Lower Extremity Kinematics Research Articles

Lower extremity kinematic and kinetic factors associated with bat speed at ball contact during the baseball swing

ABSTRACT The purpose of this study was to determine which biomechanical variables measured during the baseball swing are associated with linear bat speed at ball contact (bat speed). Twenty collegiate baseball players hit a baseball from a tee into a net. Kinematics were recorded with a motion capture system sampling at 500 Hz and kinetics were measured by force plates under each foot sampling at 1000 Hz. Associations between bat speed, individual joint and segment kinematics, joint moments and ground reaction forces (GRF) were assessed using Pearson correlations and stepwise linear regression. Average bat speed was 30 ± 2 m/s. Lead foot peak vertical (159 ± 29% BW, r = 0.622, P = 0.001), posterior (−57 ± 12% BW, r = –0.574, P = 0.008) and resultant (170 ± 30% BW, r = 0.662, P = 0.001) GRF were all correlated with bat speed. No combination of factors strengthened the relationship to bat speed beyond these individual variables. These results illustrate the role of the lead leg in generating and transferring ground reaction forces through the kinetic chain in order to accelerate the bat. Training to improve bat speed should include both general lower extremity strengthening exercises and sport-specific hitting drills to improve lower extremity force production following lead foot contact.

Comparison of lower extremity kinematics and ground reaction forces between adolescents who run in motion control shoes with adolescents who run in neutral shoes

Differences in running biomechanics have been reported in adult long-distance runners when running in motion control or neutral shoes. The influence of growth and coordination refinement during puberty limits the generalisability of adult research to adolescents and it is unknown if biomechanics differ between adolescent who run in different types of shoes. The purpose of our study was to compare lower extremity kinematics and ground reaction forces between adolescents running in motion control or neutral shoes. We matched 18 adolescent long-distance runners who ran in motion control shoes with 18 adolescent long-distance runners who ran in neutral shoes according to running speed, sex, and physical maturation. We collected three-dimensional kinematic and ground reaction force data during overground running and performed statistical parametric mapping to compare joint angle and ground reaction force waveforms between the motion control and neutral shoe groups. We found no significant differences for hip, knee, or ankle joint angles (average differences <2°) or ground reaction forces (average differences <0.05 N/kg) between runners who ran in motion control or neutral shoes. Lower extremity kinematics and ground reaction forces were similar between adolescents who ran in motion control or neutral shoes.

The use of preferred footwear versus barefoot conditions in gait analysis: A methodological investigation

Laboratory-based gait analyses traditionally analyze baseline characteristics in individuals while they are barefoot. However, there is limited evidence on whether individuals’ preferred walking shoes alter lower extremity kinematics during over-ground walking. We present novel evidence regarding the effects of shoes on lower extremity kinematics in healthy, young adults. Fifteen volunteers participated in this study which obtained lower extremity kinematic data on two over-ground walking conditions (barefoot and preferred shoes). Gait velocity, stance width, and stride length, along with sagittal plane hip, knee, and ankle angular positions were computed; hip, knee, and ankle positions were normalized to 100% of the stride. Dependent t-tests were used to compare baseline and shoe conditions for gait velocity and stance width; a two-way analysis of variance was used for stride length. A point-by-point Model Statistic analysis was used to identify significant differences in angular joint positions between conditions. Our results indicate that shoes affected the ankle angular joint position for more than half of the gait cycle, and affected the knee angular joint position, but only for approximately 20% of the cycle. The hip was unaffected by shoes. Gait velocity and stance width were statistically significant, with gait velocity being greater for shoes, and stance width being greater while barefoot. Stride length was not statistically significant between conditions. These outcomes suggest that researchers should use caution if they are considering a barefoot condition as a ‘baseline’ for healthy, young adults, as there are marked changes in the ankle, and in traditional gait metrics.

Comparison of Different Kinematic Values of Lower Extremities during Gait between Individuals with Chronic Non-Specific Low Back Pain and Healthy Persons

Objective: The primary purpose of the present study was to compare the differences in lower extremity kinematic parameters in individuals who have chronic non-specific low back pain (CNLBP) with healthy control subjects (CTRL) during subphase of the stance phase. The secondary purpose was to compare the average walking speed of individuals who had CNLBP with CTRL during stance phase. Materials and Methods: The present study was conducted with 26 patients, 13 of 26 were participants with CNLBP and the other 13 were CTRL. To study the subject’s walking characteristics, 3D motion analysis was applied. Each subject was attached to 47 retroreflective markers and asked to walk barefoot on a 10-meter walkway at the preferred walking speed. The independent t-test and Mann Whitney U-test were used to compare joint excursions of each subphase of the stance phase and the average walking speed between two groups. Results: The CNLBP group had significantly lower forefoot motion in the sagittal plane during the initial contact phase than CTRL group, (p=0.017). They exhibited significantly lower hip motion in the sagittal plane (p=0.043), and lower knee motion in the transverse plane (p=0.007) during the forefoot contact phase as well. The CNLBP group exhibited significantly increased rearfoot motion in the frontal plane (p=0.002) during the foot flat phase. Moreover, the CNLBP group had significantly lower hip motion in the sagittal plane during the push-off phase (p=0.033). Conclusion: Individuals with CNLBP might modify their walking characteristics of the lower extremities and walk slower when compared with healthy persons to accommodate the pain they were dealing with. Keywords: Lower Extremity; Kinematics; Chronic Non-specific Low Back Pain; Gait; Gait Speed

Collegiate Dancers With Chronic Ankle Instability Possess Altered Strength and saut de chat Leap Landing Mechanics.

Ankle sprains are among the most common injuries in dancers. Following one or more severe sprains, some individuals will experience residual mechanical and functional deficits, otherwise known as chronic ankle instability (CAI). Dancers who suffer from CAI may have weaker musculature surrounding the ankle and altered landing mechanics. The purpose of this study was to compare ankle strength and saut de chat landing mechanics between dancers with and without CAI. Dancers with and without CAI, defined by the Identification of Functional Ankle Instability (IdFAI), participated in the study (CAI n = 8; IdFAI = 18.75 ± 5.50 points; age = 20 ± 1.5 years; training = 15.5 ± 3.5 years) (Control n = 8; IdFAI = 7.13 ± 3.40 points; age = 19 ± 0.6 years; training = 15.9 ± 2.5 years). Strength and leap landing mechanics were measured on the affected ankle for the CAI group and on the preferred landing leg of a leap for the control group. Concentric and eccentric ankle plantar flexion, and subtalar inversion and eversion strength were determined with dynamometry set at an angular velocity of 60°•s-1. Force plates and motion capture cameras were used to calculate lower extremity kinematic and kinetic data as participants performed 3 saut de chat leaps. Independent t-tests were calculated to determine differences between groups. Compared to dancers without CAI, dancers with CAI had lower eccentric plantar flexor strength, landed with higher vertical ground reaction forces, and absorbed greater power at the knee-joint during landing. Whether dancers who are weaker are more prone to injury or ankle-joint injury leads to muscular weakness is unknown. Dancers with CAI appear to lack control during leap landing while concomitantly shifting loads proximally away from the ankle-joint. We encourage dancers with and without CAI to engage in additional training that enhances ankle strength.

A comparison of three-dimensional kinematics between markerless and marker-based motion capture in overground gait

Vision-based methods using RGB inputs for human pose estimation have grown in recent years but have undergone limited testing in clinical and biomechanics research areas like gait analysis. The purpose of the present study was to compare lower extremity kinematics during overground gait between a traditional marker-based approach and a commercial multi-view markerless system in a sample of subjects including young adults, older adults, and adults diagnosed with Parkinson’s disease. A convenience sample of 35 adults between the age of 18–85 years were included in this study, yielding a total of 114 trials and 228 gait cycles that were compared between systems. A total of 30 time normalized waveforms, including three-dimensional joint centers, segment angles, and joint angles were compared between systems using root mean-squared error (RMSE), range of motion difference (ΔROM), Pearson correlation coefficients (r), and interclass correlation coefficients (ICC). RMSEs for joint center positions were less than 28 mm in all joints with correlations indicating good to excellent agreement. RMSEs for segment and joint angles were in range of previous results, with highest agreement between systems in the sagittal plane. ΔROM differences were within reference values that characterize clinical groups like Parkinson’s disease, stroke, or knee osteoarthritis. Further improvements in pelvis tracking, markerless keypoint model definitions, and standardization of comparison study protocols are needed. Nevertheless, markerless solutions seem promising toward unrestricted motion analysis in biomechanics research and clinical settings.

Investigating the effects of heel-only and entire sole lift on lower extremity kinematics during walking in healthy individuals

Investigating the effects of heel-only and entire sole lift on lower extremity kinematics during walking in healthy individuals

The effect of bilateral heel wedge on lower extremity kinematics during walking for children with hypermobility

The effect of bilateral heel wedge on lower extremity kinematics during walking for children with hypermobility

The Association Between Lower Extremity Kinematics And Impact Load During The Drop Vertical Jump Task

The Association Between Lower Extremity Kinematics And Impact Load During The Drop Vertical Jump Task

Association of clinically-measured and dynamic ankle dorsiflexion assessed by markerless motion capture during the drop-jump task on landing biomechanics and risk of ankle injury in military personnel undergoing 10 weeks of physical training.

Determine the influence of clinically-measured maximum dorsiflexion, dynamic peak dorsiflexion and percent of clinically-measured maximum dorsiflexion used during a drop-jump task on landing biomechanics and risk of ankle injury in military personnel. Prospective cohort study. 672 participants (122 women) enrolled. The weightbearing lunge test assessed clinically-measured maximum dorsiflexion averaged across limbs (degrees). Markerless motion capture and force plates collected lower extremity kinematic and kinetic data during a drop-jump task. Percent of clinically-measured maximum dorsiflexion used during landing was calculated as dynamic peak dorsiflexion divided by clinically-measured value, multiplied by 100 (%). De-identified injury data was derived from military physical therapists. Simple linear regression analysis determined the association between dorsiflexion measures and landing biomechanics. Simple binary logistic regression analyses identified predictors of ankle injuries. Statistical significance was set at α = 0.05. Eighteen participants sustained a traumatic ankle injury from a landing. All measures of dorsiflexion were associated with movement patterns that countered the stiff-legged landing strategy with dynamic measures showing a higher predictive value. Protective factors against ankle injury included height (odds ratio: 0.818, p = 0.006) and weight (odds ratio: 0.824, p = 0.023) for women. Relative braking impulse was a risk factor for men (odds ratio: 1.890, p = 0.001). Greater clinically-measured and dynamic measures of dorsiflexion were associated with movement patterns that countered the stiff-legged landing strategy but neither measure of dorsiflexion predicted ankle injury risk. Resultant biomechanics and anthropometrics influenced ankle injury risk to warrant recognition for injury prevention initiatives.

Influence of self-perceived disability on squatting kinematics in individuals with patellofemoral pain

BackgroundIndividuals with patellofemoral pain have a heterogeneous presentation of symptoms during functional tasks; however, biomechanical data often negates self-reported disability. The single leg squat is common in patellofemoral pain literature but may not be a pain provoking task for all individuals. Therefore, our study examined the influence of self-perceived squatting disability in individuals with patellofemoral pain on lower extremity squatting kinematics. MethodsWe analyzed two-dimensional hip frontal plane projection angle, knee frontal plane projection angle, lateral trunk movement, and pelvic drop in 100 participants, 82 with patellofemoral pain and 18 pain-free controls. Participants with patellofemoral pain were dichotomized based on the level of disability reported during squatting on the anterior knee pain scale. An analysis of variance with post hoc testing was used to compare differences in lower extremity and trunk kinematics between groups, p < 0.05. FindingsParticipants who reported only being able to squat with partial weight bearing had greater hip frontal plane projection angles than those who reported squatting painful each time (p = 0.017). The partial weight bearing group had greater knee frontal plane projection angles compared those who reported pain with repeated squatting and the pain-free group, (p < 0.034). We found no significant differences in lateral trunk motion or pelvic drop between groups. InterpretationIndividuals with patellofemoral pain who self-reported worse squatting disability had greater hip and knee frontal plane motion compared to individuals with less disability and pain-free controls. Clinicians and researchers should consider specific pain provoking tasks when evaluating and treating patients with patellofemoral pain.

Markerless motion capture estimates of lower extremity kinematics and kinetics are comparable to marker-based across 8 movements

Motion analysis is essential for assessing in-vivo human biomechanics. Marker-based motion capture is the standard to analyze human motion, but the inherent inaccuracy and practical challenges limit its utility in large-scale and real-world applications. Markerless motion capture has shown promise to overcome these practical barriers. However, its fidelity in quantifying joint kinematics and kinetics has not been verified across multiple common human movements. In this study, we concurrently captured marker-based and markerless motion data on 10 healthy study participants performing 8 daily living and exercise movements. We calculated the correlation (Rxy) and root-mean-square difference (RMSD) between markerless and marker-based estimates of ankle dorsi-plantarflexion, knee flexion, and three-dimensional hip kinematics (angles) and kinetics (moments) during each movement. Estimates from markerless motion capture matched closely with marker-based in ankle and knee joint angles (Rxy ≥ 0.877, RMSD ≤ 5.9°) and moments (Rxy ≥ 0.934, RMSD ≤ 2.66 % height × weight). High outcome comparability means the practical benefits of markerless motion capture can simplify experiments and facilitate large-scale analyses. Hip angles and moments demonstrated more differences between the two systems (RMSD: 6.7–15.9° and up to 7.15 % height × weight), especially during rapid movements such as running. Markerless motion capture appears to improve the accuracy of hip-related measures, yet more research is needed for validation. We encourage the biomechanics community to continue verifying, validating, and establishing best practices for markerless motion capture, which holds exciting potential to advance collaborative biomechanical research and expand real-world assessments needed for clinical translation.

Estimating marksmanship performance during walking while maintaining weapon aim

Marksmanship performance while moving is a critical skill among tactical athletes due to the high demands of their occupational duties. Qualifications for dynamic marksmanship performance are not standardized across tactical athlete groups, which may limit comprehensive assessment of tactical athlete performance for situational awareness and adaptability to an unpredictable environment. Although static marksmanship performance provides foundational information on skills and level of ability, research is lacking on factors that influence dynamic marksmanship performance to best prepare tactical athletes for duties. The purpose of this study was to identify whether static marksmanship performance, speed of movement, load carriage, and biomechanical factors while ‘shooting on the move’ influenced dynamic marksmanship performance. Twenty-four male tactical athletes (22 active-duty Army Soldiers, two civilian SWAT operators; age: 23.83 ± 5.47 years; height: 1.80 ± 0.08 m; weight: 81.04 ± 7.87 kg) participated; final analyses did not include data from the two civilian operators to maintain sample homogeneity. Tactical athletes completed static and dynamic (‘shoot on the move’) marksmanship tasks under three load conditions: (1) no load (NL), (2) half kit (HK) of 11.34 kg, and (3) full kit (KIT) of 22.68 kg. Dynamic marksmanship was completed under three speed conditions: (1) self-selected slow speed, (2) standard speed, and (3) self-selected fast speed. Hip, knee, and ankle kinematics were collected via wireless inertial measurement units. Spatiotemporal parameters were collected via optical detection system. Marksmanship performance (accuracy) was collected via open-air acoustic target scoring and mean radial error (MRE) was calculated for both static and dynamic marksmanship tasks. Linear mixed-effects models were fit with dynamic MRE as the outcome variable with fixed effects of static MRE, load condition, speed condition, kinematics, and spatiotemporal parameters, adjusting for body mass. Alpha level was set a priori at p ≤ 0.10. The final statistical model included fixed effects of static MRE, load condition, speed condition, and time spent in double limb support. Static MRE (p < 0.01) and time spent in double limb support (p = 0.01) were significant factors. For each 1 cm increase in static MRE there was a 0.66 cm increase in dynamic MRE. For every 1% increase in time spent in double limb support while ‘shooting on the move’ there was a 0.13 cm increase in dynamic MRE. Findings from this study highlight that tactical athletes who have larger static stance MRE and spend a longer time in double limb support during a gait cycle exhibit an increase in MRE during ‘shoot on the move’ trials. Overall, dynamic shooting accuracy is not affected by lower extremity joint angles, load carriage, or speed of movement. Although strong relationships are known between gait speed, load, and lower extremity kinematics, the differences in tactical gait compared to normal gait and multi-task paradigm that likely favors marksmanship accuracy seem to present novel movement characteristics unique to occupational gait. Further investigation is warranted to identify other potential factors that may improve or worsen dynamic marksmanship performance.

Examining movement asymmetries during three single leg tasks using interlimb and single subject approaches

Purposes: To examine whether healthy individuals displayed asymmetric trunk and lower extremity kinematics in the frontal and sagittal planes using both interlimb and single subject models. MethodsTrunk, pelvis, and lower extremity kinematic waveforms were analyzed bilaterally during the single leg squat (SLS), forward step down (FSD), and lateral step down (LSD). Participants identified task specific preferred and non-preferred legs based on perceived stability for interlimb analyses. Movement patterns were also analyzed with a single subject approach that included Fisher's exact tests to assess whether asymmetries were related to the task. ResultsParticipants were found to have increased pelvic drop on the non-preferred leg during the LSD from 41 to 77% of the movement (p = 0.01). No other bilateral differences were found for interlimb analyses. Single subject analyses indicated that no task had a greater probability of finding or not finding asymmetries. Associations were found between the FSD and SLS for frontal plane hip (p < 0.01) and knee motion (p < 0.01). ConclusionsInterlimb analyses can be influenced by intraparticipant movement variability between preferred and non-preferred legs. Movement asymmetries during single leg weightbearing are likely task dependent and a battery of tests is necessary for assessing bilateral differences.

The Effects of a Custom-Designed High-Collar Shoe on Muscular Activity, Dynamic Stability, and Leg Stiffness: A Biomimetic Approach Study.

High-collar shoes are a biomimetic approach to preventing lateral ankle injuries during high-demand activities; however, the influence of collar stiffness (CS) on parameters related to lateral ankle sprain prevention during running remains unclear. In this study, we investigated the effects of a custom-designed shoe CS on muscular activity, dynamic stability, and leg stiffness (Kleg) during running using a biomimetic design approach inspired by the mechanisms of ankle sprain prevention. Sixteen healthy male participants ran on a treadmill while wearing a custom-designed high-collar shoe with low, medium, and high CS conditions, measured using circumferential ankle pressure (CAP). Lower extremity kinematics and electromyography (EMG) data were recorded simultaneously. One-way repeated-measures ANOVA was conducted to compare the CS conditions. Results indicate that high and medium CS conditions significantly reduce sagittal and frontal ankle ranges of motion (ROMs) compared to the low CS condition, providing improved stability and support against lateral ankle sprain; moreover, there was a trend towards higher dynamic stability and Kleg with increasing CS. Our study highlights the importance of considering the CAP in regulating high-collar stiffness properties and how higher CS may provide better support for the ankle during running. Nevertheless, additional research is necessary to validate the efficacy of the current design in preventing ankle sprains during high-demand activities.

Unexpected inversion perturbation during a single-leg landing in patients with chronic ankle instability

ABSTRACT It remains unclear how unexpected perturbations during single-leg landings affect lower extremity kinematics and muscle activations in patients with chronic ankle instability (CAI). The purpose of this study was to identify the differences in lower extremity movement patterns among CAI subjects, copers, and healthy controls. Sixty-six people including 22 CAI subjects, 22 copers, and 22 healthy controls volunteered to participate in the study. Lower extremity joint kinematics and EMG activations from 200-ms pre to 200-ms post the initial contact during unexpected tilted landings were measured. Functional data analysis was used to evaluate between-group differences for outcome measures. Relative to copers and healthy controls, CAI subjects showed more inversion from 40-ms to 200-ms after initial contact. Relative to healthy controls, CAI subjects and copers showed more dorsiflexion. Relative to healthy controls, CAI subjects and copers showed more muscle activation in tibialis anterior and peroneus longus, respectively. In conclusion, CAI subjects demonstrated greater inversion angles and muscle activation before initial contact compared to LAS copers and healthy controls. This suggests that CAI subjects and copers prepare for their landing with protective movements, but the prepared movements shown by CAI subjects may be insufficient to reduce risk of recurrent injury.

Lower extremity kinematic comparisons between patients with mild cognitive impairment and healthy individuals during single and dual tasks

AbstractBackgroundMild cognitive impairment (MCI) is one of the common health issues in modern societies, and it has a high rate of progression to dementia. Studies have shown that MCI has the potential to cause abnormal postural control and altered intersegmental coordination during functional activities, which may be one of the causes that lead to the increase of the risk of falls. The study aimed to compare the kinematics of the lower limb joints between patients with MCI and healthy controls during single‐task (gait) and cognitive or motor dual‐tasks (gait with arithmetic subtraction or tray handling).MethodSeventeen patients with MCI (age: 67.6±3.9 yrs; BMI:23.5±3.7) and seventeen healthy individuals (age: 67.9±3.7 yrs; BMI:24.0±4.2) were recruited in the study. Each participant performed single‐task (gait), cognitive dual tasks (gait while conducting arithmetic subtraction), and motor dual tasks (gait while balancing a ball on a tray), and the movements were recorded by a standard motion capture system. Peak angular magnitudes of the hip, knee, and ankle in the sagittal plane were extracted. Differences between the MCI and control groups were defined by independent t‐tests with a significant level at 0.05.ResultsThe significant differences between groups were found at the hip joint but not at the knee and ankle joint in all single‐ and dual‐tasks conditions. Compared to the healthy group, the MCI group demonstrated less maximum hip flexion and greater hip extension during the stance phase and less maximum hip flexion during the swing phase. The hip kinematics difference might be a change of the control of hip and pelvis muscles due to MCI thus altering the hip kinematic performance. This may also explain the increasing fall risks in patients with MCI due to this altered hip control strategy.ConclusionIn summary, the patients with MCI may have an alternative hip kinematic adaptation that is different from the healthy individuals. However, the cause of this adaptation is not clear at this point, and further investigation is necessary to make sure whether this is an important biomechanical marker or not.

Effects of customized insoles with medial wedges on lower extremity kinematics and ultrasonographic findings in plantar fasciitis persons

The customized insole is widely recommended as an effective intervention for pain reduction and foot function improvement in plantar fasciitis persons. However, it is unclear whether the additional correction of medial wedges could change the kinematics from the only insole. The objectives of this study were thus to compare customized insoles with and without medial wedges on lower extremity kinematics during gait and to determine the short-term effects of the customized insole with medial wedges on pain intensity, foot function, and ultrasonographic findings in plantar fasciitis persons. A within-subject, randomized, crossover design within motion analysis research laboratory was conducted among 35 persons with plantar fasciitis. Main outcome measures included joint motions of the lower extremity and multi-segment foot, pain intensity, foot function, and ultrasonographic findings. The customized insole with medial wedges produced less knee motion in the transverse plane and hallux motion in all planes during the propulsive phase than that without medial wedges (all p < 0.05). After the 3-month follow-up, the insoles with medial wedges decreased pain intensity and increased foot function. Abnormal ultrasonographic findings also decreased significantly after the 3-month treatment of insoles with medial wedges. Customized insoles with medial wedges seem superior to those without medial wedges on both multi-segment foot motion and knee motion during propulsion. Positive outcomes from this study supported the use of customized insoles with medial wedges as an effective conservative treatment in patients with plantar fasciitis.Trial registration: TCTR20210928006 (28/09/2021).

Effect of different ankle braces on lower extremity kinematics and kinetics following special-induced fatigue for volleyball players with functional ankle instability

BackgroundThe aim of this study is to examine the effects of different ankle braces on functional ankle instability (FAI) participants following special-induced fatigue, which will provide advice for preventing ankle sprains in volleyball game. MethodsA total of 18 male collegiate volleyball players with FAI were recruited. The kinematics and kinetics data were acquired from the participants during single-leg drop landing using the infrared motion capture system (Mars2H, Nokov, China) and the force platform (Bertec, USA). A 2 × 2 within subjects design ANOVA was adopted to analyze the data. ResultsWhether fatigue or not, soft and semi-rigid brace reduced the ankle inversion (P = 0.025). Moreover, soft brace reduced the sagittal range of motion (ROM) of the ankle joint before fatigue (P = 0.05). In addition, the semi-rigid brace shortened the time to stability in the medial and lateral directions (P = 0.039) as well as the vertical directions (P < 0.001). The semi-rigid brace reduced the ground reaction force post-fatigue (P = 0.001). ConclusionSoft ankle brace reduced the sagittal range of motion pre-fatigue. Since volleyball requires athletes to jumping and landing repeatedly, and the ankle sagittal ROM was an important cushion during landings. Thus, soft ankle brace might result in overuse injury for lower extremity. However, the semi-rigid ankle brace increased the dynamic stability in the medial and vertical directions, and reduced the ankle inversion angle and forward ground reaction force post-fatigue. This ensured that the volleyball player's ankle was in a neutral position during landing, reducing the risk of excessive inversion caused by contact with the opposing player during spike and block.

Differences in kick-leg kinematics in various side-kick heights

ABSTRACT This study aims to explore the variation of lower extremity kinematic characteristics when elite taekwondo athletes perform the side-kick on protective gear placed at various heights. Twenty distinguished male national athletes were recruited and were asked to kick targets at three different heights adjusted according to their body height. A three-dimensional (3D) motion capture system was used to collect kinematic data. Kinematic parameters differences in the side-kick at three different heights were analyzed by using a one-way ANOVA (p < .05). The results revealed significant differences in the peak linear velocities of the pelvis, hip, knee, ankle, and centre of gravity of the foot during the leg-lifting phase (p < .05). Significant differences between heights were noted in the maximum angle of pelvis left tilting and hip abduction in both phases. In addition, the maximum angular velocities of pelvis left tilting and hip internal rotation were only different in the leg-lifting phase. This study found that, to kick at a higher target, athletes increase the linear velocities of their pelvis and all lower extremity joints of attacking leg in the leg-lifting phase; however, they only increase rotational variables on the proximal segment at the peak angle of the pelvis (left tilting) and hip (abduction and internal rotation) in the same phase. As an application in actual competitions, according to the opponent’s body height, athletes can adjust both linear and rotational velocities of their proximal segements (pelvis and hip) and deliver into distal segements (knee, ankle, foot) linear velocity to perform accurate and rapid kicks.