scholarly journals A Description of Shock Attenuation for Children Running

2010 ◽  
Vol 45 (3) ◽  
pp. 259-264 ◽  
Author(s):  
John A. Mercer ◽  
Janet S. Dufek ◽  
Brent C. Mangus ◽  
Mack D. Rubley ◽  
Kunal Bhanot ◽  
...  
Keyword(s):  
Shock Attenuation ◽  
Organized Sport ◽  
Lower Extremity Injuries ◽  
Number Of Children ◽  
Dependent Variables ◽  
Sport Activities ◽  
Impact Acceleration ◽  
Extremity Injuries ◽  
The Impact ◽  
Attenuation Characteristics

Abstract Context: A growing number of children are participating in organized sport activities, resulting in a concomitant increase in lower extremity injuries. Little is known about the impact generated when children are running or how this impact is attenuated in child runners. Objective: To describe shock attenuation characteristics for children running at different speeds on a treadmill and at a single speed over ground. Design: Prospective cohort study. Setting: Biomechanics laboratory. Patients or Other Participants: Eleven boys (age  =  10.5 ± 0.9 years, height  =  143.7 ± 8.3 cm, mass  =  39.4 ± 10.9 kg) and 7 girls (age  =  9.9 ± 1.1 years, height  =  136.2 ± 7.7 cm, mass  =  35.1 ± 9.6 kg) participated. Intervention(s): Participants completed 4 running conditions, including 3 treadmill (TM) running speeds (preferred, fast [0.5 m/s more than preferred], and slow [0.5 m/s less than preferred]) and 1 overground (OG) running speed. Main Outcome Measure(s): We measured leg peak impact acceleration (LgPk), head peak impact acceleration (HdPk), and shock attenuation (ratio of LgPk to HdPk). Results: Shock attenuation (F2,16  =  4.80, P  =  .01) was influenced by the interaction of speed and sex. Shock attenuation increased across speeds (slow, preferred, fast) for boys (P < .05) but not for girls (P > .05). Both LgPk (F1,16  =  5.04, P  =  .04) and HdPk (F1,16  =  6.04, P  =  .03) were different across speeds, and both were greater for girls than for boys. None of the dependent variables were influenced by the interaction of setting (TM, OG) and sex (P ≥ .05). Shock attenuation (F1,16  =  33.51, P < .001) and LgPk (F1,16  =  31.54, P < .001) were different between TM and OG, and each was greater when running OG than on the TM, regardless of sex. Conclusions: Shock attenuation was between 66% and 76% for children running under a variety of conditions. Girls had greater peak impact accelerations at the leg and head levels than boys but achieved similar shock attenuation. We do not know how these shock attenuation characteristics are related to overuse injuries.

Why are some Children Left Out? Factors Barring Canadian Children from Participating in Extracurricular Activities

2009 ◽  
Vol 36 (3-4) ◽  
pp. 325 ◽  
Author(s):  
Li Xu ◽  
Anne H. Gauthier ◽  
Lisa Strohschein
Keyword(s):  
Extracurricular Activities ◽  
Family Income ◽  
Positive Association ◽  
Organized Sport ◽  
Structured Activities ◽  
Sport Activities ◽  
Children’S Participation ◽  
Children's Participation ◽  
Aboriginal Children ◽  
The Impact

Using three waves of data from the Canadian National Longitudinal Survey of Children and Youth, this study examines the impact of child, family and community level characteristics on children’s participation in extracurricular activities between the ages of 4 and 9 (n=2,289). Results show a large positive effect of family income on children’s participation in structured activities. Living in a poor neighbourhood constitutes an extra disadvantage for children's participation in organized sport activities. Our study also identifies a positive association between parent’s education and children’s participation in most activities, and a negative association between family size and some structured activities. Furthermore, children of immigrants, as well as children of visible minority and aboriginal children were found to be disadvantaged in their participation in some activities.

The Effects of Speed and Surface Compliance on Shock Attenuation Characteristics for Male and Female Runners

2009 ◽  
Vol 25 (3) ◽  
pp. 219-228 ◽  
Author(s):  
Janet S. Dufek ◽  
John A. Mercer ◽  
Janet R. Griffin
Keyword(s):  
Lower Extremity ◽  
Ground Contact ◽  
Shock Attenuation ◽  
Male And Female ◽  
Surface Conditions ◽  
Explained Variance ◽  
Recreational Runners ◽  
Impact Acceleration ◽  
Definition Of ◽  
Attenuation Characteristics

The purpose of the study was to examine the effects of running speed and surface compliance on shock attenuation (SA) characteristics for male and female runners. We were also interested in identifying possible kinematic explanations, specifically, kinematics of the lower extremity at foot-ground contact, for anticipated gender differences in SA. Fourteen volunteer recreational runners (7 male, 7 female) ran at preferred and slow speeds on an adjustable bed treadmill, which simulated soft, medium, and hard surface conditions. Selected kinematic descriptors of lower extremity kinematics as well as leg and head peak impact acceleration values were obtained for 10 left leg contacts per subject-condition. Results identified significant SA values between genders across conditions and more specifically, across surfaces for females, with male runners demonstrating a similar trend. Regression modeling to predict SA by gender for surface conditions elicited unremarkable results, ranging from 30.9 to 59.9% explained variance. It appears that surface compliance does affect SA during running; however, the runner’s ability to dissipate the shock wave may not be expressly explained by our definition of lower extremity kinematics at contact.

scholarly journals Differences Between Men and Women in Balance and Tremor in Relation to Plantar Fascia Laxity During the Menstrual Cycle

2018 ◽  
Vol 53 (3) ◽  
pp. 255-261 ◽  
Author(s):  
Haneul Lee ◽  
Jerrold Petrofsky
Keyword(s):  
Menstrual Cycle ◽  
Case Control Study ◽  
Outcome Measure ◽  
Postural Sway ◽  
Plantar Fascia ◽  
Force Platform ◽  
Lower Extremity Injuries ◽  
Sport Activities ◽  
Extremity Injuries ◽  
Control Study

Context:  Although much attention has been paid to the effect of estrogen on the knee ligaments, little has been done to examine the ligaments in the foot, such as the plantar fascia, and how they may be altered during the menstrual cycle. Objective:  To (1) examine sex differences in plantar fascia thickness and laxity and postural sway and (2) identify any menstrual cycle effects on plantar fascia laxity, postural sway, and neuromuscular tremor between menstruation and the ovulation phase. Design:  Case-control study. Setting:  Research laboratory. Patients or Other Participants:  Fifteen healthy women (age = 25.9 ± 1.8 years) and 15 healthy men (age = 27.3 ± 2.0 years) volunteered to participate in this study. Intervention(s):  We asked participants to perform 8 balance tasks on a force platform while we assessed postural sway and tremor. Main Outcome Measure(s):  Plantar fascia length and thickness unloaded and loaded with body weight were measured via ultrasound. Postural sway and tremor were measured using a force platform. Results:  Plantar fascia length and thickness with pressure were greater in ovulating women compared with men (P < .001), but no differences were found between women during menstruation and men. Postural sway and tremor were greater at ovulation than during menstruation (P < .05), and men had less sway than ovulating women on the 3 most difficult balance tasks (P < .01). Conclusions:  Plantar fascia laxity was increased and postural sway and tremor were decreased at ovulation compared with menstruation in women. Postural sway and tremor in men were the same as in women during menstruation. These findings support the need to be aware of the effect of sex hormones on balance to prevent lower extremity injuries during sport activities.

scholarly journals The Impact of the Helmet-Lowering Rule on Regular Season NFL Injuries

2020 ◽  
Vol 8 (7_suppl6) ◽  
pp. 2325967120S0040
Author(s):  
Erik Stapleton ◽  
Randy Cohn ◽  
Colin Burgess
Keyword(s):  
Relative Risk ◽  
Lower Extremity ◽  
Risk Reduction ◽  
Injury Risk ◽  
National Football League ◽  
Head Injuries ◽  
Lower Extremity Injuries ◽  
Extremity Injuries ◽  
The Impact ◽  
Rule Implementation

Objectives: The National Football League (NFL) has been under growing scrutiny from the public due to the apparent rise in concussions and head injuries and the subsequent deleterious effects. In efforts to address these concerns, the NFL implemented a new “Helmet-lowering” rule prior to the 2018-2019 season. This rule is defined as “a foul if a player lowers his head to initiate and make contact with his helmet against an opponent.” The purpose of this paper was to compare incidence of injuries in NFL players prior to and after implementation of this new rule. Methods: NFL injury data was retrospectively reviewed from public league records for all players in regular season games played from the 2017 and 2018 NFL seasons. An injury was defined as any player listed on a team’s injury report that was not previously documented on the team’s report one week preceding the index injury. Injury rates were reported as the number of injuries per 1000 athletic exposures (AE’s). Athletic exposures were defined as equal to the sum of the total number of NFL regular-season games played. Relative risk (with 95% CI) was calculated by using the number of injuries per 1000 athletic exposures for the season before and after the new rule implementation. Risk reduction was then calculated for the overall injuries, upper/lower extremity and head injuries. Results: Over the 2 seasons there were a total of 2,774 injuries identified. After rule implementation at the beginning of the 2018 season, there was an overall relative risk (RR) of 0.91 for injury (95% CI 0.88 to 0.95, p<0.0001), with an injury risk reduction of 8.73%. Upper extremity injuries had a RR of 0.76 (95% CI 0.65 to 0.87, p=0.0005) and a risk reduction of 24.10%. Lower extremity injuries had a RR of 0.91 (95% CI 0.87 to 0.96, p=0.0005) with a risk reduction of 8.63%. In concussions and head injuries there was an overall RR of 0.55 for injury (95% CI 0.44 to 0.69, p<0.0001), with an injury risk reduction of 45.10%. Wide receivers and linebackers were most commonly injured players on offense and defense, respectively. Conclusion: Implementation of the new Helmet-Lowering rule seems to have played a role in significantly decreasing the NFL athlete’s risk of injury across all measures, most notably in concussion and head injuries.

Pedestrian Collision Responses Using Legform Impactor Subsystem and Full-Sized Pedestrian Model on Different Workbenches

2018 ◽  
Author(s):  
Obaidur Rahman Mohammed ◽  
Shabbir Memon ◽  
Hamid M. Lankarani
Keyword(s):  
Fe Model ◽  
Finite Model ◽  
Lower Extremity Injuries ◽  
Full Size ◽  
Pedestrian Impact ◽  
Extremity Injuries ◽  
Multi Body ◽  
Impact Simulations ◽  
The Impact ◽  
Pedestrian Collisions

Car-pedestrian collision fatalities have been reported for a significant number of roadside accidents around the world. In order to reduce the lower extremity injuries in car-pedestrian collisions, it is important to determine the impact forces on the pedestrian and conditions that the car frontal side impacts on the lower extremities of the pedestrian. The Working Group 17 (WG17) of the European Enhanced Vehicle-safety Committee (EEVC) has developed a legform subsystem impactor and procedure for assessing pedestrian collisions and potential injuries. This research describes a methodology for the evaluation of the legform impactor kinematics after a collision utilizing finite element (FE) models of the legform and cars and comparing the simulation results with the ones from a multi-body legform model as well as a 50th percentile male human pedestrian model responses. Two approaches are carried out in the process. First, the collision strike simulations with the FE model using an FE lower legform is considered and validated against the EVVC/WG17 regulation criteria. Secondly, the collision strike simulations with a multi-body legform and an ellipsoidal multi-body car model are conducted to compare the responses from the FE model and the multi-body model. The results from the impact simulations of FE legform and the multi-body legform are also compared with the ones from a full-size pedestrian model at constant speeds. All the models and simulation in this are using the LS-DYNA nonlinear FE code, while the multibody legform, car, and full-sized pedestrian models are developed and evaluated in MADYMO. The results from this study demonstrate the differences between the subsystem legform and the full-size pedestrian responses as well as suitability of various FE and multibody models related to pedestrian impact responses. Different workbenches comparisons with finite model and ellipsoidal models gives more better correlation to this research.

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