scholarly journals Maintenance of ankle power and decreased inter-limb asymmetry during sprint running in fatigued multi-speed athletes

2021 ◽  
Author(s):  
Shayne Vial ◽  
Jodie Cochrane Wilkie ◽  
Mitchell Turner ◽  
Anthony J Blazevich
Keyword(s):  
Injury Risk ◽  
Reaction Force ◽  
Force Production ◽  
Knee Joints ◽  
Horizontal Force ◽  
Running Speed ◽  
Sprint Running ◽  
Limb Asymmetry ◽  
Hip Flexion ◽  
Distal Joint

The ability to shift from walking and jogging to sprinting gaits, even when fatigued after prolonged effort, would have been as useful to our hunter-gatherer ancestors as it is in modern day sports. During prolonged jogging, joint moment and work are reduced in the distal (ankle) joint but increased at proximal (hip/knee) joints as fatigue progresses, and might be expected to occur in sprinting. Fatigue is also thought to increase inter-limb kinematic and force production asymmetries, which are speculated to influence injury risk. However, the effects of running-related fatigue on sprint running gait have been incompletely studied, so these hypotheses remain untested. We studied 3-D kinematics and ground reaction force production in dominant (DL) and non-dominant (NDL) legs during both non-fatigued and fatigue sprinting in habitual but uncoached running athletes. Contrary to the tested hypotheses, relative between-leg differences were greater in non-fatigued than fatigued sprinting. When not fatigued, DL produced greater propulsive impulse through both greater positive and negative work being performed at the ankle, whilst NDL produced more vertical impulse, possibly resulting from the greater hip flexion observed prior to the downwards acceleration of the foot towards the ground. Whilst few changes were detected in DL once fatigued, NDL shifted towards greater horizontal force production, largely resulting from an increase in plantarflexion (distal-joint) moments and power. After fatiguing running, therefore, inter-limb asymmetry was reduced and no distal-to-proximal shift in work/power was detected during sprinting. Speculatively, these adaptations may help to attenuate decreases in running speed whilst minimising injury risk.

Selected Kinematic Patterns of Visually Impaired Youth in Sprint Running

1985 ◽  
Vol 2 (3) ◽  
pp. 206-213 ◽  
Author(s):  
Robert W. Arnhold ◽  
Peter McGrain
Keyword(s):  
Regression Analysis ◽  
Visually Impaired ◽  
Recovery Phase ◽  
Running Speed ◽  
Sprint Running ◽  
Joint Range Of Motion ◽  
Hip Flexion ◽  
Sprinting Speed ◽  
Joint Range ◽  
Hip Extension

The purpose of this study was to determine which set of selected kinematic variables affected the speed of visually impaired residential youth in the sprint run. The subjects were 27 students, 16 males and 11 females, between the ages of 9.4 and 16.4 years. Film data were collected during two trials of the 50-m dash. A Fortran computer program produced nine variables from these digitized data. A multiple regression analysis was performed on the variables using running speed as the dependent variable. Results of a correlation matrix yielded five variables with significant bivariate correlations to running speed. Results of a regression analysis indicated that the cycle length and hip joint range of motion had significant effects on running speed. Implications for an increase in sprinting speed include increasing stride length via the generation of greater hip extension during the drive phase and a greater hip flexion during the recovery phase of sprint running.

scholarly journals Sprint Specificity of Isolated Hamstring-Strengthening Exercises in Terms of Muscle Activity and Force Production

2021 ◽  
Vol 2 ◽  
Author(s):  
Caroline Prince ◽  
Jean-Benoît Morin ◽  
Jurdan Mendiguchia ◽  
Johan Lahti ◽  
Kenny Guex ◽  
...  
Keyword(s):  
Muscle Activity ◽  
Production Capacity ◽  
Force Production ◽  
Electromyographic Activity ◽  
Horizontal Force ◽  
Hamstring Muscle ◽  
Strengthening Exercises ◽  
Hip Flexion ◽  
Production Capacities ◽  
Hip Extension

To train hamstring muscle specifically to sprint, strengthening programs should target exercises associated with horizontal force production and high levels of hamstring activity. Therefore, the objectives of this study were to analyze the correlation between force production capacities during sprinting and hamstring strengthening exercises, and to compare hamstring muscle activity during sprinting and these exercises. Fourteen track and field regional level athletes performed two maximal 50-m sprints and six strengthening exercises: Nordic hamstring exercises without and with hip flexion, Upright-hip-extension in isometric and concentric modalities, Standing kick, and Slide-leg-bridge. The sprinting horizontal force production capacity at low (F0) and high (V0) speeds was computed from running velocity data. Hamstring muscle performances were assessed directly or indirectly during isolated exercises. Hamstring muscle electromyographic activity was recorded during all tasks. Our results demonstrate substantially large to very large correlations between V0 and performances in the Upright-hip-extension in isometric (rs = 0.56; p = 0.040), Nordic hamstring exercise without hip flexion (rs = 0.66; p = 0.012) and with 90° hip flexion (rs = 0.73; p = 0.003), and between F0 and Upright-hip-extension in isometric (rs = 0.60; p = 0.028) and the Nordic hamstring exercise without hip flexion (rs = 0.59; p = 0.030). However, none of the test exercises activated hamstring muscles more than an average of 60% of the maximal activation during top-speed sprinting. In conclusion, training programs aiming to be sprint-specific in terms of horizontal force production could include exercises such as the Upright-hip-extension and the Nordic hamstring exercise, in addition to maximal sprinting activity, which is the only exercise leading to high levels of hamstring muscle activity.

Gait adaptations during load carrying on level and inclined surfaces

2004 ◽  
Vol 4 (1) ◽  
pp. 11-26
Author(s):  
Rakié Cham ◽  
Mark S. Redfern
Keyword(s):  
Reaction Force ◽  
Knee Joints ◽  
Ground Reaction Forces ◽  
Normal Loading ◽  
Gait Biomechanics ◽  
Inclined Surfaces ◽  
Heel Contact ◽  
Load Carrying ◽  
Reaction Forces ◽  
Hip Flexion

The complex human processes involved in balance maintenance and fall prevention during normal locomotion are further complicated by load carrying and/or the presence of slippery floors. The goal of this study was to investigate the effect of carrying loads (2-handed method) on gait biomechanics relevant to slips/falls. Participants walked down surfaces of varying inclinations (0°, 5° and 10°), while ground reaction forces and body/foot motion were recorded. Three load conditions (no load, 2.3 and 6.8 kg) were included. Load carrying was associated with increases in the peak normal ground reaction force and in the rate of the normal loading phase on the leading foot. Shear ground reaction forces were not affected by load carrying. Changes in the ground reaction forces recorded during load carrying led to reduced required coefficient of friction (RCOF) values, a variable used to rate slip potential. This RCOF reduction is partly due to postural adaptations such as increased knee and hip flexion adopted during load carrying. Furthermore, load carrying was accompanied by slower heel contact heel velocity in the direction of motion. Finally, moments generated at the hip and knee joints were significantly biased towards the extensor and flexor direction, respectively.

Very-Heavy Sled Training for Improving Horizontal-Force Output in Soccer Players

2017 ◽  
Vol 12 (6) ◽  
pp. 840-844 ◽  
Author(s):  
Jean-Benoît Morin ◽  
George Petrakos ◽  
Pedro Jiménez-Reyes ◽  
Scott R. Brown ◽  
Pierre Samozino ◽  
...  
Keyword(s):  
Body Mass ◽  
Effect Size ◽  
Reaction Force ◽  
Force Production ◽  
Sprint Performance ◽  
Soccer Players ◽  
Control Group ◽  
Horizontal Force ◽  
Sprint Training ◽  
Practical Applications

Background:Sprint running acceleration is a key feature of physical performance in team sports, and recent literature shows that the ability to generate large magnitudes of horizontal ground-reaction force and mechanical effectiveness of force application are paramount. The authors tested the hypothesis that very-heavy loaded sled sprint training would induce an improvement in horizontal-force production, via an increased effectiveness of application.Methods:Training-induced changes in sprint performance and mechanical outputs were computed using a field method based on velocity–time data, before and after an 8-wk protocol (16 sessions of 10- × 20-m sprints). Sixteen male amateur soccer players were assigned to either a very-heavy sled (80% body mass sled load) or a control group (unresisted sprints).Results:The main outcome of this pilot study is that very-heavy sled-resisted sprint training, using much greater loads than traditionally recommended, clearly increased maximal horizontal-force production compared with standard unloaded sprint training (effect size of 0.80 vs 0.20 for controls, unclear between-groups difference) and mechanical effectiveness (ie, more horizontally applied force; effect size of 0.95 vs –0.11, moderate between-groups difference). In addition, 5-m and 20-m sprint performance improvements were moderate and small for the very-heavy sled group and small and trivial for the control group, respectively.Practical Applications:This brief report highlights the usefulness of very-heavy sled (80% body mass) training, which may suggest value for practical improvement of mechanical effectiveness and maximal horizontal-force capabilities in soccer players and other team-sport athletes.Results:This study may encourage further research to confirm the usefulness of very-heavy sled in this context.

scholarly journals Effect of acute augmented feedback on between limb asymmetries and eccentric knee flexor strength during the Nordic hamstring exercise

PeerJ ◽  
2018 ◽  
Vol 6 ◽  
pp. e4972
Author(s):  
Wade J. Chalker ◽  
Anthony J. Shield ◽  
David A. Opar ◽  
Evelyne N. Rathbone ◽  
Justin W.L. Keogh
Keyword(s):  
Risk Factors ◽  
Real Time ◽  
Injury Risk ◽  
Force Production ◽  
Mean Difference ◽  
Peak Force ◽  
Augmented Feedback ◽  
Knee Flexor ◽  
Significant Difference ◽  
Limb Asymmetry

BackgroundHamstring strain injuries (HSI) are one of the most prevalent and serious injuries affecting athletes, particularly those in team ball sports or track and field. Recent evidence demonstrates that eccentric knee flexor weakness and between limb asymmetries are possible risk factors for HSIs. While eccentric hamstring resistance training, e.g. the Nordic hamstring exercise (NHE) significantly increases eccentric hamstring strength and reduces HSI risk, little research has examined whether between limb asymmetries can be reduced with training. As augmented feedback (AF) can produce significant acute and chronic increases in muscular strength and reduce injury risk, one way to address the limitation in the eccentric hamstring training literature may be to provide athletes real-time visual AF of their NHE force outputs with the goal to minimise the between limb asymmetry.MethodsUsing a cross over study design, 44 injury free, male cricket players from two skill levels performed two NHE sessions on a testing device. The two NHE sessions were identical with the exception of AF, with the two groups randomised to perform the sessions with and without visual feedback of each limb’s force production in real-time. When performing the NHE with visual AF, the participants were provided with the following instructions to ‘reduce limb asymmetries as much as possible using the real-time visual force outputs displayed in front them’. Between limb asymmetries and mean peak force outputs were compared between the two feedback conditions (FB1 and FB2) using independentt-tests to ensure there was no carryover effect, and to determine any period and treatment effects. The magnitude of the differences in the force outputs were also examined using Cohendeffect size.ResultsThere was a significant increase in mean peak force production when feedback was provided (mean difference, 21.7 N; 95% CI [0.2–42.3 N];P= 0.048;d= 0.61) and no significant difference in between limb asymmetry for feedback or no feedback (mean difference, 5.7%; 95% CI [−2.8% to 14.3%];P= 0.184;d= 0.41). Increases in force production under feedback were a result of increased weak limb (mean difference, 15.0 N; 95% CI [1.6–28.5 N];P= 0.029;d= 0.22) force contribution compared to the strong limb.DiscussionThe results of this study further support the potential utility of AF in improving force production and reducing risk in athletic populations. While there are currently some financial limitations to the application of this training approach, even in high-performance sport, such an approach may improve outcomes for HSI prevention programs. Further research with more homogenous populations over greater periods of time that assess the chronic effect of such training practices on injury risk factors and injury rates are also recommended.

Biomechanics Differ for Individuals With Similar Self-Reported Characteristics of Patellofemoral Pain During a High-Demand Multiplanar Movement Task

2020 ◽  
pp. 1-10
Author(s):  
Matthew K. Seeley ◽  
Seong Jun Son ◽  
Hyunsoo Kim ◽  
J. Ty Hopkins
Keyword(s):  
Ground Reaction Force ◽  
Injury Risk ◽  
Reaction Force ◽  
Patellofemoral Pain ◽  
Joint Torque ◽  
Whole Body ◽  
Ground Contact ◽  
High Demand ◽  
Contact Phase ◽  
Hip Extension

Context: Patellofemoral pain (PFP) is often categorized by researchers and clinicians using subjective self-reported PFP characteristics; however, this practice might mask important differences in movement biomechanics between PFP patients. Objective: To determine whether biomechanical differences exist during a high-demand multiplanar movement task for PFP patients with similar self-reported PFP characteristics but different quadriceps activation levels. Design: Cross-sectional design. Setting: Biomechanics laboratory. Participants: A total of 15 quadriceps deficient and 15 quadriceps functional (QF) PFP patients with similar self-reported PFP characteristics. Intervention: In total, 5 trials of a high-demand multiplanar land, cut, and jump movement task were performed. Main Outcome Measures: Biomechanics were compared at each percentile of the ground contact phase of the movement task (α = .05) between the quadriceps deficient and QF groups. Biomechanical variables included (1) whole-body center of mass, trunk, hip, knee, and ankle kinematics; (2) hip, knee, and ankle kinetics; and (3) ground reaction forces. Results: The QF patients exhibited increased ground reaction force, joint torque, and movement, relative to the quadriceps deficient patients. The QF patients exhibited: (1) up to 90, 60, and 35 N more vertical, posterior, and medial ground reaction force at various times of the ground contact phase; (2) up to 4° more knee flexion during ground contact and up to 4° more plantarflexion and hip extension during the latter parts of ground contact; and (3) up to 26, 21, and 48 N·m more plantarflexion, knee extension, and hip extension torque, respectively, at various times of ground contact. Conclusions: PFP patients with similar self-reported PFP characteristics exhibit different movement biomechanics, and these differences depend upon quadriceps activation levels. These differences are important because movement biomechanics affect injury risk and athletic performance. In addition, these biomechanical differences indicate that different therapeutic interventions may be needed for PFP patients with similar self-reported PFP characteristics.

Roller Massage Prior to Running Does Not Affect Gait Mechanics in Well-Trained Runners

2021 ◽  
pp. 1-9
Author(s):  
Jessica G. Hunter ◽  
Gina L. Garcia ◽  
Sushant M. Ranadive ◽  
Jae Kun Shim ◽  
Ross H. Miller
Keyword(s):  
Repeated Measures ◽  
Reaction Force ◽  
Force Production ◽  
Endurance Athletes ◽  
Jump Height ◽  
Jump Performance ◽  
Average Load ◽  
Load Rate ◽  
Free Moment ◽  
Muscle Force Production

Context: Understanding if roller massage prior to a run can mitigate fatigue-related decrements in muscle force production during prolonged running is important because of the association between fatigue and running-related injury. Objective: The authors investigated whether a bout of roller massage prior to running would (1) mitigate fatigue-related increases in vertical average load rate and free moment of the ground reaction force of running and (2) mitigate decreases in maximal countermovement jump height. Design: Repeated-measures study. Setting: Laboratory. Participants: A total of 14 recreational endurance athletes (11 men and 3 women) volunteered for the study. Interventions: A 12.5-minute foam roller protocol for the lower extremities and a fatiguing 30-minute treadmill run. Main Outcome Measures: Vertical average load rate, free moment, and maximal jump height before (PRE) and after (POST) the fatiguing treadmill run on separate experimental days: once where participants sat quietly prior to the fatiguing run (REST) and another where the foam roller protocol was performed prior to the run (ROLL). Results: A 2-way multiple analysis of variance found no significant differences in vertical average load rate, free moment, and jump height between PRE/POST times in both REST/ROLL conditions. Conclusions: The authors concluded that recreational endurance athletes maintain running mechanics and jump performance after a fatiguing run regardless of prerun roller massage and may not rely on prerun roller massage as a form of injury prevention.

A New Lower Extremity Modeling of Human Body With Variable Feet Links

2000 ◽  
Author(s):  
Nader Arafati ◽  
Jean Yves Lazennec ◽  
Roger Ohayon
Keyword(s):  
Ground Reaction Force ◽  
Sagittal Plane ◽  
Reaction Force ◽  
Human Movement ◽  
Knee Joints ◽  
Foot Pressure ◽  
Ankle Joints ◽  
Reaction Forces ◽  
Human Movement Modeling ◽  
Force Vectors

Abstract Human movement modeling has been the object of much research for the past 30 years. In these models the position of foot link was fixed on the ground. We propose to model the feet links as variable, since the position of foot pressure center changes from heel to toes. The ground reaction forces could also be analyzed in real time. We examined this model for some static postures. In standing anatomical position, the maximum articular forces are localized in hip and knee joints. In sagittal plane, the ground reaction force vectors are positioned nearly under ankle joints. The pathological postures like body with pes cavus or with global spine kyphosis increase the articular and muscular forces. In these cases, the position of ground reaction force vectors is moved toward the toes.

Zapateado Technique as an Injury Risk in Mexican Folkloric and Spanish Dance: An Analysis of Execution, Ground Reaction Force, and Muscle Strength

2013 ◽  
Vol 28 (2) ◽  
pp. 80-83 ◽  
Author(s):  
Soledad Echegoyen ◽  
Takeshi Aoyama ◽  
Cristina Rodríguez
Keyword(s):  
Risk Factors ◽  
Muscle Strength ◽  
Ground Reaction Force ◽  
Knee Flexion ◽  
Injury Risk ◽  
Reaction Force ◽  
Knee Injuries ◽  
Flat Foot ◽  
Lateral Plane ◽  
Muscle Groups

Zapateado is a repetitive percussive footwork in dance. This percussive movement, and the differences in technique, may be risk factors for injury. A survey on zapateado dance students found a rate of 1.5 injuries/1,000 exposures. Knee injuries are more frequent than in Spanish dancers than folkloric dancers. The aim of this research was to study the relationship between technique and ground reaction force between zapateado on Spanish and Mexican folkloric dancers. Ten female dance students (age 22.4 ± 4 yrs), six Spanish dancers and four Mexican folkloric dancers, were considered. Each student performed zapateado with a flat foot, wearing high-heeled shoes during 5 seconds on a force platform. Videotapes were taken on a lateral plane, and knee and hip angles in each movement phase were measured with Dartfish software. Additionally, knee and ankle flexor and extensor strength was measured with a dynamometer. Ground reaction forces were lower for Spanish dancers than Mexican folkloric dancers. Spanish dancers had less knee flexion when the foot contacted to the ground than did Mexican folkloric dancers. On Spanish dancers, the working leg had more motion in relation to hip and knee angles than was seen in folkloric dancers. The ankle extensors were stronger on folkloric dancers, and there were no differences for the other muscle groups. Knee flexion at foot contact and muscle strength imbalance could be risk factors for injuries. It is suggested that the technique in Spanish dance in Mexico be reviewed, although more studies are required to define more risk factors.

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