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Ruth A. Maulucci and Richard H. Eckhouse

The study of range of joint motion is of theoretical and practical interest to basic research, workspace design, rehabilitation, and mathematical models. Nude range of motion has been extensively explored, whereas range of motion under clothed conditions, although equally important in applications, has received less attention. A project was designed to investigate modern instrumentation and methodologies for examining clothed range of joint motion. An empirical study was conducted using three distinct techniques simultaneously, involving 6 subjects, two military ensembles, and 46 planar motions. The results of the study showed one of the techniques, a computerized six-degree-of-freedom electromagnetic tracker, to be superior for joint motion applications under clothed conditions. Customized physical modifications and software were implemented to adapt the device for physiological applications, and algorithms were created for extracting joint motion information. Standardized procedures for performance strategies were defined. Recommendations were also given for the use of the other two techniques in applications having different requirements.

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Jennifer E. Earl, Jay Hertel and Craig R. Denegar

Context:

Dynamic malalignment (DM), abnormal muscle activation, and static malalignments all might lead to patellofemoral pain (PFP) but have not been examined using a multifactorial approach.

Objective:

To determine which measures of static malalignment, DM, and muscle-onset times best predict PFP.

Design and Setting:

Between-subjects, laboratory.

Subjects:

2 groups (PFP and uninjured) of 16 subjects each.

Interventions:

EMG and 3-D kinematic data were recorded during a step-down. Five static-alignment assessments were performed.

Measurements:

Three discriminant analyses using injury as the grouping variable and static measures, joint angles, and EMG onsets as the predictor variables. A final combined discriminant analysis using the most predictive variables from each set.

Results:

The static-alignment discriminant function was most predictive (81.3% correct), followed by the kinematic (69%) and the EMG (67%) functions. The final discriminant function included iliotibial-band flexibility, navicular drop, pronation, knee flexion, hip adduction, gluteus medius, and vastus medialis obliquus onset time and correctly classified 92.3% of PFP subjects.

Conclusions:

PFP can most accurately be predicted when multiple measures of lower extremity function are considered together.

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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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Darren J. Stefanyshyn, Benno M. Nigg, Veronica Fisher, Barry O'Flynn and Wen Liu

The purpose of this investigation was to determine whether a graded response in gait kinematics, kinetics, and EMG occurs as shoe heel height increases. Four different shoes, including one flat shoe and three shoes with high heels, were tested in this investigation. The average heel heights of the four shoes were 1.4 cm, 3.7 cm, 5.4 cm, and 8.5 cm. Kinematics, kinetics, and muscle EMG were measured during the stance phase of gait on 13 healthy female subjects while wearing each of these 4 shoes. Systematic increases in the active vertical, propulsive, and braking forces were found as shoe height increased. Ankle and knee flexion and soleus and rectus femoris activity showed a graded response as heel height increased. One surprising result was the behavior of the maximal vertical impact force peak and the maximal loading rate during heel impact. The vertical impact force peaks and the maximal vertical loading rates were highest for the shoe with 3.7 cm heel height and lowest for the flat shoe and the shoe with heel height of 8.5 cm.

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Heather D. Hartsell and Sandi J. Spaulding

Because the effects of bracing on dynamic torque production are unknown, the purpose of this study was to determine the effects of flexible and semirigid braces on isokinetic torque production at varying velocities produced by the invertor and evertor muscles for the chronically unstable ankle. Ten healthy and 14 chronically unstable ankles were tested, with a repeated-measures design including joint motion (inversion, eversion), muscle contraction type (concentric, eccentric), brace condition (unbraced, flexible, semirigid), and velocity (60, 120, 180, 240°/s). Multiple ANOVAs with repeated-measures and Bonferroni-adjusted comparisons were performed. Results showed that the chronically unstable ankle was significantly weaker than the healthy ankle, regardless of muscle contraction type or joint motion, and that bracing did not deter the muscles' ability to produce peak torque either concentrically or eccentrically. The chronically unstable ankle requires enhanced strengthening, particularly eccentrically and at higher, more functional velocities. Bracing can reduce or prevent injury to the ankle without deterring torque production.

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William S. Quillen, John S. Halle and Leon H. Rouillier

The sports therapist or athletic trainer will frequently encounter individuals who have difficulty regaining normal shoulder joint motion following injury. This tends to occur in spite of the recent advances in arthroscopic surgical techniques, use of constant passive motion (CPM) devices, and sophisticated functional postoperative rehabilitative regimens. A typical approach to the restricted shoulder involves manual therapy techniques. This paper will review the basic physiological and therapeutic principles of mobilization, a primary manual therapy technique. Mobilization procedures are illustrated for the most commonly encountered shoulder restrictions.

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Brian R. Umberger and Philip E. Martin

Lower extremity motions during cycling are often assumed to occur in the sagittal plane. While seemingly logical, this assumption has not been rigorously tested. Frontal plane rotation of the ankle joint (inversion/eversion) has been studied extensively during gait but infrequently during cycling despite the suggestion that excessive eversion or pronation may be related to overuse knee injuries. Two-dimensional sagittal plane hip, knee, and ankle joint kinematics were generally found to be similar to simultaneously measured 3-D values. Despite the similarity in motion patterns, maximum hip angle was 34° more flexed in 2-D than 3-D. Maximum and minimum frontal plane ankle joint angles were similar in 2-D and 3-D. However, during the middle of the pedal cycle, 2-D frontal plane ankle joint motion deviated from 3-D, such that maximum ankle eversion was reached 36% of the pedal cycle later in 2-D versus 3-D. The discrepancy at the hip was due primarily to differences in hip angle definition for 2-D and 3-D approaches, and an alternate convention for hip angle in 2-D is suggested. Discrepancies in frontal plane ankle joint motion are due to weaknesses in the planar approach and would be difficult to overcome without resorting to 3-D measurement.

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Jill L. McNitt-Gray

During a landing impact, the human body is exposed to large forces and moments that create the potential for injury. To determine the effect of impact velocity and landing experience on the strategy selected, the preferred landing strategies used by male collegiate gymnasts and recreational athletes from three drop heights were characterized using mechanical descriptors. Kinematic and reaction force data were acquired simultaneously using highspeed film and a force plate. Reaction forces and lower extremity joint motion were used to characterize the strategies. Results indicated that statistically significant increases in joint flexion (with the exception of ankle joint flexion), angular velocity, and impact force resulted as impact velocity increased. Gymnasts and recreational athletes demonstrated similar adjustment patterns to increases in landing impact velocities; however, significant differences in degree of joint flexion, total landing phase time, and relative adjustments over impact velocity conditions were found.

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Doris I. Miller and Carolyn F. Munro

A temporal and joint position analysis was conducted on Greg Louganis' forward and reverse 3-m springboard takeoffs performed during National Sports Festival V in Colorado Springs. The most notable differences between Louganis' technique and those of eight women finalists in the 1982 Canadian Winter Nationals (Miller & Munro, 1984) were in his greater ranges of joint motion particularly at the knees, hips, and shoulders. He also employed a straighter arm-swing. The fact that Louganis' takeoff duration averaged 0.45 ± 0.01 s, compared with a mean of 0.38 s for the women, allowed him more time to complete joint flexion and extension. This raised questions of adapting technique to progressive changes in skill and strength and monitoring improvement in performance objectively on a longitudinal basis.

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Marianne J.R. Gittoes and Cassie Wilson

This study aimed to develop insight into the lower extremity joint coupling motions used in the maximal velocity phase of sprint running. Two-dimensional coordinate data were used to derive sagittal plane joint angle profiles of sprint running trials. Intralimb joint coupling motions were examined using a continuous relative phase (CRP) analysis. The knee-ankle (KA) coupling was more out of phase compared with the hip-knee (HK) coupling across the step phase (mean CRP: KA 89.9° HK 34.2°) and produced a lower within-athlete CRP variability (VCRP) in stance. Touchdown (TD) produced more out-of-phase motions and a larger VCRP than toe-off. A destabilization of the lower extremity coordination pattern was considered necessary at TD to allow for the swing-to-stance transition. The key role that the KA joint motion has in the movement patterns used by healthy athletes in the maximal velocity phase of sprint running was highlighted.