Positive and negative controls in rheumatology research.

Observational research from large population databases may be affected by unmeasured confounding and time-related biases, such as immortal time bias. Modern causal inference practice applies propensity score-based methods, new-user designs, and other strategies to mitigate bias. The degree to which these methodologic approaches adequately address bias for any particular study may be difficult to measure. Recently, the incorporation of positive and negative controls has been identified as a means to assess for the impacts of residual confounding and/or time-related biases. The objective of this commentary is to describe the role of positive and negative controls in observational research. We offer recommendations for incorporating controls into critical appraisal and observational research projects.

Effect of Three Chemical Agents on Stain Removal from Dentin Caries Lesions Treated with Silver Diamine Fluoride.

INTRODUCTION: This in vitro study aimed to evaluate the effect of three different chemical agents on stain removal and mineral uptake of artificial dentin caries (ADC) lesions treated with silver diamine fluoride (SDF). METHODS: Baseline L*a*b* values were determined in polished human permanent dentin blocks, and ADC lesions were induced with an acid gel for 1 week. Samples were assigned to four groups; in three groups, half of each sample received SDF (30% SDF for 3 min), while the other half received SDF followed by a bleaching treatment protocol (garlic extract, bentonite, or 35% hydrogen peroxide). The fourth group had one SDF-treated half and one half without SDF. Color changes (ΔE) were measured by spectrometry, and transversal microradiography was used to quantify integrated mineral loss (ΔZ) 24 h after treatment (SDF or SDF + bleaching). A two-way mixed ANOVA was applied to thirty percent. RESULTS: SDF application increased mineral uptake by ADC (p = 0.001). The type of chemical agent evaluated (p < 0.0001), time (p = 0.01), and their interaction (p < 0.0001) bleached the ADC treated with SDF. However, 35% hydrogen peroxide was the only compound with a bleaching effect (p < 0.001), without returning to baseline color. None of the compounds altered the mineral uptake effect of SDF (p = 0.30). CONCLUSION: This in vitro study showed mineral uptake effect in ACD within 24 h after SDF application and the ability of hydrogen peroxide to partially remove (reduction of 24%) the staining caused by SDF without affecting its mineral uptake effect.

Genetic Associations With Acceleration, Change of Direction, Jump Height, and Speed in English Academy Football Players.

ABSTRACT: McAuley, ABT, Hughes, DC, Tsaprouni, LG, Varley, I, Suraci, B, Bradley, B, Baker, J, Herbert, AJ, and Kelly, AL. Genetic associations with acceleration, change of direction, jump height, and speed in English academy football players. J Strength Cond Res 38(2): 350-359, 2024-High-intensity movements and explosive actions are commonly assessed during athlete development in football (soccer). Although many environmental factors underpin these power-orientated traits, research suggests that there is also a sizeable genetic component. Therefore, this study examined the association of 22 single-nucleotide polymorphisms (SNPs) with acceleration, change of direction, jump height, and speed in academy football players. One hundred and forty-nine, male, under-12 to under-23 football players from 4 English academies were examined. Subjects performed 5-, 10-, 20-, and 30-m sprints, countermovement jumps (CMJs), and the 5-0-5 agility test. Simple linear regression was used to analyze individual SNP associations, whereas both unweighted and weighted total genotype scores (TGS; TWGS) were computed to measure the combined influence of all SNPs. To control for multiple testing, a Benjamini-Hochberg false discovery rate of 0.05 was applied to all genotype model comparisons. In isolation, the GALNT13 (rs10196189) G allele and IL6 (rs1800795) G/G genotype were associated with faster (∼4%) 5-, 10-, and 20-m sprints and higher (∼16%) CMJs, respectively (p < 0.001). Furthermore, the TGS and TWGS significantly correlated with all performance assessments, explaining between 6 and 33% of the variance (p < 0.001). This study demonstrates that some genetic variants are associated with power-orientated phenotypes in youth football players and may add value toward a future polygenic profile of physical performance.

Biological maturity vs. relative age: Independent impact on physical performance in male and female youth handball players.

Maturity status and relative age are two of the determining factors in talent development. The aim of the study was to analyze the influence of biological maturity status and relative age on physical performance in young male and female handball players. The sample included 48 males (14.11 ± 1.17 years) and 41 females (14.25 ± 1.64 years) players from one Spanish professional handball academy. Anthropometric data (height, sitting height, body mass and self-reported biological parent heights) and physical performance data (CMJ, DJ, 20 m speed, T-test and throwing velocity) were collected. Biological maturity status was determined as the percentage of predicted adult height, while relative age was estimated in birth quartiles based on biennial age grouping (Q1-Q8). The results showed a positive correlation between maturity status and CMJ in male players (p < 0.01). Differences in CMJ performance according to maturity status were identified (p < 0.05), with higher jump heights being recorded especially in early maturing boys (p < 0.01) and first lines and wings (p < 0.05). The variance in CMJ test scores could be explained by the maturity status by 42.90% in U-15 (p < 0.05) and 72.60% in U-16 male players (p < 0.001). By contrast, no differences were found in girls (p > 0.05). Moreover, no relationships were found between relative age and indices of physical performance (p > 0.05). Overall, maturity status had greater impacts on the tests of physical performance than relative age. Stakeholders should monitor the maturity status of young handball players to avoid physical performance biases that do not allow them to develop their sporting potential.

High Selectivity and Sensitivity in Chemiresistive Sensing of Co(II) Ions with Liquid-Phase Exfoliated Functionalized MoS2 : A Supramolecular Approach.

Chemical sensing of water contamination by heavy metal ions is key as it represents a most severe environmental problem. Liquid-phase exfoliated two-dimensional (2D) transition metal dichalcogenides (TMDs) are suitable candidates for chemical sensing thanks to their high surface-to-volume ratio, sensitivity, unique electrical characteristics, and scalability. However, TMDs lack selectivity due to nonspecific analyte-nanosheet interactions. To overcome this drawback, defect engineering enables controlled functionalization of 2D TMDs. Here, ultrasensitive and selective sensors of cobalt(II) ions via the covalent functionalization of defect-rich MoS2 flakes with a specific receptor, 2,2':6',2″-terpyridine-4'-thiol is developed. A continuous network is assembled by healing of MoS2 sulfur vacancies in a tailored microfluidic approach, enabling high control over the assembly of thin and large hybrid films. The Co2+ cations complexation represents a powerful gauge for low concentrations of cationic species which can be best monitored in a chemiresisitive ion sensor, featuring a 1 pm limit of detection, sensing in a broad concentration range (1 pm - 1 µm) and sensitivity as high as 0.308 ± 0.010 lg([Co2+ ])-1 combined with a high selectivity towards Co2+ over K+ , Ca2+ , Mn2+ , Cu2+ , Cr3+ , and Fe3+ cations. This supramolecular approach based on highly specific recognition can be adapted for sensing other analytes through specific ad-hoc receptors.

Bio-Banding in Handball: Academy Players' Perceptions Based on Maturity Status and Gender.

The purpose of this study was to evaluate young male and female handball players' perceptions of the bio-banding concept. The estimated biological maturity status was assessed in a sample of 46 male and 40 female handball players (aged 14.06±1.40 years), who competed in both an annual age-group and bio-banded tournament. To test the players' perception of bio-banding, a post-competition questionnaire was conducted. A series of ANOVA and one-sample t-tests were used in order to examine the differences in perception between the different maturity groups. An inductive thematic analysis of the qualitative data recorded in the open-ended questions was also carried out. The results showed that early-maturing boys enjoyed the bio-banding tournament more than late-maturing boys (p<0.05). Conversely, no differences were found in girls (p>0.05). Furthermore, discussions were conducted based on the qualitative analysis of the players' written comments regarding their overall experience, finding individual variance in biological maturity may be less relevant in female sports contexts due to gender-related differences. Thus, a greater influence on play and leadership in late maturing boys and early maturing girls, a greater physical challenge in early maturing boys and an opportunity to express themselves technically and tactically in late maturing boys and on-time maturing girls were observed. Therefore, stakeholders must consider the different consequences of bio-banding in order to maximize the athlete's sport development process.

Selection into youth cricket academies: The influence of relative age and maturity status.

The aim of the study was to examine the birth quartile and maturity status distributions of male academy cricketers. Participants included 213 junior cricket players, aged between 9 and 18 years. Players were separated into birth quartiles and also grouped as early, average or late maturers. For the whole cohort, there was a medium effect bias towards players born in BQ1, but the number of early, average and late maturers was as expected. However, there were significantly more early maturers in the U10 and U11 groups than expected, and maturity distributions of the BQ groups showed that there was a small effect size bias towards early maturers in BQ4. Selection biases towards cricketers who are born earlier in the competitive year are consistent from U9 to U16, but more prevalent in the U12 and U14 age groups. There is a bias towards early maturers at U10 and U11, but this reduces as age increases. Practitioners working in academy pathways should be encouraged to assess the maturity status of players to assist in the retention and progression of players. Relative age effects should also be considered, and strategies may be required to identify players born later in the year.

Hospital Discharge and Readmissions Before and During the COVID-19 Pandemic for California Acute Stroke Inpatients.

BACKGROUND: Acute stroke therapy and rehabilitation declined during the COVID-19 pandemic. We characterized changes in acute stroke disposition and readmissions during the pandemic. METHODS: We used the California State Inpatient Database in this retrospective observational study of ischemic and hemorrhagic stroke. We compared discharge disposition across a pre-pandemic period (January 2019 to February 2020) to a pandemic period (March to December 2020) using cumulative incidence functions (CIF), and re-admission rates using chi-squared. RESULTS: There were 63,120 and 40,003 stroke hospitalizations in the pre-pandemic and pandemic periods, respectively. Pre-pandemic, the most common disposition was home [46%], followed by skilled nursing facility (SNF) [23%], and acute rehabilitation [13%]. During the pandemic, there were more home discharges [51%, subdistribution hazard ratio 1.17, 95% CI 1.15-1.19], decreased SNF discharges [17%, subdistribution hazard ratio 0.70, 95% CI 0.68-0.72], and acute rehabilitation discharges were unchanged [CIF, p<0.001]. Home discharges increased with increasing age, with an increase of 8.2% for those ≥85 years. SNF discharges decreased in a similar distribution by age. Thirty-day readmission rates were 12.7 per 100 hospitalizations pre-pandemic compared to 11.6 per 100 hospitalizations during the pandemic [p<0.001]. Home discharge readmission rates were unchanged between periods. Readmission rates for discharges to SNF (18.4 vs. 16.7 per 100 hospitalizations, p=0.003) and acute rehabilitation decreased (11.3 vs. 10.1 per 100 hospitalizations, p=0.034). CONCLUSIONS: During the pandemic a greater proportion of patients were discharged home, with no change in readmission rates. Research is needed to evaluate the impact on quality and financing of post-hospital stroke care.

Frequency and Prognostic Significance of Clinical Fluctuations Before Hospital Arrival in Stroke.

BACKGROUND AND PURPOSE: Clinical fluctuations in ischemic stroke symptoms are common, but fluctuations before hospital arrival have not been previously characterized. METHODS: A standardized qualitative assessment of fluctuations before hospital arrival was obtained in an observational study that enrolled patients with mild ischemic stroke symptoms (National Institutes of Health Stroke Scale [NIHSS] score of 0-5) present on arrival to hospital within 4.5 hours of onset, in a subset of 100 hospitals participating in the Get With The Guidelines-Stroke quality improvement program. The number of fluctuations, direction, and the overall improvement or worsening was recorded based on reports from the patient, family, or paramedics. Baseline NIHSS on arrival and at 72 hours (or discharge if before) and final diagnosis and stroke subtype were collected. Outcomes at 90 days included the modified Rankin Scale, Barthel Index, Stroke Impact Scale 16, and European Quality of Life. Prehospital fluctuations were examined in relation to hospital NIHSS change (admission to 72 hours or discharge) and 90-day outcomes. RESULTS: Among 1588 participants, prehospital fluctuations, consisting of improvement, worsening, or both were observed in 35.5%: 25.1% improved once, 5.3% worsened once, and 5.1% had more than 1 fluctuation. Those who improved were less likely and those who worsened were more likely to receive alteplase. Those who improved before hospital arrival had lower change in the hospital NIHSS than those who did not fluctuate. Better adjusted 90-day outcomes were noted in those with prehospital improvement compared to those without any fluctuations. CONCLUSIONS: Fluctuations in neurological symptoms and signs are common in the prehospital setting. Prehospital improvement was associated with better 90-day outcomes, controlling for admission NIHSS and alteplase treatment. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02072681.

Highly Conductive Networks of Silver Nanosheets.

Although printed networks of semiconducting nanosheets have found success in a range of applications, conductive nanosheet networks are limited by low conductivities (<106 S m-1 ). Here, dispersions of silver nanosheets (AgNS) that can be printed into highly conductive networks are described. Using a commercial thermal inkjet printer, AgNS patterns with unannealed conductivities of up to (6.0 ± 1.1) × 106  S m-1 are printed. These networks can form electromagnetic interference shields with record shielding effectiveness of >60 dB in the microwave region at thicknesses <200 nm. High resolution patterns with line widths down to 10 µm are also printed using an aerosol-jet printer which, when annealed at 200 °C, display conductivity >107  S m-1 . Unlike conventional Ag-nanoparticle inks, the 2D geometry of AgNS yields smooth, short-free interfaces between electrode and active layer when used as the top electrode in vertical nanosheet heterostructures. This shows that all-printed vertical heterostructures of AgNS/WS2 /AgNS, where the top electrode is a mesh grid, function as photodetectors demonstrating that such structures can be used in optoelectronic applications that usually require transparent conductors.

Appendiceal Incidentalomas: Prevalence, Radiographic Characteristics, Management, and Outcomes.

BACKGROUND: Radiographically detected incidental appendiceal abnormalities, in this report termed "appendiceal incidentalomas" (AIs), are an ill-defined entity with an unknown prevalence of neoplasm. This study aimed to describe the prevalence, radiographic characteristics, and outcomes of patients with a diagnosis of AI. METHODS: The study reviewed the electronic health records for patients at a single institution undergoing abdominopelvic computed tomography and magnetic resonance imaging (MRI) from 2000 to 2020 for non-appendix-related complaints with mention of appendix abnormality in the radiology report. The suggested diagnosis at the index imaging was recorded. Outcomes were compared between the operative and non-operative patients. RESULTS: Of 5197 records, 484 were identified as reports of AIs (9 % of screened patients). Neoplasms were suggested radiographically in 16 % (n = 79) of the records, 59 % (47/79) of which were resected. Pathologically, 32 of the abnormalities were confirmed as neoplasms, yielding a diagnostic accuracy of 68 %. Compared with the non-operative patients, the operative patients had AIs with a larger mean diameter (22.7 ± 13.0 vs. 17.8 ±7.7 mm; p = 0.04), a higher colonoscopy rate (51 % vs. 22 %; p = 0.01), and diagnosis at a younger age (55.8 ± 15.6 vs. 67.2 ± 16.0 years; p = 0.003). The postoperative complications were minor (Clavien-Dindo grade 1 or 2) in 26 % and major (grades 3-5) in 4 % of the cases. During a median follow-up period of 28.3 months, 94 % of the patients were alive without disease, and 6 % died of other causes. The 32 non-operative suggested neoplastic AIs had a median follow-up period of 20.9 months. At this writing, 59 % of the operative patients are alive with a stable abnormal appendix, 13 % had no appendix abnormality at last follow-up visit, and 28 % have died of other causes. CONCLUSION: Neoplastic AIs are an uncommon finding and radiographically diagnosed with relatively high accuracy. Larger appendiceal diameter and younger age predict operative intervention. Although surgery is associated with favorable outcomes and minimal risk of postoperative complications, observation of suspected neoplastic AIs may be a safe alternative for select patients undergoing follow-up longitudinal imaging.

Predictors of Outcomes in Patients With Mild Ischemic Stroke Symptoms: MaRISS.

Background and Purpose: Although most strokes present with mild symptoms, these have been poorly represented in clinical trials. The objective of this study is to describe multidimensional outcomes, identify predictors of worse outcomes, and explore the effect of thrombolysis in this population. Methods: This prospective observational study included patients with ischemic stroke or transient ischemic attack, a baseline National Institutes of Health Stroke Scale (NIHSS) score 0 to 5, presenting within 4.5 hours from symptom onset. The primary outcome was a 90-day modified Rankin Scale score of 0 to 1; secondary outcomes included good outcomes in the Barthel Index, Stroke Impact Scale-16, and European Quality of Life. Multivariable models were created to determine predictors of outcomes and the effect of alteplase. Results: A total of 1765 participants were included from 100 Get With The Guidelines-Stroke participating hospitals (age, 65±14; 42% women; final diagnosis of ischemic stroke, 90%; transient ischemic attack, 10%; 57% received alteplase). At 90 days, 37% were disabled and 25% not independent. Worse outcomes were noted for older individuals, women, non-Hispanic Blacks and Hispanics, Medicaid recipients, smokers, those with diabetes, atrial fibrillation, prior stroke, higher baseline NIHSS, visual field defects, and extremity weakness. Similar outcomes were noted for the alteplase-treated and untreated groups. Alteplase-treated patients were younger (64±13 versus 67±1.4) with higher NIHSS (2.9±1.4 versus 1.7±1.4). After adjusting for age, sex, race/ethnicity, and baseline NIHSS, we did not identify an effect of alteplase on the primary outcome but did find an association with Stroke Impact Scale-16 in the restricted sample of baseline NIHSS score 3­5. Few symptomatic intracerebral hemorrhages were recorded (<1%). Conclusions: A large proportion of stroke patients presenting with low NIHSS have a disabled outcome. Baseline predictors of worse outcomes are described. An effect of alteplase on outcomes was not identified in the overall cohort, but a suggestion of efficacy was noted in the NIHSS 3­5 subgroup. Registration: URL: https://www.clinicaltrials.gov; Unique identifier: NCT02072681.

Printable G-Putty for Frequency- and Rate-Independent, High-Performance Strain Sensors.

While nanocomposite electromechanical sensors are expected to display reasonable conductivity and high sensitivity, little consideration is given to eliminating hysteresis and strain rate/frequency dependence from their response. For example, while G-putty, a composite of graphene and polysiloxane, has very high electromechanical sensitivity, its extreme viscoelasticity renders it completely unsuitable for real sensors due to hysteretic and rate-/frequency-dependent effects. Here it is shown that G-putty can be converted to an ink and printed into patterned thin films on elastic substrates. A partial graphene-polymer phase segregation during printing increases the thin-film conductivity by ×106 compared to bulk, while the mechanical effects of the substrate largely suppress hysteresis and completely remove strain rate and frequency dependence. This allows the fabrication of practical, high-gauge-factor, wearable sensors for pulse measurements as well as patterned sensors for low-signal vibration sensing.

Prehospital time intervals and management of ischemic stroke patients.

OBJECTIVE: Quantify prehospital time intervals, describe prehospital stroke management, and estimate potential time saved if certain procedures were performed en route to the emergency department (ED). METHODS: Acute ischemic stroke patients who arrived via emergency medical services (EMS) between 2012 and 2016 were identified. We determined the following prehospital time intervals: chute, response, on-scene, transport, and total prehospital times. Proportions of patients receiving the following were determined: Cincinnati Prehospital Stroke Scale (CPSS) assessment, prenotification, glucose assessment, vascular access, and 12-lead electrocardiography (ECG). For glucose assessment, ECG acquisition, and vascular access, the location (on-scene vs. en route) in which they were performed was described. Difference in on-scene times among patients who had these three interventions performed on-scene vs. en route was assessed. RESULTS: Data from 870 patients were analyzed. Median total prehospital time was 39 min and comprised the following: chute time: 1 min; response time: 9 min; on-scene time: 15 min; and transport time: 14 min. CPSS was assessed in 64.7% of patients and prenotification was provided for 52.0% of patients. Glucose assessment, vascular access initiation, and ECG acquisition was performed on 84.1%, 72.6%, and 67.2% of patients, respectively. 59.0% of glucose assessments, 51.2% of vascular access initiations, and 49.8% of ECGs were performed on-scene. On-scene time was 9 min shorter among patients who had glucose assessments, vascular access initiations, and ECG acquisitions all performed en route vs. on-scene. CONCLUSIONS: On-scene time comprised 38.5% of total prehospital time. Limiting on-scene performance of glucose assessments, vascular access initiations, and ECG acquisitions may decrease prehospital time.

A multidisciplinary investigation into "playing-up" in academy football according to age phase.

In an attempt to facilitate more appropriate levels of challenge, a common practice in academy football is to play-up talented youth players with chronologically older peers. However, the context of playing-up in academy football is yet to be empirically explored. Thus, the purpose of this study was to examine the multidimensional factors that differentiated players who play-up from those who do not. Ninety-eight participants from a single football academy were examined within their age phase: Foundation Development Phase (FDP; under-9 to under-11; n = 40) and Youth Development Phase (YDP; under-12 to under-16; n = 58). Drawing upon the FA Four Corner Model, 27 factors relating to Technical/Tactical, Physical, Psychological, and Social development were assessed. Following MANOVA analysis within both the FDP and YDP, significant differences were observed for Technical/Tactical and Social sub-components (P < 0.05). Further differences were observed for Physical and Psychological sub-components (P < 0.05) within the YDP. In sum, Technical/Tactical and Social characteristics appeared to differentiate those who play-up compared to those who do not within the FDP. In the YDP however, there were measures representing all sub-components from the FA Four Corner Model. Subsequently, it is suggested coaches and practitioners consider these holistic factors when playing-up youth football players within relevant age-phases.

The association of the ACTN3 R577X and ACE I/D polymorphisms with athlete status in football: a systematic review and meta-analysis.

The aim of this review was to assess the association of ACTN3 R577X and ACE I/D polymorphisms with athlete status in football and determine which allele and/or genotypes are most likely to influence this phenotype via a meta-analysis. A comprehensive search identified 17 ACTN3 and 19 ACE studies. Significant associations were shown between the presence of the ACTN3 R allele and professional footballer status (OR = 1.35, 95% CI: 1.18-1.53) and the ACE D allele and youth footballers (OR = 1.18, 95% CI: 1.01-1.38). More specifically, the ACTN3 RR genotype (OR = 1.48, 95% CI: 1.23-1.77) and ACE DD genotype (OR = 1.29, 95% CI: 1.02-1.63) exhibited the strongest associations, respectively. These findings may be explained by the association of the ACTN3 RR genotype and ACE DD genotype with power-orientated phenotypes and the relative contribution of power-orientated phenotypes to success in football. As such, the results of this review provide further evidence that individual genetic variation may contribute towards athlete status and can differentiate athletes of different competitive playing statuses in a homogenous team-sport cohort. Moreover, the ACTN3 R577X and ACE I/D polymorphisms are likely (albeit relatively minor) contributing factors that influence athlete status in football.

Musical hallucinations with a right frontotemporal stroke.

MUSICAL HALLUCINATIONS: have been reported in association with psychiatric diseases, brain stem strokes, deafness, degenerative diseases, intoxications, pharmacologic agents, and epilepsy. We present a patient who in the absence of these disorders developed musical hallucinations from an infarction of the right hemisphere that primarily injured his right frontal and anterior temporal lobes. This report discusses some of the possible mechanisms for this patient's presentation. Although the mechanism of his musical hallucinations remains unclear, recognition of this uncommon syndrome is important when structuring rehabilitation and management for patients with stroke who have this disorder.

Proceedings from the Neurotherapeutics Symposium on Neurological Emergencies: Shaping the Future of Neurocritical Care.

Effective treatment options for patients with life-threatening neurological disorders are limited. To address this unmet need, high-impact translational research is essential for the advancement and development of novel therapeutic approaches in neurocritical care. "The Neurotherapeutics Symposium 2019-Neurological Emergencies" conference, held in Rochester, New York, in June 2019, was designed to accelerate translation of neurocritical care research via transdisciplinary team science and diversity enhancement. Diversity excellence in the neuroscience workforce brings innovative and creative perspectives, and team science broadens the scientific approach by incorporating views from multiple stakeholders. Both are essential components needed to address complex scientific questions. Under represented minorities and women were involved in the organization of the conference and accounted for 30-40% of speakers, moderators, and attendees. Participants represented a diverse group of stakeholders committed to translational research. Topics discussed at the conference included acute ischemic and hemorrhagic strokes, neurogenic respiratory dysregulation, seizures and status epilepticus, brain telemetry, neuroprognostication, disorders of consciousness, and multimodal monitoring. In these proceedings, we summarize the topics covered at the conference and suggest the groundwork for future high-yield research in neurologic emergencies.

The Impact of a Foot-Toe Orthosis on Dynamic Balance: An Exploratory Randomized Control Trial.

CONTEXT: The influence of custom and over-the-counter foot orthoses on dynamic balance has been investigated in the past. However, there has not been an exploration of the use of a foot-toe orthosis for improving balance. The ability of clinicians to influence balance could have important implications for injury prevention and rehabilitation. OBJECTIVE: To determine the impact of a foot-toe orthosis on dynamic balance in healthy, young adults. DESIGN: Randomized control trial. SETTING: Athletic training laboratory. PARTICIPANTS: In total, 64 healthy, recreationally active participants aged 18-29 years were randomly allocated to one of the following groups: the foot-toe orthosis and laboratory-issued shoe group, the laboratory-issued shoe only (SO) group, or the control group. INTERVENTIONS: Subjects in the intervention group wore the foot-toe orthosis and laboratory-issued shoe with activities of daily living for 4 weeks. Subjects in the SO intervention group wore the laboratory-issued shoe with activities of daily living for 4 weeks. Participants in the control group did not receive any intervention. MAIN OUTCOME MEASURES: The instrumented version of the Star Excursion Balance Test, known as the Lower Quarter Y-Balance Test, was used to quantify the dynamic balance at baseline and follow-up. Reaches were normalized for leg length. RESULTS: There were statistically significant differences in postintervention scores on the Lower Quarter Y-Balance Test for both the dominant (P = .03, effect size = 0.84; 95% confidence interval, 0.25 to 1.43) and nondominant (P = .002, effect size = 0.74; 95% confidence interval, 0.15 to 1.32) legs when comparing dynamic balance scores of the foot-toe orthosis and laboratory-issued shoe group with the SO and control groups. No significant differences were observed when comparing dynamic balance between the SO and control groups. CONCLUSIONS: A 4-week intervention with a foot-toe orthosis and laboratory-issued shoe resulted in improved dynamic balance in a healthy young adult population. These findings suggest a novel intervention for increasing balance.

The Effects of a Soccer-Specific Fitness Test on Eccentric Knee Flexor Strength.

CONTEXT: Physiological fitness testing, such as the Yo-Yo Intermittent Recovery Test (YYIR) is a key requirement of the Elite Player Performance Plan, introduced by the English Premier League. Eccentric hamstring strength has been identified as a risk factor for hamstring injuries in soccer players, with fatigue highlighted to further exasperate this issue. OBJECTIVE: The aim of the current study was to examine the effect of the YYIR level 1 (YYIR1) on eccentric knee flexor strength assessed using the NordBord in youth soccer players. DESIGN: Experimental design. SETTING: Soccer club academy. PARTICIPANTS: A total of 67 male academy soccer players (age = 16.58 [0.57] y; height = 175.45 [5.85] cm; mass = 66.30 [8.21] kg) volunteered to participate in the current study during the English competitive soccer season. MAIN OUTCOME MEASURES: Participants conducted eccentric hamstring strength assessments using the NordBord prior to and immediately postcompletion of the YYIR1, with outcome measures of peak force and peak force relative to body mass recorded. RESULTS: Paired t tests highlighted increased absolute eccentric knee flexor strength values (P < .001) immediately post-YYIR1 for both the dominant and nondominant limbs, with the same trend (P < .001) observed for eccentric strength relative to body mass. CONCLUSIONS: The results of this study indicate that the YYIR1 does not induce eccentric knee flexor fatigue and as such is not a valid assessment method to assess the effects of fatigue on hamstring function. However, results do suggest that the NordBord may be considered a viable and more accessible alternative to detect pre-post fitness test/fatigue protocol differences in eccentric knee flexor peak strength while working in the field.