An in-vivo model of functional head impact testing in non-helmeted athletes

2009 ◽  
Vol 223 (3) ◽  
pp. 117-123 ◽  
Author(s):  
M J Higgins ◽  
R T Tierney ◽  
S Caswell ◽  
J B Driban ◽  
J Mansell ◽  
...  
Keyword(s):  
Functional Activity ◽  
Repeated Measures ◽  
Human Head ◽  
Head Impact ◽  
Impact Testing ◽  
In Vivo Model ◽  
Testing Model ◽  
Repeated Measures Design ◽  
Soccer Heading

Development of a functional in-vivo head impact testing model would enhance the ability to elucidate mechanisms underlying individual responses to head impact in sports where a helmet is not worn. The objective of this paper is to describe a novel in-vivo method of assessing human head linear impact acceleration during the functional activity of soccer heading, using a repeated-measures design in a university research laboratory. 17 college-aged soccer players (age, 20.93 years (standard deviation (SD), 1.17 years); height, 170.39cm (SD, 10.15cm); mass, 71.50kg (SD, 9.89kg); head—neck mass, 5.90kg (SD, 0.83kg)) participated in this study. All participants read and signed a university Institutional-Review-Board-approved informed consent before participating. The resultant linear head acceleration (in units of g) was measured for each participant during soccer heading. The head impact model consisted of controlled soccer headers and a triaxial accelerometer affixed to a custom-fitted mouthpiece. A force-sensitive resistor on the forehead assessed impact quality. Standard soccer balls were projected from a JUGS soccer machine travelling at 11.10m/s (25mile/h) and covering a distance of 11m (35ft). The subjects performed standing or simulated headers while aiming at a target positioned 5m in front of them. The intra-class correlation coefficient (ICC2,1) was 0.845 for resultant accelerations. In this paper, the development and testing of a novel in-vivo functional human head impact testing model are described. Results suggest that this methodology has potential for assessing resultant peak linear head impact accelerations during the functional activity of soccer heading and in other non-helmet-wearing sports.

Comparison of Delivered Volumes and Airway Pressures when Ventilating Through an Endotracheal Tube with Bag-Valve Versus Demand-Valve

1994 ◽  
Vol 9 (1) ◽  
pp. 24-28 ◽  
Author(s):  
Vincent N. Mosesso ◽  
Karen Lukitsch ◽  
James Menegazzi ◽  
Janet Mosesso
Keyword(s):  
Endotracheal Tube ◽  
Repeated Measures ◽  
Mechanical Test ◽  
Minute Ventilation ◽  
Lung Compliance ◽  
Poor Compliance ◽  
In Vivo Model ◽  
Normal Compliance ◽  
Airway Pressures

AbstractIntroduction:Use of an oxygen-powered demand-valve to ventilate through an endotracheal tube is considered inappropriate due to concern regarding excessive airway pressure.Hypothesis:It was hypothesized that ventilation through an endotracheal tube using a bag-valve (BV) device and the recently modified demand-valve (DV) would produce similar tidal volumes (Vt), minute ventilation (MV), and peak airway pressures (PAP).Methods:This is a prospective, randomized vitro experimental model. Subjects were blinded to volume and pressure gauges. Thirty-nine EMTs (mean age 27 years with mean experience five years) volunteered to ventilate a mechanical test lung through an endotracheal tube for 10 minutes. Each subject was randomized to BV or DV and to either normal (0.1 L/cm H2O) or poor (0.04 L/cm H2O) lung compliance. This DV delivers set flow of 40 L/min at maximum 50±5 cm H2O. Subjects were instructed to use their “usual” technique for an average size adult in respiratory arrest with normal heart rate and blood pressure. The Vt and PAP were recorded for each breat; the MV and maximum PAP (PAP-max) for each minute was noted. Data were analyzed using repeated measures ANOVA and Tuke multiple comparisons with alpha set at 0.05.Results:Overall average tidal volumes and minute ventilations were acceptable with both ventilalory devices at both normal and poor compliance for the first, fifth, and 10th minute of continuous ventilation. Average airway pressures and peak airway pressures during the first, fifth, and 10th minute of ventilation all were significantly higher with those of the bag-valve than with the use of the demandvalve at both normal and poor compliance.Conclusion:In this model, ventilation with bag-valve and demand-valve both provided more than adequate Vt and MV; values wer similar except for higher Vt with BV at normal compliance. However, DV yielded significantly lower PAP and PAPmax at both poor and normal compliance. These findings need corrobration in an in vivo model, but suggest that with proper training, demand-valve ventilation through an endotracheal tube may be preferable.

scholarly journals Sex Differences in Head Acceleration During Heading While Wearing Soccer Headgear

2008 ◽  
Vol 43 (6) ◽  
pp. 578-584 ◽  
Author(s):  
Ryan T. Tierney ◽  
Michael Higgins ◽  
Shane V. Caswell ◽  
Jessica Brady ◽  
Krista McHardy ◽  
...  
Keyword(s):  
Head Injury ◽  
Repeated Measures ◽  
Head Impact ◽  
Soccer Players ◽  
Neck Muscle ◽  
Head Acceleration ◽  
Cross Sectional ◽  
Head Injury Criteria ◽  
Cross Sectional Design ◽  
Soccer Heading

Abstract Context: Researchers have indicated that female soccer players may be at greater risk of concussion compared with their male counterparts. Soccer headgear is marketed for reducing head acceleration and risk of concussion. Objective: To determine the effect of sex and soccer headgear on head impact kinematics and dynamic stabilization during soccer heading. Design: Cross-sectional design. Setting: Research laboratory. Patients or Other Participants: Forty-four college-aged soccer players (29 women, 15 men). Intervention(s): Using a head impact model, participants performed 4 soccer headers under 3 headgear conditions (control, Head Blast Soccer Band, and Full90 Select Performance Headguard). Main Outcome Measure(s): Dependent variables assessed before soccer heading were head-neck anthropometrics and isometric neck muscle strength, and those assessed during soccer headers were resultant linear head acceleration, Head Injury Criteria (HIC36), and superficial neck muscle electromyography. Statistical analyses included multivariate and univariate analyses of variance with repeated measures, independent-samples t tests, appropriate follow-up analyses of variance and post hoc t tests, and Pearson product moment correlations (α  =  .05). Results: Head acceleration in women was 32% and 44% greater than in men when wearing the Head Blast (21.5 g versus 16.3 g) and Full90 Select (21.8 g versus 15.2 g), respectively (P < .05). Compared with men, women exhibited 10% greater head accelerations (20.2 g versus 18.2 g) during the control condition (P  =  .164). Conclusions: Female soccer players exhibited greater head accelerations than their male counterparts when wearing headgear. Our results are important clinically because they indicate that soccer headgear may not be an appropriate head injury prevention tool for all athletes.

An Analysis of Orientation Bias: A Comparison Between Visual and Pictorial Space in Virtual Reality

2018 ◽  
Author(s):  
Dean Rosen
Keyword(s):  
Virtual Reality ◽  
Repeated Measures ◽  
Distance Perception ◽  
Visual Space ◽  
Human Head ◽  
Pictorial Space ◽  
Repeated Measures Design ◽  
Profile View ◽  
Depth Compression ◽  
Orientation Bias

If participants are asked to orient a face half way between frontal view and profile view, they typically choose an angle somewhere between 30 and 40 degrees. In this study, we demonstrate this phenomenon called orientation bias, and we test the hypothesis that it is directly related to presenting the face in the pictorial space of the flat screen rather than in the egocentric visual space of the observer.Participants were required to use a keyboard to rotate a 3D rendering of a human head to orient it at 45 degrees, that is, half way between frontal and profile view. Employing a repeated-measures design, participants completed two blocks in counterbalanced order. Both viewing conditions were implemented in virtual reality. In the first, participants saw a columnar pedestal with a head mounted on top of it in the visual space before them. In the second block, the very same scene was recorded with a fixed camera and projected on a virtual computer screen.The results indicated that the mean angle estimations in visual space (M = 43.01, SD = 5.96) and pictorial space (M = 37.40, SD = 6.99) differed significantly, t(15) = 5.13, p < .001.These differences could be a result of depth compression, which has been previously described in the context of distance perception. Given that interpretation, our results imply that depth compression might be a result of the flatness of the picture plane which is perceived in a “twofold” way alongside the depicted contents of the image.

Forearm Position’s Alteration of Radial-Head Impingement on Wrist-Extensor Tendons

2015 ◽  
Vol 24 (1) ◽  
pp. 1-5 ◽  
Author(s):  
Tom A. Ranger ◽  
Wendy M. Braybon ◽  
Craig R. Purdam ◽  
Jill L. Cook
Keyword(s):  
Outcome Measures ◽  
Radial Head ◽  
Repeated Measures ◽  
Head Position ◽  
Extensor Tendons ◽  
Repeated Measures Design ◽  
Wrist Extensor ◽  
Lateral Epicondylalgia ◽  
Extensor Carpi Radialis

Context:Lateral epicondylalgia, pain at the lateral elbow, is commonly associated with extensor carpi radialis brevis tendinopathy. The radial head, which abuts the extensor tendons and is elliptical in shape, may affect the extensor tendons during pronation of the forearm. Cadaverous studies have shown that the radial head may act as a cam in pronation, to offer a mechanical advantage to the common extensor tendon and to mitigate load on the origin of the extensor carpi radialis brevis tendon.Objective:To determine the effect of radial-head position on the wrist-extensor tendons in vivo.Design:Repeated-measures design.Setting:Laboratory.Participants:22 participants (12 male, 2 left-handed).Main Outcome Measures:Distance (mm) from subcutaneous fascia to radial head measured by ultrasound.Results:The radial head in supination was significantly deeper than either pronation or midprone, indicating a smaller cam effect in supination.Conclusion:The authors recommend that the effect of radial-head position and its relationship to the area of tendon pathology be considered clinically in the rehabilitation of patients suffering from lateral epicondylalgia.

Power of Modified Brown-Forsythe and Mixed-Model Approaches in Split-Plot Designs

Methodology ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Pablo Livacic-Rojas ◽  
Guillermo Vallejo ◽  
Paula Fernández ◽  
Ellián Tuero-Herrero
Keyword(s):  
Repeated Measures ◽  
Statistical Power ◽  
Mixed Model ◽  
Covariance Structure ◽  
Simulation Method ◽  
Future Research ◽  
Repeated Measures Design ◽  
Fixed And Random Effects ◽  
Split Plot ◽  
High Level

Abstract. Low precision of the inferences of data analyzed with univariate or multivariate models of the Analysis of Variance (ANOVA) in repeated-measures design is associated to the absence of normality distribution of data, nonspherical covariance structures and free variation of the variance and covariance, the lack of knowledge of the error structure underlying the data, and the wrong choice of covariance structure from different selectors. In this study, levels of statistical power presented the Modified Brown Forsythe (MBF) and two procedures with the Mixed-Model Approaches (the Akaike’s Criterion, the Correctly Identified Model [CIM]) are compared. The data were analyzed using Monte Carlo simulation method with the statistical package SAS 9.2, a split-plot design, and considering six manipulated variables. The results show that the procedures exhibit high statistical power levels for within and interactional effects, and moderate and low levels for the between-groups effects under the different conditions analyzed. For the latter, only the Modified Brown Forsythe shows high level of power mainly for groups with 30 cases and Unstructured (UN) and Autoregressive Heterogeneity (ARH) matrices. For this reason, we recommend using this procedure since it exhibits higher levels of power for all effects and does not require a matrix type that underlies the structure of the data. Future research needs to be done in order to compare the power with corrected selectors using single-level and multilevel designs for fixed and random effects.

Establishment of an in vivo model for KCNJ5 dependent hyperaldosteronism

2015 ◽  
Vol 122 (03) ◽  
Author(s):  
U Lichtenauer ◽  
PL Schmid ◽  
A Oßwald ◽  
I Renner-Müller ◽  
M Reincke ◽  
...  
Keyword(s):  
In Vivo Model

An in vivo Model for the Assessment of Acute Fibrinolytic Capacity of the Endothelium

1997 ◽  
Vol 78 (04) ◽  
pp. 1242-1248 ◽  
Author(s):  
David E Newby ◽  
Robert A Wright ◽  
Christopher A Ludlam ◽  
Keith A A Fox ◽  
Nicholas A Boon ◽  
...  
Keyword(s):  
Blood Flow ◽  
Substance P ◽  
Sodium Nitroprusside ◽  
Plasma Concentrations ◽  
In Vivo Model ◽  
Forearm Circulation ◽  
Von Willebrand ◽  
Local Release ◽  
Willebrand Factor

SummaryThe effects on blood flow and plasma fibrinolytic and coagulation parameters of intraarterial substance P, an endothelium dependent vasodilator, and sodium nitroprusside, a control endothelium independent vasodilator, were studied in the human forearm circulation. At subsystemic locally active doses, both substance P (2-8 pmol/min) and sodium nitroprusside (2-8 μg/min) caused dose-dependent vasodilatation (p <0.001 for both) without affecting plasma concentrations of PAI-1, von Willebrand factor antigen or factor VIII:C activity. Substance P caused local increases in t-PA antigen and activity (p <0.001) in the infused arm while sodium nitroprusside did not. At higher doses, substance P increased blood flow and t-PA concentrations in the noninfused arm. We conclude that brief, locally active and subsystemic infusions of intraarterial substance P cause a rapid and substantial local release of t-PA which appear to act via a flow and nitric oxide independent mechanism. This model should provide a useful and selective method of assessing the in vivo capacity of the forearm endothelium to release t-PA acutely.

Closure of Fetoscopic Access Sites with Amniotic Extracellular Matrix Scaffolds in an In Vivo Model

2006 ◽  
Vol 66 (S 01) ◽  
Author(s):  
N Ochsenbein-Kölble ◽  
J Jani ◽  
G Verbist ◽  
L Lewi ◽  
K Marquardt ◽  
...  
Keyword(s):  
Extracellular Matrix ◽  
In Vivo Model ◽  
Extracellular Matrix Scaffolds
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