bluuebunny/crossref_metadata_2025 huggingface dataset:
Imaginary Companions and Young Children's Coping and Competence
Authors: Gleason Tracy R. , Kalpidou Maria
Published: April 2014

Imaginary companions (ICs) are purported to bolster children's coping and self‐competence, but few studies address this claim. We expected that having/not havingICswould distinguish children's coping strategies and competence less than type of companion (i.e., personified object or invisible friend) or quality of child–ICrelationship (i.e., egalitarian or hierarchical). We interviewed 72 three‐ to six‐year‐olds and their mothers about children's coping strategies and competence; teachers rated competence. Mothers reportedICs.ICpresence and type did not differentiate coping strategies, but children with egalitarian relationships chose more constructive/prosocial coping strategies, and teachers rated them more socially competent than children with hierarchical child–ICrelationships. Mothers relatedICsto cognitive competence. Findings highlight (1) modest relations between imaginary relationships and coping/competence; (2) distinctions between mothers' perceptions andICfunctions; and (3) thatICsparallel real relationships in that different dimensions (presence, type/identity, and relationship quality) might be unique contributors to children's socioemotional development.
Racial Identity and Intergroup Attitudes: A Multiracial Youth Analysis*
Authors: Sullivan Jas M. , Ghara Alexandra
Published: April 2014

Objective

This article examines the racial identity attitudes of white, black, and Hispanic youth and explores how these identities shape their feelings toward various racial and ethnic groups (whites, blacks, Asians, Hispanics, Arabs, and biracial individuals).

Methods

Using the 2005 Youth Culture Survey data set, we test our theoretical expectations using descriptive statistics and multiple regression models.

Results

The relationship between racial identification and out‐group attitudes varies among racial groups; specifically, racial identity variables do not have a significant impact on whites’ out‐group attitudes, but they do matter for blacks and Hispanics.

Conclusion

While American society has changed in many ways (i.e., increased number of minorities and more tolerance, or at least more discussion of acceptance, for racial groups), our research finds that race still plays a consequential role in the lives of young racial minorities.
Education as “the Great Equalizer”: Health Benefits for Black and White Adults
Authors: Holmes Christopher J. , Zajacova Anna
Published: April 2014

Objective

Many social policies and academic studies assume that education is “the great equalizer” that is capable of counteracting the unequal social resources of different demographic groups. This study aims to determine whether non‐Hispanic whites and racial/ethnic minorities indeed experience comparable health benefits with greater educational attainment.

Methods

Data from the National Health Interview Survey 1997–2012 were used to conduct ordered logistic models comparing the self‐rated health of 518,288 non‐Hispanic whites and racial/ethnic minorities aged 30–65 across the full spectrum of educational attainment.

Results

Educational attainment was found to affect the health of whites more than minorities, even with the inclusion of a wide range of potential sociodemographic, behavioral, and economic mediators.

Conclusion

We discuss the possibility that unmeasured variables, such as childhood environment and other individual characteristics, are responsible for the stronger effect of education for whites than minorities, and what the implications are for future policy and research.
Senate Responsiveness to Minority Constituencies: Latino Electoral Strength and Representation
Authors: Fine Jeffrey A. , Avery James M.
Published: April 2014

Objective

While most research on minority representation in Congress finds that the African‐American constituency size influences representation of the group's interests, most recent studies examining Latinos find no such relationship. We argue that the failure to find a relationship stems from the focus of prior research on the proportion of the Latino population in the total geographic constituency rather than the proportion of Latinos in the electoral constituency, what we term “Latino electoral strength” (LES).

Methods

Using data on Latino turnout at the state level, we examine the effect of LES on representation of Latino interests in the U.S. Senate. We use ordinary least squares (OLS) regression that accounts for the time serial, cross‐sectional (TSCS) nature of our data.

Results

Consistent with other studies, we find no influence of Latino population size on Latino representation. However, LES has a significant, negative effect on Latino representation.

Conclusions

Our results suggest that greater LES leads to worse representation of their interests, and that this relationship increases as LES grows. This is consistent with existing studies of racial threat theory.
Returns to Postincarceration Education for Former Prisoners*
Authors: Brown Christian
Published: April 2014

Objectives

I estimate the returns to education for individuals who attain education after an incarceration spell.

Methods

Returns to labor supply and wages are estimated using data from the National Longitudinal Survey of Youth and a variety of regression and matching techniques.

Results

A positive relationship is found between postincarceration education and labor outcomes, especially for college completion. The General Equivalency Diploma (GED) is not associated with direct benefits.

Conclusions

The returns to post‐incarceration education are positive but diminished, implying that programs targeted at college completion may best serve prisoners after release.
Social Capital, Information, and Perceived Safety from Crime: The Differential Effects of Reassuring Social Connections and Vicarious Victimization*
Authors: Drakulich Kevin M.
Published: April 2014

Objective

The study investigates the role of information obtained through local social connections in judgments about the safety of a neighborhood from crime.

Methods

The study employs a neighborhood‐based survey of Seattle residents.

Results

Residents who are embedded in local social networks are more likely to become familiar with their neighbors, and this familiarity is associated with greater perceptions of safety. On the other hand, residents who are embedded in local social networks may also be exposed to accounts of local victimizations by talking with neighbors about local crime problems, which is associated with lower perceptions of neighborhood safety.

Conclusion

This work poses an explanation for weak and inconsistent findings in prior research on the role of social connections in perceptions of crime: that connections matter in ways that are dependent on the kinds of information residents receive through them. Connections to broader debates about the value‐neutral role of social networks are discussed.
Creating Partisan “Footprints”: The Influence of Parental Religious Socialization on Party Identification
Authors: Ammann Sky L.
Published: April 2014

Objective

No studies in the American context consider the influence of parental religious socialization on the development of individuals’ party identifications (PIDs). This study attempts to fill the gap. The theory posits that parental religious socialization plays an important developmental role in shaping a child's PID. However, the precise relationship between a parent's religion and the child's PID may vary over time and across generations in response to changing religio‐partisan conflicts.

Methods

The expectations are tested using child‐parent pairs from the Youth–Parent Socialization Panel Study. Conventional bivariate and multivariate techniques are employed to estimate a child's seven‐point PID. Measures of parental religious belonging, beliefs, and behaviors, as well as a parent's PID, other parental sociodemographic controls, and measures of a child's religion are included in the multivariate models.

Results

In the 1960s, 1970s, and 1980s, a pre‐Boomer parent's religious belonging and to a very limited extent religious behavior are more influential for the Baby Boomer child's PID than religious beliefs. However, for the younger generation included in the study, in the 1990s, a Baby Boomer parent's religious beliefs become more influential to his or her post‐Boomer child's PID than does the parent's religious belonging or behavior.

Conclusions

The findings imply an important and evolving role of parental religious socialization in shaping individuals’ PIDs.
Acute prostatitis caused by Raoultella planticola in a renal transplant recipient: a novel case
Authors: Koukoulaki M. , Bakalis A. , Kalatzis V. , Belesiotou E. , Papastamopoulos V. , Skoutelis A. , Drakopoulos S.
Published: April 2014

We present a unique case of acute bacterial prostatitis caused by a very rare human pathogen, Raoultella planticola, in a renal allograft recipient 3.5 months post transplantation. Only a few cases of human infection by this pathogen have been reported worldwide. The present study reports the case of a 67‐year‐old man who was admitted to our transplant unit 3.5 months post transplantation with fever, dysuria, suprapubic pain, symptoms and signs of acute prostatitis, and elevated markers of inflammation and prostate‐specific antigen. R. planticola was isolated in the urine culture. The patient was treated with ciprofloxacin (based on the antibiogram) and had a full recovery, with satisfactory renal function. To the best of our knowledge, this is not only the first reported case of R. planticola prostatitis, but also the first report of such an infection in a solid organ transplant recipient or in a patient on immunosuppressive medication.
Efficacy and safety of hepatitis A vaccination in kidney transplant recipients
Authors: Jeon H.J. , Ro H. , Jeong J.C. , Koo T.Y. , Han M. , Min S.‐I. , Oh K.‐H. , Ha J. , Ahn C. , Yang J.
Published: April 2014

Background

In recent years, symptomatic hepatitis A virus (HAV) infection has been reported with increasing frequency in Korea. Therefore, HAV vaccination should be considered in kidney transplant recipients (KTRs). The study investigated the efficacy and safety of HAV vaccination in KTRs under modern triple immunosuppressive agents.

Methods

We evaluated the seroprevalence of anti‐HAV immunoglobulin‐G (IgG) in KTRs who had visited the Seoul National University Hospital from March 2011 to August 2012. Seronegative patients were immunized with 2 doses of HAV vaccine at a 6‐month interval. Seroconversion of anti‐HAV IgG was determined 1 month after the second vaccine dose, and adverse effects were monitored after each vaccination.

Results

Among a total 416 KTRs who were screened, 338 (81.2%) patients were seropositive for anti‐HAV IgG. However, among patients who were under 40 years of age, only 31.8% were seropositive. Fifty‐two seronegative recipients (mean age 34.1 years, 71.2% male) had received 2 doses of vaccine, and only 14 of these patients (26.9%) showed seroconversion. Vaccine responders had lower serum creatinine (1.19 ± 0.24 vs. 1.45 ± 0.49 mg/dL, P = 0.013), higher plasma hemoglobin levels (14.4 ± 1.9 vs. 12.8 ± 1.8 g/dL, P = 0.006), and had lower tacrolimus use than cyclosporine use (57.1% vs. 84.2%, P = 0.040) compared with non‐responders. Responders had a tendency of taking lower dose of prednisolone (3.5 ± 1.6 vs. 4.3 ± 1.2 mg/day, P = 0.076), and having fewer infection events (14.3 vs. 40.5%, P = 0.076). Multivariate analysis indicated that higher hemoglobin levels and lower serum creatinine levels were significant prognostic factors for seroconversion. Overall, the vaccine was well tolerated in all patients.

Conclusion

HAV IgG screening is necessary for KTRs, especially young recipients. HAV vaccination was safe in KTRs; however, poor response to HAV vaccination makes it important to identify seronegative patients as early as possible and vaccinate them before end‐stage renal disease occurs.
Survey of point‐of‐care instrumentation, analysis, and quality assurance in veterinary practice
Authors: Bell Regan , Harr Kendal , Rishniw Mark , Pion Paul
Published: April 2014

Background

While there have been ASVCP meeting discussions regarding quality assurance plans and lack thereof for in‐clinic analyzers, there are little published data regarding in‐clinic quality assurance and control practices.

Objectives

The purpose of this study was the identification of the common equipment used in hematologic, biochemical, urinalysis, and other testing, and assessment of quality control and assurance programs currently being performed in‐clinic.

Methods

All members of the Veterinary Information Network (VIN) were solicited to participate in an online survey between July and September 2007.

Results

In total, 452 complete or partial responses were received. Eighty‐nine percent of respondents (361/404) said that veterinary technicians (unlicensed, licensed, and registered) performed the majority of analyses. Eighty‐eight percent (366/417) of respondents performed some quality assurance on their laboratory equipment, most commonly on chemistry (91%, 324/357), and hematology (84%, 292/347) analyzers, and least commonly on fecal analyses (57%, 148/260) and ELISA assays (25%, 65/256). Ignorance of how to perform quality assurance was the most commonly stated reason (49%, 25/51) for lack of a quality assurance program. The majority of practices (316/374) utilized manufacturer‐provided reference intervals without further adjustment or assessment. Roughly one‐third of respondents (126/374) used reference intervals from textbooks, which is discouraged by ASVCP guidelines.

Conclusions

This study found that the majority of respondents were not in compliance with ASVCP guidelines, illustrating the need for improved education of technical staff, veterinary students, and veterinarians regarding limitations of in‐clinic laboratory equipment and the importance of regular quality control, maintenance, training, and reference interval development.
Time Domain Transfer Function of the Induction Motor
Authors: Barsoum N N
Published: April 2014

Small signal stability of electrical machines at frequency domain has been shown by toque coefficients and eigenvalue of motional impedance matrix in state space form. The relation of damping, synchronizing and total synchronizing torque coefficients with the eigenvalue or the roots of the characteristic equation of the perturbed machine shows that the instability occurs at 2 different modes. Static mode represented by real root at over load condition, and dynamic mode represented by complex root at the condition when the total synchronizing coefficient exhibits zero value within the negative range of the damping torque coefficient. However, small signal instability details at time domain are not given in the literatures. This paper discusses with figures the time domain signals of the induction motor perturbation variables under hunting condition, and presents the differences observed between inverse Laplace transform and Fourier transform in time domain response, based on the transform of the transfer function from the frequency domain, The figures demonstrate and confirm the machine small signal stability performance given in frequency domain.
Validity and Reliability of the 45-15 Test for Aerobic Fitness in Young Soccer Players
Authors: Castagna Carlo , Iellamo Ferdinando , Impellizzeri Franco Maria , Manzi Vincenzo
Published: April 2014

The aim of this study was to examine the reliability and validity of a popular field test for aerobic fitness used in soccer (45-15) in Italy. Alternating progressive 45-s runs with 15 s passive recovery until exhaustion, the test considers peak speed (PS) as a reflection of maximal aerobic speed (MAS). The validity and reliability of the 45-15 was assessed in 18 young male soccer players (age 16.7 ± 1.8 y, body mass 70 ± 7.45 kg, height 177 ± 0.5 cm, 55.62 ± 5.56 mL · kg−1 · min−1) submitted to laboratory testing for aerobic fitness and repeatedly to the 45-15. Results showed that 45-15 PS was significantly related to VO2max (r = .80, P < .001, 95%CI .47–.93) and MAS (r = .78, P = .001, 95%CI .43–.93). No significant bias between MAS 45-15 PS (P = .11) was found during the measurement-consistency study. Receiver-operating-characteristic (ROC) analysis showed that 45-15 PS was sensitive in detecting VO2max changes in subjects as revealed by area under the curve (.97; 95%CI .73–1). Players with peak 45-15 speed equal to or above 16.5 km/h (ie, ROC cutoff) may be considered to have good aerobic fitness. In light of this study’s findings, the 45-15 test may be considered a reliable and valid test to evaluate meaningful information to direct generic aerobic training in soccer.
The Influence of Hot Humid and Hot Dry Environments on Intermittent-Sprint Exercise Performance
Authors: Hayes Mark , Castle Paul C. , Ross Emma Z. , Maxwell Neil S.
Published: April 2014

Purpose:

To examine the effect of a hot humid (HH) compared with a hot dry (HD) environment, matched for heat stress, on intermittent-sprint performance. In comparison with HD, HH environments compromise evaporative heat loss and decrease exercise tolerance. It was hypothesized that HH would produce greater physiological strain and reduce intermittent-sprint exercise performance compared with HD.

Method:

Eleven male team-sport players completed the cycling intermittent-sprint protocol (CISP) in 3 conditions, temperate (TEMP; 21.2°C ± 1.3°C, 48.6% ± 8.4% relative humidity [rh]), HH (33.7°C ± 0.5°C, 78.2% ± 2.3% rh), and HD (40.2°C ± 0.2°C, 33.1% ± 4.9% rh), with both heat conditions matched for heat stress.

Results:

All participants completed the CISP in TEMP, but 3 failed to completed the full protocol of 20 sprints in HH and HD. Peak power output declined in all conditions (P< .05) but was not different between any condition (sprints 1–14 [N = 11]: HH 1073 ± 150 W, HD 1104 ± 127 W, TEMP, 1074 ± 134; sprints 15–20 [N = 8]: HH 954 ± 114 W, HD 997 ± 115 W, TEMP 993 ± 94;P> .05). Physiological strain was not significantly different in HH compared with HD, but HH was higher than TEMP (P< .05).

Conclusion:

Intermittent-sprint exercise performance of 40 min duration is impaired, but it is not different in HH and HD environments matched for heat stress despite evidence of a trend toward greater physiological strain in an HH environment.
Long-Range Correlations and Complex Regulation of Pacing in Long-Distance Road Racing
Authors: Hoos Olaf , Boeselt Tobias , Steiner Martin , Hottenrott Kuno , Beneke Ralph
Published: April 2014

Purpose:

To analyze time-domain, spectral, and fractal properties of speed regulation during half-marathon racing.

Methods:

In 21 male experienced runners, high-resolution data on speed (V), stride frequency (SF), and stride length (SL) were assessed during half-marathon competition (21,098 m). Performance times, timeand frequency-domain variability, spectral-scaling exponent (beta), and fractal dimension (FD) of V, SF, and SL were analyzed.

Results:

V of 3.65 ± 0.41 m/s, SF of 1.41 ± 0.05 Hz, and SL of 2.58 ± 0.25 m occurred with higher (P< .05) individual variability in V and SL than in SF. Beta and FD were always 1.04–1.88 and 1.56–1.99, respectively. Beta and FD differed (P< .05) in SF and SL compared with V and were correlated in V and SL (r= .91,P< .05). Spectral peaks of V, SF, and SL occurred at wavelengths of 3–35 min, and those of V and SL were interrelated (r= .56,P< .05). Mean SF and mean SL were significantly correlated with performance (r= .59 andr= .95,P< .05). SL accounted for 84% ± 6% and SF for 16% ± 6% of speed variability.

Conclusions:

The observed nonrandom fluctuations in V, SF, and SL correspond to nonstationary fractional Brownian motion with inherent long-range correlations. This indicates a similar complex regulation process in experienced runners that is primarily mediated via SL.
Fluid Balance, Carbohydrate Ingestion, and Body Temperature During Men’s Stage-Race Cycling in Temperate Environmental Conditions
Authors: Ross Megan L. , Stephens Brian , Abbiss Chris R. , Martin David T. , Laursen Paul B. , Burke Louise M.
Published: April 2014

Purpose:

To observe voluntary fluid and carbohydrate intakes and thermoregulatory characteristics of road cyclists during 2 multiday, multiple-stage races in temperate conditions.

Methods:

Ten internationally competitive male cyclists competed in 2 stage races (2009 Tour of Gippsland, T1, n = 5; 2010 Tour of Geelong, T2, n = 5) in temperate conditions (13.2–15.8°C; 54–80% relative humidity). Body mass (BM) was recorded immediately before and after each stage. Peak gastrointestinal temperature (TGI peak) was recorded throughout each stage. Cyclists recalled the types and volumes of fluid and food consumed throughout each stage.

Results:

Although fluid intake varied according to the race format, there were strong correlations between fluid intake and distance across all formats of racing, in both tours (r = .82, r = .92). Within a stage, the relationship between finishing time and fluid intake was trivial. Mean BM change over a stage was 1.3%, with losses >2% BM occurring on 5 out of 43 measured occasions and the fastest competitors incurring lower BM changes. Most subjects consumed carbohydrate at rates that met the new guidelines (30–60 g/h for 2–3 h, ~90 g/h for >3 h), based on event duration. There were consistent observations of TGI peak >39°C during stages of T1 (67%) and T2 (73%) despite temperate environmental conditions.

Conclusion:

This study captured novel effects of highintensity stage racing in temperate environmental conditions. In these conditions, cyclists were generally able to find opportunities to consume fluid and carbohydrate to meet current guidelines. We consistently observed high TGI peak, which merits further investigation.
Short-Term Training Effects of Vertically and Horizontally Oriented Exercises on Neuromuscular Performance in Professional Soccer Players
Authors: Arcos Asier Los , Yanci Javier , Mendiguchia Jurdan , Salinero Juan J. , Brughelli Matt , Castagna Carlo
Published: April 2014

Purpose:

The aim of this study was to compare the effects of 2 strength and conditioning programs involving either purely vertically oriented or combining vertically and horizontally oriented exercises on soccer-relevant performance variables (ie, acceleration, jumping ability, peak power, and endurance).

Methods:

Twenty-two professional male soccer players were randomly assigned to 2 training groups: vertical strength (VS, n = 11) and vertical and horizontal strength (VHS, n = 11). Players trained 2 times per week during all the preseason (5 wk) and 3 weeks of the competitive season. The effect of the training protocols was assessed using doubleand single-leg vertical countermovement jumps (CMJ), half-squat peak power (PP), sprint performance over 5 and 15 m, and blood lactate concentration at selected running speeds.

Results:

Both groups obtained significant improvements in PP (P < .05; ES = 0.87 and 0.80 for VS and VHS, respectively) and small practical improvements in 5-m- (P < .05; ES = 0.27 and 0.25 for VS and VHS, respectively) and 15-m-sprint time (P < .05; ES = 0.19 and 0.24 for VS and VHS, respectively). The CMJ performance showed a small improvement (P < .05, ES = 0.34) only in the VHS group. Submaximal aerobic-fitness changes were similar in both groups (P < .05; ES = 1.89 and 0 .71 for VS and VHS, respectively).

Conclusion:

This study provided a small amount of practical evidence for the consideration of preseason training protocols that combine exercises for vertical- and horizontal-axis strength development in professional male soccer players. Further studies using more aggressive training protocols involving horizontally oriented conditioning exercises are warranted.
Bioimpedance and Impedance Vector Patterns as Predictors of League Level in Male Soccer Players
Authors: Micheli Matteo Levi , Pagani Luca , Marella Mario , Gulisano Massimo , Piccoli Antonio , Angelini Fabrizio , Burtscher Martin , Gatterer Hannes
Published: April 2014

Purpose:

Bioelectrical-impedance standards (resistance, reactance, and phase angle) are well established for the normal population or in the clinical setting and are considered indicators for cell mass, cell function, and hydration status. However, such standards do not exist for the male soccer population. Therefore, the goal of the current investigation was to provide a set of bioelectrical-impedance data of a large sample of soccer players with different performance levels.

Methods:

A sample of 893 players, registered in all Italian soccer divisions, was divided into 5 groups according to their performance level. Whole-body impedance measurements were performed during the first half of the competitive period. Besides estimation of body composition, bioelectrical-impedance vector analysis (BIVA) was performed. BIVA does not depend on equations and displays differences in hydration and body-cell mass (BCM). Individual vectors can be classified by using the 50%, 75%, and 95% tolerance ellipse.

Results:

In comparison with the other divisions and the normal population, the mean vector of the elite level showed a shift to the left (P < .001). Compared with the elite level, players of a lower performance level had lower phase angles, BCM, and fat-free mass.

Conclusions:

In conclusion, soccer players belong to a specific population. Muscle mass and function, as indicated by BCM and phase angle, increase with increasing performance level. The soccer-specific tolerance ellipses might be used for classifying individual vectors and to define target regions for low-level players.
Time–Motion and Physiological Profile of Football Training Sessions Performed by Under-15, Under-17, and Under-19 Elite Portuguese Players
Authors: Abade Eduardo A. , Gonçalves Bruno V. , Leite Nuno M. , Sampaio Jaime E.
Published: April 2014

Purpose:

To provide the time–motion and physiological profile of regular training sessions (TS) performed during the competitive season by under-15 (U15), under-17 (U17), and under-19 (U19) elite-level Portuguese soccer players.

Methods:

One hundred fifty-one elite players of U15 (age 14.0 ± 0.2 y, n = 56), U17 (age 15.8 ± 0.4 y, n = 66), and U19 (age 17.8 ± 0.6 y, n = 29) participated in the study during a 9-wk period. Time–motion and body-impact data were collected using GPS technology (15 Hz) across 38 randomly selected TS that resulted in a total of 612 samples. In addition, heart rate (HR) was continuously monitored (1 Hz) in the selected TS.

Results:

The total distances covered (m) were higher in U17 (4648.3 ± 831.9), followed by U19 (4212.5 ± 935.4) and U15 (3964.5 ± 725.4) players (F = 45.84, P < .001). Total body impacts and relative impacts were lower in U15 (total: 490.8 ± 309.5, F = 7.3, P < .01), but no differences were identified between U17 (total: 584.0 ± 363.5) and U19 (total: 613.1 ± 329.4). U19 players had less high- and very-high-intensity activity (above 16 km/h; F = 11.8, P < .001) and moderate-intensity activity (10.0–15.9 km/h; F = 15.07, P < .001). HR values showed significant effects of zone (F = 575.7, P < .001) and interaction with age group (F = 9.7, P < .001), with pairwise differences between all zones (zone 1, <75%; zone 2, 75–84.9%; zone 3, 85–89.9%; zone 4, ≥90%). All players spent most of their time below 75% HRmax (U15, ~50%; U17, ~42%; U19, ~50%).

Conclusion:

Results showed high variability between TS, refraining from identifying meaningful trends when measuring performance, although different demands were identified according to age group. The U15 TS were less physiologically demanding, probably because of increased focus on small-sided games to develop basic tactical principles and technical skills. The focus on game-like situations imposed higher external and internal workloads on U17 and U19 players.
The Role and Development of Sprinting Speed in Soccer
Authors: Haugen Thomas A. , Tønnessen Espen , Hisdal Jonny , Seiler Stephen
Published: April 2014

The overall objective of this review was to investigate the role and development of sprinting speed in soccer. Time–motion analyses show that short sprints occur frequently during soccer games. Straight sprinting is the most frequent action before goals, both for the scoring and assisting player. Straight-line sprinting velocity (both acceleration and maximal sprinting speed), certain agility skills, and repeated-sprint ability are shown to distinguish groups from different performance levels. Professional players have become faster over time, indicating that sprinting skills are becoming more and more important in modern soccer. In research literature, the majority of soccer-related training interventions have provided positive effects on sprinting capabilities, leading to the assumption that all kinds of training can be performed with success. However, most successful intervention studies are time consuming and challenging to incorporate into the overall soccer training program. Even though the principle of specificity is clearly present, several questions remain regarding the optimal training methods within the larger context of the team-sport setting. Considering time-efficiency effects, soccer players may benefit more by performing sprint-training regimens similar to the progression model used in strength training and by world-leading athletics practitioners, compared with the majority of guidelines that traditionally have been presented in research literature.
Contrast Loading: Power Output and Rest Interval Effects on Neuromuscular Performance
Authors: Sotiropoulos Konstantinos , Smilios Ilias , Douda Helen , Christou Marios , Tokmakidis Savvas P.
Published: April 2014

Purpose:

This study examined the effect of rest interval after the execution of a jump-squat set with varied external mechanical-power outputs on repeated-jump (RJ) height, mechanical power, and electromyographic (EMG) activity.

Methods:

Twelve male volleyball players executed 6 RJs before and 1, 3, 5, 7, and 10 min after the execution of 6 repetitions of jump squats with a load: maximized mechanical-power output (Pmax), 70% of Pmax, 130% of Pmax, and control, without extra load.

Results:

RJ height did not change (P = .44) after the jump squats, mechanical power was higher (P = .02) 5 min after the 130%Pmax protocol, and EMG activity was higher (P = .001) after all exercise protocols compared with control. Irrespective of the time point, however, when the highest RJ set for each individual was analyzed, height, mechanical power, and EMG activity were higher (P = .001–.04) after all loading protocols compared with control, with no differences observed (P = .53–.72) among loads.

Conclusions:

Rest duration for a contrast-training session should be individually determined regardless of the load and mechanical-power output used to activate the neuromuscular system. The load that maximizes external mechanical-power output compared with a heavier or a lighter load, using the jump-squat exercise, is not more effective for increasing jumping performance afterward.
Monitoring Accelerations With GPS in Football: Time to Slow Down?
Authors: Buchheit Martin , Haddad Hani Al , Simpson Ben M. , Palazzi Dino , Bourdon Pitre C. , Salvo Valter Di , Mendez-Villanueva Alberto
Published: April 2014

The aims of the current study were to examine the magnitude of between-GPS-models differences in commonly reported running-based measures in football, examine between-units variability, and assess the effect of software updates on these measures. Fifty identical-brand GPS units (15 SPI-proX and 35 SPIproX2, 15 Hz, GPSports, Canberra, Australia) were attached to a custom-made plastic sled towed by a player performing simulated match running activities. GPS data collected during training sessions over 4 wk from 4 professional football players (N = 53 files) were also analyzed before and after 2 manufacturersupplied software updates. There were substantial differences between the different models (eg, standardized difference for the number of acceleration >4 m/s2 = 2.1; 90% confidence limits [1.4, 2.7], with 100% chance of a true difference). Between-units variations ranged from 1% (maximal speed) to 56% (number of deceleration >4 m/s2). Some GPS units measured 2–6 times more acceleration/deceleration occurrences than others. Software updates did not substantially affect the distance covered at different speeds or peak speed reached, but 1 of the updates led to large and small decreases in the occurrence of accelerations (–1.24; –1.32, –1.15) and decelerations (–0.45; –0.48, –0.41), respectively. Practitioners are advised to apply care when comparing data collected with different models or units or when updating their software. The metrics of accelerations and decelerations show the most variability in GPS monitoring and must be interpreted cautiously.
Improving the Value of Fitness Testing for Football
Authors: Pyne David B. , Spencer Matt , Mujika Iñigo
Published: April 2014

One of the challenges for sports scientists working in football is to balance the needs for routine fitness testing with daily fatigue and well-being monitoring to best manage the physical preparation of players. In this commentary, the authors examine contemporary issues of fitness testing in football to identify ways of improving the value of routine testing and monitoring. A testing program must be well planned and organized to ensure that the results are useful. Different tests can be employed for younger and older players. A rigorous approach to analysis and interpretation of results is desirable, and database management must address both short- and long-term requirements of players, staff, and programs.
Motion Characteristics of Women’s College Soccer Matches: Female Athletes in Motion (FAiM) Study
Authors: Vescovi Jason D. , Favero Terence G.
Published: April 2014

Purpose:

To quantify the locomotor demands of college female soccer matches and compare the relative proportion of distances in specified velocity bands between players completing an entire half with substitutes.

Methods:

College female soccer players (n = 113) were assessed during a regular-season match using global positioning system technology. An ANCOVA was used to compare the locomotor characteristics for positions and substitutes, adjusting for duration played. Paired t tests compared the proportion of distances for players substituted out and back into the second half.

Results:

Defenders covered less total absolute distance than midfielders (first half) and midfielders and forwards (second half) with concomitantly lower work rates. Moderate- and high-intensity running were similar between positions within each half. Midfielders substituted into the match had a lower proportion of moderate-intensity running than those substituted out (15% ± 1.8% vs 19% ± 0.9%), and defenders completing an entire first half had a lower proportion of high-intensity running than defenders substituted in or out (6% ± 1.0% vs 11% ± 1.0% and 16% ± 2.8%). There were no differences in the proportion of distances covered within each velocity band for any position in the second half or for the players substituted out and then back in during the second half.

Conclusions:

The current findings provide novel insight linking the developmental progression between youth and high-level matches for overall demands and work rates. Moderate- and high-intensity distances cumulatively range from 2100 to 2600 m (26–28% total distance) in female college matches. The high amount of consistency observed for the proportions of distance covered suggest that substitution patterns have little impact on locomotor distribution.
Bridging the Gap Between Empirical Results, Actual Strategies, and Developmental Programs in Soccer
Authors: Figueiredo António J. , Gonçalves Carlos E. , Tessitore Antonio
Published: April 2014

Being one of the most prominent globalized sports, soccer played at club, national, and continental levels has a relevant societal role. At present, the specific competencies, interests, and languages of the different actors involved in the selection, development, and support of long-lasting careers of players might limit opportunities for potential talented players. Unless the cultural environment of soccer resolves the gaps between empirical results and actual soccer strategies, scientific discussion relating to the effectiveness of talent selection and development remains limited. This commentary is intended to highlight the need for developmental programs to prepare soccer personnel for a transdisciplinary dialogue, which could foster a future development of this sport. Finally, in considering the wide soccer-related employment opportunities at local, national, and international levels, the need for a clear qualification framework is crucial.
Adductor Longus Activation During Common Hip Exercises
Authors: Delmore Robert J. , Laudner Kevin G. , Torry Michael R.
Published: April 2014

Context:

Hip-adductor strains are among the most common lower-extremity injuries sustained in athletics. Treatment of these injuries involves a variety of exercises used to target the hip adductors.

Objective:

To identify the varying activation levels of the adductor longus during common hip-adductor exercises.

Design:

Descriptive study.

Setting:

Laboratory.

Participants:

24 physically active, college-age students.

Intervention:

None.

Main Measurement Outcomes:

Peak and average electromyographic (EMG) activity of the adductor longus muscle during the following 6 hip-adductor rehabilitation exercises: side-lying hip adduction, ball squeezes, rotational squats, sumo squats, standing hip adduction on a Swiss ball, and side lunges.

Results:

The side-lying hip-adduction exercise produced more peak and average activation than any other exercise (P < .001). Ball squeezes produced more peak and average activation than rotational squats, sumo squats, and standing adduction on a Swiss ball (P < .001). Ball squeezes had more average activation than side lunges (P = .001). All other variables for peak activation during the exercises were not statistically significant (P > .08). These results allowed the authors to provide an overall ranking system (highest to lowest muscle activation): side-lying hip adduction, ball squeezes, side lunges, standing adduction on a Swiss ball, rotational squats, and sumo squats.

Conclusion:

The study provides a ranking system on the activation levels of the adductor longus muscle for 6 common hip-adductor rehabilitation exercises, with the side-lying hip-adduction and ball-squeeze exercises displaying the highest overall activation.
Development of a Core-Stability Model: A Delphi Approach
Authors: Majewski-Schrage Tricia , Evans Todd A. , Ragan Brian
Published: April 2014

Context:

Despite widespread acceptance, there is currently no consensus on the definition, components, and the specific techniques most appropriate to measure and quantify core stability.

Objective:

To develop a comprehensive core-stability model addressing its definition, components, and assessment techniques.

Design:

Delphi technique.

Setting:

University laboratory.

Participants:

15 content experts from United States and Canada, representing a variety of disciplines.

Main Outcome Measure:

The authors distributed an open-ended questionnaire pertaining to a core-stability definition, components, and assessment techniques specific to each expert. They collected data over 2 rounds of telephone interviews. They concluded data collection once a consensus was achieved that equated with 51% agreement among respondents.

Results:

The authors developed a working definition of core stability as the ability to achieve and sustain control of the trunk region at rest and during precise movement. Eighty-three percent of the experts considered the definition satisfactory. Therefore, the definition was accepted. Furthermore, the experts agreed that muscles (14/15 = 93.3%) and neuromuscular control (8/12 = 66.7%) were components of core stability. Assessment techniques were identified and inconsistencies were highlighted; however, no consensus was established.

Conclusions:

A consensus core-stability definition was created and 2 components were identified. However, of the initial definitions provided by the experts, no 2 were identical, which revealed the inconsistencies among experts and the importance of this study. Nonetheless, the goal of obtaining a consensus definition was obtained. Although a consensus for the assessment techniques of core stability could not be reached, it was a beneficial starting point to identify the inconsistencies that were discovered among the content experts.
Lower-Extremity Muscle Activity During Aquatic and Land Treadmill Running at the Same Speeds
Authors: Silvers W. Matthew , Bressel Eadric , Dickin D. Clark , Killgore Garry , Dolny Dennis G.
Published: April 2014

Context:

Muscle activation during aquatic treadmill (ATM) running has not been examined, despite similar investigations for other modes of aquatic locomotion and increased interest in ATM running.

Objectives:

The objectives of this study were to compare normalized (percentage of maximal voluntary contraction; %MVC), absolute duration (aDUR), and total (tACT) lower-extremity muscle activity during land treadmill (TM) and ATM running at the same speeds.

Design:

Exploratory, quasi-experimental, crossover design.

Setting:

Athletic training facility.

Participants:

12 healthy recreational runners (age = 25.8 ± 5 y, height = 178.4 ± 8.2 cm, mass = 71.5 ± 11.5 kg, running experience = 8.2 ± 5.3 y) volunteered for participation.

Intervention:

All participants performed TM and ATM running at 174.4, 201.2, and 228.0 m/min while surface electromyographic data were collected from the vastus medialis, rectus femoris, gastrocnemius, tibialis anterior, and biceps femoris.

Main Outcome Measures:

For each muscle, a 2 × 3 repeated-measures ANOVA was used to analyze the main effects and environment–speed interaction (P ≤ .05) of each dependent variable: %MVC, aDUR, and tACT.

Results:

Compared with TM, ATM elicited significantly reduced %MVC (−44.0%) but increased aDUR (+213.1%) and tACT (+41.9%) in the vastus medialis, increased %MVC (+48.7%) and aDUR (+128.1%) in the rectus femoris during swing phase, reduced %MVC (−26.9%) and tACT (−40.1%) in the gastrocnemius, increased aDUR (+33.1%) and tACT (+35.7%) in the tibialis anterior, and increased aDUR (+41.3%) and tACT (+29.2%) in the biceps femoris. At faster running speeds, there were significant increases in tibialis anterior %MVC (+8.6−15.2%) and tACT (+12.7−17.0%) and rectus femoris %MVC (12.1−26.6%; swing phase).

Conclusion:

No significant environment–speed interaction effects suggested that observed muscle-activity differences between ATM and TM were due to environmental variation, ie, buoyancy (presumed to decrease %MVC) and drag forces (presumed to increase aDUR and tACT) in the water.
Effect of Running Retraining on Pain, Function, and Lower-Extremity Biomechanics in a Female Runner With Iliotibial Band Syndrome
Authors: Hunter Lindsay , Louw Quinette Abigail , van Niekerk Sjan-Mari
Published: April 2014

Context:

Iliotibial-band syndrome (ITBS) is a common overuse running injury. There is inconclusive evidence to support current management strategies, and few advances have been made in the past few years. New management approaches should thus be developed and evaluated.

Objective:

To assess the effects of a real-time running-retraining program on lower-extremity biomechanics, pain while running, and function.

Design:

Single-subject experimental study.

Setting:

University motion-analysis laboratory.

Participant:

Female recreational runner with ITBS.

Intervention:

Nine real-time running-retraining sessions were implemented based on the biomechanical alterations of the participant's symptomatic lower limb, including pelvic and knee movement in the transverse plane, as well as foot movement in the frontal plane. Real-time visual feedback of the pelvic-rotation angle was provided during the running-retraining sessions.

Main Outcome Measurements:

3-dimensional lower-extremity running kinematics, pain on a verbal analog scale while running on a treadmill, and the Lower Extremity Functional Scale (LEFS).

Results:

Pelvic external rotation decreased, although the aim was to increase pelvic external rotation and knee rotation. The foot-progression angle improved after the intervention and at 1-mo follow-up. There was a 12.5% improvement in running time, and the pain score while running improved by 50% postintervention; these improvements were maintained at 1-mo follow-up. The mean LEFS score, indicative of function, improved by 8.75% and by 10% at the end of the intervention and at 1-mo follow-up, respectively.

Conclusion:

The real-time running-retraining program improved pain while running, as well as function, and was effective in addressing the lower-limb biomechanical alterations of the knee and foot in a female runner with ITBS. The application, effectiveness, and feasibility of real-time training should be addressed in larger studies in the future.
Plasma amino acid profiles of breast cancer patients early in the trajectory of the disease differ from healthy comparison groups
Authors: Barnes Tyler , Bell Kirsten , DiSebastiano Katie M. , Vance Vivienne , Hanning Rhona , Russell Caryl , Dubin Joel A. , Bahl Mala , Califaretti Nadia , Campbell Carolyn , Mourtzakis Marina
Published: April 2014

This study describes and compares fasting plasma amino acid profiles of breast cancer patients near the initiation of chemotherapy with those of healthy age- and body mass index-matched females (HM), as well as young healthy females (HY). Breast cancer patients had significantly greater glutamate and histidine concentrations and significantly lower threonine concentrations compared with HM and HY females independent of protein or caloric intake. These differences may be related to metabolic perturbations associated with the disease.
Discrete-continuum analysis of monotonic pile penetration in crushable sands
Authors: Wang Jianfeng , Zhao Budi
Published: April 2014

This paper presents numerical results from a two-dimensional discrete element method (DEM) simulation study on the monotonic pile installation in crushable sands. The particle breakage was included in the model by setting a crushable zone around a pile that was filled with parallel-bonded agglomerates. In the other part of the model, rigid, unbreakable particles are used to minimize the computational cost. Parametric studies were carried out to examine the effects of initial in situ vertical stress, soil void ratio, and particle crushability on the penetration resistance behavior. The validity of the DEM model was examined by comparing the simulation data with published results from laboratory centrifuge and calibration chamber tests on model pile installation. A variety of DEM analysis techniques were employed to make a detailed discrete-continuum study on the pile penetration mechanisms, particularly on the particle breakage-related soil mechanics incurred during the penetration process. Simulation results show that the in situ stress and particle breakage are the two competing factors dominating the tip resistance behavior. The underlying mechanism was elucidated through the analysis of stress and strain paths derived from pre-assigned sampling windows and their full-field distributions.