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1.
OBJECTIVE: To compare the effects of an isokinetic fatigue protocol and a functional fatigue protocol on time to stabilization (TTS), ground reaction force (GRF), and joint kinematics during a jump landing. DESIGN AND SETTING: Subjects were assessed on 2 occasions for TTS, GRF, and joint kinematics immediately before and after completing a fatigue protocol. One week separated the 2 sessions, and the order of fatigue protocols was randomly assigned and counterbalanced. SUBJECTS: Twenty healthy male (n = 8, age = 21.8 +/- 1.4 years, height = 180.6 +/- 7.6 cm, and mass = 74.1 +/- 13.0 kg) and female (n = 12, age = 22.2 +/- 2.1 years, height = 169.3 +/- 9.8 cm, and mass = 62.5 +/- 10.1 kg) subjects volunteered to participate. MEASUREMENTS: Subjects performed 2-legged jumps equivalent to 50% of maximum jump height, followed by a single-leg landing onto the center of a forceplate 70 cm from the starting position. Peak vertical GRF and vertical, medial-lateral, and anterior-posterior TTS were obtained from forceplate recordings. Maximum ankle dorsiflexion, knee-flexion, and knee-valgum angles were determined using 3-dimensional motion analysis. RESULTS: A 2-way analysis of variance with repeated measures revealed no significant differences when comparing TTS, GRF, and joint kinematics after isokinetic and functional fatigue protocols. CONCLUSIONS: No difference was noted between isokinetic and functional fatigue protocols relative to dynamic stability when landing from a jump. 相似文献
2.
The knee joint, together with the hip and ankle, contributes to overall shock absorption through their respective flexion motions during landing. This study sought to investigate the presence of a lower extremity coordination pattern by determining mathematical relationships that associate knee flexion angles with hip flexion and ankle dorsiflexion angles during landing phase, and to determine relative postures of the hip and ankle, with reference to the knee, and examine how these relative postures change during key events of the landing phase. Eight healthy male subjects were recruited to perform double-leg landing from 0.6-m height. Motion capture system and force-plates were used to obtain kinematics and ground reaction forces (GRF) respectively. Non-linear regression analysis was employed to determine appropriate mathematical relationships of the hip flexion and ankle dorsiflexion angles with knee flexion angles during the landing phase. Relative lower extremity postures were compared between events of initial contact, peak GRF and maximum knee flexion, using ANOVA on ranks. Our results demonstrated a lower extremity coordination pattern, whereby the knee flexion angles had strong exponential (R2 = 0.92–0.99, p < 0.001) and natural logarithmic (R2 = 0.85–0.97, p < 0.001) relationships with hip flexion and ankle dorsiflexion angles respectively during the landing phase. Furthermore, we found that the subjects adopted distinctly different relative lower extremity postures (p < 0.05) during peak GRF as compared to initial contact. These relative postures were further maintained till the end of the landing phase. The occurrence of these relative postures may be a reflexive mechanism for the subjects to efficiently absorb the impact imposed by the peak GRF. 相似文献
3.
There has been an increasing use of orthotic knee braces in the management of knee injuries but, to our knowledge, there is no gait analysis study assessing the accuracy of these braces. Eight healthy male subjects were studied to determine the accuracy of immobilisation or splintage provided by a lockable orthotic knee brace using gait analysis. Six types of immobilisation were studied: locked at 0, 10, 20, 30° and unlocked in an orthotic knee brace, and without a brace. The knee flexion angles measured using the kinematic instruments at 0 and 10° were significantly greater than those set at the knee brace. The knee flexion angle measured using the unlocked knee brace was significantly greater than that measured in the absence of a brace. This study highlights inaccuracies in a knee brace at low knee flexion angles. The higher actual angles alter the biomechanics of the knee joint and result in greater forces across the knee joint and especially the extensor mechanism. 相似文献
4.
Smith R Ford KR Myer GD Holleran A Treadway E Hewett TE 《Journal of Athletic Training》2007,42(4):470-476
CONTEXT: The recent increase in women's varsity soccer participation has been accompanied by a lower extremity injury rate that is 2 to 6 times that of their male counterparts. OBJECTIVE: To define the differences between lower extremity biomechanics (knee abduction and knee flexion measures) and performance (maximal vertical jump height) between National Collegiate Athletic Association Division I and III female soccer athletes during a drop vertical jump. DESIGN: Mixed 2 x 2 design. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-four female collegiate soccer players (Division I: n = 19; Division III: n = 15) participated in the study. The groups were similar in height and mass. INTERVENTION(S): Each subject performed a maximal vertical jump, followed by 3 drop vertical jumps. MAIN OUTCOME MEASURE(S): Kinematics (knee abduction and flexion angles) and kinetics (knee abduction and flexion moments) were measured with a motion analysis system and 2 force platforms during the drop vertical jumps. RESULTS: Knee abduction angular range of motion and knee abduction external moments were not different between groups (P > .05). However, Division I athletes demonstrated decreased knee flexion range of motion (P = .038) and greater peak external knee flexion moment (P = .009) compared with Division III athletes. Division I athletes demonstrated increased vertical jump height compared with Division III (P = .008). CONCLUSIONS: Division I athletes demonstrated different sagittal-plane mechanics than Division III athletes, which may facilitate improved performance. The similarities in anterior cruciate ligament injury risk factors (knee abduction torques and angles) may correlate with the consistent incidence of anterior cruciate ligament injury across divisions. 相似文献
5.
Matthew C. Hoch Kelley E. Farwell Stacey L. Gaven Joshua T. Weinhandl 《Journal of Athletic Training》2015,50(8):833-839
Context
People with chronic ankle instability (CAI) exhibit less weight-bearing dorsiflexion range of motion (ROM) and less knee flexion during landing than people with stable ankles. Examining the relationship between dorsiflexion ROM and landing biomechanics may identify a modifiable factor associated with altered kinematics and kinetics during landing tasks.Objective
To examine the relationship between weight-bearing dorsiflexion ROM and single-legged landing biomechanics in persons with CAI.Design
Cross-sectional study.Setting
Laboratory.Patients or Other Participants
Fifteen physically active persons with CAI (5 men, 10 women; age = 21.9 ± 2.1 years, height = 168.7 ± 9.0 cm, mass = 69.4 ± 13.3 kg) participated.Intervention(s)
Participants performed dorsiflexion ROM and single-legged landings from a 40-cm height. Sagittal-plane kinematics of the lower extremity and ground reaction forces (GRFs) were captured during landing.Main Outcome Measure(s)
Static dorsiflexion was measured using the weight-bearing–lunge test. Kinematics of the ankle, knee, and hip were observed at initial contact, maximum angle, and sagittal displacement. Sagittal displacements of the ankle, knee, and hip were summed to examine overall sagittal displacement. Kinetic variables were maximum posterior and vertical GRFs normalized to body weight. We used Pearson product moment correlations to evaluate the relationships between dorsiflexion ROM and landing biomechanics. Correlations (r) were interpreted as weak (0.00–0.40), moderate (0.41–0.69), or strong (0.70–1.00). The coefficient of determination (r2) was used to determine the amount of explained variance among variables.Results
Static dorsiflexion ROM was moderately correlated with maximum dorsiflexion (r = 0.49, r2 = 0.24), ankle displacement (r = 0.47, r2 = 0.22), and total displacement (r = 0.67, r2 = 0.45) during landing. Dorsiflexion ROM measured statically and during landing demonstrated moderate to strong correlations with maximum knee (r = 0.69–0.74, r2 = 0.47–0.55) and hip (r = 0.50–0.64, r2 = 0.25–0.40) flexion, hip (r = 0.53–0.55, r2 = 0.28–0.30) and knee (r = 0.53–0.70, r2 = 0.28–0.49) displacement, and vertical GRF (−0.47– −0.50, r2 = 0.22–0.25).Conclusions
Dorsiflexion ROM was moderately to strongly related to sagittal-plane kinematics and maximum vertical GRF during single-legged landing in persons with CAI. Persons with less dorsiflexion ROM demonstrated a more erect landing posture and greater GRF.Key Words: ankle sprain, drop landing, neuromuscular control, kinematics, kineticsKey Points
- During a single-legged landing, persons with chronic ankle instability demonstrated moderate to strong relationships between dorsiflexion range of motion (ROM) and sagittal-plane kinematics at the knee and hip and vertical ground reaction forces.
- Persons with less dorsiflexion ROM exhibited a less flexed landing strategy that attenuated ground reaction forces less efficiently.
- Identifying dorsiflexion deficits may enable clinicians to implement interventions to increase ROM and potentially modify the landing biomechanics that persons with chronic ankle instability exhibit.
6.
目的 探究护踝对功能性踝关节不稳(functional ankle instability,FAI)患者的保护作用,为其护踝的选择提供依据。 方法 15 名 FAI 患者随机佩戴半刚性、弹性护踝及无护踝以自选速度步行和跑步,运用红外光点运动捕捉系统和三维测力台采集其下肢运动生物力学参数。 通过 3×2 重复设计的双因素方差分析检验护踝和运动模式对下肢运动学、动力学和能量吸收的影响。 结果 护踝与运动模式对本研究中所有指标均无交互作用(P>0. 05)。不论运动模式,与无护踝相比,弹性护踝显著减少了 FAI 患者踝关节内翻角峰值、内翻角速度和踝关节能量吸收(P<0. 05),同时增加了踝关节外翻力矩( P < 0. 001);而半刚性护踝增加了踝关节内翻角峰值和内翻角速度(P<0. 05)。 此外,弹性护踝可降低着地时刻的膝关节内旋力矩和外旋力矩峰值(P<0. 05)。 结论 与无护踝相比,弹性护踝通过减小踝关节内翻角、内翻角速度和能量吸收,增大踝关节外翻力矩,继而起到预防踝关节扭伤的作用。 FAI 患者佩戴半刚性护踝后需定时关注踝关节慢性损伤风险。 整体来看,弹性护踝的防护效果可能更有效,且未引起膝关节功能补偿,可作为预防 FAI 患者踝关节扭伤的有效措施。 相似文献
7.
Kovaleski JE Norrell PM Heitman RJ Hollis JM Pearsall AW 《Journal of Athletic Training》2008,43(3):242-248
CONTEXT: Anterior drawer testing of the ankle is commonly used to diagnose lateral ligamentous instability. Our hypothesis was that changing knee and ankle positions would change the stability of the ankle complex during anterior drawer testing. OBJECTIVES: To assess the effects of knee and ankle position on anterior drawer laxity and stiffness of the ankle complex. DESIGN: A repeated-measures design with knee and ankle position as independent variables. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: Bilateral ankles of 10 female (age = 19.8 +/- 1.1 years) and 10 male (age = 20.8 +/- 1.2 years) collegiate athletes were tested. INTERVENTION(S): Each ankle complex underwent loading using an ankle arthrometer under 4 test conditions consisting of 2 knee positions (90 degrees and 0 degrees of flexion) and 2 ankle positions (0 degrees and 10 degrees of plantar flexion [PF]). MAIN OUTCOME MEASURE(S): Recorded anterior laxity (mm) and stiffness (N/mm). RESULTS: Anterior laxity of the ankle complex was maximal with the knee positioned at 90 degrees of flexion and the ankle at 10 degrees of PF when compared with the knee positioned at 0 degrees of flexion and the ankle at 10 degrees or 0 degrees of PF (P < .001), whereas ankle complex stiffness was greatest with the knee positioned at 0 degrees of flexion and the ankle at 0 degrees of PF (P < .009). CONCLUSIONS: Anterior drawer testing of the ankle complex with the knee positioned at 90 degrees of flexion and the ankle at 10 degrees of PF produced the most laxity and the least stiffness. These findings indicate that anterior drawer testing with the knee at 90 degrees of flexion and the ankle at 10 degrees of PF may permit better isolation of the ankle capsuloligamentous structures. 相似文献
8.
CONTEXT: Ankle braces may enhance ankle joint proprioception, which in turn may affect reflexive ankle muscle activity during a perturbation. Despite the common occurrence of plantar-flexion inversion ankle injuries, authors of previous studies of ankle muscle latencies have focused on inversion stresses only. OBJECTIVE: To examine the latency of the peroneus longus (PL), peroneus brevis (PB), and tibialis anterior (TA) muscles in response to various degrees of combined plantar-flexion and inversion stresses in braced and unbraced asymptomatic ankles. DESIGN: Repeated measures. SETTING: University biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty-eight healthy females and 12 healthy males (n = 40: mean age = 23.63 years, range = 19 to 30 years; height = 172.75 +/- 7.96 cm; mass = 65.53 +/- 12.0 kg). INTERVENTION(S): Participants were tested under 2 conditions: wearing and not wearing an Active Ankle T1 brace while dropping from a custom-made platform into 10 degrees , 20 degrees , and 30 degrees of plantar flexion and 30 degrees of inversion. MAIN OUTCOME MEASURE(S): The time between platform drop and the onset of PL, PB, and TA electromyographic activity was measured to determine latencies. We calculated a series of 2-way analyses of variance to determine if latencies were different between the conditions (braced and unbraced) and among the plantar-flexion angles (alpha = .05). RESULTS: No interaction was found between condition and plantar-flexion angle. No significant main effects were found for condition or plantar-flexion angle. Overall means for braced and unbraced conditions were not significantly different for each muscle tested. Overall means for angle for the PL, PB, and TA were not significantly different. CONCLUSIONS: Reflexive activity of the PL, PB, or TA was unaffected by the amount of plantar flexion or by wearing an Active Ankle T1 brace during an unanticipated plantar-flexion inversion perturbation. 相似文献
9.
Context: Although prophylactic ankle bracing has been shown to be effective in reducing the incidence of ankle sprains,how these ankle braces might affect the other joints of the lower extremity is not clearly understood.Objective: To determine the effects of a prophylactic ankle brace on knee joint varus-valgus and internal-external rotation torque during a drop landing onto a slanted surface.Design: A repeated-measures design.Setting: Biomechanics research laboratory. Patients or Other Participants: Twenty-four physically active college students.Intervention(s): Participants were tested in a brace and no brace condition. Main Outcome Measure(s): We measured 3 dependent variables:(1) peak ankle inversion-eversion torque, (2) peak knee varus-valgus torque, and (3) peak knee internal-external rotation torque. A force plate was used to collect ground reaction force data, and 6 motion analysis cameras collected kinematic data during the unilateral drop landing. An adjustable bar was hung from the ceiling, and a slant board was positioned over the center of the force plate, so that the ankle of the participant's dominant leg would invert upon landing. Peak torque was measure din both the brace and no-brace conditions. The average of the peak values in 3 trials for both conditions was used for the statistical analysis.Results: Ankle eversion torque was significantly greater in the brace condition (F1,23 19.75, P < .01). Knee external rotation torque was significantly greater in the brace condition(F1,23 4.33, P <.05). Valgus knee torque was smaller in the brace condition, but the difference was not statistically significant(F1,23 3.45, P .08).Conclusions: This study provides an important first step in understanding the effects of prophylactic ankle bracing on other joints of the lower extremity. We found that prophylactic ankle bracing did have an effect on knee torque when the subject was landing on a slanted surface. Specifically, knee external rotation torque increased when the ankle was braced. 相似文献
10.
The objective of this research was to determine whether joint angles at critical gait events and during major energy generation/absorption phases of the gait cycle would reliably discriminate age-related degeneration during unobstructed walking. The gaits of 24 healthy adults (12 young and 12 elderly) were analysed using the PEAK Motus motion analysis system. The elderly participants showed significantly greater single (60.3% versus 62.3%, p < 0.01) and double ( p < 0.05) support times, reduced knee flexion (47.7 degrees versus 43.0 degrees , p < 0.05) and ankle plantarflexion (16.8 degrees compared to 3.3 degrees , p = 0.053) at toe off, reduced knee flexion during push-off and reduced ankle dorsiflexion (16.8 degrees compared to 22.0 degrees , p < 0.05) during the swing phase. The plantarflexing ankle joint motion during the stance to swing phase transition (A2) for the young group (31.3 degrees ) was about twice ( p < 0.05) that of the elderly (16.9 degrees ). Reduced knee extension range of motion suggests that the elderly favoured a flexed-knee gait to assist in weight acceptance. Reduced dorsiflexion by the elderly in the swing phase implies greater risk of toe contact with obstacles. Overall, the results suggest that joint angle measures at critical events/phases in the gait cycle provide a useful indication of age-related degeneration in the control of lower limb trajectories during unobstructed walking. 相似文献
11.
背景:佩带膝关节外翻矫形器已被证明是一种可以有效减轻内侧间室膝骨关节炎患者疼痛的方法,但是佩带矫形器后的膝关节所产生的运动学以及动力学变化至今尚不明确。
目的:观察内侧间室膝骨关节炎患者佩带膝关节矫形器前后的膝关节运动学以及动力学参数变化,便于为将来设计新型膝关节矫形器提供依据。
方法:纳入20例内侧间室膝骨关节炎患者,分别通过三维步态分析系统和测力板对其在佩带膝外翻矫形器及不佩带膝外翻矫形器两种情况步行中的运动学及动力学参数进行采集,并进行对比。
结果与结论:相比未佩带膝关节外翻支具,佩带膝关节外翻支具后患者在步行过程中膝关节内收力矩明显减小,与此同时膝关节内翻角度明显减小,外翻角度明显增加(P均< 0.05),膝关节在步行过程中的最大屈曲角度以及时间空间参数差异无显著性意义。提示膝关节外翻矫形器可有效地通过增加内侧间室膝骨关节炎患者膝关节在步行过程中的外翻角度减小内翻角度从而降低膝内侧间室所承受的压力,与此同时纠正膝关节非正常对线。 相似文献
12.
CONTEXT: The effects of prophylactic ankle braces on lower extremity functional performance in healthy participants have not been studied extensively. OBJECTIVE: To determine if prophylactic ankle braces affected multidirectional reach distances during a test of dynamic balance. DESIGN: Crossover. SETTING: Laboratory. PATIENTS OR OTHER PARTICIPANTS: Thirty-six healthy, physically active volunteers (18 men, 18 women; age = 23.6 +/- 2.7 years, height = 173.8 +/- 9.3 cm, mass = 74.4 +/- 12.7 kg, reach-leg length = 91.9 +/- 5.1 cm). INTERVENTION(S): Volunteers performed balance testing in 3 conditions: unbraced, while wearing a semirigid ankle brace, and while wearing a lace-up ankle brace. MAIN OUTCOME MEASURE(S): We used the Star Excursion Balance Test, calculating the mean of 3 attempts in 8 directions (anterior, anterior-medial, medial, posterior-medial, posterior, posterior-lateral, lateral, and anterior-lateral), normalized by the participant's reach-leg length. Data were collected after 6 practice attempts for each of the conditions according to a balanced Latin square. RESULTS: Bracing condition had no effect (P > .05) on any of the Star Excursion Balance Test directional measures. The largest mean difference due to bracing was 2.5% between the lace-up brace condition and the control in the posterior reach direction. This indicates that the actual reach differences due to bracing were less than 5.08 cm (2 inches) in length. CONCLUSIONS: Clinicians can be confident that the prophylactic use of ankle braces does not disrupt lower extremity dynamic balance during a reaching task in healthy participants. 相似文献
13.
OBJECTIVE: To determine the effectiveness of glenohumeral-joint stability braces in limiting active and passive shoulder abduction and external rotation in collegiate football players. DESIGN AND SETTING: A 2-factor, repeated-measures design was used. The independent variables were brace condition (Denison and Duke Wyre harness, Sawa shoulder brace) and force application (active, passive). The dependent variables were shoulder abduction (45 degrees braced limit) and external-rotation angular displacements. SUBJECTS: Fifteen National Collegiate Athletic Association Division I male college football players (age = 19.9 +/- 1.37 years, height = 183.2 +/- 7.85 cm, mass = 89.9 +/- 14.79 kg) participated in the study. MEASUREMENTS: We used the PEAK Motus motion analysis system to measure angular displacements. RESULTS: Neither brace maintained the arm position at the 45 degrees braced limit during active or passive shoulder abduction (motion ranged from 56.8 degrees to 73.0 degrees ). Although we did not use a priori external-rotation limits in this study, motion ranged from 71.6 degrees to 93.9 degrees with the braces. A repeated-measures multivariate analysis of variance indicated no significant interaction effect (P =.41), but main effects were significant for brace condition and force application (P <.001). Reported differences are statistically significant. For abduction, the Denison and Duke Wyre harness resulted in 12.3 degrees (21%) greater angular displacement than the Sawa shoulder brace, and passive abduction resulted in 3.9 degrees (6%) more angular displacement than active abduction. For external rotation, the Denison and Duke Wyre harness resulted in 6.7 degrees (9%) more angular displacement than the Sawa shoulder brace, and passive external rotation resulted in 15.6 degrees (21%) more angular displacement than active external rotation. CONCLUSIONS: Preset, braced abduction motion limits were not realized during active and passive physiologic loading of the glenohumeral joint. However, protection against the vulnerable position of 90 degrees of abduction and external rotation was attained at a preset braced limit of 45 degrees of abduction (the exception was the Denison and Duke Wyre harness during passive external rotation). The Sawa shoulder brace was most effective for this purpose. 相似文献
14.
《The Knee》2019,26(3):564-577
BackgroundBraces for medial knee osteoarthritis can reduce medial joint loads through a combination of three mechanisms: application of an external brace abduction moment, alteration of gait dynamics, and reduced activation of antagonistic muscles. Although the effect of knee bracing has been reported independently for each of these parameters, no previous study has quantified their relative contributions to reducing medial knee loads.MethodsIn this study, we used a detailed musculoskeletal model to investigate immediate changes in medial and lateral loads caused by two different knee braces: OA Assist and OA Adjuster 3 (DJO Global). Seventeen osteoarthritis subjects and eighteen healthy controls performed overground gait trials in unbraced and braced conditions.ResultsAcross all subjects, bracing reduced medial loads by 0.1 to 0.3 times bodyweight (BW), or roughly 10%, and increased lateral loads by 0.03 to 0.2 BW. Changes in gait kinematics due to bracing were subtle, and had little effect on medial and lateral joint loads. The knee adduction moment was unaltered unless the brace moment was included in its computation. Only one muscle, biceps femoris, showed a significant change in EMG with bracing, but this did not contribute to altered peak medial contact loads.ConclusionsKnee braces reduced medial tibiofemoral loads primarily by applying a direct, and substantial, abduction moment to each subject's knee. To further enhance brace effectiveness, future brace designs should seek to enhance the magnitude of this unloader moment, and possibly exploit additional kinematic or neuromuscular gait modifications. 相似文献
15.
Background
Knee braces are considered to be extremely useful tools in reducing the shear force of knee joints for non-contact anterior cruciate ligament (ACL) injury prevention. However, the effectiveness of sports knee braces and sleeves remains to be identified. Therefore, the purpose of this study was to evaluate the effectiveness of wearing commercialized sports knee braces and sleeves on knee kinematics, kinetics, and ACL force during drop jumps using musculoskeletal modeling analysis.Methods
Musculoskeletal modeling analysis was conducted on 19 male alpine skiers who performed drop jump motions from a 40-cm box under three conditions: without a brace/sleeve, with a brace, and while wearing a neoprene sleeve.Results
The physical performance (i.e., the center of mass of the jumping height) was not affected by the type of brace or sleeve. However, wearing a brace or sleeve during drop jump tasks reduced the knee joint's maximum flexion, abduction angles, and adduction moment. The knee joint shear force when wearing the brace or sleeve exhibited no statistical differences. Further, the ACL load estimated in this study did not exhibit any statistical differences in relation to wearing a brace or sleeve.Conclusions
The knee braces and sleeves reduced flexion and abduction movement, and adduction moment but did not reduce the knee joint shear force, internal rotation moment, or the ACL force. Therefore, if a sports knee brace that controls the knee joint's shear force and internal rotation moment is developed, it may aid in preventing ACL injuries. 相似文献16.
Martin Alfuth Dieter Klein Raphael Koch Dieter Rosenbaum 《Journal of Athletic Training》2014,49(5):608-616
Context:
Various designs of braces including hinged and nonhinged models are used to provide external support of the ankle. Hinged ankle braces supposedly allow almost free dorsiflexion and plantar flexion of the foot in the sagittal plane. It is unclear, however, whether this additional degree of freedom affects the stabilizing effect of the brace in the other planes of motion.Objective:
To investigate the dynamic and passive stabilizing effects of 3 ankle braces, 2 hinged models that provide free plantar flexion–dorsiflexion in the sagittal plane and 1 ankle brace without a hinge.Design:
Crossover study.Setting:
University Movement Analysis Laboratory.Patients or Other Participants:
Seventeen healthy volunteers (5 women, 12 men; age = 25.4 ± 4.8 years; height = 180.3 ± 6.5 cm; body mass = 75.5 ± 10.4 kg).Intervention(s):
We dynamically induced foot inversion on a tilting platform and passively induced foot movements in 6 directions via a custom-built apparatus in 3 brace conditions and a control condition (no brace).Main Outcome Measure(s):
Maximum inversion was determined dynamically using an in-shoe electrogoniometer. Passively induced maximal joint angles were measured using a torque and angle sensor. We analyzed differences among the 4 ankle-brace conditions (3 braces, 1 control) for each of the dependent variables with Friedman and post hoc tests (P < .05).Results:
Each ankle brace restricted dynamic foot-inversion movements on the tilting platform as compared with the control condition, whereas only the 2 hinged ankle braces differed from each other, with greater movement restriction caused by the Ankle X model. Passive foot inversion was reduced with all ankle braces. Passive plantar flexion was greater in the hinged models as compared with the nonhinged brace.Conclusions:
All ankle braces showed stabilizing effects against dynamic and passive foot inversion. Differences between the hinged braces and the nonhinged brace did not appear to be clinically relevant.Key Words: ankle–foot complex, inversion, joint motion, ankle stabilizationKey Points
- Both the hinged and nonhinged braces appeared to sufficiently restrict dynamically and passively induced foot inversion.
- Other than the existence of a hinge, factors related to brace design, material, or application seemed to be responsible for differences in movement restriction.
- The Ankle X brace provided the greatest amount of restriction against dynamic inversion.
17.
Prophylactic knee braces are designed to prevent and reduce the severity of ligamentous injuries to the knee. Conflicting evidence is reported concerning their efficacy. The purpose of this study was to determine the effect of prophylactic knee bracing on the proprioceptive parameters of balance and joint position sense. Active and passive joint position sense were assessed using the Cybex II + Isokinetic Dynamometer (Cybex Division of Lumex, Inc, Ronkonkoma, NY). Sway index and center of balance were assessed using the Chattecx Dynamic Balance System (Chattanooga Group, Hixson, TN). Thirty-six male subjects were measured with and without prophylactic knee braces. Joint position sense was measured in degrees of error from four preselected target angles. Sway index and center of balance measures were recorded in centimeters under the following platform conditions: stable, plantar flexion/dorsiflexion, and inversion/eversion. Separate repeated measures ANOVAs were performed to determine if there were differences between the braced and unbraced conditions for center of balance, sway index, and joint position sense. Center of balance with the platform moving in a dorsi/plantar flexion direction was improved while wearing the knee braces. In addition, differences in both center of balance and sway were recorded across the three platform conditions with and without knee bracing. Bracing did not affect joint position sense. The results of this study suggest that prophylactic knee braces have very little impact on proprioceptive feedback mechanisms. 相似文献
18.
目的比较两种疲劳方案对人体落地动作下肢关节运动学及冲击力时/频域特征的影响。方法选取15名优秀跑、跳类专项男性运动员,利用Vicon运动捕捉系统和Kistler三维测力台比较两种疲劳方案(恒速跑、折返跑+垂直纵跳)前后落地时矢、额状面运动学和地面反作用力(ground reaction force,GRF)时/频域特征。结果(1)两种疲劳方案均会造成髋、膝关节在矢状面上的角度减小、屈曲活动度增加,且采用跑+跳方案时踝关节屈曲活动度、膝关节最大屈曲角速度增加(P0.05),髋关节外展活动度以及髋、膝关节最大外展角速度增加(P0.05);(2)两种疲劳方案前后,冲击力时域特征均无显著差异;采用跑和跑+跳方案,分别在3.51、8.20 Hz及1.17、3.51、7.03 Hz下表现出GRF频谱振幅减小(P0.05)。结论两种疲劳方案均会导致下肢在受到落地冲击时更多采用屈曲着地方式,但跑+跳方案表现更明显且干预时间更短,从实验方法学角度更具优势。研究结果可为研究疲劳后的力特征提供进一步参考。 相似文献
19.
CONTEXT: Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. OBJECTIVE: To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60 degrees of knee flexion while performing a single-limb squat at different decline angles. DESIGN: Participants acted as their own controls in a repeated-measures design. PATIENTS OR OTHER PARTICIPANTS: We recruited 10 participants who had no pain, injury, or neurologic disorder. INTERVENTION(S): Participants performed single-limb squats at different decline angles. MAIN OUTCOME MEASURE(S): Angle-specific knee and ankle moments were calculated at 60 degrees of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60 degrees of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. RESULTS: An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P = .001), but EMG activity in the gastrocnemius increased between 16 degrees and 24 degrees (P = .018). CONCLUSIONS: As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24 degrees decline angle compared with the 16 degrees decline angle. This indicates that decline squats at an angle greater than 16 degrees may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee. 相似文献
20.
Limitations of mechanical walking orthoses for paraplegics are high energy consumption and upper limb loading. Flexing of the knee during swing phase has been used as a means of attempting to reduce these. It has been found that this has little effect because using knee flexion results in no change in the compensatory mechanisms required for swing foot clearance. This is because knee flexion can result in an increase in effective leg length, i.e. hip to toe distance. A combination of knee flexion and ankle dorsiflexion during swing phase is suggested as a means of reducing compensatory mechanisms. To examine this hypothesis, an orthosis incorporating knee and ankle flexion was constructed. The design used a novel mechanism to link the motion of the knee to that of the ankle, and also used functional electrical stimulation. Two spinal cord-injured subjects were trained to use the orthosis in two configurations. The first configuration used knee flexion and ankle dorsiflexion and the second configuration used knee flexion alone. Kinematic data were obtained to measure the compensatory mechanisms used during gait. The results showed that a combination of knee flexion and ankle dorsiflexion during swing phase resulted in a reduction in compensatory mechanisms when compared with knee flexion alone. 相似文献