Association Between Impact Peak and Hip Flexor Activity During Running

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.

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Rectus-sparing approach to the periacetabular osteotomy in adolescents preserves hip flexion strength

Journal of Children s Orthopaedics ◽

10.1302/1863-2548.14.190168 ◽

2020 ◽

Vol 14 (3) ◽

pp. 208-212

Author(s):

David A. Podeszwa ◽

Kirsten Tulchin-Francis ◽

Adriana De La Rocha ◽

DeRaan Collins ◽

Daniel J. Sucato

Keyword(s):

Periacetabular Osteotomy ◽

Rectus Femoris ◽

Harris Hip Score ◽

Level Of Evidence ◽

One Year ◽

Modified Harris Hip Score ◽

Hip Flexion ◽

Hip Flexor ◽

Flexion Strength ◽

Flexor Strength

Purpose The classic periacetabular osteotomy (PAO) approach can result in hip flexor weakness in adolescents. The rectus-sparing approach (PAO-RS) preserves the origin of the rectus femoris tendon which may prevent hip flexor weakness and improve functional outcome. Methods This is a prospective analysis of adolescents treated with a PAO or PAO-RS. The PAO group included 24 hips/21 patients (18 female, meanage 16 years (sd 4)); the PAO-RS group included ten hips (eight female, mean age 16 years (sd 1)). Preoperatively, the PAO group had decreased hip flexion strength compared with the PAO-RS group (83 Nm/kg versus 102 Nm/kg). A subset of PAO patients (n = 13 hips/12 patients, nine female, mean age 15 years (sd 3)) were matched for preoperative flexion strength to the PAO-RS group. Radiographic parameters, modified Harris hip score (mHHS), isokinetic hip strength and instrumented motion analysis preoperatively, six months and one-year postoperatively were compared. Results There were no differences in preoperative deformity, postoperative correction or degree of correction between groups. Hip flexor strength decreased significantly at six months in the PAO group compared with the PAO-RS group (-35 Nm/kg versus -7 Nm/kg; p = 0.012), as did hip flexion pull-off power (1.33 W/kg PAO versus 1.76 W/kg PAO-RS; p = 0.010). Hip flexion strength improved from six months to one year in the PAO group, with no significant differences in strength at one year between groups (80 Nm/kg versus 90 Nm/kg). There were no differences between groups in mHHS any time point; both groups improved significantly postoperatively. Conclusion Preserving the rectus femoris may lead to improved short-term hip flexor strength and pull-off power. Further assessment at long-term follow-up is needed to determine if this strength leads to improved functional outcomes. Level of Evidence II

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Relevance of Frequency-Domain Analyses to Relate Shoe Cushioning, Ground Impact Forces and Running Injury Risk: A Secondary Analysis of a Randomized Trial With 800+ Recreational Runners

Frontiers in Sports and Active Living ◽

10.3389/fspor.2021.744658 ◽

2021 ◽

Vol 3 ◽

Author(s):

Laurent Malisoux ◽

Paul Gette ◽

Anne Backes ◽

Nicolas Delattre ◽

Jan Cabri ◽

...

Keyword(s):

Frequency Domain ◽

High Frequency ◽

Injury Risk ◽

Peak Force ◽

Recent Trial ◽

Frequency Signal ◽

High Frequency Signal ◽

Impact Forces ◽

Impact Peak ◽

Force Characteristics

Cushioning systems in running shoes are used assuming that ground impact forces relate to injury risk and that cushioning materials reduce these impact forces. In our recent trial, the more cushioned shoe version was associated with lower injury risk. However, vertical impact peak force was higher in participants with the Soft shoe version. The primary objective of this study was to investigate the effect of shoe cushioning on the time, magnitude and frequency characteristics of peak forces using frequency-domain analysis by comparing the two study groups from our recent trial (Hard and Soft shoe group, respectively). The secondary objective was to investigate if force characteristics are prospectively associated with the risk of running-related injury. This is a secondary analysis of a double-blinded randomized trial on shoe cushioning with a biomechanical running analysis at baseline and a 6-month follow-up on running exposure and injury. Participants (n = 848) were tested on an instrumented treadmill at their preferred running speed in their randomly allocated shoe condition. The vertical ground reaction force signal for each stance phase was decomposed into the frequency domain using the discrete Fourier transform. Both components were recomposed into the time domain using the inverse Fourier transform. An analysis of variance was used to compare force characteristics between the two study groups. Cox regression analysis was used to investigate the association between force characteristics and injury risk. Participants using the Soft shoes displayed lower impact peak force (p < 0.001, d = 0.23), longer time to peak force (p < 0.001, d = 0.25), and lower average loading rate (p < 0.001, d = 0.18) of the high frequency signal compared to those using the Hard shoes. Participants with low average and instantaneous loading rate of the high frequency signal had lower injury risk [Sub hazard rate ratio (SHR) = 0.49 and 0.55; 95% Confidence Interval (CI) = 0.25–0.97 and 0.30–0.99, respectively], and those with early occurrence of impact peak force (high frequency signal) had greater injury risk (SHR = 1.60; 95% CI = 1.05–2.53). Our findings may explain the protective effect of the Soft shoe version previously observed. The present study also demonstrates that frequency-domain analyses may provide clinically relevant impact force characteristics.Clinical Trial Registration:https://clinicaltrials.gov/, identifier: 9NCT03115437.

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Impact testing of snowboarding wrist protectors

Proceedings of the Institution of Mechanical Engineers Part P Journal of Sports Engineering and Technology ◽

10.1177/17543371211054752 ◽

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.

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Unique method for analysing pressure distribution accross the knuckles during boxing

10.7287/peerj.preprints.917v1 ◽

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.

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Characteristics of Contact Force and Muscle Activation During Choreographed Falls With 2 Common Landing Techniques in Contemporary Dance

Journal of Applied Biomechanics ◽

10.1123/jab.2018-0081 ◽

2019 ◽

Vol 35 (4) ◽

pp. 256-262

Author(s):

Chad Van Ramshorst ◽

Woochol Joseph Choi

Keyword(s):

Muscle Activation ◽

Plantar Flexion ◽

Knee Injuries ◽

Rectus Femoris ◽

Gluteus Medius ◽

Contact Forces ◽

Contemporary Dance ◽

Maximal Voluntary Isometric Contraction ◽

Collegiate Level ◽

Hip Flexion

This study investigated the contact forces and muscle activation during 2 choreographed fall techniques in contemporary dancers and how these were affected by the fall technique. Ten collegiate-level dancers were instructed in 2 choreographed falls: (1) an anteriorly focused fall involving ankle plantar flexion, knee flexion, and hip flexion with dispersion of forces up the anterior surface of the shank (technique 1) and (2) a laterally focused fall involving inversion at the ankle with dispersion of forces up the lateral aspect of the shank (technique 2). The knee and hip contact forces were 26.3% smaller (technique 1: 1743 N vs technique 2: 1284 N) and 24.1% greater (technique 1: 1334 N vs technique 2: 1656 N), respectively, in technique 2 (P < .03). At the time of knee contact, percentage of maximal voluntary isometric contraction (%MVIC) was 45.8% greater for rectus femoris muscle (technique 1: 7.2% vs technique 2: 10.5%) and 96.9% greater for gluteus medius muscle (technique 1: 3.2% vs technique 2: 6.3%) (P < .01) in technique 2. The results provide insight into determining safer landing strategies to avoid knee injuries in individuals who experience a fall (ie, dancers, athletes, and older adults).

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Unique method for analysing pressure distribution accross the knuckles during boxing

10.7287/peerj.preprints.917 ◽

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.

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Transport and Chronic Injuries Caused by Improper Use of Cell Phones：Evidences from 41 Studies (Preprint)

10.2196/preprints.21313 ◽

2020 ◽

Author(s):

Xinxi Cao ◽

Yangyang Cheng ◽

Chenjie Xu ◽

Yabing Hou ◽

Hongxi Yang ◽

...

Keyword(s):

Human Body ◽

Cell Phone ◽

Injury Risk ◽

Negative Impact ◽

Mental Disease ◽

Cell Phones ◽

Cell Phone Use ◽

Improper Use ◽

Chronic Injuries ◽

The Impact

BACKGROUND Cell phone use brought convenience to people, but using phones for a long period of time or in the wrong way and with a wrong posture might cause damage to the human body. OBJECTIVE To assess the impact of improper cell phone use on transport and chronic injuries. METHODS Studies were systematically searched in PubMed, EMBASE, Cochrane, and Web of Science up to April 4, 2019 and relevant reviews were searched to identify additional studies. A random-effects model was used to estimate the overall pooled estimates. RESULTS Cell phone users were at a higher risk for transport injuries (RR: 1.37, 95%CI: 1.221.55), long-term use of cell phones increased the transport injury risk to non-use or short-term use (RR: 2.10, 95% CI: 1.632.70). Neoplasm risk caused by cell phone use was 1.07 times that of non-use (95% CI: 1.011.14); Compared with non-use, cell phone use had a higher risk of eye disease, with a risk of 2.03 (95% CI: 1.273.23), the risk of mental disease was 1.26 (95% CI: 1.171.35), the risk of neurological disorder was 1.16 (95% CI: 1.021.32), and a pooled risk of other chronic injuries was 1.20 (95% CI: 0.981.59). CONCLUSIONS Cell phone use at inappropriate situations has a negative impact on the human body. Therefore, it is necessary to use cell phones correctly and reasonably.

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