the VP and the FW. The training sessions were separated by 72 h. Barbell displacement (cm), peak velocity (m/s), peak acceleration (m/s2), mean propulsive velocity (m/s), mean propulsive acceleration (m/s2), propulsive phase (%), and mean and maximal force (N) were continuously recorded during each repetition. Blood lactate concentration was measured after each training session (end) and 3 min and 5 min later. Barbell displacement (+4.8%, small ES), peak velocity (+4.5% small ES), mean propulsive acceleration (+8.8%, small ES), and eccentric force (+26.7, large ES) were substantially higher with VP than with FW. Blood lactate concentration was also greater after the VP exercise (end +32.9%, 3 min later +36%, 5 min later +33.8%; large ES). Maximal concentric force was substantially higher with FW than VP during the 6th set (+6.4%, small ES). In the cohort and exercise investigated in the current study, VP training can be considered an efficient training device to induce an accentuated eccentric overload and augmented metabolic demands (ie, blood lactate concentration).
Understanding the Mismatch Between Coaches’ and Players’ Perceptions of Exertion
Authors: Brink Michel S. , Kersten Anna W. , Frencken Wouter G.P.
Published: September 2016

A mismatch between the training exertion intended by a coach and the exertion perceived by players is well established in sports. However, it is unknown whether coaches can accurately observe exertion of individual players during training. Furthermore, the discrepancy in coaches’ and players’ perceptions has not been explained.

Purpose:

To determine the relation between intended and observed training exertion by the coach and perceived training exertion by the players and establish whether on-field training characteristics, intermittent endurance capacity, and maturity status explain the mismatch.

Methods:

During 2 mesocycles of 4 wk (in November and March), rating of intended exertion (RIE), rating of observed exertion (ROE), and rating of perceived exertion (RPE) were monitored in 31 elite young soccer players. External and internal training loads were objectively quantified with accelerometers (PlayerLoad) and heart-rate monitors (TRIMPmod). Results of an interval shuttle-run test (ISRT) and age at peak height velocity (APHV) were determined for all players.

Results:

RIE, ROE, and RPE were monitored in 977 training sessions. The correlations between RIE and RPE (r = .58; P < .01) and between ROE and RPE (r = .64; P < .01) were moderate. The mean difference between RIE and RPE was –0.31 ± 1.99 and between ROE and RPE was –0.37 ± 1.87. Multilevel analyses showed that PlayerLoad and ISRT predicted RIE and ROE.

Conclusion:

Coaches base their intended and observed exertion on what they expect players will do and what they actually did on the field. When doing this, they consider the intermittent endurance capacity of individual players.
Morning Exercise: Enhancement of Afternoon Sprint-Swimming Performance
Authors: McGowan Courtney J. , Pyne David B. , Thompson Kevin G. , Raglin John S. , Rattray Ben
Published: September 2016

Context:

An exercise bout completed several hours prior to an event may improve competitive performance later that same day.

Purpose:

To examine the influence of morning exercise on afternoon sprint-swimming performance.

Methods:

Thirteen competitive swimmers (7 male, mean age 19 ± 3 y; 6 female, mean age 17 ± 3 y) completed a morning session of 1200 m of variedintensity swimming (SwimOnly), a combination of varied-intensity swimming and a resistance-exercise routine (SwimDry), or no morning exercise (NoEx). After a 6-h break, swimmers completed a 100-m time trial.

Results:

Time-trial performance was faster in SwimOnly (1.6% ± 0.6, mean ± 90% confidence limit, P < .01) and SwimDry (1.7% ± 0.7%, P < .01) than in NoEx. Split times for the 25- to 50-m distance were faster in both SwimOnly (1.7% ± 1.2%, P = .02) and SwimDry (1.5% ± 0.8%, P = .01) than in NoEx. The first 50-m stroke rate was higher in SwimOnly (0.70 ± 0.21 Hz, mean ± SD, P = .03) and SwimDry (0.69 ± 0.18 Hz, P = .05) than in NoEx (0.64 ± 0.16 Hz). Before the afternoon session, core (0.2°C ± 0.1°C [mean ± 90% confidence limit], P = .04), body (0.2°C ± 0.1°C, P = .02), and skin temperatures (0.3°C ± 0.3°C, P = .02) were higher in SwimDry than in NoEx.

Conclusions:

Completion of a morning swimming session alone or together with resistance exercise can substantially enhance sprint-swimming performance completed later the same day.
Intra- and Intersession Reliability of Surface Electromyography on Muscles Actuating the Forearm During Maximum Voluntary Contractions
Authors: Gaudet Guillaume , Raison Maxime , Maso Fabien Dal , Achiche Sofiane , Begon Mickael
Published: September 2016

The aim of this study is to determine the intra- and intersession reliability of nonnormalized surface electromyography (sEMG) on the muscles actuating the forearm during maximum voluntary isometric contractions (MVIC). A subobjective of this study is to determine the intra- and intersession reliability of forearm MVIC force or torque, which is a prerequisite to assess sEMG reliability. Eighteen healthy adults participated at 4 different times: baseline, 1-h post, 6-h post, and 24-h post. They performed 3 MVIC trials of forearm flexion, extension, pronation, and supination. sEMG of the biceps brachii short head, brachialis, brachioradialis, triceps brachii long head, pronator teres, and pronator quadratus were measured. The intraclass correlation coefficient (ICC) on MVIC ranged from 0.36 to 0.99. Reliability was excellent for flexion, extension, and supination MVIC for both intra- and intersession. The ICC on sEMG ranged from 0.58 to 0.99. sEMG reliability was excellent for brachialis, brachioradialis, and pronator quadratus, and good to excellent for triceps brachii, biceps brachii, and pronator teres. This study shows that performing 3 MVICs is sufficient to obtain highly reliable maximal sEMG over 24 h for the main muscles actuating the forearm. These results confirm the potential of sEMG for muscle motor functional monitoring.
Social Cognitive Determinants of Physical Activity in Czech Older Adults
Authors: Mudrak Jiri , Slepicka Pavel , Elavsky Steriani
Published: September 2016

We tested a social cognitive model of physical activity (PA) in the cultural context of the Czech Republic, a postcommunist central European country. In total, 546 older Czech adults (mean age = 68 years, data collected in 2013) completed a battery of questionnaires assessing indicators of PA and related social cognitive constructs, including self-efficacy, social support, and self-regulation strategies. Subsequently, a structural equation model was used to test the relationship between the social cognitive constructs and PA. Our analyses indicated an acceptable fit of the proposed model (CFI = .911; SRMR = .046; RMSEA = .073). Self-regulation was predicted by self-efficacy (β = .67) and social support (β = .23), which predicted PA (β = .45). The model explained 60.4% of the variance in PA self-regulation and 20.5% of the variance in PA participation. The results provide further evidence for the role of self-efficacy and social support in enabling PA in older adults, and suggest that this relationship is partially mediated by self-regulation.
Motivators and Barriers for Older People Participating in Resistance Training: A Systematic Review
Authors: Burton Elissa , Farrier Kaela , Lewin Gill , Pettigrew Simone , Hill Anne-Marie , Airey Phil , Bainbridge Liz , Hill Keith D.
Published: September 2016

Regular participation in resistance training is important for older people to maintain their health and independence, yet participation rates are low. The study aimed to identify motivators and barriers to older people participating in resistance training. A systematic review was conducted including quantitative, qualitative, and mixed-method studies. Searches generated 15,920 citations from six databases, with 14 studies (n = 1,937 participants) included. In total, 92 motivators and 24 barriers were identified. Motivators specific to participating in resistance training included preventing deterioration (disability), reducing risk of falls, building (toning) muscles, feeling more alert, and better concentration. Looking too muscular and thinking participation increased the risk of having a heart attack, stroke, or death, despite the minimal likelihood of these occurring, were barriers. The analysis indicates that increasing participation in resistance training among older people should focus on the specific benefits valued by older people and the dissemination of accurate information to counter misperceptions.
Effect of Retraining Approach-Avoidance Tendencies on an Exercise Task: A Randomized Controlled Trial
Authors: Cheval Boris , Sarrazin Philippe , Pelletier Luc , Friese Malte
Published: September 2016

Background:

Promoting regular physical activity (PA) and lessening sedentary behaviors (SB) constitute a public health priority. Recent evidence suggests that PA and SB are not only related to reflective processes (eg, behavioral intentions), but also to impulsive approach-avoidance tendencies (IAAT). This study aims to test the effect of a computerized IAAT intervention on an exercise task.

Methods:

Participants (N = 115) were randomly assigned to 1 of 3 experimental conditions, in which they were either trained to approach PA and avoid SB (ApPA-AvSB condition), to approach SB and avoid PA (ApSB-AvPA condition), or to approach and avoid PA and SB equally often (active control condition). The main outcome variable was the time spent carrying out a moderate intensity exercise task.

Results:

IAAT toward PA decreased in the ApSB-AvPA condition, tended to increase in the ApPA-AvSB condition, and remained stable in the control condition. Most importantly, the ApPA-AvSB manipulation led to more time spent exercising than the ApSB-AvPA condition. Sensitivity analyses excluding individuals who were highly physically active further revealed that participants in the ApPA-AvSB condition spent more time exercising than participants in the control condition.

Conclusions:

These findings provide preliminary evidence that a single intervention session can successfully change impulsive approach tendencies toward PA and can increase the time devoted to an exercise task, especially among individuals who need to be more physically active. Potential implications for health behavior theories and behavior change interventions are outlined.
Physical Activity Status in Patients With Coronary Heart Disease: Results From the Cross-Sectional EUROASPIRE Surveys
Authors: De Smedt Delphine , Clays Els , Prugger Christof , De Sutter Johan , Fras Zlatko , De Backer Guy , Lovic Dragan , Baert Anneleen , Kotseva Kornelia , De Bacquer Dirk
Published: September 2016

Background:

The study aim was to assess the physical activity levels as well as the intention to become physically active in patients with stable coronary heart disease (CHD) with a special focus on the association with their risk profile.

Methods:

Analyses are based on the cross-sectional EUROASPIRE IV surveys. Information was available on 8966 patients in EUROASPIRE III and on 7998 patients in EUROASPIRE IV. Physical activity level according to patients risk profile and their medical management was assessed, the intention to become physically active was investigated and a time trend analysis was performed.

Results:

A better cardiovascular risk profile as well as receiving physical activity advice or weight loss advice was associated with better physical activity levels. The physical activity status improved significantly over time, the proportion of patients reporting vigorous physical activity for at least 20 minutes ≥ 3 times/week increased from 14.1% to 20.2% (P < .001). Similarly, a significantly greater proportion of patients are in the maintenance stage (36.6% vs. 27.4%) and a smaller proportion in the precontemplation stage (43.2% vs. 52.3%).

Conclusion:

Although an increase was seen in the proportion of patients being adequately physical active, physical activity levels remain suboptimal in many CHD patients.
Mastery Motivational Climates: Motivating Children to Move and Learn in Physical Education Contexts
Authors: Rudisill Mary E.
Published: September 2016

For 30 years I have been interested in achievement motivation and factors that influence children’s motivation to move and learn to move. This work has been grounded in achievement goal theory, which explains what motivates individuals by how success is perceived and competence is valued (Nicholls, 1989). According to this theory, behavioral outcomes are related to goal-oriented behaviors described as task (e.g., competence and success are self-referenced) or ego (e.g., competence and success are based on the reference of others). A task-oriented goal perspective has been associated with increased enjoyment and intrinsic motivation inmovement-related activities such as sport and physical activity. Achievement goal theory also proposes that environments can be structured to emphasize factors that determine one’s goal involvement and subsequent cognitions, affect, and behaviors. In this review, I discuss mastery motivational climates and the research we have conducted related to this topic over the years.
Dance Interventions to Increase Physical Activity Among Youth: A Systematic Review
Authors: Robertson-Wilson Jennifer , Reinders Nicole , Bryden Pamela J.
Published: September 2016

Given the potential for dance to serve as a way to engage in physical activity, this review was undertaken to examine the use and effectiveness of physical activity interventions using dance among children and adolescents.Five databases were examined for dance-related physical activity interventions published between 2009–2016 fitting the inclusion criteria. Studies meeting the inclusion criteria were then evaluated for studyquality against the Effective Public Health Practice Project assessment tool (Thomas, Ciliska, Dobbins, & Micucci. 2004) and key study information was extracted. Thirteen papers detailing 11 interventions wereobtained. Intervention study quality was rated as weak (based on scoring) for all studies. Multiple forms of dance were used, including exergaming approaches. Four interventions yielded increases in physical activity(reported in six articles), four interventions were inconclusive, and three interventions produced nonstatistically significant findings. Further research is required in this area to determine the effects of dance interventionson physical activity among youth.