Influence of high-heeled shoe parameters on biomechanical performance of young female adults during stair ascent motion

BackgroundHigh-heeled shoes are currently preferred by women due to contemporary aesthetics. However, high-heeled shoes may increase the effort required to ascend stairs and, hence, alter biomechanical performance.Research question: How do high-heel shoe parameters affect the pelvis position, lower extremities kinematics, and ground reaction force in young women during stair ascent motion?MethodsStair ascent experiments were performed with 20 healthy adult women. The participants were instructed to ascend a 3-step staircase, wearing heeled shoes of different heel heights and heel types and one pair of flat shoes as the control group. Changes in lower body biomechanics were analyzed with kinematics and ground reaction force variables collected from the dominant limb. A two-way repeated ANOVA was performed to determine which variables were affected by heel type and which were affected by heel height or a combination of both.ResultsAs the heel height increased, an increased range of ankle dorsiflexion-plantarflexion, as well as pelvic rotation, was observed(P = 0.039 and P = 0.003, respectively). A thinner heel type displayed a larger pelvic forward tilt movement(P = 0.026)and 1st peak vertical force(P = 0.025), as well as a smaller 2nd peak vertical force (P = 0.002). With high heels, increased external rotation of the knee, inversion and plantar flexion, and flexion values of the knee were observed. We also observed decreased external rotation of the pelvis, ankle eversion, varum, and dorsiflexion.SignificanceTo stabilize body posture during stair ascent motion with high-heeled shoes, compensatory response including increasd pelvic range of motion and changing the joint angles of the lower extremities.     

Influence of shoe midsole hardness on plantar pressure distribution in four basketball-related movements

This study examined how shoe midsole hardness influenced plantar pressure in basketball-related movements. Twenty male university basketball players wore customized shoes with hard and soft midsoles (60 and 50 Shore C) to perform four movements: running, maximal forward sprinting, maximal 45° cutting and lay-up. Plantar loading was recorded using an in-shoe pressure measuring system, with peak pressure (PP) and pressure time integral (PTI) extracted from 10 plantar regions. Compared with hard shoes, subjects exhibited lower PP in one or more plantar regions when wearing the soft shoes across all tested movements (Ps < 0.05). Lower PTI was also observed in the hallux for 45° cutting, and the toes and forefoot regions during the first step of lay-up in the soft shoe condition (Ps < 0.05). In conclusion, using a softer midsole in the forefoot region may be a plausible remedy to reduce the high plantar loading experienced by basketball players.     

The influence of heel height on utilized coefficient of friction during walking

Wearing high heel shoes has been associated with an increased potential for slips and falls. The association between wearing high heels and the increased potential for slipping suggests that the friction demand while wearing high heels may be greater when compared to wearing low heel shoes. The purpose of this study was to determine if heel height affects utilized friction (uCOF) during walking. A secondary purpose of this study was to compare kinematics at the ankle, knee, and hip that may explain uCOF differences among shoes with varied heel heights. Fifteen healthy women (mean age 24.5 ± 2.5 yrs) participated. Subjects walked at self-selected velocity under 3 different shoe conditions that varied in heel height (low: 1.27 cm, medium: 6.35 cm, and high: 9.53 cm). Ground reaction forces (GRFs) were recorded using a force platform (1560 Hz). Kinematic data were obtained using an 8 camera motion analysis system (120 Hz). Utilized friction was calculated as the ratio of resultant shear force to vertical force. One-way repeated measures ANOVAs were performed to test for differences in peak uCOF, GRFs at peak uCOF and lower extremity joint angles at peak uCOF. On average, peak uCOF was found to increase with heel height. The increased uCOF observed in high heel shoes was related to an increase in the resultant shear force and decrease in the vertical force. Our results signify the need for proper public education and increased footwear industry awareness of how high heel shoes affect slip risk.     

Sagittal subtalar and talocrural joint assessment between barefoot and shod walking: A fluoroscopic study

BackgroundWhile wearing shoes is common in daily activities, most foot kinematic models report results on barefoot conditions. It is difficult to describe foot position inside shoes. This study used fluoroscopic images to determine talocrural and subtalar motion.Research QuestionWhat are the differences in sagittal talocrual and subtalar kinematics between walking barefoot and while wearing athletic walking shoes?MethodsThirteen male subjects (mean age 22.9 ± 2.9 years, mean weight 77.2 ± 6.9 kg, mean height 178.2 ± 3.7 cm) screened for normal gait were tested. A fluoroscopy unit was used to collect images during stance. Sagittal motion of the talocrural and subtalar joints of the right foot were analyzed barefoot and in an athletic walking shoe.ResultsShod talocrural position at heel strike was 6.0° of dorsiflexion and shod peak talocrural plantarflexion was 4.2°. Barefoot talocrural plantarflexion at heel strike was 4.2° and barefoot peak talocrural plantarflexion was 10.9°. Shod subtalar position at heel strike was 2.6° of plantarflexion and peak subtalar dorsiflexion was 1.5°. The barefoot subtalar joint at heel strike was in 0.4° dorsiflexion and barefoot peak subtalar dorsiflexion was 3.5°. As the result of wearing shoes, average walking speed and stride length increased and average cadence decreased. Comparing barefoot to shod walking there was a statistical significance in talocrural dorsiflexion and at heel strike and peak talocrural dorsiflexion, subtalar plantarflexion at heel strike and peak subtalar dorsiflexion, walking speed, stride length, and cadence.SignificanceThis work demonstrates the ability to directly measure talocrural and subtalar kinematics of shod walking using fluoroscopy. Future work using this methodology can be used to increase understanding of hindfoot kinematics during a variety of non-barefoot activities.     

Landing technique affects knee loading and position during athletic tasks

Anterior cruciate ligament (ACL) injuries have been reported to occur with the ankle in a dorsiflexed position at initial contact. Few studies have attempted to quantify the biomechanical parameters related with such landing patterns during athletic tasks.ObjectivesThe purpose of this study was to evaluate the effects that two landing techniques have in lower extremity biomechanics while performing two tasks.DesignSingle-group repeated measures design.MethodsTwenty female soccer athletes from a Division I institution performed two landing techniques (forefoot and rearfoot) during two unanticipated tasks (sidestep cutting and pivot). Repeated measures analyses of variance were conducted to assess differences in the kinematic and kinetic parameters between landing techniques for each task.ResultsThe forefoot landing technique had significantly higher internal knee adductor moment than the rearfoot for both the pivot and sidestep cutting task (p < 0.001 and p = 0.003, respectively). For the sidestep cutting task, participants had increased knee valgus angle with the rearfoot, whereas for the pivot they had increased knee valgus with the forefoot landing technique (p < 0.05).ConclusionsThe results of this study highlighted that there are inherent differences in biomechanical outcomes between foot-landing techniques. The forefoot landing technique increasingly affects knee adduction moment loading, which can potentially place a higher strain on the ACL. Essentially, the demands of the landing technique on lower extremity biomechanics (e.g., hip and knee) are task dependent.     

Ankle injuries in basketball: injury rate and risk factors

OBJECTIVES: To determine the rate of ankle injury and examine risk factors of ankle injuries in mainly recreational basketball players. METHODS: Injury observers sat courtside to determine the occurrence of ankle injuries in basketball. Ankle injured players and a group of non-injured basketball players completed a questionnaire. RESULTS: A total of 10 393 basketball participations were observed and 40 ankle injuries documented. A group of non-injured players formed the control group (n = 360). The rate of ankle injury was 3.85 per 1000 participations, with almost half (45.9%) missing one week or more of competition and the most common mechanism being landing (45%). Over half (56.8%) of the ankle injured basketball players did not seek professional treatment. Three risk factors for ankle injury were identified: (1) players with a history of ankle injury were almost five times more likely to sustain an ankle injury (odds ratio (OR) 4.94, 95% confidence interval (CI) 1.95 to 12.48); (2) players wearing shoes with air cells in the heel were 4.3 times more likely to injure an ankle than those wearing shoes without air cells (OR 4.34, 95% CI 1.51 to 12.40); (3) players who did not stretch before the game were 2.6 times more likely to injure an ankle than players who did (OR 2.62, 95% CI 1.01 to 6.34). There was also a trend toward ankle tape decreasing the risk of ankle injury in players with a history of ankle injury (p = 0.06). CONCLUSIONS: Ankle injuries occurred at a rate of 3.85 per 1000 participations. The three identified risk factors, and landing, should all be considered when preventive strategies for ankle injuries in basketball are being formulated.     

Changes in temporal gait characteristics and pressure distribution for bare feet versus various heel heights

The purpose of this study was to identify changes in temporal gait characteristics and pressure generation across the sole of the foot due to various heel heights in women's dress pumps. Thirty female subjects, aged 18-30 years, volunteered to participate. Subjects were required to have normal gait and to wear comfortably either size 7 or size 9 shoes. Subjects were tested initially in bare feet using electrodynography (Langer Biomechanics Group, 21 East Industry Court, Deer Park, NY 11729-9986) (EDG) at a cadence of ~100 steps/min set by metronome. EDG trials with 4 pairs of shoes were then performed in random order. Shoes were women's dress pumps identical except for heel height. Heel heights were 1.75, 3.12, 5.72 and 8.74 cm. Data were collected over ~ 30 steps and averaged over this period. Data were analyzed using a one-way ANOVA, and changes were only considered significant if the ANOVA identified significant variations bilaterally. Considering temporal gait variables, we concluded that: (1) stance phase was shortened in shoes vs. bare feet but was unaffected by heel height, (2) the percentage of stance spent in weight bearing on the lateral and medial calcaneus decreased above a 3.12 cm heel height, (3) the percentage of stance spent in weight bearing on the first and second metatarsal heads increased in shoes vs. bare feet but was unaffected by heel height, (4) the percentage of stance spent in weight bearing on the fifth metatarsal was less in the 8.74 cm heel than in any other shoe or in bare feet. With regard to pressure variables, we found that: (1) peak pressure under the fifth metatarsal head was inversely related to heel height, (2) pressure under the third metatarsal head peaked earliest in heels greater than 5.72 cm high, and (3) pressure under the medial calcaneus peaked latest in heels greater than 5.72 cm high.     

Anterior bony ankle impingement

Anterior bony ankle impingement results from osteophyte formation on the anterior edge of the distal tibia and/or neck of the talus, secondary to direct trauma during extreme or repetitive ankle dorsiflexion. It is common in ballet dancers, gymnasts, soccer players, football players, runners, and high jumpers. Typically, patients will complain of painful limitation of dorsiflexion, catching, and swelling in the ankle. These symptoms can be debilitating and considerably limit their athletic performance. The suspected diagnosis is confirmed with a plain lateral ankle radiograph that shows the anterior osteophytes. Initial treatment includes rest, an internal or external heel lift, rubber-sole wedge shoes, nonsteroidal anti-inflammatory drugs, physical therapy, and intra-articular steroid injections. If nonoperative treatment fails, removal of the anterior osteophytes by open or arthroscopic technique offers symptomatic relief of pain in most patients.     

Heel height affects lower extremity frontal plane joint moments during walking

Wearing high heels alters walking kinematics and kinetics and can create potentially adverse effects on the body. Our purpose was to determine how heel height affects frontal plane joint moments at the hip, knee, and ankle, with a specific focus on the knee moment due to its importance in joint loading and knee osteoarthritis. 15 women completed overground walking using three different heel heights (1, 5, and 9 cm) for fixed speed (1.3 ms(-1)) and preferred speed conditions while kinematic and force platform data were collected concurrently. For both fixed and preferred speeds, peak internal knee abduction moment increased systematically as heel height increased (fixed: 0.46, 0.48, 0.55 N m kg(-1); preferred: 0.47, 0.49, 0.53 N m kg(-1)). Heel height effects on net frontal plane moments of the hip and ankle were similar to those for the knee; peak joint moments increased as heel height increased. The higher peak internal knee abduction moment with increasing heel height suggests greater medial loading at the knee. Kinetic changes at the ankle with increasing heel height may also contribute to larger medial loads at the knee. Overall, wearing high heels, particularly those with higher heel heights, may put individuals at greater risk for joint degeneration and developing medial compartment knee osteoarthritis.     

The influence of shoe aging on children running biomechanics

Athletic children are prone to overuse injuries, especially at the heel and knee. Since footwear is an extrinsic factor of lower limb injury risk, the aim of this study was to assess the influence of shoe aging on children running biomechanics. Fourteen children active in sports participated in a laboratory biomechanical evaluation. A new pair of shoes was provided to each participant at an inclusion visit. Four months later, the participants performed a running task and their kinematics and kinetics were assessed both with their used shoes and with a new pair of shoes identical to the first. Furthermore, mechanical cushioning properties of shoes were evaluated before and after in-vivo aging. After 4 months of use, the sole stiffness increased by 16% and the energy loss capacity decreased by 18% (p < 0.001). No ankle or knee kinematic adjustment was found at foot strike in used shoes but changes were observed later during stance. Running with used shoes produced a higher loading rate of the vertical ground reaction force (+23%, p = 0.016), suggesting higher compressive forces under the heel and placing children at risk to experience impact-related injuries. Nevertheless, the decreased peak ankle and knee power absorption in used shoes (−11%, p = 0.010 and −12%, p = 0.029, respectively) suggests a lower ankle and knee joints loading during the absorption phase that may be beneficial regarding stretch-related injuries.     

Midfoot and ankle motion during heel rise and gait are related in people with diabetes and peripheral neuropathy

BackgroundMidfoot and ankle movement dysfunction in people with diabetes mellitus and peripheral neuropathy (DMPN) is associated with midfoot deformity and increased plantar pressures during gait. If midfoot and ankle motion during heel rise and push-off of gait have similar mechanics, heel rise performance could be a clinically feasible way to identify abnormal midfoot and ankle function during gait.Research questionIs midfoot and ankle joint motion during a heel rise associated with midfoot and ankle motion at push-off during gait in people with DMPN?MethodsSixty adults with DMPN completed double-limb heel rise, single-limb heel rise, and walking. A modified Oxford multi-segment foot model (forefoot, hindfoot, shank) was used to analyze midfoot (forefoot on hindfoot) and ankle (hindfoot on shank) sagittal angle during heel rise and gait. Pearson correlation was used to test the relationship between heel rise and gait kinematic variables (n = 60). Additionally, we classified 60 participants into two subgroups based on midfoot and ankle position at peak heel rise: midfoot and ankle dorsiflexed (dorsiflexed; n = 23) and midfoot and ankle plantarflexed (plantarflexed; n = 20). Movement trajectories of midfoot and ankle motion during single-limb heel rise and gait of the subgroups were examined.ResultsPeak double-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.49 and r = 0.40, respectively). Peak single-limb heel rise and gait midfoot and ankle angles were significantly correlated (r = 0.63 and r = 0.54, respectively). The dorsiflexed subgroup, identified by heel rise performance showed greater midfoot and ankle dorsiflexion during gait compared to the plantarflexed subgroup (mean difference between subgroups: midfoot 3°, ankle 3°).SignificancePeople with DMPN who fail to plantarflex the midfoot and ankle during heel rise have difficulty plantarflexing the midfoot and ankle during gait. Utilizing a heel rise task may help identify midfoot and ankle dysfunction associated with gait in people with DMPN.     

Effects of heel height and high-heel experience on foot stability during quiet standing

BackgroundThe use of high-heeled shoes (HHS) introduces instability into the wearer’s balance system but how high-heel experience might influence standing balance is less examined in literature.Research question(1) Does foot stability decrease in both the antero-posterior (AP) and medial-lateral (ML) directions with increasing heel height during quiet standing?(2) Does high-heel experience improve the wearer’s foot stability during quiet standing in high-heeled conditions?MethodsTwenty-four young females (12 regular and 12 non-regular HHS wearers) were recruited to perform quiet standing while wearing shoes with heel heights of 1 cm, 5 cm, 8 cm and 10 cm. The effects of heel height on the mean center of pressure (COP), their variability (standard deviations) and mean COP velocities in both the AP and ML directions were analysed by one-way repeated measures ANOVA and Bonferroni post-hoc test. The effects of high-heel experience were analysed through independent samples t-tests.ResultsThe variability of the COP in both directions increased with heel height, although significance was found only in the ML direction. The COP velocities in both directions were highest for the 1 cm heel, decreased as the heel increased to 8 cm and increased again for the 10 cm heel. Experienced HHS wearers exhibited significantly smaller COP variances (AP) for the 8 cm and 10 cm heels, smaller COP velocities (AP) for all heels, and smaller COP variances (ML) and COP velocities (ML) for the 10 cm heel.SignificanceThe use of HHS results in greater stability distortions in both AP and ML directions but high-heel experience improves balance control under high-heeled conditions. Our findings enhance the understanding of how high-heel experience might influence standing balance in different heel height, and highlights the importance of the ML components of the in-foot COP measures in the examination of standing balance in HHS.     

Systematic ankle stabilization and the effect on performance

Stabilization of the ankle joint is used as a deterrent to injury, however, insufficient or excessive ankle control can cause negative effects. This study determined the effects of systematic changes in ankle and subtalar joint stabilization on performance through an obstacle course. Data were collected on six subjects as they completed two test procedures. Ankle range of motion in the sagittal and frontal planes was determined using a modified Inman apparatus. Completion time through an obstacle course, set up on a basketball court, was used as a measure of performance. High-top basketball shoes were constructed with pockets which allowed strips of plastic (stiffeners) to be positioned just anterior and posterior to the medial and lateral malleoli. Four shoe conditions were used including the shoe with no stiffeners. Significant differences (P less than 0.05) in eversion, flexion, and inversion were found between the shoe conditions. A general trend of decreased range of motion with increased restriction was observed. Significant differences (P less than 0.05) in performance were found between the shoe conditions, with a general trend of increased times with increased restriction. These results indicate that systematic changes in the range of motion of the ankle and subtalar joints can measurably affect performance.     

Biomechanics of running with rocker shoes

Objectives

Load reduction is an important consideration in conservative management of tendon overuse injuries such as Achilles tendinopathy. Previous research has shown that the use of rocker shoes can reduce the positive ankle power and plantar flexion moment which might help in unloading the Achilles tendon. Despite this promising implication of rocker shoes, the effects on hip and knee biomechanics remain unclear. Moreover, the effect of wearing rocker shoes on different running strike types is unexplored. The aim of this study was to investigate biomechanics of the ankle, knee and hip joints and the role of strike type on these outcomes.

Textured insole effects on ankle movement discrimination while wearing athletic shoes

Aspects of athletic footwear were examined for their relationship to subjects' discrimination between different extents of inversion at the ankle. Testing was conducted separately on both feet with elite netballers who made discrete, active ankle movements while standing on an apparatus in an upright, non-restrained and weightbearing posture. Wearing conventional athletic socks only did not enhance discrimination over that achieved when barefoot. Movement discrimination scores were significantly worse when subjects wore their athletic shoes and socks, as compared to barefoot data collected at the same time. On the final occasion of testing, the addition of textured insoles to the shoes was found to restore movement discrimination back to barefoot levels. This outcome was interpreted in terms of enhanced cutaneous feedback, applying at the surface of the sole of the foot and the raised surface of the insole, serving to enhance feedback from movement. Across the 36 weeks of the study, movement discrimination scores for the barefoot condition showed significant improvement, a finding which is consistent with previous data gathered from athletes also engaged in wobbleboard training.     

The effect of high-heeled shoes on overground gait kinematics in young healthy women

Purpose

The purpose of this study was to assess the modifications in body center of mass (CoM), total mechanical work and walking characteristics during low-heeled and high-heeled gait performed in ecological conditions.

Methods

The 3D coordinates of 19 body landmarks were recorded by an optoelectronic motion analyzer in 13 women while walking overground at self-selected speed with either low-heeled or high-heeled shoes (minimum height, 70 mm). Using mean anthropometric data, the CoM was estimated, and its position evaluated during normalized gait cycles. Shoulders, pelvic and knee orientations were also assessed together with estimates of total mechanical work.

Results

High-heeled walking was performed with significantly lower horizontal speed (p < 0.05) but with the same cadence than low-heeled walking. During the whole gait cycle, the CoM (calculated from the malleolus landmarks) was 3 % lower during high-heeled walking (p < 0.05), had higher vertical displacements and vertical velocity modifications (p < 0.001), and it was significantly more anterior (p < 0.01). On average, walking with high heels at self-selected speed required a 16 % higher total mechanical work, but the difference was not significant. At heel strike with high heels, the shoulders were more inclined (p < 0.05), the support limb knee was significantly more flexed (p < 0.05), with a 12 % reduced total range of motion (p < 0.001), while the back limb knee was less flexed (p < 0.05).

Conclusions

Wearing high-heeled shoes significantly alters the normal displacement of human CoM; high-heeled gait exaggerated female walking characteristics with a more anterior CoM position, a wider vertical movement and a slower velocity.     

Effect of prophylactic ankle taping on ankle and knee biomechanics during basketball-specific tasks in females

ObjectiveThe aim of this study was to investigate the effects of ankle taping on ankle and knee joint biomechanics during cutting and rebound activities in females.DesignCross-sectional.SettingLaboratory.ParticipantsTwenty semi-professional female basketball players performed a cut and rebound task under two conditions (taped and no-tape).Main Outcome MeasuresKinematic and ground reaction force data were collected during the deceleration phase of each movement task.ResultsTaping resulted in a significant reduction in peak ankle dorsiflexion, inversion and internal rotation angles and range of motion (ROM) at the ankle joint; and reduced knee ROM in the sagittal plane during the rebound task only. Taping significantly reduced peak knee flexion moment (0.29 Nm/kg, P = 0.013) and increased knee internal rotation moment (0.63 Nm/kg, P = 0.026) during the cutting task compared to control. Taping also significantly reduced the internal rotation moment (0.07 Nm/kg, P = 0.025), and medial shear forces (0.14 N/kg, P = 0.012) in the rebound task.ConclusionResults of the study suggest that ankle taping restrict ankle range of movement in the rebound task only and ankle taping appears to have upstream effects on the knee, which may have injury implications.     

Number of knee and ankle injuries is associated with poor physical but not mental health

The knee and ankle are among the most commonly injured joints in the body. Long-term strength and neuromuscular control deficits are common following these injuries, yielding lifelong disability and poor quality of life. However, it is unknown how the number of injuries sustained influences quality of life.

Objectives: Determine the association between the number of ankle or knee injuries sustained and physical and mental quality of life.

Methods: A total of 806 ankle-injured (age:45.2 ± 15.3 yrs; body mass index [BMI]:28.6 ± 7.4 kg/m²), 658 knee-injured (age:49.3 ± 16.1 yrs; BMI:28.4 ± 7.4 kg/m²), and 996 uninjured (age:43.4 ± 16.1 yrs; BMI:26.9 ± 6.5 kg/m²) adults completed the SF-8 survey to determine the physical (PCS) and mental (MCS) contributions to quality of life. Respondents were categorized by injury history (ankle, knee, none) and number of injuries (0, 1, 2, or 3 or more [3+]) to the same joint. Backward linear regression models were used to determine the association between quality of life, age, and injury history separately for SF-8 PCS and MCS, as well as ankle versus knee injury.

Results: Reporting 1, 2, or 3+ ankle injuries along with age predicted SF-8 PCS (P < 0.001). Further, 1 or 2 ankle injuries and age (P < 0.001) predicted SF-8 MCS. Reporting 1, 2, or 3+ knee injuries along with age significantly predicted SF-8 PCS (P < 0.001). Age, but not knee injury history, significantly predicted SF-8 MCS (P < 0.001).

Conclusion: Current age and history of sustaining at least one injury negatively impact physical quality of life following either a knee or ankle injury. However, mental quality of life was predicted most consistently by age. Efforts to reduce injuries should be employed to improve quality of life, but more research is needed to determine what other factors contribute to quality of life across the lifespan.     

Physiological coxa varus–genu valgus influences internal knee and ankle joint moments in females during crossover cutting

This study evaluated the ankle and knee electromyographic, kinematic, and kinetic differences of 20 nonimpaired females with either neutral (group 1) or coxa varus–genu valgus (group 2) alignment during crossover cutting stance phase. Two-way mixed model ANOVA (group, session) assessed mean differences (p<0.05) and correlation analysis further delineated relationships. During impact absorption, group 2 displayed earlier peak horizontal braking (anterior-posterior) ground reaction force timing, decreased and earlier peak internal knee extension moments (eccentric function), and earlier peak internal ankle dorsiflexion moment timing (eccentric function). During the pivot phase, group 2 displayed later and eccentrically-biased peak ankle plantar flexion moments, increased peak internal knee flexion moments (eccentric function), and later peak knee internal rotation timing. Correlation analysis revealed that during impact absorption, subjects with coxa varus–genu valgus alignment (group 2) displayed a stronger relationship between knee internal rotation velocity and peak internal ankle dorsiflexion moment onset timing (r=–0.64 vs r =–0.26) and between peak horizontal braking ground reaction forces and peak internal ankle dorsiflexion moment onset timing (r=0.61 vs r=0.24). During the pivot phase these subjects displayed a stronger relationship between peak horizontal braking ground reaction forces and peak internal ankle plantar flexion moment onset timing (r=–0.63 vs r=–0.09) and between peak horizontal braking forces and peak internal ankle plantar flexion moments (r=–0.72 vs r=–0.26). Group differences suggest that subjects with coxa varus–genu valgus frontal-plane alignment have an increased dependence on both ankle dorsiflexor and plantar flexor muscle group function during crossover cutting. Greater dependence on ankle muscle group function during the performance of a task that requires considerable 3D dynamic knee joint control suggests a greater need for frontal and transverse plane weight bearing tasks that facilitate eccentric ankle muscle group function to optimize injury prevention conditioning and post-surgical rehabilitation programs.     

Ground reaction force and 3D biomechanical characteristics of walking in short-leg walkers

Short-leg walking boots offer several advantages over traditional casts. However, their effects on ground reaction forces (GRF) and three-dimensional (3D) biomechanics are not fully understood. The purpose of the study was to examine 3D lower extremity kinematics and joint dynamics during walking in two different short-leg walking boots. Eleven (five females and six males) healthy subjects performed five level walking trials in each of three conditions: two testing boot conditions, Gait Walker (DeRoyal Industries, Inc.) and Equalizer (Royce Medical Co.), and one pair of laboratory shoes (Noveto, Adidas). A force platform and a 6-camera Vicon motion analysis system were used to collect GRFs and 3D kinematic data during the testing session. A one-way repeated measures analysis of variance (ANOVA) was used to evaluate selected kinematic, GRF, and joint kinetic variables (p < 0.05). The results revealed that both short-leg walking boots were effective in minimizing ankle eversion and hip adduction. Neither walker increased the bimodal vertical GRF peaks typically observed in normal walking. However, they did impose a small initial peak (<1 BW) earlier in the stance phase. The Gait Walker also exhibited a slightly increased vertical GRF during midstance. These characteristics may be related to the sole materials/design, the restriction of ankle movements, and/or the elevated heel heights of the tested walkers. Both walkers appeared to increase the demand on the knee extensors while they decreased the demand of the knee and hip abductors based on the joint kinetic results.