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Mitchell L. Cordova, Yosuke Takahashi, Gregory M. Kress, Jody B. Brucker, and Alfred E. Finch

Objective:

To investigate the effects of external ankle support (EAS) on lower extremity joint mechanics and vertical ground-reaction forces (VGRF) during drop landings.

Design:

A 1 × 3 repeated-measures, crossover design.

Setting:

Biomechanics research laboratory.

Patients:

13 male recreationally active basketball players (age 22.3 ± 2.2 y, height 177.5 ± 7.5 cm, mass 72.2 ± 11.4 kg) free from lower extremity pathology for the 12 mo before the study.

Interventions:

Subjects performed a 1-legged drop landing from a standardized height under 3 different ankle-support conditions.

Main Outcome Measures:

Hip, knee, and ankle angular displacement along with specific temporal (TGRFz1, TGRFz2; s) and spatial (GRFz1, GRFz2; body-weight units [BW]) characteristics of the VGRF vector were measured during a drop landing.

Results:

The tape condition (1.08 ± 0.09 BW) demonstrated less GRFz1 than the control (1.28 ± 0.16 BW) and semirigid conditions (1.28 ± 0.21 BW; P < .0001), and GRFz2 was unaffected. For TGRFz1, no-support displayed slower time (0.017 ± 0.004 s) than the semirigid (0.014 ± 0.001 s) and tape conditions (0.014 ± 0.002 s; P < .05). For TGRFz2, no-support displayed slower time (0.054 ±.006 s) than the semirigid (0.050 ± 0.006 s) and tape conditions (0.045 ± 0.004 s; P < .05). Semirigid bracing was slower than the tape condition, as well (P < .05). Ankle-joint displacement was less in the tape (34.6° ± 7.7°) and semirigid (36.8° ± 9.3°) conditions than in no-support (45.7° ± 7.3°; P < .05). Knee-joint displacement was larger in the no-support (45.1° ± 9.0°) than in the semirigid (42.6° ± 6.8°; P < .05) condition. Tape support (43.8° ± 8.7°) did not differ from the semirigid condition (P > .05). Hip angular displacement was not affected by EAS (F 2,24 = 1.47, P = .25).

Conclusions:

EAS reduces ankle- and knee-joint displacement, which appear to influence the spatial and temporal characteristics of GRFz1 during drop landings.

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Seong-won Han, Andrew Sawatsky, and Walter Herzog

( 2 ): 235 – 241 . PubMed ID: 19878947 doi:10.1016/j.jbiomech.2009.08.043 10.1016/j.jbiomech.2009.08.043 14. Han SW , Sawatsky A , de Brito Fontana H , Herzog W . Contribution of individual quadriceps muscles to knee joint mechanics . J Exp Biol . 2019 ; 222 : jeb188292 . doi:10.1242/jeb

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Mu Qiao

Although the dynamics of center of mass can be accounted for by a spring-mass model during hopping, less is known about how each leg joint (ie, hip, knee, and ankle) contributes to center of mass dynamics. This work investigated the function of individual leg joints when hopping unilaterally and vertically at 4 frequencies (ie, 1.6, 2.0, 2.4, and 2.8 Hz). The hypotheses are (1) all leg joints maintain the function as torsional springs and increase their stiffness when hopping faster and (2) leg joints are controlled to maintain the mechanical load in the joints or vertical peak accelerations at different body locations when hopping at different frequencies. Results showed that all leg joints behaved as torsional springs during low-frequency hopping (ie, 1.6 Hz). As hopping frequency increased, leg joints changed their functions differently; that is, the hip and knee shifted to strut, and the ankle remained as spring. When hopping fast, the body’s total mechanical energy decreased, and the ankle increased the amount of energy storage and return from 50% to 62%. Leg joints did not maintain a constant load at the joints or vertical peak accelerations at different body locations when hopping at different frequencies.

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Thomas G. Almonroeder, Lauren C. Benson, and Kristian M. O’Connor

The mechanism of action of a foot orthotic is poorly understood. The purpose of this study was to use principal components analysis (PCA) to analyze the effects of a prefabricated foot orthotic on frontal plane knee and ankle mechanics during running. Thirty-one healthy subjects performed running trials with and without a foot orthotic and PCA was performed on the knee and ankle joint angles and moments to identify the dominant modes of variation. MANOVAs were conducted on the retained principal components of each waveform and dependent t tests (P < .05) were performed in the case of significance. Mechanics of the ankle were not affected by the foot orthotic. However, mechanics of the knee were significantly altered as subjects demonstrated an increase in the magnitude of the knee abduction moment waveform in an orthotic condition. Subjects also demonstrated a significant shift in the timing of the knee abduction moment waveform toward later in the stance phase in the orthotic condition. These orthotic effects were not related to subject’s foot mobility, measured using the navicular drop test. The mechanism of action of a foot orthotic may be related to their effect on the timing of frontal plane knee loading.

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Guillaume Mornieux, Elmar Weltin, Monika Pauls, Franz Rott, and Albert Gollhofer

Trunk positioning has been shown to be associated with knee joint loading during athletic tasks, especially changes of direction. The purpose of the present study was to test whether a full-body compression suit (FBCS) would improve trunk positioning and knee joint control during lateral movements. Twelve female athletes performed lateral reactive jumps (LRJ) and unanticipated cuttings with and without the customized FBCS, while 3D kinematics and kinetics were measured. FBCS did not influence trunk positioning during LRJ and led to increased trunk lateral lean during cuttings (P < .001). However, while wearing FBCS, knee joint abduction and internal rotation angles were reduced during LRJ (P < .001 and P = .013, respectively), whereas knee joint moments were comparable during cuttings. FBCS cannot support the trunk segment during unanticipated dynamic movements. But, increased trunk lateral lean during cutting maneuvers was not high enough to elicit increased knee joint moments. On the contrary, knee joint abduction and internal rotation were reduced during LRJ, speaking for a better knee joint alignment with FBCS. Athletes seeking to improve trunk positioning may not benefit from a FBCS.

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Louis Howe, Jamie S. North, Mark Waldron, and Theodoros M. Bampouras

Context: Ankle dorsiflexion range of motion (DF ROM) has been associated with a number of kinematic and kinetic variables associated with landing performance that increase injury risk. However, whether exercise-induced fatigue exacerbates compensatory strategies has not yet been established. Objectives: (1) Explore differences in landing performance between individuals with restricted and normal ankle DF ROM and (2) identify the effect of fatigue on compensations in landing strategies for individuals with restricted and normal ankle DF ROM. Design: Cross-sectional. Setting: University research laboratory. Patients or Other Participants: Twelve recreational athletes with restricted ankle DF ROM (restricted group) and 12 recreational athletes with normal ankle DF ROM (normal group). Main Outcome Measure(s): The participants performed 5 bilateral drop-landings, before and following a fatiguing protocol. Normalized peak vertical ground reaction force, time to peak vertical ground reaction force, and loading rate were calculated, alongside sagittal plane initial contact angles, peak angles, and joint displacement for the ankle, knee, and hip. Frontal plane projection angles were also calculated. Results: At the baseline, the restricted group landed with significantly less knee flexion (P = .005, effect size [ES] = 1.27) at initial contact and reduced peak ankle dorsiflexion (P < .001, ES = 1.67), knee flexion (P < .001, ES = 2.18), and hip-flexion (P = .033, ES = 0.93) angles. Sagittal plane joint displacement was also significantly less for the restricted group for the ankle (P < .001, ES = 1.78), knee (P < .001, ES = 1.78), and hip (P = .028, ES = 0.96) joints. Conclusions: These findings suggest that individuals with restricted ankle DF ROM should adopt different landing strategies than those with normal ankle DF ROM. This is exacerbated when fatigued, although the functional consequences of fatigue on landing mechanics in individuals with ankle DF ROM restriction are unclear.

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Rodrigo R. Bini, Aline C. Tamborindeguy, and Carlos B. Mota

Context:

It is not clear how noncyclists control joint power and kinematics in different mechanical setups (saddle height, workload, and pedaling cadence). Joint mechanical work contribution and kinematics analysis could improve our comprehension of the coordinative pattern of noncyclists and provide evidence for bicycle setup to prevent injury.

Objective:

To compare joint mechanical work distribution and kinematics at different saddle heights, workloads, and pedaling cadences.

Design:

Quantitative experimental research based on repeated measures.

Setting:

Research laboratory.

patients:

9 healthy male participants 22 to 36 years old without competitive cycling experience.

Intervention:

Cycling on an ergometer in the following setups: 3 saddle heights (reference, 100% of trochanteric height; high, + 3 cm; and low, − 3 cm), 2 pedaling cadences (40 and 70 rpm), and 3 workloads (0, 5, and 10 N of braking force).

Main Outcome Measures:

Joint kinematics, joint mechanical work, and mechanical work contribution of the joints.

Results:

There was an increased contribution of the ankle joint (P = .04) to the total mechanical work with increasing saddle height (from low to high) and pedaling cadence (from 40 to 70 rpm, P < .01). Knee work contribution increased when saddle height was changed from high to low (P < .01). Ankle-, knee-, and hip-joint kinematics were affected by saddle height changes (P < .01).

Conclusions:

At the high saddle position it could be inferred that the ankle joint compensated for the reduced knee-joint work contribution, which was probably effective for minimizing soft-tissue damage in the knee joint (eg, anterior cruciate ligament and patellofemoral cartilage). The increase in ankle work contribution and changes in joint kinematics associated with changes in pedaling cadence have been suggested to indicate poor pedaling-movement skill.

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Peter B. Thomsen, Jacob W. Aumeier, Chelsey A. Wilbur, Evan G. Oro, Hunter B. Carlson, and Jesse C. Christensen

studies of older adult walking have revealed the use of altered joint mechanics (ie, angle, moment, power) to overcome external joint demands when compared with younger adults. Current evidence suggests a distal to proximal shift of joint contributions to support the center of mass against gravity, 7

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Tobias Alt, Igor Komnik, Jannik Severin, Yannick T. Nodler, Rita Benker, Axel J. Knicker, Gert-Peter Brüggemann, and Heiko K. Strüder

injuries. 2 , 11 , 14 , 15 It has been suggested that the synergy of hip and knee joint mechanics in the late swing phase is crucial for optimizing sprint performance. 2 , 4 , 7 , 9 However, the biomechanical interplay between hip and knee joint mechanics under maximal sprint velocity is still not

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Sarah C. Moudy, Neale A. Tillin, Amy R. Sibley, and Siobhán Strike

forward progression. This could provide an indication of deficiencies in the intact limb following amputation, which may be useful for informing rehabilitation protocols. A unilateral drop landing onto the intact limb can be used to examine joint mechanics and load attenuation in response to a consistent