Effect of Upper and Lower Extremity Control Strategies on Predicted Injury Risk During Simulated Forward Falls: A Study in Healthy Young Adults

2008 ◽  
Vol 130 (4) ◽  
Author(s):  
JiaHsuan Lo ◽  
James A. Ashton-Miller
Keyword(s):  
Kinetic Energy ◽  
Injury Risk ◽  
Impact Force ◽  
The Body ◽  
Whole Body ◽  
Joint Control ◽  
Negative Work ◽  
Impact Forces ◽  
Hip Flexion ◽  
The Impact

Fall-related wrist fractures are common at any age. We used a seven-link, sagittally symmetric, biomechanical model to test the hypothesis that systematically alterations in the configuration of the body during a forward fall from standing height can significantly influence the impact force on the wrists. Movement of each joint was accomplished by a pair of agonist and antagonist joint muscle torque actuators with assigned torque-angle, torque-velocity, and neuromuscular latency properties. Proportional-derivative joint controllers were used to achieve desired target body segment configurations in the pre- and∕or postground contact phases of the fall. Outcome measures included wrist impact forces and whole-body kinetic energy at impact in the best, and worst, case impact injury risk scenarios. The results showed that peak wrist impact force ranged from less than 1kN to more than 2.5kN, reflecting a fourfold difference in whole-body kinetic energy at impact (from less than 40J to more than 160J) over the range of precontact hip and knee joint angles used at impact. A reduction in the whole-body kinetic energy at impact was primarily associated with increasing negative work associated with hip flexion. Altering upper extremity configuration prior to impact significantly reduced the peak wrist impact force by up to 58% (from 919Nto2212N). Increased peak wrist impact forces associated greater shoulder flexion and less elbow flexion. Increasing postcontact arm retraction can reduce the peak wrist impact force by 28% (from 1491Nto1078N), but postcontact hip and knee rotations had a relatively small effect on the peak wrist impact force (8% reduction; from 1411Nto1303N). In summary, the choice of the joint control strategy during a forward fall can significantly affect the risk of wrist injury. The most effective strategy was to increase the negative work during hip flexion in order to dissipate kinetic energy thereby reducing the loss in potential energy prior to first impact. Extended hip or elbow configurations should be avoided in order to reduce forearm impact forces.

scholarly journals Effective Formula for Impact Damping Ratio for Simulation of Earthquake-induced Structural Pounding

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 347 ◽  
Author(s):  
Seyed Mohammad Khatami ◽  
Hosein Naderpour ◽  
Rui Carneiro Barros ◽  
Anna Jakubczyk-Gałczyńska ◽  
Robert Jankowski
Keyword(s):  
Kinetic Energy ◽  
Impact Force ◽  
Damping Ratio ◽  
Dissipated Energy ◽  
Force Model ◽  
Single Collision ◽  
Structural Pounding ◽  
Impact Forces ◽  
The Impact ◽  
Impact Damping

Structural pounding during earthquakes may cause substantial damage to colliding structures. The phenomenon is numerically studied using different models of collisions. The aim of the present paper is to propose an effective formula for the impact damping ratio, as a parameter of the impact force model used to study different problems of structural pounding under seismic excitations. Its accuracy has been verified by four various approaches. Firstly, for the case of collisions between two structural elements, the dissipated energy during impact has been compared to the loss of kinetic energy. In the second stage of verifications, the peak impact forces during single collision have been analyzed. Then, the accuracy of different equations have been verified by comparing the impact force time histories for the situation when a concrete ball is dropped on a rigid concrete surface. Finally, pounding between two structures during earthquakes has been studied. The results of the analysis focused on comparison between dissipated and kinetic energy show relatively low errors between calculated and assumed values of the coefficient of restitution when the proposed equation is used. In addition, the results of the comparison between experimentally and numerically determined peak impact forces during single collision confirm the effectiveness of the approach. The same conclusion has been obtained for the whole impact time history for collision between a ball and a rigid surface. Finally, the results of the comparative analysis, conducted for pounding between two structures during an earthquake, confirm the simulation accuracy when the proposed approach is used. The above conclusions indicate that the proposed formula for impact damping ratio, as a parameter of impact force model for simulation of earthquake-induced structural pounding, is very effective and accurate in numerical simulations in the case of different scenarios.

Association Between Impact Peak and Hip Flexor Activity During Running

2016 ◽  
Author(s):  
Anne Schmitz ◽  
Jaclyn Norberg ◽  
Kristen Snarski ◽  
Davide Piovesan
Keyword(s):  
Injury Risk ◽  
Rectus Femoris ◽  
Gluteus Medius ◽  
Gait Retraining ◽  
Impact Forces ◽  
Impact Peak ◽  
Flexion Moment ◽  
Hip Flexion ◽  
The Impact ◽  
Hip Flexor

Gait retraining techniques to reduce impact forces during running is of significant interest to clinicians interested in reducing running injury risk. Increased peak rectus femoris activity during swing was significantly correlated with decreased impact peak during running (r = −0.654, p = 0.01) due to the muscle’s large hip flexion moment arm (43 to 54 mm). Gluteus medius (r = −0.204, p = 0.466) and adductor longus (r = 0.104, p = 0.714) activity were not significantly correlated with impact peak. These results suggest that gait retraining programs aimed at reducing the impact peak during running should focus on increased rectus femoris activity during swing.

scholarly journals Impact testing of snowboarding wrist protectors

2021 ◽  
pp. 175433712110547
Author(s):  
Caroline Adams ◽  
Tom Allen ◽  
Terry Senior ◽  
David James ◽  
Nick Hamilton
Keyword(s):  
Injury Risk ◽  
Impact Force ◽  
Impact Testing ◽  
Finite Element Models ◽  
Vertical Force ◽  
Test Device ◽  
Wrist Extension ◽  
Impact Forces ◽  
Pendulum Test ◽  
The Impact

The wrist is a common injury site for snowboarders who often fall onto an outstretched hand. Wrist protectors are worn by some snowboarders to prevent wrist injuries by attenuating impact forces and limiting wrist extension. This paper presents a bespoke pendulum test device for impacting wrist protectors when fitted to a wrist surrogate. The rig can replicate injury risk scenarios, while measuring temporal forces and wrist extension angles. Results from testing 12 snowboarding wrist protectors are presented, including differences in peak vertical force, the time to reach this peak, and energy absorption between products. When compared to an unprotected surrogate, all 12 products lowered the peak force by at least 24% and increased the time to reach this peak by at least 1.8 times. Due to the severity of the load case employed, none of the products lowered the impact force below 2.8 kN, which is the value presented in the literature to fracture a cadaveric wrist. The developed rig could be used to support the development of new wrist protectors, as well as the development of finite element models for predicting wrist protector performance.

scholarly journals Unique method for analysing pressure distribution accross the knuckles during boxing

2015 ◽  
Author(s):  
Mike Loosemore ◽  
Joseph Lightfoot ◽  
Jay Meswania ◽  
Chris Beardsley
Keyword(s):  
Injury Risk ◽  
Impact Force ◽  
Reliability And Validity ◽  
Distribution Patterns ◽  
Stationary Target ◽  
Impact Forces ◽  
Within Subjects ◽  
The Individual ◽  
The Impact ◽  
Proportional Distribution

Objectives: The hand is commonly injured in boxing but it is not clear why some athletes sustain hand injuries while others do not. It is possible that there are differences in the distribution of impact forces at the knuckle during punching between athletes and that certain distribution patterns may be predictive of increased injury risk. We developed a method of analysing the distribution of impact forces at the knuckle during punching using pressure film. Pressure film allows a calculation of the distribution and magnitude of pressure and force between any two surfaces that come into contact. Methods: Pressure film was inserted into the gloves of three male subjects prior to punching a stationary target. After each punch, the pressure film was removed and analysed to determine the distribution of the impact force during each punch across each of the four knuckles. Punches were repeated multiple times for each subject. The proportional distribution of the impact force during punches was compared between knuckles and within subjects. Results: The proportional distribution of the impact force exerted during punches was significantly different between knuckles and within subjects (p < 0.05). Knuckle 2 displayed the largest proportion of impact forces while knuckle 3 displayed the smallest proportion of impact forces. Conclusions: Pressure film inserted into boxing gloves can be used to analyse the distribution of impact forces across the knuckles during punching. Further work is needed to confirm the reliability and validity of the technique and establish whether there is an association between the impact forces at the individual knuckles and hand injury risk during boxing.

Vertical Impact Forces during Bench-Step Aerobics: Exercise Rate and Experience

1997 ◽  
Vol 84 (1) ◽  
pp. 267-274 ◽  
Author(s):  
M. Scharff-Olson ◽  
H. N. Williford ◽  
D. L. Blessing ◽  
R. Moses ◽  
T. Wang
Keyword(s):  
Body Weight ◽  
Impact Force ◽  
The Body ◽  
Distinctive Pattern ◽  
Novice Group ◽  
Impact Forces ◽  
Force Curves ◽  
The Mean ◽  
The Impact ◽  
Vertical Impact

The purpose of this study was to determine the effects of two bench-step exercise speeds on vertical impact forces and to explore this variable between novices and instructors. 12 women (mean age 24 yr.) randomly performed 8-min. protocols of the “basic” bench-stepping technique and a more advanced “travel” technique at 30 and 33 cycles · min.−1. Analysis showed that the faster exercise rate yielded significantly higher vertical impact forces on a reference (B-8) step height (20.3 cm). At 33 cycles · min.−1, the instructors' and novices' responses were both higher than those at 30 cycles · min.−1. The mean peak vertical impact force ranged from 1.54 times the body weight for the novice group at 30 cycles · min.−1 to 1.87 times the body weight for instructors at 33 cycles · min.−1. A comparison of the groups' force curves showed a distinctive pattern in the loading of the impact forces. Specifically, the instructors consistently produced a transitory decrement in force prior to attaining peak force. In addition, the novices exhibited nonuniform increases in the production of vertical impact force across other step heights at the faster (33 cycles · min.−1) speed. Thus, experience with bench-step exercise may afford an ability to make uniform and force-absorbing adjustments in the resultant vertical impact forces at increased speeds.

Identification of the most effective muscles in landing impact forces

2021 ◽  
pp. 175433712110324
Author(s):  
Marzieh Mojaddarasil ◽  
Mohammad Jafar Sadigh ◽  
Sayed Jalal Zahabi
Keyword(s):  
Lower Limb ◽  
Muscle Activation ◽  
Impact Force ◽  
Experimental Tests ◽  
The Body ◽  
Promising Tool ◽  
Impact Forces ◽  
Drop Landing ◽  
The Impact

The aim of this study was to evaluate the role of the main lower limb muscles in increasing or decreasing each lower limb joint impact force during drop landing. To do so, the body was modeled by a four-link musculoskeletal model consisting of eight main Hill-type muscles. Different drop landing scenarios were modeled by changing the activation levels of the considered muscles. In each landing simulation, the impact GRF and impact joint forces were obtained. In order to compare and rank the muscles with respect to their effect on each impact force, a computationally feasible zero-one (off-on) muscle activation analysis was proposed. The proposed approach revealed important features regarding the relation between different impact forces and muscle activations. Specifically, the results can be interpreted in terms of the role that each muscle potentially plays in causing or preventing certain injuries. Moreover, the results obtained from the analysis were further used to classify the muscles into four categories, depending on the effect they have on each impact force. The proposed theoretical analysis is seen to be a promising tool in predicting the role of muscles and their order of importance in the generation of lower limb impact forces in landing, without the need for experimental tests.

scholarly journals Unique method for analysing pressure distribution accross the knuckles during boxing

2015 ◽  
Author(s):  
Mike Loosemore ◽  
Joseph Lightfoot ◽  
Jay Meswania ◽  
Chris Beardsley
Keyword(s):  
Injury Risk ◽  
Impact Force ◽  
Reliability And Validity ◽  
Distribution Patterns ◽  
Stationary Target ◽  
Impact Forces ◽  
Within Subjects ◽  
The Individual ◽  
The Impact ◽  
Proportional Distribution

Objectives: The hand is commonly injured in boxing but it is not clear why some athletes sustain hand injuries while others do not. It is possible that there are differences in the distribution of impact forces at the knuckle during punching between athletes and that certain distribution patterns may be predictive of increased injury risk. We developed a method of analysing the distribution of impact forces at the knuckle during punching using pressure film. Pressure film allows a calculation of the distribution and magnitude of pressure and force between any two surfaces that come into contact. Methods: Pressure film was inserted into the gloves of three male subjects prior to punching a stationary target. After each punch, the pressure film was removed and analysed to determine the distribution of the impact force during each punch across each of the four knuckles. Punches were repeated multiple times for each subject. The proportional distribution of the impact force during punches was compared between knuckles and within subjects. Results: The proportional distribution of the impact force exerted during punches was significantly different between knuckles and within subjects (p < 0.05). Knuckle 2 displayed the largest proportion of impact forces while knuckle 3 displayed the smallest proportion of impact forces. Conclusions: Pressure film inserted into boxing gloves can be used to analyse the distribution of impact forces across the knuckles during punching. Further work is needed to confirm the reliability and validity of the technique and establish whether there is an association between the impact forces at the individual knuckles and hand injury risk during boxing.

Influence of Attached Masses on Impact Forces and Running Style in Heel-Toe Running

1987 ◽  
Vol 3 (3) ◽  
pp. 264-275 ◽  
Author(s):  
Alexander Bahlsen ◽  
Benno M. Nigg
Keyword(s):  
Body Mass ◽  
High Speed ◽  
Impact Force ◽  
Force Plate ◽  
The Body ◽  
Additional Mass ◽  
Impact Forces ◽  
Running Shoes ◽  
High Speed Film ◽  
Vertical Impact

Impact forces analysis in heel-toe running is often used to examine the reduction of impact forces for different running shoes and/or running techniques. Body mass is reported to be a dominant predictor of vertical impact force peaks. However, it is not evident whether this finding is only true for the real body mass or whether it is also true for additional masses attached to the body (e.g., running with additional weight or heavy shoes). The purpose of this study was to determine the effect of additional mass on vertical impact force peaks and running style. Nineteen subjects (9 males, 10 females) with a mean mass of 74.2 kg/56.2 kg (SD = 10.0 kg and 6.0 kg) volunteered to participate in this study. Additional masses were attached to the shoe (.05 and .1 kg), the tibia (.2, .4, .6 kg), and the hip (5.9 and 10.7 kg). Force plate measurements and high-speed film data were analyzed. In this study the vertical impact force peaks, Fzi, were not affected by additional masses, the vertical active force peaks, Fza, were only affected by additional masses greater than 6 kg, and the movement was only different in the knee angle at touchdown, ϵ0, for additional masses greater than .6 kg. The results of this study did not support findings reported earlier in the literature that body mass is a dominant predictor of external vertical impact force peaks.

The Effects of Upstream Flexible Barrier on the Debris Flow Entrainment and Impact Dynamics on a Terminal Barrier

2021 ◽  
Author(s):  
Hervé Vicari ◽  
C.W.W. Ng ◽  
Steinar Nordal ◽  
Vikas Thakur ◽  
W.A. Roanga K. De Silva ◽  
...  
Keyword(s):  
Debris Flow ◽  
Debris Flows ◽  
Impact Force ◽  
Dynamic Pressure ◽  
Pressure Coefficient ◽  
Flexible Barrier ◽  
Impact Forces ◽  
Flexible Barriers ◽  
The Impact ◽  
Bed Entrainment

The destructive nature of debris flows is mainly caused by flow bulking from entrainment of an erodible channel bed. To arrest these flows, multiple flexible barriers are commonly installed along the predicted flow path. Despite the importance of an erodible bed, its effects are generally ignored when designing barriers. In this study, three unique experiments were carried out in a 28 m-long flume to investigate the impact of a debris flow on both single and dual flexible barriers installed in a channel with a 6 m-long erodible soil bed. Initial debris volumes of 2.5 m<sup>3</sup> and 6 m<sup>3</sup> were modelled. For the test setting adopted, a small upstream flexible barrier before the erodible bed separates the flow into several surges via overflow. The smaller surges reduce bed entrainment by 70% and impact force on the terminal barrier by 94% compared to the case without an upstream flexible barrier. However, debris overflowing the deformed flexible upstream barrier induces a centrifugal force that results in a dynamic pressure coefficient that is up to 2.2 times higher than those recommended in guidelines. This suggests that although compact upstream flexible barriers can be effective for controlling bed entrainment, they should be carefully designed to withstand higher impact forces.

scholarly journals Comparison of branded rugby headguards on their effectiveness in reducing impact on the head

2018 ◽  
Vol 4 (1) ◽  
pp. e000361 ◽  
Author(s):  
Erin R A Frizzell ◽  
Graham P Arnold ◽  
Weijie Wang ◽  
Rami J Abboud ◽  
Tim S Drew
Keyword(s):  
Impact Force ◽  
Linear Acceleration ◽  
Baseline Measurement ◽  
Peak Acceleration ◽  
Impact Forces ◽  
Impact Attenuation ◽  
The Mean ◽  
Force Reduction ◽  
The Right ◽  
The Impact

AimTo compare the available brands of rugby headguards and evaluate their impact attenuation properties at various locations on the cranium, with regard to concussion prevention.MethodsSeven different branded headguards were fitted onto a rigid headform and drop-tested in three different positions. An accelerometer measured the linear acceleration the headform experienced on impact with the ground. Each test involved dropping the headform from a height that generated 103.8 g on average when bare, which is the closest acceleration to the upper limit of the concussion threshold of 100 g. A mean peak acceleration for each drop position was calculated and compared with the bare baseline measurement.ResultsEach headguard demonstrated a significant decrease in the mean peak acceleration from the baseline value (all p≤0.01). Overall the Canterbury Ventilator was the most effective headguard, decreasing the impact force on average by 47%. The least effective was the XBlades Elite headguard, averaging a force reduction of 27%. In five of the seven headguards, the right side of the headwear was the most effective at reducing impact force.ConclusionOverall, the results indicate that it would be beneficial to wear a headguard during rugby in order to reduce the impact forces involved in head collisions. There was also a clear difference in performance between the tested brands, establishing the Canterbury headguard as the most effective. However, only one model of headguard from each brand was tested, so further research evaluating all other models should be considered.

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