Foot Strike and the Properties of the Human Heel Pad

1989 ◽  
Vol 203 (4) ◽  
pp. 191-196 ◽  
Author(s):  
R F Ker ◽  
M B Bennett ◽  
R McN Alexander ◽  
R C Kester
Keyword(s):  
Force Plate ◽  
Human Locomotion ◽  
Peak Force ◽  
Ground Contact ◽  
Substantial Portion ◽  
Heel Pad ◽  
Foot Strike ◽  
Compression Data ◽  
Rapid Deceleration ◽  
The Relationship

Many force-plate records of human locomotion show an impulse (the foot strike) shortly after ground contact. The authors' hypothesis is that this results from the rapid deceleration of a mass (the ‘effective foot’) under forces which compress the heel pad. The quantitative implications are investigated through an illustrative calculation. The observations used are (a) the peak force reached in foot strike (b) the vertical velocity of the foot immediately before ground contact and (c) the properties of the heel pad in compression. Data for (a) and (b) are available in the literature; measurements for (c) are presented here. The deductions are: (a) the time taken to reach peak force is about 5.4 ms, which agrees with published measurements; (b) the mass of the effective foot is about 3.6 kg. The effective foot thus includes a substantial portion of the leg: this seems reasonable. The models used for the calculations clarify the relationship between the foot strike and the shock wave, which it generates.

scholarly journals The Influence of Countermovement Jump Protocol on Reactive Strength Index Modified and Flight Time: Contraction Time in Collegiate Basketball Players

Sports ◽  
2019 ◽  
Vol 7 (2) ◽  
pp. 37 ◽  
Author(s):  
Aaron Heishman ◽  
Brady Brown ◽  
Bryce Daub ◽  
Ryan Miller ◽  
Eduardo Freitas ◽  
...  
Keyword(s):  
Force Plate ◽  
Flight Time ◽  
Contraction Time ◽  
Strength Index ◽  
Countermovement Jump ◽  
Basketball Players ◽  
Arm Swing ◽  
Collegiate Basketball ◽  
Positive Correlations ◽  
The Relationship

The purpose of the present investigation was to evaluate differences in Reactive Strength Index Modified (RSIMod) and Flight Time to Contraction Time Ratio (FT:CT) during the countermovement jump (CMJ) performed without the arm swing (CMJNAS) compared to the CMJ with the arm swing (CMJAS), while exploring the relationship within each variable between jump protocols. A secondary purpose sought to explore the relationship between RSIMod and FT:CT during both jump protocols. Twenty-two collegiate basketball players performed both three CMJNAS and three CMJAS on a force plate, during two separate testing sessions. RSIMod was calculated by the flight-time (RSIModFT) and impulse-momentum methods (RSIModIMP). CMJ variables were significantly greater during the CMJAS compared to CMJNAS (p < 0.001). There were large to very large correlations within each variable between the CMJAS and CMJNAS. There were significant positive correlations among RSIModFT, RSIModIMP, and FT:CT during both the CMJAS (r ≥ 0.864, p < 0.001) and CMJNAS (r ≥ 0.960, p < 0.001). These findings identify an increase in RSIMod or FT:CT during the CMJAS, that may provide independent information from the CMJNAS. In addition, either RSIMod or FT:CT may be utilized to monitor changes in performance, but simultaneous inclusion may be unnecessary.

Approximation of the Kinematics of Foot Joints by Using Passive Elastic Characteristics of Joint

2007 ◽  
Vol 342-343 ◽  
pp. 621-624
Author(s):  
Hyeon Ki Choi ◽  
Si Yeol Kim ◽  
Won Hak Cho
Keyword(s):  
Joint Angle ◽  
Reaction Force ◽  
Force Plate ◽  
Least Square Method ◽  
Least Square ◽  
Biomechanical Analysis ◽  
Clinical Evaluations ◽  
Foot Joints ◽  
The Relationship ◽  
Elastic Characteristics

We investigated the relationship between kinematic and kinetic characteristics of foot joints resisting ground reaction force (GRF). Passive elastic characteristics of joint were obtained from the experiment using three cameras and one force plate. The relationship between joint angle and moment was mathematically modeled by using least square method. The calculated ranges of motion were 7o for TM joint, 4o for TT joint and 20o for MP joint. With the model that relates joint angle and plantar pressure, we could get the kinematic data of the joints which are not available from conventional motion analysis. The model can be used not only for biomechanical analysis which simulates gait but also for the clinical evaluations.

Characteristics of Eight Irish Dance LandingsConsiderations for Training and Overuse Injury Prevention

2021 ◽  
Vol 25 (1) ◽  
pp. 30-37
Author(s):  
Sarah Klopp Christensen ◽  
Aaron Wayne Johnson ◽  
Natalie Van Wagoner ◽  
Taryn E. Corey ◽  
Matthew S. McClung ◽  
...  
Keyword(s):  
Large Range ◽  
Force Plate ◽  
Three Dimensional ◽  
The Body ◽  
Peak Force ◽  
Warm Up ◽  
Dance Training ◽  
Rise Rate ◽  
Dance Movements ◽  
Reaction Forces

Irish dance has evolved in aesthetics that lead to greater physical demands on dancers' bodies. Irish dancers must land from difficult moves without letting their knees bend or heels touch the ground, causing large forces to be absorbed by the body. The majority of injuries incurred by Irish dancers are due to overuse (79.6%). The purpose of this study was to determine loads on the body of female Irish dancers, including peak force, rise rate of force, and impulse, in eight common Irish hard shoe and soft shoe dance movements. It was hypothesized that these movements would produce different ground reac- tion force (GRF) characteristics. Sixteen female Irish dancers were recruited from the three highest competitive levels. Each performed a warm-up, reviewed the eight movements, and then performed each movement three times on a force plate, four in soft shoes and four in hard shoes. Ground reaction forces were measured using a three-dimensional force plate recording at 1,000 Hz. Peak force, rise rate, and vertical impulse were calculated. Peak forces normalized by each dancer's body weight for each of these variables were significantly different between move- ments and shoe types [F(15, 15)= 65.4, p < 0.01; F(15, 15) = 65.0, p < 0.01; and F(15, 15) = 67.4, p < 0.01, respectively]. The variable years of experience was not correlated with peak force, rise rate, or impulse (p > 0.40). It is concluded that there was a large range in GRF characteristics among the eight movements studied. Understanding the force of each dance step will allow instructors to develop training routines that help dancers adapt gradually to the high forces experienced in Irish dance training and competitions, thereby limiting the potential for overuse injuries.

Maximal Aerobic Power in Aging Men: Insights From a Record of 1-Hour Unaccompanied Cycling

2018 ◽  
Vol 13 (1) ◽  
pp. 112-114 ◽  
Author(s):  
Carlo Capelli
Keyword(s):  
Aerobic Power ◽  
Average Rate ◽  
Human Locomotion ◽  
Maximal Aerobic Power ◽  
Metabolic Power ◽  
Master Athletes ◽  
Active Lifestyle ◽  
Average Percentage ◽  
Aging Men ◽  
The Relationship

Purpose: To analyze best 1-h unaccompanied performances of master athletes in ages ranging from 35 to 105 y to estimate the decay of maximal aerobic power (MAP) across the spectrum of age. Methods: MAP at the various ages was estimated by computing the metabolic power () maintained to cover the distances during best 1-h unaccompanied performances established by master athletes of different classes of age and by assuming that they were able to maintain an equal to 88% of their MAP during 1 h of exhaustive exercise. Results: MAP started monotonically decreasing at 47 y of age. Thereafter, it showed an average rate of decrease of ∼14% for the decades up to 105 y of age, similar to other classes of master athletes. Conclusions: The results confirm, by extending the analysis to centennial subjects, that MAP seems to start declining from the middle of the 5th decade of age, with an average percentage decay that is faster than that traditionally reported, even when one maintains a very active lifestyle. The proposed approach may be applied to other types of human locomotion for which the relationship between speed and is known.

scholarly journals The Relationship Between Vertical Loadrates and Tibial Acceleration Across Footstrike Patterns

2018 ◽  
Vol 3 (3) ◽  
pp. 2473011418S0020 ◽  
Author(s):  
Irene Davis ◽  
Todd Hayano ◽  
Adam Tenforde
Keyword(s):  
Impact Loading ◽  
Ground Reaction Force ◽  
Reaction Force ◽  
Force Plate ◽  
Correlation Coefficients ◽  
Strongly Correlated ◽  
Vertical Ground Reaction Force ◽  
Vertical Ground ◽  
Tibial Acceleration ◽  
The Relationship

Category: Other Introduction/Purpose: While the etiology of injuries is multifactorial, impact loading, as measured by the loadrate of the vertical ground reaction force has been implicated. These loadrates are typically measured with a force plate. However, this limits the measure of impacts to laboratory environments. Tibial acceleration, another measure of running impacts, is considered a surrogate for loadrate. It can be measured using new wearable technology that can be used in a runner’s natural environment. However, the correlation between tibial acceleration measured from mobile devices and vertical ground reaction force loadrates, measured from forceplates, is unknown. The purpose of this study was to determine the correlation between vertical and resultant loadrates to vertical and resultant tibial acceleration across different footstrike patterns (FSP) in runners. Methods: The study involved a sample of convenience made up of 169 runners (74 F, 95 M; age: 38.66±13.08 yrs) presenting at a running injury clinic. This included 25 habitual forefoot strike (FFS), 17 midfoot strike (MFS) and 127 rearfoot strike (RFS) runners. Participants ran on an instrumented treadmill (average speed 2.52±0.25 m/s), with a tri-axial accelerometer attached at the left distal medial tibia. Only subjects running with pain <3/10 on a VAS scale during the treadmill run were included to reduce the confounding effect of pain. Vertical average, vertical instantaneous and resultant instantaneous loadrates (VALR, VILR and RILR) and peak vertical and resultant tibial accelerations (VTA, RTA) were averaged for 8 consecutive left steps. Correlation coefficients (r) were calculated between tibial accelerations and loadrates. Results: All tibial accelerations were significantly correlated across all loadrates, with the exception of RTA with VILR for FFS (Table 1) which was nearly significant (p=0.068). Correlations ranged from 0.37-0.82. VTA was strongly correlated with all loadrates (r = 0.66). RTA was also strongly correlated with both loadrates for RFS and MFS, but only moderately correlated with loadrates for FFS (r = 0.47). Correlations were similar across the different loadrates (VALR, VILR, RILR). Conclusion: The stronger correlation between vertical tibial acceleration and all loadrates (VALR, VILR, RILR) suggests that it may be the best surrogate for loadrates when studying impact loading in runners.

Investigation on the load-displacement curves of a human healthy heel pad: In vivo compression data compared to numerical results

2012 ◽  
Vol 34 (9) ◽  
pp. 1253-1259 ◽  
Author(s):  
C.G. Fontanella ◽  
S. Matteoli ◽  
E.L. Carniel ◽  
J.E. Wilhjelm ◽  
A. Virga ◽  
...  
Keyword(s):  
Numerical Results ◽  
Heel Pad ◽  
Compression Data ◽  
Load Displacement

Shock Absorbency of Factors in the Shoe/Heel Interaction—With Special Focus on Role of the Heel Pad

Foot & Ankle ◽  
1989 ◽  
Vol 9 (6) ◽  
pp. 294-299 ◽  
Author(s):  
Uffe Jørgensen ◽  
Finn Bojsen-Møller
Keyword(s):  
Force Plate ◽  
Heel Strike ◽  
Overuse Injuries ◽  
Special Focus ◽  
Shock Absorption ◽  
Ethyl Vinyl ◽  
Shock Absorbers ◽  
Heel Pad ◽  
Eva Foam

The heel pad acts as a shock absorber in walking and in heel-strike running. In some patients, a reduction of its shock-absorbing capacity has been connected to the development of overuse injuries. In this article, the shock absorption of the heel pad as well as external shock absorbers are studied. Individual variation and the effect of trauma and confinement on the heel pad were specifically investigated. Drop tests, imitating heel impacts, were performed on a force plate. The test specimens were cadaver heel pads (n = 10); the shoe sole component consisted of ethyl vinyl acetate (EVA) foam and Sorbothane inserts. The shock absorption was significantly greater in the heel pad than in the external shock absorbers. The mean heel pad shock absorption was 1.1 times for EVA foam and 2.1 times for Sorbothane. The shock absorption varied by as much as 100% between heel pads. Trauma caused a decrease in the heel pad shock absorbency (24%), whereas heel pad confinement increased the shock absorbency (49% in traumatized heel pads and 29.5% in nontraumatized heel pads). These findings provide a biomechanical rationale for the clinical observations of a correlation between heel pad shock absorbency loss and heel strike-dependent overuse injuries. To increase shock absorbency, confinement of the heel pad should be attempted in vivo.

Effectiveness of Accentuated Eccentric Loading: Contingent on Concentric Load

2021 ◽  
Vol 16 (1) ◽  
pp. 66-72
Author(s):  
Justin J. Merrigan ◽  
James J. Tufano ◽  
Michael Falzone ◽  
Margaret T. Jones
Keyword(s):  
Peak Power ◽  
Performance Enhancement ◽  
Force Plate ◽  
Relative Difference ◽  
Peak Force ◽  
Acute Effects ◽  
Mean Power ◽  
Mean Velocity ◽  
Eccentric Load ◽  
Back Squat

Purpose: To identify acute effects of a single accentuated eccentric loading (AEL) repetition on subsequent back-squat kinetics and kinematics with different concentric loads. Methods: Resistance-trained men (N = 21) participated in a counterbalanced crossover design and completed 4 protocols (sets × repetitions at eccentric/concentric) as follows: AEL65, 3 × 5 at 120%/65% 1-repetition maximum (1-RM); AEL80, 3 × 3 at 120%/80% 1-RM; TRA65, 3 × 5 at 65%/65% 1-RM; and TRA80, 3 × 3 at 80%/80% 1-RM. During AEL, weight releasers disengaged from the barbell after the eccentric phase of the first repetition and remained off for the remaining repetitions. All repetitions were performed on a force plate with linear position transducers attached to the barbell, from which eccentric and concentric peak and mean velocity, force, and power were derived. Results: Eccentric peak velocity (−0.076 [0.124] m·s−1; P = .01), concentric peak force (187.8 [284.4] N; P = .01), eccentric mean power (−145.2 [62.0] W; P = .03), and eccentric peak power (−328.6 [93.7] W; P < .01) during AEL65 were significantly greater than TRA65. When collapsed across repetitions, AEL65 resulted in slower eccentric velocity and power during repetition 1 but faster eccentric and concentric velocity and power in subsequent repetitions (P ≤ .04). When comparing AEL80 with TRA80, concentric peak force (133.8 [56.9] N; P = .03), eccentric mean power (−83.57 [38.0] W; P = .04), and eccentric peak power (−242.84 [67.3] W; P < .01) were enhanced. Conclusions: Including a single supramaximal eccentric phase of 120% 1-RM increased subsequent velocity and power with concentric loads of 65% 1-RM, but not 80% 1-RM. Therefore, AEL is sensitive to the magnitude of concentric loads, which requires a large relative difference to the eccentric load, and weight releasers may not need to be reloaded to induce performance enhancement.

The Relationship Between Trunk Muscle Thickness and Static Postural Balance in Older Adults

2020 ◽  
Vol 28 (2) ◽  
pp. 269-275
Author(s):  
Ece Acar ◽  
Tamer Çankaya ◽  
Serkan Öner
Keyword(s):  
Older Adults ◽  
Postural Balance ◽  
Postural Sway ◽  
Force Plate ◽  
Muscle Thickness ◽  
Trunk Muscle ◽  
Rectus Abdominis ◽  
Trunk Muscles ◽  
The Relationship ◽  
Stability Area

Trunk muscles are required for safety of movement in aging. The authors aimed to investigate the relationship between trunk muscle thickness and the static postural balance in older adults. A total of 31 females and 23 males with a mean age of 73.39 ± 6.09 completed the study. The thickness of the trunk muscles was determined with ultrasound imaging. Postural balance was assessed with force plate. There was a positive weak correlation between right and left upper rectus abdominis muscle thickness and anterior stability area (p < .05, r > .3). The negative and moderate correlation was determined between the left lower rectus abdominis and the perturbated stability sway value (p < .01, r > .5). The increase in trunk muscle thickness in older adults increases the postural stability area and decreases the postural sway especially in the mediolateral direction.

scholarly journals Testing the Performance of an Innovative Markerless Technique for Quantitative and Qualitative Gait Analysis

Sensors ◽  
2020 ◽  
Vol 20 (22) ◽  
pp. 6654
Author(s):  
Laura Simoni ◽  
Alessandra Scarton ◽  
Filippo Gerli ◽  
Claudio Macchi ◽  
Federico Gori ◽  
...  
Keyword(s):  
Gait Analysis ◽  
Low Cost ◽  
Human Locomotion ◽  
Healthy Individuals ◽  
Step Frequency ◽  
Web Based ◽  
Main Frequency ◽  
Highly Correlated ◽  
Gait Abnormalities ◽  
The Relationship

Gait abnormalities such as high stride and step frequency/cadence (SF—stride/second, CAD—step/second), stride variability (SV) and low harmony may increase the risk of injuries and be a sentinel of medical conditions. This research aims to present a new markerless video-based technology for quantitative and qualitative gait analysis. 86 healthy individuals (mead age 32 years) performed a 90 s test on treadmill at self-selected walking speed. We measured SF and CAD by a photoelectric sensors system; then, we calculated average ± standard deviation (SD) and within-subject coefficient of variation (CV) of SF as an index of SV. We also recorded a 60 fps video of the patient. With a custom-designed web-based video analysis software, we performed a spectral analysis of the brightness over time for each pixel of the image, that reinstituted the frequency contents of the videos. The two main frequency contents (F1 and F2) from this analysis should reflect the forcing/dominant variables, i.e., SF and CAD. Then, a harmony index (HI) was calculated, that should reflect the proportion of the pixels of the image that move consistently with F1 or its supraharmonics. The higher the HI value, the less variable the gait. The correspondence SF-F1 and CAD-F2 was evaluated with both paired t-Test and correlation and the relationship between SV and HI with correlation. SF and CAD were not significantly different from and highly correlated with F1 (0.893 ± 0.080 Hz vs. 0.895 ± 0.084 Hz, p < 0.001, r2 = 0.99) and F2 (1.787 ± 0.163 Hz vs. 1.791 ± 0.165 Hz, p < 0.001, r2 = 0.97). The SV was 1.84% ± 0.66% and it was significantly and moderately correlated with HI (0.082 ± 0.028, p < 0.001, r2 = 0.13). The innovative video-based technique of global, markerless gait analysis proposed in our study accurately identifies the main frequency contents and the variability of gait in healthy individuals, thus providing a time-efficient, low-cost means to quantitatively and qualitatively study human locomotion.

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