scholarly journals Running impact forces: from half a leg to holistic understanding – comment on Nigg et al.

2018 ◽  
Author(s):  
Kenneth P. Clark ◽  
Andrew B. Udofa ◽  
Laurence J. Ryan ◽  
Peter G. Weyand
Keyword(s):  
Lower Limb ◽  
Reaction Force ◽  
The Body ◽  
Vertical Ground Reaction Force ◽  
Validation Data ◽  
Motion Data ◽  
Impact Forces ◽  
Holistic Understanding ◽  
Speed Level ◽  
Force Time

Running impact forces have immediate relevance for the muscle tuning paradigm proposed here and broader relevance for overuse injuries, shoe design and running performance. Here, we consider their mechanical basis. Several studies demonstrate that the vertical ground reaction force-time (vGRFT) impulse, from touchdown to toe-off, corresponds to the instantaneous accelerations of the body’s entire mass (Mb) divided into two or more portions. The simplest, a two-mass partitioning of the body (lower-limb, M1=0.08•Mb; remaining mass, M2=0.92•Mb) can account for the full vGRFT waveform under virtually all constant-speed, level-running conditions. Model validation data indicate that: 1) the non-contacting mass, M2, often accounts for one-third or more of the early “impact” portion of the vGRFT, and 2) extracting a valid impact impulse from measured force waveforms requires only lower-limb motion data and the fixed body mass fraction of 0.08 for M1.

scholarly journals Running ground reaction forces across footwear conditions are predicted from the motion of two body mass components

2019 ◽  
Vol 126 (5) ◽  
pp. 1315-1325 ◽  
Author(s):  
Andrew B. Udofa ◽  
Kenneth P. Clark ◽  
Laurence J. Ryan ◽  
Peter G. Weyand
Keyword(s):  
Ground Reaction Force ◽  
Lower Limb ◽  
Reaction Force ◽  
Ground Reaction Forces ◽  
Vertical Ground Reaction Force ◽  
Time Patterns ◽  
Foot Strike ◽  
Reaction Forces ◽  
Vertical Ground ◽  
Force Time

Although running shoes alter foot-ground reaction forces, particularly during impact, how they do so is incompletely understood. Here, we hypothesized that footwear effects on running ground reaction force-time patterns can be accurately predicted from the motion of two components of the body’s mass (mb): the contacting lower-limb (m1 = 0.08mb) and the remainder (m2 = 0.92mb). Simultaneous motion and vertical ground reaction force-time data were acquired at 1,000 Hz from eight uninstructed subjects running on a force-instrumented treadmill at 4.0 and 7.0 m/s under four footwear conditions: barefoot, minimal sole, thin sole, and thick sole. Vertical ground reaction force-time patterns were generated from the two-mass model using body mass and footfall-specific measures of contact time, aerial time, and lower-limb impact deceleration. Model force-time patterns generated using the empirical inputs acquired for each footfall matched the measured patterns closely across the four footwear conditions at both protocol speeds ( r2 = 0.96 ± 0.004; root mean squared error  = 0.17 ± 0.01 body-weight units; n = 275 total footfalls). Foot landing angles (θF) were inversely related to footwear thickness; more positive or plantar-flexed landing angles coincided with longer-impact durations and force-time patterns lacking distinct rising-edge force peaks. Our results support three conclusions: 1) running ground reaction force-time patterns across footwear conditions can be accurately predicted using our two-mass, two-impulse model, 2) impact forces, regardless of foot strike mechanics, can be accurately quantified from lower-limb motion and a fixed anatomical mass (0.08mb), and 3) runners maintain similar loading rates (ΔFvertical/Δtime) across footwear conditions by altering foot strike angle to regulate the duration of impact. NEW & NOTEWORTHY Here, we validate a two-mass, two-impulse model of running vertical ground reaction forces across four footwear thickness conditions (barefoot, minimal, thin, thick). Our model allows the impact portion of the impulse to be extracted from measured total ground reaction force-time patterns using motion data from the ankle. The gait adjustments observed across footwear conditions revealed that runners maintained similar loading rates across footwear conditions by altering foot strike angles to regulate the duration of impact.

Effect of stud shape on lower limb kinetics during football-related movements

2019 ◽  
Vol 234 (1) ◽  
pp. 3-10
Author(s):  
Xiang Lv ◽  
Yuqi He ◽  
Dong Sun ◽  
Julien S Baker ◽  
Rongrong Xuan ◽  
...  
Keyword(s):  
Lower Limb ◽  
Peak Pressure ◽  
Reaction Force ◽  
Traction Force ◽  
Vertical Ground Reaction Force ◽  
Time Integral ◽  
Bone Injury ◽  
Explosive Force ◽  
Force Time ◽  
Straight Ahead

Different football shoe designs used under the same turf condition can impact athletic performance and influence the risk of injury. The purpose of this study was to investigate the effect of different shape studs of football shoes on lower limb kinetics during straight-ahead running and 45° left sidestep cutting movements. Twelve male football players were recruited from university football teams. They were asked to perform six trials using straight-ahead running and a 45° left sidestep cutting movement on artificial turf while wearing football shoes with the following three stud configurations: knife stud, triangle stud and round stud. The contact time of knife stud was longer than triangle stud and round stud. In the straight-ahead running task, the ground force in the direction of movement of knife stud and round stud was lower than triangle stud. The peak pressure on the lateral forefoot (5 metatarsal region) in knife stud was higher than triangle stud and round stud in the cutting movements. The peak pressure and force–time integral on the medial (1 metatarsal region) and central (2–4 metatarsal region) forefoot in triangle stud were smaller than round stud. The different stud shapes of firm ground soccer shoes have little effect on the traction force. Knife stud has a higher risk of fifth metatarsal bone injury. The triangle stud shows good explosive force and provides the ability to change direction quickly. The round stud generally produces the minimum peak vertical ground reaction force and has a good capability of changing direction among the three shoes.

scholarly journals Muscle forces and the demands of human walking

Biology Open ◽  
2021 ◽  
Vol 10 (7) ◽  
Author(s):  
Adam D. Sylvester ◽  
Steven G. Lautzenheiser ◽  
Patricia Ann Kramer
Keyword(s):  
Lower Limb ◽  
Reaction Force ◽  
The Body ◽  
Muscle Forces ◽  
Skeletal Morphology ◽  
Lower Limb Muscles ◽  
Fossil Hominins ◽  
Force Curves ◽  
Behavior Function ◽  
The Relationship

ABSTRACT Reconstructing the locomotor behavior of extinct animals depends on elucidating the principles that link behavior, function, and morphology, which can only be done using extant animals. Within the human lineage, the evolution of bipedalism represents a critical transition, and evaluating fossil hominins depends on understanding the relationship between lower limb forces and skeletal morphology in living humans. As a step toward that goal, here we use a musculoskeletal model to estimate forces in the lower limb muscles of ten individuals during walking. The purpose is to quantify the consistency, timing, and magnitude of these muscle forces during the stance phase of walking. We find that muscles which act to support or propel the body during walking demonstrate the greatest force magnitudes as well as the highest consistency in the shape of force curves among individuals. Muscles that generate moments in the same direction as, or orthogonal to, the ground reaction force show lower forces of greater variability. These data can be used to define the envelope of load cases that need to be examined in order to understand human lower limb skeletal load bearing.

scholarly journals The use of yank-time signal as an alternative to identify kinematic events and define phases in human countermovement jumping

2020 ◽  
Vol 7 (8) ◽  
pp. 192093
Author(s):  
Sofyan B. Sahrom ◽  
Jodie C. Wilkie ◽  
Kazunori Nosaka ◽  
Anthony J. Blazevich
Keyword(s):  
Muscle Activation ◽  
Vertical Jump ◽  
Reaction Force ◽  
Mass Movement ◽  
Time Signal ◽  
Time Data ◽  
Vertical Ground Reaction Force ◽  
Activation Patterns ◽  
Muscle Activation Patterns ◽  
Force Time

Detailed examinations of both the movement and muscle activation patterns used by animals and humans to complete complex tasks are difficult to obtain in many environments. Therefore, the ability to infer movement and muscle activation patterns after capture of a single set of easily obtained data is highly sought after. One possible solution to this problem is to capture force-time data through the use of appropriate transducers, then interrogate the signal's derivative, the yank-time signal, which amplifies, and thus highlights, temporal force-time changes. Because the countermovement vertical jump (CMJ) is a complex movement that has been well studied in humans, it provides an excellent preliminary model to test the validity of this solution. The aim of the present study was therefore to explore the use of yank-time signal, derived from vertical ground reaction force-time data, to identify and describe important kinematic (captured using three-dimensional motion analysis) and kinetic events in the CMJ, and to relate these to possible muscle activation (electromyography) events that underpin them. It was found that the yank-time signal could be used to accurately identify several key events during the CMJ that are likely to be missed or misidentified when only force-time data are inspected, including the first instances of joint flexion and centre of mass movement. Four different jump profiles (i.e. kinematic patterns) were inferred from the yank-time data, which were linked to different patterns of muscle activation. Therefore, yank-time signal interrogation provides a viable method of estimating kinematic patterns and muscle activation strategies in complex human movements.

scholarly journals Force-Time Waveform Shape Reveals Countermovement Jump Strategies of Collegiate Athletes

Sports ◽  
2020 ◽  
Vol 8 (12) ◽  
pp. 159
Author(s):  
Trent M. Guess ◽  
Aaron D. Gray ◽  
Brad W. Willis ◽  
Matthew M. Guess ◽  
Seth L. Sherman ◽  
...  
Keyword(s):  
Ground Reaction Force ◽  
National Collegiate Athletic Association ◽  
Reaction Force ◽  
Collegiate Athletes ◽  
Principal Component ◽  
Countermovement Jump ◽  
Vertical Ground Reaction Force ◽  
Vertical Ground ◽  
Force Time ◽  
Time Waveform

The purpose of this study was to relate the shape of countermovement jump (CMJ) vertical ground reaction force waveforms to discrete parameters and determine if waveform shape could enhance CMJ analysis. Vertical ground reaction forces during CMJs were collected for 394 male and female collegiate athletes competing at the National Collegiate Athletic Association (NCAA) Division 1 and National Association of Intercollegiate Athletics (NAIA) levels. Jump parameters were calculated for each athlete and principal component analysis (PCA) was performed on normalized force-time waveforms consisting of the eccentric braking and concentric phases. A K-means clustering of PCA scores placed athletes into three groups based on their waveform shape. The overall average waveforms of all athletes in each cluster produced three distinct vertical ground reaction force waveform patterns. There were significant differences across clusters for all calculated jump parameters. Athletes with a rounded single hump shape jumped highest and quickest. Athletes with a plateau at the transition between the eccentric braking and concentric phase (amortization) followed by a peak in force near the end of the concentric phase had the lowest jump height and slowest jump time. Analysis of force-time waveform shape can identify differences in CMJ strategies in collegiate athletes.

scholarly journals Children’s Single-Leg Landing Movement Capability Analysis According to the Type of Sport Practiced

2020 ◽  
Vol 17 (17) ◽  
pp. 6414 ◽  
Author(s):  
Isaac Estevan ◽  
Gonzalo Monfort-Torres ◽  
Roman Farana ◽  
David Zahradnik ◽  
Daniel Jandacka ◽  
...  
Keyword(s):  
Lower Limb ◽  
Impact Force ◽  
Reaction Force ◽  
Force Plate ◽  
Statistical Parametric Mapping ◽  
Sport Performance ◽  
Joint Angles ◽  
Vertical Ground Reaction Force ◽  
Lower Limb Injury ◽  
Sport Practice

(1) Background: Understanding children’s motor patterns in landing is important not only for sport performance but also to prevent lower limb injury. The purpose of this study was to analyze children’s lower limb joint angles and impact force during single-leg landings (SLL) in different types of jumping sports using statistical parametric mapping (SPM). (2) Methods: Thirty children (53.33% girls, M = 10.16 years-old, standard deviation (SD) = 1.52) divided into three groups (gymnastics, volleyball and control) participated in the study. The participants were asked to do SLLs with the dominant lower limb (barefoot) on a force plate from a height of 25 cm. The vertical ground reaction force (GRF) and lower limb joint angles were assessed. SPM{F} one-way analysis of variance (ANOVA) and SPM{t} unpaired t-tests were performed during the landing and stability phases. (3) Results: A significant main effect was found in the landing phase of jumping sport practice in GRF and joint angles. During the stability phase, this effect was exhibited in ankle and knee joint angles. (4) Conclusions: Evidence was obtained of the influence of practicing a specific sport in childhood. Child volleyball players performed SLL with lower impact force and higher knee flexion than child gymnasts. Training in specific jumping sports (i.e., volleyball and gymnastics) could affect the individual capacity to adapt SLL execution.

A treadmill-mounted force platform

1989 ◽  
Vol 67 (4) ◽  
pp. 1692-1698 ◽  
Author(s):  
R. Kram ◽  
A. J. Powell
Keyword(s):  
Full Range ◽  
Center Of Mass ◽  
Reaction Force ◽  
Vertical Displacement ◽  
The Body ◽  
Force Platform ◽  
Vertical Force ◽  
Vertical Ground Reaction Force ◽  
Contact Phase ◽  
Frictional Forces

Muscle, bone, and tendon forces; the movement of the center of mass, and the spring properties of the body during terrestrial locomotion can be measured using ground-mounted force platforms. These measurements have been extremely time consuming because of the difficulty in obtaining repeatable constant speed trials (particularly with animals). We have overcome this difficulty by mounting a force platform directly under the belt of a motorized treadmill. With this arrangement, vertical force can be recorded from an unlimited number of successive ground contacts in a much shorter time. With this treadmill-mounted force platform it is possible to accurately make the following measurements over the full range of steady speeds and under various perturbations of normal gait: 1) vertical ground reaction force over the course of the contact phase; 2) peak forces in bone, muscle, and tendon; 3) the vertical displacement of the center of mass; and 4) contact time for the limbs. In our treadmill-force platform design, belt forces and frictional forces cause no measurable cross-talk problem. Natural frequency (160 Hz), nonlinearity (less than 5%), and position independence (less than 2%) are all quite acceptable. Motor-caused vibrations are greater than 150 Hz and thus can be easily filtered.

scholarly journals Acute fatigue effects on ground reaction force of lower limbs during countermovement jumps

2013 ◽  
Vol 19 (4) ◽  
pp. 737-745
Author(s):  
Carlos Gabriel Fábrica ◽  
Paula V. González ◽  
Jefferson Fagundes Loss
Keyword(s):  
Body Weight ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
The Body ◽  
Lower Limbs ◽  
Vertical Ground Reaction Force ◽  
External Work ◽  
Jumping Performance ◽  
Vertical Ground ◽  
The Relationship

Parameters associated with the performance of countermovement jumps were identified from vertical ground reaction force recordings during fatigue and resting conditions. Fourteen variables were defined, dividing the vertical ground reaction force into negative and positive external working times and times in which the vertical ground reaction force values were lower and higher than the participant's body weight. We attempted to explain parameter variations by considering the relationship between the set of contractile and elastic components of the lower limbs. We determined that jumping performance is based on impulsion optimization and not on instantaneous ground reaction force value: the time in which the ground reaction force was lower than the body weight, and negative external work time was lower under fatigue. The results suggest that, during fatigue, there is less contribution from elastic energy and from overall active state. However, the participation of contractile elements could partially compensate for the worsening of jumping performance.

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