Ankle Displacement Research Articles

Influence of anterior talofibular ligament injury and mechanical ankle anterior displacement on symptoms in individuals with chronic ankle instability.

Repeated ankle sprains can lead to injuries, including those of the anterior talofibular ligament; however, the extent to which these ligament injuries are associated with symptoms of chronic ankle instability remains unclear. To examine the influence of anterior talofibular ligament injury and ankle anterior displacement on symptoms of chronic ankle instability. Case-Control Study. A university laboratory. A total of 426 college students completed a questionnaire survey on the history of ankle sprain. Thirty-four (24 males, 10 females; age = 20.6 ± 0.5 years), 49 (38 males, 11 females; age = 20.2 ± 1.2 years), and 39 (24 males, 15 females; age = 20.1 ± 1.1 years) participants were enrolled in the healthy, coper, and chronic ankle instability groups, respectively. One examiner measured the anterior talofibular ligament delineation using ultrasound and anterior ankle displacement using a capacitance-type sensor device. The Cumberland Ankle Instability Tool was applied to assess pain and perceived instability. The anterior talofibular ligament was normal significantly more frequently in healthy participants and abnormal significantly more frequently in patients with chronic ankle instability (p < 0.001). Anterior ankle displacement was significantly greater in the coper and chronic ankle instability groups than in healthy individuals (p < 0.001), but no significant difference was observed between the coper and chronic ankle instability groups. There was no significant correlation between the anterior ankle displacement and Cumberland Ankle Instability Tool scores (p = 0.709) in participants with previous ankle sprains. Observation of an abnormal anterior talofibular ligament on ultrasonography is associated with anterior displacement of the ankle joint. However, it is assumed that the influence of anterior ankle displacement due to damage to the anterior talofibular ligament on the pain and perceived instability in chronic ankle instability is small.

A Physically Active Lifestyle Can Protect against Age-Related Decline in Ankle Proprioception

This study examined whether physically active middle-aged (50-64 years) and older adults (65-80 years) demonstrate age-related ankle proprioceptive decline relative to younger counterparts. Empirical data indicate that ankle proprioception declines with aging and such sensory decline negatively affects balance. Using a passive motion apparatus, we employed a psychophysical forced-choice paradigm in which the ankle was passively plantarflexed to a reference position (15° or 25°) and a comparison position that was always smaller than the reference. Subsequently, participants indicated which position was more plantarflexed. As outcome measures of ankle position sense acuity, a just-noticeable-difference (JND) threshold and the uncertainty area (UA) were derived from the psychometric stimulus-response difference function for each participant. The JND threshold is a measure of proprioceptive bias and UA constitutes a measure of precision. The main results are: First, at the 15° reference, most middle-aged (74%) and older adults (71%) had thresholds within the range of the young adults. The respective median JND threshold of young adults was statistically lower when compared to both older groups. Second, no differences between age groups were observed at the 25° reference. Third, no age-related differences were found for UA at either reference. These data indicate that physically active aging adults may be spared from age-related decline in ankle position sense and that age-related differences emerge for small ankle displacements. The findings underscore the importance of remaining active during aging.

Multi-joint protective effects of lumbar brace on lumbar, hip, knee, and ankle in parachute landing with backpack load.

There were high injury risks on lumbar and lower limb joints in parachuting landing, and the lumbar brace could protect lumbar. Besides, a backpack load was necessary in parachute landing and increased the injury risk. This study aimed to evaluate multi-joints protective effects of the lumbar brace on lumbar and lower limb joints in parachuting landing with the backpack load. Seven participants landed from a 120 cm height platform without and with a lumbar brace and without and with a 5-kg backpack load, respectively. Infrared makers were pasted on trunk, pelvis, and lower limb in order to build a multi-rigid-body model for calculating kinematic and kinetic parameters. The joint angular displacements of lumbar and ankle and the peak vertical ground reaction force were significantly decreased from 29.2 ± 9.2°, 45.2 ± 7.8°, and 14.7 ± 2.0 bodyweight to 21.6 ± 4.9° (p < 0.05), 39.0 ± 10.1° (p < 0.05) and 10.7 ± 1.3 bodyweight (p < 0.05) respectively by the lumbar brace with no backpack load, and the joint angular displacement of hip was significantly increased from 52.6 ± 7.2° to 68.3 ± 12.5° (p < 0.05). The joint angular displacement of lumbar and ankle were significantly decreased from 29.0 ± 5.0° and 53.8 ± 5.1° to 25.1 ± 5.2° (p < 0.05) and 48.5 ± 2.5° (p < 0.05) respectively by the lumbar brace with the backpack load, and the joint angular displacement of hip and knee were significantly increased from 60.1 ± 8.2° and 110.1 ± 9.3° to 69.7 ± 13.2° (p < 0.05) and 116.8 ± 5.8° (p < 0.05), respectively. The lumbar brace could provide the multi-joint protective effect by decreasing injuries of lumbar and ankle in landing both without and with the backpack load.

Effects of anticipation on joint kinematics during inversion perturbation in individuals with chronic ankle instability.

Although chronic ankle instability (CAI) patients display altered reactive joint kinematics after inversion perturbation, little is known about the effects of anticipation on reactive joint kinematics among CAI, coper, and control groups. To assess changes in reactive joint kinematics after different inverted landing situations including planned- and unplanned-condition among groups of CAI, coper, and control. Sixty-six volunteers participated (22 per group). Participants completed three trials of both planned and unplanned single-leg landing onto an inverted force platform while reactive joint kinematic data were collected from initial-contact to 200 ms after initial-contact. Two-way repeated measures ANOVAs were used to examine the differences between condition (planned-, unplanned-conditions) and group (CAI, coper, control). There were significant group by condition interactions for total ankle displacement in the frontal plane (p < 0.01) and maximum ankle inversion velocity (p=0.01). CAI patients displayed increased ankle displacement (p < 0.01) and maximum inversion velocity (p < 0.01) under the unplanned condition compared to the planned condition. However, copers did not show any differences in ankle displacement and maximum inversion velocity between the two conditions. CAI patients displayed greater changes in ankle joint displacement and maximum ankle inversion velocity occurred after inversion perturbation under unplanned condition compared with copers and controls. Current data suggest that altered reactive joint kinematics under the unanticipated condition in CAI patients may contribute to the condition of CAI after ankle sprains. Clinicians should focus on rehabilitation programs to recover and/or develop feedback control for CAI patients during functional movements under unanticipated condition to prevent further injuries.

Diagnostic Evaluation of Mechanical Ankle Instability by Comparing Injured and Uninjured Contralateral Ankles Using Arthrometry.

Individuals with mechanical ankle instability (MAI) have obvious lateral ligament laxity and excessive ankle joint motion beyond the physiological range. Arthrometry has been introduced to quantitatively measure the laxity of the ankle joint. However, the diagnostic accuracy of arthrometry in MAI is still debatable. To (1) evaluate the difference in laxity between bilateral ankles in patients with and those without MAI and (2) calculate the diagnostic accuracy of ankle arthrometry using bilateral comparisons. Cross-sectional study. Research laboratory. A total of 38 individuals with unilateral MAI (age = 31.24 ± 7.90 years, height = 168.93 ± 7.69 cm, mass = 65.72 ± 10.47 kg) and 38 individuals without MAI (control group; age = 32.10 ± 7.10 years, height = 166.59 ± 7.89 cm, mass = 62.93 ± 10.72 kg). Bilateral ankle laxity in each participant was quantitatively measured by performing the arthrometric anterior drawer test. Continuous data of loading force and joint displacement were recorded. Data from both ankles were compared for the ankle joint displacement at a loading force of 75 N (D75) and load-displacement ratio from 10 to 40 N (LDR 10-40). The D75 between injured and uninjured ankles in patients with MAI was different (t37 = 9.78, P < .001). The mean LDR 10-40 in injured ankles was higher than that in uninjured ankles (t37 = 9.80, P < .001). In the control group, no differences were found between the left and right ankles. The MAI group had larger bilateral differences than the control group (t37 range = 7.33-8.18; P < .001). When LDR 10-40 was used to diagnose MAI, the arthrometer showed sensitivity and specificity of 0.900 and 0.933, respectively, with a cutoff value of 0.0351 mm/N. An ankle arthrometer can be used to quantitatively measure the difference in bilateral ankle laxity in patients with MAI. Arthrometer-measured LDR 10-40 can be used to diagnose MAI with high diagnostic accuracy.

Validity and inter-rater reliability of ankle motion observed during a single leg squat.

BackgroundThe single leg squat (SLS) test is a clinical functional test commonly used to evaluate clinically aberrant movement patterns of the knee. The SLS could be an interesting option to analyze ankle control in the frontal plane during dynamic load analysis. However, to date, there are no studies that have analyzed the associations between the increased subtalar joint pronation by navicular drop (ND) test and ankle control with single leg squat (SLSankle) using a three-point scale. The purpose of this study was to evaluate the reliability of a clinical observation method to assess and determine the relationship between navicular drop (ND) and ankle control on the SLSankle score.MethodsA total of fifty-five healthy, physically active (31 females and 24 males) volunteers participated in this study. The degree of subtalar pronation was assessed through the ND test, and the ankle control was defined as the ankle displacement in the frontal plane during the SLS.ResultsWe found good intra-rater and inter-rater agreement during SLSankle, with Kappa values from 0.731 to 0.750. The relationship between the SLSankle and ND was significant ; the Spearman’s rank correlation coefficient was 0.504 (p < 0.05).ConclusionsThe SLSankle score supplied the clinical practice with a reliable and valid alternative for quantifying foot mobility in comparison to the ND test.

Development of an AFO with Dual-material using an FDM Printer

This paper presents a design and development of an Ankle Foot Orthosis (AFO) printed with a multi-extrusion Fused Deposition Modelling (FDM) printer. AFO is crucial in the healing of patients with ankle joint displacement. It helps to heal the foot easily. The model is designed to print with dual materials such as flex and polylactic acid (PLA). The critical problem in building a prototype is to obtain excellent bonding properties between the layers of different materials. The Flex material is softer than the PLA and both have different melting temperatures. Thus, successfully printing with an excellent adhesive is the key concern in multimaterial applications. The paper also presents the simulation results of an AFO to justify the mechanical properties and required materials for sustainable development.

"Going Backward": Effects of age and fatigue on posterior-directed falls in Parkinson disease.

Nearly half of persons with Parkinson disease (PD) report fatigue as a factor in their fall history. However, it is unknown whether these self-reported falls are caused by a sensation of fatigue or performance fatigue. We sought to investigate the influences of performance fatigue and age on postural control in persons with PD. Individuals with PD (n = 14) underwent postural control assessments before (T0) and immediately after (T1) fatiguing exercise. Biomechanical data were gathered on participants completing a treadmill-induced, posterior-directed fall. Performance fatigue was produced using lower extremity resistance exercise on an isokinetic ergometer. Repeated measures ANCOVAs were used with age as a covariate to determine the effects of performance fatigue on biomechanical variables. After adjustment for age, there was a statistically significant difference in peak center of pressure (COP) latency during the support phase of recovery. Pairwise comparisons demonstrated a decrease in peak ankle displacement from T0 to T1. Age was also found to be significantly related to reaction time and peak knee displacement while participants were fatigued. The decreased peak COP latency, along with decreased ankle angular displacement, suggest that persons with PD adopt a stiffening strategy in response to backward directed falls. Postural stiffening is not uncommon in persons with PD and could be a risk factor for falls. Older individuals with PD demonstrate slower mobility scores and decreased reaction times in the setting of fatigue, suggesting a combined effect of the aging and fatigue processes.

Parametric analysis of landing injury : The effect of landing posture and joint displacement.

During landing, the lower limb joints work concertedly to reduce landing forces. Changing the biomechanics of one joint can alter landing strategies in other joints thus affecting the probability of injury. Therefore, understanding the mutual effects between the joints is crucial for the prevention of lower extremity injuries. The purpose of this study is to evaluate the effect of joint displacement and initial contact posture on the impact forces and joint kinematics during drop landing, via computational modeling. The impact dynamics of drop landing is modeled by a three link planar model. Different landing scenarios are then simulated to investigate how restricting the displacement of one joint and changing its initial contact angle affect the other joints' ranges of motion, the trunk motion, and the impact forces. Our study suggests that the impact force increases by up to [Formula: see text], [Formula: see text] and [Formula: see text], by restricting the hip, knee and ankle joints, respectively. Restricting each one of the hip and knee joints decreases the displacement of the other one. The association between the ankle displacement and the hip/knee motion depends on joints' stiffness and landing posture. Moreover, changing the landing posture affects the joints kinematics and impact forces significantly. A safe landing posture is a fore-foot landing with knee flexion angle of around 30° to 40° and a foot-ground angle of 40° to 55°, which decreases the impact force by more than [Formula: see text] in comparison to the erect posture with horizontal foot. The obtained results are of practical importance in training landing skills and designing force-reducing external components.

Accurate Heuristic Terrain Prediction in Powered Lower-Limb Prostheses Using Onboard Sensors.

This study describes the development and offline validation of a heuristic algorithm for accurate prediction of ground terrain in a lower limb prosthesis. This method is based on inference of the ground terrain geometry using estimation of prosthetic limb kinematics during gait with a single integrated inertial measurement unit. We asked five subjects with below-knee amputations to traverse level ground, stairs, and ramps using a high-range-of-motion powered prosthesis while internal sensor data were remotely logged. We used these data to develop three terrain prediction algorithms. The first two employed state-of-the-art machine learning approaches, while the third was a directly tuned heuristic using thresholds on estimated prosthetic ankle joint translations and ground slope. We compared the performance of these algorithms using resubstitution error for the machine learning algorithms and overall error for the heuristic algorithm. Our optimal machine learning algorithm attained a resubstitution error of 3.4% using 45 features, while our heuristic method attained an overall prediction error of 2.8% using only 5 features derived from estimation of ground slope and horizontal and vertical ankle joint displacement. Compared with pattern recognition, the heuristic performed better on each individual subject, and across both level and non-level strides. These results demonstrate a method for heuristic prediction of ground terrain in a powered prosthesis. The method is more accurate, more interpretable, and less computationally expensive than machine learning methods considered state-of-the-art for intent recognition, and relies only on integrated prosthesis sensors. Finally, the method provides intuitively tunable thresholds to improve performance for specific walking conditions.

BIOMECHANICAL EFFECTS OF HYPERPRONATION ON MULTIDIRECTIONAL ANKLE ANGULAR DISPLACEMENT AND STIFFNESS

Hyperpronation of the foot is believed to contribute to ankle hypermobility and associated stiffness reduction, but the underlying biomechanical mechanisms remain unknown. This study aimsed to investigate multidirectional ankle displacement and associated stiffness when a posterior–anterior impact force was applied to the posterior knee compartment. Forty healthy adults with and without foot hyperpronation were recruited. A three-dimensional motion capture system and force plates were used to acquire angular displacement and ankle joint moment data. The independent [Formula: see text]-test and Mann–Whitney [Formula: see text] test were used to compare the group differences in ankle angular displacement, moment, and stiffness. Spearman’s rho test was performed to determine the relationship between ankle angular displacement and stiffness. The hyperpronation group demonstrated significantly greater sagittal ([Formula: see text]) and frontal plane ([Formula: see text]) angular displacements and reduced sagittal plane ankle stiffness ([Formula: see text]) than the neutral group. The Spearman’s correlation analysis showed a close inverse relationship between the ankle angular displacement and stiffness, ranging from [Formula: see text] to [Formula: see text]. The biomechanical data in our study suggest that individuals with foot hyperpronation present with multidirectional hypermobility and a reduction in ankle stiffness. These factors contribute to an increased risk of ankle-foot injury in individuals with foot hyperpronation.

Organisation of instep kicking in young U11 to U20 soccer players

ABSTRACT Aim: The main purpose of the study was to investigate kicking kinematics and performance in young-trained soccer players according to age, playing status, and biological maturity.Methods: Youth male soccer players (N = 105) from five age groups (under-11, under-13, under-15, under-17, and under-20) were evaluated. Four digital video cameras (300 Hz) captured the participants’ lower extremity and ball kinematics during penalty kick trials using dominant limb.Results: It was possible to identify non-linear differences in angular joint kinematics (displacement and velocity) of hip, knee and ankle across age-groups. Kicked ball speed and lower extremity mechanical factors discriminated among under-15 players with distinct status (e.g., ball speed and foot-to-ball speed ratio: starters > non-starters and non-participating substitutes; effect size = 1.05 to 1.49 [large]). Estimated maturity offset was not correlated with performance outputs in any age-group (r = −0.28 to 0.39; P > 0.05).Conclusion: We conclude that from ages ~10 to 19 years, differences in kicking kinematics and performance vary across time in youth players. Transition phase between under-13 to under-15 appears the most sensible period for powerful instep kick performance development. Kicking speed in youth soccer is discriminated according to player status, but not estimated biological maturity.

Improved Ankle Mobility After a 4-Week Training Program Affects Landing Mechanics: A Randomized Controlled Trial.

Howe, LP, Bampouras, TM, North, JS, and Waldron, M. Improved ankle mobility after a 4-week training program affects landing mechanics: a randomized controlled trial. J Strength Cond Res 36(7): 1875-1883, 2022-This study examined the effects of a 4-week ankle mobility intervention on landing mechanics. Twenty subjects with restricted ankle dorsiflexion range of motion (DF ROM) were allocated to either a strength training only (n = 9) or a strength training and ankle mobility program (n = 11). Subjects performed a weight-bearing lunge test and bilateral drop-landings before and after the intervention. Normalized peak vertical ground reaction force (vGRF), time to peak vGRF, and loading rate were calculated, alongside sagittal-plane initial contact angles, peak angles, and sagittal-plane joint displacement for the ankle, knee, and hip. Frontal-plane projection angles were also calculated. After the intervention, only the strength and mobility group improved ankle DF ROM (mean difference = 4.1°, effect size [ES] = 1.00, p = 0.002). A one-way analysis of covariance found group effects for ankle joint angle at initial contact (p = 0.045), ankle (p < 0.001) and hip joint angle at peak flexion (p = 0.041), and sagittal-plane ankle (p < 0.001) and hip joint displacement (p = 0.024) during bilateral drop-landings. Post hoc analysis revealed that the strength and mobility group landed with greater ankle plantarflexion at initial contact (mean difference = 1.4 ± 2.0°, ES = 0.46) and ankle dorsiflexion at peak flexion (mean difference = 6.3 ± 2.9°, ES = 0.74) after the intervention, resulting in a greater ankle joint displacement (mean difference = 7.7 ± 4.0°, ES = 1.00). However, the strength training only group landed with increased peak hip flexion (mean difference = 14.4 ± 11.0°, ES = 0.70) and hip joint displacement (mean difference = 8.0 ± 6.6°, ES = 0.44) during post-testing. The findings suggest that changes in landing strategies following the performance of a strength training program are specific to whether restrictions in ankle mobility are considered as part of the intervention.

Development of vertical and forward jumping skills in typically developing children in the context of referent control of motor actions.

The empirically based referent control theory of motor actions provides a new framework for understanding locomotor maturation. Mature movement patterns of referent control are characterized by periods of minimization of activity across multiple muscles (global electromyographic [EMG] minima) resulting from transient matching between actual and referent body configurations. We identified whether locomotor maturation in young children was associated with (a) development of referent control and (b) children's frequency of participation in everyday activities evaluated by parents. Kinematics and EMG activity were recorded from typically developing children (n=15, 3-5years) and young adults (n=10, 18-25years) while walking, vertical or forward jumping. Presence and location of global EMG minima in movement cycles, slopes of ankle vertical/sagittal displacements, and shoulder displacement ratios were evaluated. Children had fewer global EMG minima compared to adults during specific phases of vertical and forward jumps. Ankle displacement profiles for walking and jumping forward were related to each other in adults, whereas those for walking and vertical jumping were related in children. Higher frequency of participation was significantly correlated with more mature jumping patterns in children. A decrease in the number of global EMG minima and changes in ankle movement patterns could be indicators of locomotor immaturity in typically developing children.

Effect of Ankle-Pivot Misalignment and Upward Ankle Vertical Displacement on Stability and Equilibrium Location for an Ankle-Hip Model of Balance on a Balance Board

AbstractDuring individual training on a balance board (BB), misalignment between the ankle joint and the BB axis of rotation may exist. The ankle-pivot misalignment influences the dynamics of human balance and more importantly, the stability properties of the equilibrium positions of the human-BB dynamical system. Similarly, ankle displacement in the upward direction with respect to the BB pivot also plays a critical role in the stability properties of the human-BB system. This paper investigates these effects through bifurcation analyses performed to the ankle-hip model of balance on a BB developed in our previous work. By using local bifurcation analyses, we have obtained the stability regions of the upright posture (UP) of a human-BB model of balance in different parameter spaces. The stability regions are delimited by Hopf, pitchfork, and saddle-node bifurcation curves in some selected parameter spaces. Results show that ankle-pivot misalignment has an impact on the location of the Hopf and unfolds the pitchfork bifurcation curves (found in the aligned case) into saddle-node bifurcation curves. Moreover, ankle-pivot misalignment breaks the mirror symmetry of upright static equilibrium positions and induces the establishment of equilibrium positions away from the vertical UP. With respect to the ankle vertical displacement, it has a minimal impact on the location of the pitchfork bifurcation curves but has a large impact on the location of the Hopf bifurcation curves, especially when combined with large BB time delay. This suggests that a larger ankle vertical displacement may result in sway oscillations of larger amplitude. The analyses also provide insight into different mechanisms of stability that can be found in the ankle-hip model of balance on a BB, namely, limit cycle oscillations and leaning postures. If an individual suffers from neuropathy, results from this study can be useful for researchers and clinicians in understanding what types of instabilities might be encountered, and during rehabilitation how to position the subjects carefully to avoid inadvertent instabilities.

Dominant/non-dominant support limb kinematics and approach run parameters in futsal kicking of stationary and rolling ball.

Task constraints and players' asymmetry influences on lower extremity (i.e. kicking limb) kinematics during futsal instep kicking. However, support limb behavior when shooting in a futsal context was not previously investigated, and its potential role on such discrepant motor outputs is still unclear. Thus, the study aimed to compare kinematic features of the support limb and approach run between kicking a stationary and a rolling ball using dominant and non-dominant limbs. Ten futsal players participated (21.88±2.86 years-old, 73.66±4.17 kg and 1.75±0.04 m) and performed kicks (five per limb per condition) with the dominant and non-dominant limbs in stationary and rolling ball conditions. Kinematic analysis comprised determination of support limb angular joint (hip, knee and ankle) displacement and velocity, approach run distance, angle, linear velocity, step length and width, support foot-to-ball distance, ball velocity (120 Hz) and accuracy (60 Hz). Hip adjustments (greater extension) in the support limb when kicking a rolling ball contributed in maintaining similar performance (e.g., ball velocity) to kicking a stationary ball, compensating for the lower approach run velocity and longer support foot to ball distance. Kicking with the non-dominant limb demonstrated a lower approach run velocity and the non-dominant support limb presented different angular motion compared to the dominant support limb in hip (< internal rotation), knee (< flexion), and ankle joints (< plantar flexion), being harmful to performance in both kicking stationary and rolling balls. Kicking a stationary and rolling ball presented similar performance, but compared to the dominant side, futsal instep kicks performed with the non-dominant support limb induces lower approach run velocity and inefficient angular joint motion, either harmful to performance output.

Bilateral Comparison of Vertical Jump Landings and Step-off Landings From Equal Heights.

Harry, JR, Silvernail, JF, Mercer, JA, and Dufek, JS. Bilateral comparison of vertical jump landings and step-off landings from equal heights. J Strength Cond Res 32(7): 1937-1947, 2018-The purpose of this investigation was to examine kinetic, kinematic, and temporal parameters during vertical jump landings (VJL) and step-off landings (STL) from equal heights. Five men (25.0 ± 1.6 years; 1.7 ± 0.4 m; 79.7 ± 7.1 kg) and 5 women (20.8 ± 1.6 years; 1.6 ± 0.4 m; 68.5 ± 7.1 kg) performed 15 VJL and 15 STL. Paired-samples t-tests (α = 0.05) compared impact velocity and the times to the first (F1) and second (F2) peak vertical ground reaction force magnitudes (tF1 and tF2) and the end of impact. Two-way analyses of variance (α = 0.05) compared limb and task differences in F1, F2, hip, knee, and ankle joint angles at ground contact, F1, F2, and the end of impact, and hip, knee, and ankle joint displacements between contact and F1, F1 and F2, and F2 and the end of impact. Impact velocity was not different between STL and VJL, although STL produced a greater F1 and a more rapid tF2. Greater hip, knee, and ankle flexion/dorsiflexion occurred during STL throughout the majority of impact regardless of limb. Lesser hip, knee, and ankle joint displacements occurred during STL regardless of limb between F1 and F2, whereas greater joint displacement occurred between F2 and the end of impact. Lastly, knee joint angles at ground contact differed between limbs during STL only. Strength and conditioning professionals aiming to improve an athlete's performance during sport-specific jump landings should consider the likely impact attenuation outcomes before selecting STL or VJL in training.

Light touch compensates peripheral somatosensory degradation in postural control of older adults

The present study aimed to investigate the sensitivity of detecting lower limb passive motion and use of additional sensory information from fingertip light touch for the postural control of older adults in comparison with young adults. A total of 11 older and 11 young adults (aged 68.1 ± 5.2 and 24.2 ± 2.2 years, respectively) underwent two tasks. We evaluated their sensitivity to passive ankle joint movement while seated in the first task. Participants then stood quietly on a force plate in a semi-tandem stance, for 30 s under two fingertip contact force conditions (no touch and light touch limited to 1 N). The results showed that the threshold of passive ankle displacement and body sway is higher in older adults than in young adults. The body sway reduced for both older and young adults with the addition of light touch at the fingertips. The maximum cross-correlation coefficient and time lags between body sway and fingertip light touch center of pressure was similar between both groups, suggesting that older adults used light touch to reduce body sway, similar to young adults. A higher threshold in detecting passive ankle joint movement may contribute to the increased body sway observed in older adults. These deficits may be compensated by additional sensory cues that would provide enhanced information used to control the upright stance.

Effect of Cognitive Dual Tasks on Lower Extremity Kinematics and Ground Reaction Force during Repeated Tuck Jump Landings

Many sports-related injuries occur due to a combination of physical, high joints load during sport-specific maneuvers and cognitive factors, such as keeping other players or the ball in short-term memory. This addition of cognitive challenges can degrade physical performance and increase joint loading. However, previous studies have focused on a single movement and it is unknown how cognitive load influences repeated landing that better simulate the continuous demand of athletic performance. PURPOSE: To determine if a cognitive challenge during tuck jumping affect lower extremity landing biomechanics. METHODS: Recreational collegiate athletes (N=20, 71.7±11.9kg, 171.1±9.7cm) participated in this study. A baseline: BASE condition of repeated tuck jumps and a cognitive: COG condition of tuck jumps while performing an addition problem from a stream of digits on a computer screen. The tuck jump consisted of 3 sets of 10 seconds repeated double leg vertical tuck jumps. Dominant-side sagittal plane lower extremity angular kinematics and vertical ground reaction forces (VGRF: 1,000 Hz) were compared between the two conditions paired t-tests (p<.05). RESULTS: COG, compared to the BASE, resulted in increased ankle angle (30.1±1.7° and 29.3±0.7°) and decreased knee angle (20.5±0.6° and 21.5±0.6°) at initial contact. Also, decreased ankle (21.8±1.4° and 22.4±1.0°) and knee (63.0±0.7° and 67.9±0.9°) maximum angle occurred. Additionally, COG resulted in an increased ankle (52.6±0.9° and 51.6±0.9°), decreased knee (42.5±1.2° and 46.4±0.8°) and hip (31.7±1.1° and 33.0±0.7°) displacements. No significant differences were found in VGRF between conditions. CONCLUSION: We surmised that COG, compared to the BASE, change lower extremity biomechanics that may increase injury risk and knee loading. The more extended knee position at initial contact and reduced sagittal displacement during the COG condition may contribute to increased injury risk when under cognitive load. However, greater ankle displacement during the COG condition may be adaptation strategy to protect the knee under cognitive load.

불안정 판을 이용한 훈련이 높은 굽 신발을 신은 여자 대학생의 발목관절 변위와 동적균형능력에 미치는 영향

본 연구는 불안정 판을 이용한 훈련이 높은 굽 신발을 신은 여자대학생의 발목관절의 변위와 동적균형에 어떤 영향을 미치는지 알아보기 위해 실시하였다. 여자 대학생 18명을 무작위로 실험군과 대조군으로 나누고, 굽 높이가 9cm인 신발을 착용 한 후 3D 동작분석기를 이용하여 5m 보행 시의 발뒤꿈치와 발목의 변위를 검사하고, 동적균형능력 평가를 실시하였다. 중재 프로그램은 실험군에게 4주 동안 주 3회, 불안정 판을 이용한 균형 훈련을 실시하고, 대조군에게는 중재를 실시하지 않았다. 연구 결과, 중재 후 실험군의 발목관절의 변위는 전반적으로 감소하였고, 동적균형능력은 유의하게 상승하였다. 대조군은 발목관절의 변위, 동적균형능력의 변화가 거의 없었다. 불안정 판을 이용한 훈련이 대상자들의 발목관절을 안정화 시켜주고 동적균형능력을 향상시키는 것으로 나타났다.