Effect of sensor location for modifying center of pressure during gait using haptic feedback in people with chronic ankle instability.

BACKGROUND: Gait retraining using haptic biofeedback medially shifts the center of pressure (COP) while walking in orthopedic populations. However, the ideal sensor location needed to effectively shift COP medially has not been identified in people with chronic ankle instability (CAI). RESEARCH QUESTIONS: Can a heel sensor location feasibly be employed in people with CAI without negatively altering kinematics? Does a heel sensor placement relative to the 5th metatarsal head (5MH) impact COP location while walking in people with CAI? METHODS: In this exploratory crossover study, 10 participants with CAI walked on a treadmill with vibration feedback for 10 minutes with a plantar pressure sensor under the heel and 5MH. Separate 2×2 repeated measures analyses of covariances (rmANCOVAs) were used to compare the averaged COP location and 3-D lower extremity kinematics from the first 10% of stance before and after training and between sensor locations. Baseline measures served as covariates to adjust for baseline differences. RESULTS: Feedback triggered by a heel sensor resulted in 40% of participants avoiding a heel strike. There were no significant main effects or interactions between time and sensor location on COP location when controlling for baseline COP (p>0.05). However, with the 5MH placement, participants displayed less ankle internal rotation(IR) (5MH/Heel: -4.12±0.00º/ -6.43±0.62º), less forefoot abduction (-4.29±0.00º/ -5.14±1.01º), more knee flexion (3.40±0.32º/ 0.14±0.57º), less knee external rotation (-10.95±0.00º/-11.24±1.48º), less hip extension (-0.20±0.00º/-1.42±1.05º), and less hip external rotation (3.12±0.00º/3.75±1.98º). SIGNIFICANCE: A 5MH location may be more feasible based on difficulties maintaining heel strike when the sensor was under the heel. While no sensor location was statistically better at changing the COP, the 5MH location decreased proximal transverse plane motions making participants' gait more like controls. Individual response variations support comprehensive lower extremity assessments and the need to identify responder profiles using sensory feedback in people with CAI.

The effect of Tai Chi lower extremity exercise on the balance control of older adults in assistant living communities.

BACKGROUND: Although Tai Chi (TC) is an evidence-based fall prevention training for older adults, its effective movements remain unclear, which may limit the practice of TC. The purpose of this study was to compare the effectiveness of TC lower extremity exercise (TC LEE), the 8-form Tai Chi (8-form TC), and a stretching control intervention for improving balance and functional mobility among older adults. METHODS: This was a randomized controlled trial. A total of 102 participants (79 ± 6 years old) were recruited from assisted living facilities. All participants were randomly assigned to the TC LEE (n = 40), 8-form TC (n = 31), and stretching (n = 31) groups in which they received the respective interventions for 16 weeks. The Berg Balance Scale (BBS), Timed Up and Go (TUG) test, and center of pressure (COP) measurements during quiet stance were collected prior to and following the 16-week interventions. Comparisons on all measurements were conducted among all groups. RESULTS: Significant improvements were found in BBS (P = 0.002), TUG test (P = 0.001), root mean square amplitude of COP displacement in the anterior-posterior (P = 0.001) and medial-lateral (P = 0.001) directions, and average COP speed in the anterior-posterior (P = 0.001) and medial-lateral (P = 0.001) directions after training in the TC intervention groups compared with the stretching group. The upper limit of the 95% confidence interval (CI) of differences in change scores on the BBS (-0.8 - 1.3 points) between the TC LEE group and the 8-form TC group was within equivalence margins (1.8 points), while the upper limit of the 95% CI of differences in change scores on the TUG test (0.1 - 2.1 s) exceeded the equivalence margin (0.7 s) with the TC LEE group having the larger change scores. CONCLUSION: TC LEE can improve balance and functional mobility in older adults, and may have greater effect than the 8-form TC on improving functional mobility as measured by the TUG test. TRIAL REGISTRATION: ChiCTR2300070600 retrospectively registered.

Effects of corrective insole on leg muscle activation and lower extremity alignment in rice farmers with pronated foot: a preliminary report.

BACKGROUND: Execution of strenuous activities in conjunction with slippery and viscous muddy working terrain in rice cultivation leads to a high prevalence of farmer musculoskeletal disorders and malalignments. Recommended intervention strategies originally designed for congenitally disabled individuals may also be applicable to farmers, including simple corrective wedges to reduce foot eversion. The objective of the present study was to conduct a preliminary investigation of the effects of corrective wedges on lower extremity muscle activity and alignment when subjects stood on flat rigid ground or muddy terrain, simulating typical work conditions encountered by the unique but populous Thai rice farming workforce. METHODS: Nine healthy farmers with pronated feet were recruited to participate and wedges were custom fabricated for each farmer based on physical therapy assessment and use of rapid prototyping techniques. Participants were asked to stand barefoot or with wedges on the two surface types. RESULTS: Results revealed foot pronation and knee valgus to improve (ranging, on average between 5.5 and 16.1 degrees) when participants were equipped with corrective wedges. The muscle activity of the peroneus longus and the tibialis anterior increased for muddy terrain, as compared with the rigid surface. In general, the wedges induced less tibialis anterior activity and greater peroneus longus activity, compared to when participants were standing barefoot. An elevation in evertor muscle activity may reflect stretching of the shortened muscle as a result of the reduced degree of foot pronation. CONCLUSIONS: Findings demonstrate potential benefits of corrective insole usage for farmers with pronated feet, including improved lower extremity alignment and invertor muscle activity reduction for both rigid and muddy terrains.

Tibiofemoral joint mobilizations following total knee arthroplasty and manipulation under anesthesia.

STUDY DESIGN: Case report. BACKGROUND: The purpose of this case report is to describe the use of tibiofemoral joint mobilizations to improve knee flexion in a patient with arthrofibrosis following total knee arthroplasty (TKA) and failed manipulation under anesthesia (MUA). CASE DESCRIPTION: A 62-year-old female presented to physical therapy 15 days after TKA with full knee extension, 45 deg of active knee flexion, 48 deg of passive knee flexion, pain, and a Lower Extremity Functional Scale (LEFS) score of 28. INTERVENTIONS/OUTCOMES: A multimodal intervention strategy was used initially with minimal improvement in knee flexion. The patient was diagnosed with fibrosis and MUA was performed. Passive knee flexion was 80 deg before MUA and 75 deg after MUA. Focused grade III and IV tibiofemoral joint mobilizations were used after MUA. At discharge, the patient had 90 deg of active and 116 deg of passive knee flexion, no pain, and an LEFS score of 80. DISCUSSION: A conventional multimodal intervention approach was ineffective for a patient who developed arthrofibrosis following TKA. A focused intervention approach of grade III and IV tibiofemoral joint mobilizations improved knee flexion, pain, and function following TKA and failed MUA.

The effect of performance demands on lower extremity biomechanics during landing and cutting tasks.

BACKGROUND: Anterior cruciate ligament (ACL) injuries commonly occur during the early phase of landing and cutting tasks that involve sudden decelerations. The purpose of this study was to investigate the effects of jump height and jump speed on lower extremity biomechanics during a stop-jump task and the effect of cutting speed on lower extremity biomechanics during a side-cutting task. METHODS: Thirty-six recreational athletes performed a stop-jump task under 3 conditions: jumping fast, jumping for maximum height, and jumping for 60% of maximum height. Participants also performed a side-cutting task under 2 conditions: cutting at maximum speed and cutting at 60% of maximum speed. Three-dimensional kinematic and kinetic data were collected. RESULTS: The jumping fast condition resulted in increased peak posterior ground reaction force (PPGRF), knee extension moment at PPGRF, and knee joint stiffness and decreased knee flexion angle compared with the jumping for maximum height condition. The jumping for 60% of maximum height condition resulted in decreased knee flexion angle compared with the jumping for maximum height condition. Participants demonstrated greater PPGRF, knee extension moment at PPGRF, knee valgus angle and varus moment at PPGRF, knee joint stiffness, and knee flexion angle during the cutting at maximum speed condition compared with the cutting at 60% maximum speed condition. CONCLUSION: Performing jump landing at an increased jump speed resulted in lower extremity movement patterns that have been previously associated with an increase in ACL loading. Cutting speed also affected lower extremity biomechanics. Jump speed and cutting speed need to be considered when designing ACL injury risk screening and injury prevention programs.

Concerns About Ankle Injury Prophylaxis and Acceptance of the Parachute Ankle Brace Among Jumpmaster Students.

Introduction: Several studies have shown that the parachute ankle brace (PAB) is safe, cost-effective, and reduces the rates of ankle injuries during military parachuting. However, the acceptability and usability of the PAB has not been well established in units that regularly do airborne exercises. Many anecdotal concerns in the past may be limiting common use. The purpose of the study is to ascertain the attitudes toward the PAB among experienced paratroopers. Methods: One hundred experienced paratroopers training to be jumpmasters at the Advanced Airborne School (Fort Bragg, NC) voluntarily responded to a 13-item, paper questionnaire to assess attitudes toward the PAB, its use, and concerns about future ankle injuries. The survey was offered to all 100 students enrolled in an Advanced Airborne School course. Results were input into an online database using Qualtrics and qualitative responses were evaluated for thematic content and categorized appropriately. Analysis was performed using Qualtrics and SPSS for descriptive statistics, two-sample t-tests, and chi-square tests. The Wilcoxon signed-rank test was used to evaluate Likert-type responses. Results: Of the 100 paratroopers who responded to the survey 32% had over 10 yr of military service, 58% had over 5 yr of service, and 32% had over 5 yr on active jump status. Results show that none of the respondents had ever used the PAB; 62% had never heard of the PAB, and 72% had never observed use of the PAB. A majority of respondents (87%) had never injured an ankle during a parachute landing fall (PLF), but 79% believed that an ankle injury could affect their career potential as a paratrooper. Almost one-half of the respondents (47%) had seen that ankle injuries affect another paratrooper's career. A third of the respondents (35%) said that they had concerns that would keep them from using the PAB, whereas 21% were uncertain, as they had never heard of it. Only 19% of the respondents were willing to use measures such as taping, lace-up bracing, semi-rigid brace inside a normal boot, specialized jump boot with stabilizing braces built in, or outside-the-boot braces to prevent ankle injury. However, 40% said that they were likely to use these measures on jumps after experiencing an ankle injury. Discussion: Previous research clearly establishes the advantages of the PAB. None of the participants had ever used the PAB but expressed a fear about how an ankle injury might impact their future career potential. Yet half of the jumpmasters indicated a willingness to use prophylactic measures after an ankle injury. Conclusion: This survey assessed the attitude and knowledge related to the PAB among jumpmaster students. Results show that despite the benefits of the PAB, a negative attitude exists toward the PAB, and it is not currently being used. This survey clearly demonstrates the need either to educate paratroopers on the existence of the PAB or to explore other designs that may be more readily accepted in the airborne community.

Differential Diagnosis and Intervention of Proximal Median Nerve Entrapment: A Resident's Case Problem.

Study Design Resident's case problem. Background Entrapment neuropathies represent a diagnostic challenge and require a comprehensive understanding of the nerve's path and the anatomical structures that may cause compression of the nerve. This resident's case problem details the evaluation and differential diagnosis process for median nerve entrapment resulting from forceful and repetitive pronation/supination motions. Diagnosis Median nerve compression syndromes include pronator syndrome, anterior interosseous nerve syndrome, and carpal tunnel syndrome. A cluster of clinical special tests were performed to determine the anatomical site of median nerve entrapment. Based on the patient's history and clinical test results, a diagnosis of pronator syndrome was determined. Provocation testing specific to pronator syndrome assisted with further localizing the site of entrapment to the pronator teres muscle, which guided effective management strategies. Discussion This resident's case problem illustrates the importance of detailed anatomical knowledge and a differential diagnostic process when evaluating a patient with signs and symptoms of an entrapment neuropathy of the median nerve. Electrodiagnostic studies are useful in ruling out carpal tunnel and anterior interosseous nerve syndromes, but are often inconclusive in cases of pronator syndrome. Therefore, a diagnosis of pronator syndrome in this case problem was based on a detailed understanding of median nerve anatomy, potential sites of compression, and unique clinical features associated with this condition. Level of Evidence Differential diagnosis, level 4. J Orthop Sports Phys Ther 2016;46(9):800-808. Epub 5 Aug 2016. doi:10.2519/jospt.2016.6723.

Adding Stiffness to the Foot Modulates Soleus Force-Velocity Behaviour during Human Walking.

Previous studies of human locomotion indicate that foot and ankle structures can interact in complex ways. The structure of the foot defines the input and output lever arms that influences the force-generating capacity of the ankle plantar flexors during push-off. At the same time, deformation of the foot may dissipate some of the mechanical energy generated by the plantar flexors during push-off. We investigated this foot-ankle interplay during walking by adding stiffness to the foot through shoes and insoles, and characterized the resulting changes in in vivo soleus muscle-tendon mechanics using ultrasonography. Added stiffness decreased energy dissipation at the foot (p < 0.001) and increased the gear ratio (i.e., ratio of ground reaction force and plantar flexor muscle lever arms) (p < 0.001). Added foot stiffness also altered soleus muscle behaviour, leading to greater peak force (p < 0.001) and reduced fascicle shortening speed (p < 0.001). Despite this shift in force-velocity behaviour, the whole-body metabolic cost during walking increased with added foot stiffness (p < 0.001). This increased metabolic cost is likely due to the added force demand on the plantar flexors, as walking on a more rigid foot/shoe surface compromises the plantar flexors' mechanical advantage.

Physical therapy vs. internet-based exercise training (PATH-IN) for patients with knee osteoarthritis: study protocol of a randomized controlled trial.

BACKGROUND: Physical activity improves pain and function among individuals with knee osteoarthritis (OA), but most people with this condition are inactive. Physical therapists play a key role in helping people with knee OA to increase appropriate physical activity. However, health care access issues, financial constraints, and other factors impede some patients from receiving physical therapy (PT) for knee OA. A need exists to develop and evaluate other methods to provide physical activity instruction and support to people with knee OA. This study is examining the effectiveness of an internet-based exercise training (IBET) program designed for knee OA, designed by physical therapists and other clinicians. METHODS/DESIGN: This is a randomized controlled trial of 350 participants with symptomatic knee OA, allocated to three groups: IBET, standard PT, and a wait list (WL) control group (in a 2:2:1 ratio, respectively). The study was funded by the Patient Centered Outcomes Research Institute, which conducted a peer review of the proposal. The IBET program provides patients with a tailored exercise program (based on functional level, symptoms, and current activity), video demonstrations of exercises, and guidance for appropriate exercise progression. The PT group receives up to 8 individual visits with a physical therapist, mirroring standard practice for knee OA and with an emphasis on a home exercise program. Outcomes are assessed at baseline, 4 months (primary time point) and 12 months (to assess maintenance of treatment effects). The primary outcome is the Western Ontario and McMaster Universities Osteoarthritis Index, and secondary outcomes include objective physical function, satisfaction with physical function, physical activity, depressive symptoms and global assessment of change. Linear mixed models will be used to compare both the IBET and standard PT groups to the WL control group, examine whether IBET is non-inferior to PT (a treatment that has an established evidence base for knee OA), and explore whether participant characteristics are associated with differential effects of IBET and/or standard PT. This research is in compliance with the Helsinki Declaration and was approved by the Institutional Review Board of the University of North Carolina at Chapel Hill. DISCUSSION: The IBET program could be disseminated widely at relatively low cost and could be an important resource for helping patients with knee OA to adopt and maintain appropriate physical activity. This trial will provide an important evaluation of the effectiveness of this IBET program for knee OA. TRIAL REGISTRATION: NCT02312713.

Clinician Recommendations and Perceptions of Factors Associated With Ankle Brace Use.

BACKGROUND: Little information is available regarding the ankle braces orthopaedic sports medicine clinicians recommend or clinicians' concerns that may influence their decisions to recommend use of an ankle brace. HYPOTHESES: (1) Clinicians most frequently recommend lace-up braces with straps. (2) Clinicians who are concerned about potential adverse side effects from ankle brace use are less likely to recommend an ankle brace to prevent ankle sprain injuries. STUDY DESIGN: Descriptive survey study. LEVEL OF EVIDENCE: Level 3. METHODS: Surveys were sent via e-mail to 1000 randomly selected members of the Orthopaedic Section of the American Physical Therapy Association (APTA) and 1000 randomly selected members of the National Athletic Trainers' Association (NATA). A total of 377 individuals responded to the survey. RESULTS: Lace-up braces, specifically lace-up braces with straps, were the most frequently recommended type of ankle brace. Regression analyses indicated that the only perceived adverse side effect significantly related to frequency of ankle brace recommendation was a potential negative influence on ankle strength. CONCLUSION: Based on our sample, clinicians recommend lace-up ankle braces with straps most frequently to prevent ankle sprain injuries. Clinicians who are concerned about weakness of ankle musculature may be less likely to recommend use of an ankle brace. CLINICAL RELEVANCE: Clinicians may effectively reduce the number of ankle sprain injuries by recommending an ankle brace use after an initial ankle sprain injury.

Lower Extremity Biomechanics and Self-Reported Foot-Strike Patterns Among Runners in Traditional and Minimalist Shoes.

CONTEXT: The injury incidence rate among runners is approximately 50%. Some individuals have advocated using an anterior-foot-strike pattern to reduce ground reaction forces and injury rates that they attribute to a rear-foot-strike pattern. The proportion of minimalist shoe wearers who adopt an anterior-foot-strike pattern remains unclear. OBJECTIVE: To evaluate the accuracy of self-reported foot-strike patterns, compare negative ankle- and knee-joint angular work among runners using different foot-strike patterns and wearing traditional or minimalist shoes, and describe average vertical-loading rates. DESIGN: Descriptive laboratory study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 60 healthy volunteers (37 men, 23 women; age = 34.9 ± 8.9 years, height = 1.74 ± 0.08 m, mass = 70.9 ± 13.4 kg) with more than 6 months of experience wearing traditional or minimalist shoes were instructed to classify their foot-strike patterns. INTERVENTION(S): Participants ran in their preferred shoes on an instrumented treadmill with 3-dimensional motion capture. MAIN OUTCOME MEASURE(S): Self-reported foot-strike patterns were compared with 2-dimensional video assessments. Runners were classified into 3 groups based on video assessment: traditional-shoe rear-foot strikers (TSR; n = 22), minimalist-shoe anterior-foot strikers (MSA; n = 21), and minimalist-shoe rear-foot strikers (MSR; n = 17). Ankle and knee negative angular work and average vertical-loading rates during stance phase were compared among groups. RESULTS: Only 41 (68.3%) runners reported foot-strike patterns that agreed with the video assessment (κ = 0.42, P < .001). The TSR runners demonstrated greater ankle-dorsiflexion and knee-extension negative work than MSA and MSR runners (P < .05). The MSA (P < .001) and MSR (P = .01) runners demonstrated greater ankle plantar-flexion negative work than TSR runners. The MSR runners demonstrated a greater average vertical-loading rate than MSA and TSR runners (P < .001). CONCLUSIONS: Runners often cannot report their foot-strike patterns accurately and may not automatically adopt an anterior-foot-strike pattern after transitioning to minimalist running shoes.

The effects of 2 landing techniques on knee kinematics, kinetics, and performance during stop-jump and side-cutting tasks.

BACKGROUND: Anterior cruciate ligament injuries (ACL) commonly occur during jump landing and cutting tasks. Attempts to land softly and land with greater knee flexion are associated with decreased ACL loading. However, their effects on performance are unclear. HYPOTHESIS: Attempts to land softly will decrease peak posterior ground-reaction force (PPGRF) and knee extension moment at PPGRF compared with a natural landing during stop-jump and side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact will increase knee flexion at PPGRF compared with a natural landing during both tasks. In addition, both landing techniques will increase stance time and lower extremity mechanical work as well as decrease jump height and movement speed compared with a natural landing during both tasks. STUDY DESIGN: Controlled laboratory study. METHODS: A total of 18 male and 18 female recreational athletes participated in the study. Three-dimensional kinematic and kinetic data were collected during stop-jump and side-cutting tasks under 3 conditions: natural landing, soft landing, and landing with greater knee flexion at initial ground contact. RESULTS: Attempts to land softly decreased PPGRF and knee extension moment at PPGRF compared with a natural landing during stop-jump tasks. Attempts to land softly decreased PPGRF compared with a natural landing during side-cutting tasks. Attempts to land with greater knee flexion at initial ground contact increased knee flexion angle at PPGRF compared with a natural landing during both stop-jump and side-cutting tasks. Attempts to land softly and land with greater knee flexion at initial ground contact increased stance time and lower extremity mechanical work, as well as decreased jump height and movement speed during both stop-jump and side-cutting tasks. CONCLUSION: Although landing softly and landing with greater knee flexion at initial ground contact may reduce ACL loading during stop-jump and side-cutting tasks, the performance of these tasks decreased, as indicated by increased stance time and mechanical work as well as decreased jump height and movement speed. CLINICAL RELEVANCE: Training effects tested in laboratory environments with the focus on reducing ACL loading may be reduced in actual competition environments when the focus is on athlete performance. The effects of training programs for ACL injury prevention on lower extremity biomechanics in athletic tasks may need to be evaluated in laboratories as well as in actual competitions.

Ergonomics-related risk identification and pain analysis for farmers involved in rice field preparation.

BACKGROUND: A previous ergonomic screening of rice field preparation revealed farmer exposure to high risks of musculoskeletal disorders at the shoulders, hands, wrists and back. The screening method was not applied to muddy soil farming in which analysts could not observe farmer legs and feet. This study analyzed farmer pain in all stages of field preparation. OBJECTIVE: To examine the relationship of farmer experience and demographics to perceptions of pain and to identify body areas exposed to ergonomics risks, unknown to farmers. Results were expected to support interventions and guidelines for famers on physical behaviors towards minimizing risk of injury as well as validation of the screening approach. METHODS: Comparison of analyst screening results and farmer pain ratings using self-ratings and interviews. RESULTS: Farmer experience and age were significantly correlated with occurrence of pain and cramping. Less experienced farmers reported less pain in high-risk body parts (e.g., neck and lower back). More experienced farmers reported more pain in the legs, as compared with analyst risk ratings. CONCLUSIONS: Results demonstrated less experienced farmers to be unaware of critical areas of exposure to ergonomics risks. Correlation of farmer ratings of pain with analyst risk assessments support validity of the screening method for hazard identification and control.

A comparison of negative joint work and vertical ground reaction force loading rates in Chi runners and rearfoot-striking runners.

STUDY DESIGN: Observational. OBJECTIVES: To compare lower extremity negative joint work and vertical ground reaction force loading rates in rearfoot-striking (RS) and Chi runners. BACKGROUND: Alternative running styles such as Chi running have become a popular alternative to RS running. Proponents assert that this running style reduces knee joint loading and ground reaction force loading rates. METHODS: Twenty-two RS and 12 Chi runners ran for 5 minutes at a self-selected speed on an instrumented treadmill. A 3-D motion analysis system was used to obtain kinematic data. Average vertical ground reaction force loading rate and negative work of the ankle dorsiflexors, ankle plantar flexors, and knee extensors were computed during the stance phase. Groups were compared using a 1-way analysis of covariance for each variable, with running speed and age as covariates. RESULTS: On average, RS runners demonstrated greater knee extensor negative work (RS, -0.332 J/body height × body weight [BH·BW]; Chi, -0.144 J/BH·BW; P<.001), whereas Chi runners demonstrated more ankle plantar flexor negative work (Chi, -0.467 J/BH·BW; RS, -0.315 J/BH·BW; P<.001). RS runners demonstrated greater average vertical ground reaction force loading rates than Chi runners (RS, 68.6 BW/s; Chi, 43.1 BW/s; P<.001). CONCLUSION: Chi running may reduce vertical loading rates and knee extensor work, but may increase work of the ankle plantar flexors.

Relationships among self-reported shoe type, footstrike pattern, and injury incidence.

CONTEXT: Some runners are experimenting with barefoot or minimalist shoe running to reduce lower extremity overuse injuries. However, there has been little research to examine injury trends associated with barefoot or minimalist shoe running. OBJECTIVE: To assess the association of self-reported shoe selection with reported foot strike patterns, compare overall injury incidence associated with different shoe conditions, and identify differences in injury location between different shoe conditions. DESIGN: Retrospective descriptive epidemiology survey. METHODS: We recruited 2,509 runners (1,254 male, 1,255 female) aged 18 to 50 to complete an anonymous online survey. The survey assessed running tendencies, footstrike patterns, shoe preferences, and injury history. Reported footstrike patterns were compared among 3 shoe groups: traditionally shod, minimalist shoes, and barefoot runners. Overall and specific anatomical injury incidence was compared between traditionally shod and minimalist shoe-wearing runners. We did not include 1,605 runners in the analyses due to incomplete data or recent changes in footstrike patterns and/or shoe selection. RESULTS: Shoe selection was significantly associated with reported footstrike (χ² (4df) =143.4, P<.001). Barefoot and minimalist runners reported a more anterior footstrike than traditionally shod runners. Traditionally shod runners were 3.41 times more likely to report injuries than experienced minimalist shoe wearers (46.7% shod vs 13.7% minimalist, χ² (1df) =77.4, P<.001, n=888). Minimalist shoe wearers also reported fewer injuries at the hip, knee, lower leg, ankle, and foot than traditionally shod runners. CONCLUSION: Barefoot and minimalist shoe wearers reported a more anterior footstrike than traditionally shod runners. Traditionally shod runners were more likely to report injuries of the lower extremities than runners who wear minimalist shoes. Additional longitudinal prospective research is required to examine injury incidence among various footstrike patterns and shoe preferences.

A review of mechanics and injury trends among various running styles.

CONTEXT: Running related overuse injuries are a significant problem with half of all runners sustaining an injury annually. Many medical providers and coaches question how to advise their running clients to prevent injuries. Alternative running styles with a more anterior footstrike such as barefoot running, POSE running, and Chi running are becoming more popular. Little information, however, has been published comparing the mechanics and injury trends of different running styles. OBJECTIVE: The original purpose of this paper was to examine evidence concerning the biomechanics and injury trends of different running styles. Little to no injury data separated by running style existed. Therefore, we discuss the biomechanics of different running styles and present biomechanical findings associated with different running injuries. DATA SOURCES: English language articles published in peer reviewed journals were identified by searching PubMed, CINAHL, and SPORTDiscus databases. Nearly all of the studies identified by the search were observational studies. RESULTS: A more anterior initial foot contact present in barefoot or other alternative running styles may decrease or eliminate the initial vertical ground reaction peak or "impact transient," possibly reducing knee joint loads and injuries. A more anterior foot strike, however, may increase mechanical work at the ankle and tensile stress within the plantarflexors. Wearing minimal footwear may also increase contact pressure imposed on the metatarsals. CONCLUSION: More research is needed to determine which individuals with certain morphological or mechanical gait characteristics may benefit from alternative running styles that incorporate a more anterior initial foot contact with or without shoes.

Effects of foot orthoses on balance in older adults.

STUDY DESIGN: Controlled laboratory study using a single-cohort design. OBJECTIVES: To determine if balance in older adults could be significantly improved with foot-orthotic intervention. BACKGROUND: Poor balance has been associated with risk for falls. Limited evidence exists indicating that foot orthoses influence balance. METHODS: Thirteen individuals older than 65 years, who reported at least 1 unexplained fall during the past year and demonstrated poor balance, participated in the study. Subjects were tested for 1-leg stance, tandem stance, tandem gait, and alternating step tests during the first (SCREEN) and second (PRE) sessions prior to foot-orthotic intervention. Tests were repeated during the second testing session immediately after custom foot-orthotic intervention (POST) and 2 weeks following foot-orthotic use (FU). SCREEN and PRE measures were compared for stability using absolute difference computations and the Friedman rank test. PRE, POST, and FU data were analyzed using the Friedman rank test (α = .05), with Bonferroni correction for multiple post hoc comparisons. RESULTS: Each balance measure was statistically equivalent between the SCREEN and PRE measurements. One-leg stance times for PRE were significantly less than POST (P = .002) and FU (P = .013) measurements. Tandem stance times for PRE were significantly less than POST (P = .013) and FU (P = .013) measurements. Steps taken for the tandem gait test during the PRE measurements were significantly fewer than steps taken for the FU test (P = .007). Steps taken during the alternating step test for the PRE test were significantly fewer than steps taken during the POST (P = .002) and FU (P =.001) tests. POST and FU measurements were not significantly different for any of the 4 outcome measures. CONCLUSIONS: The results provide preliminary evidence that foot orthoses can effect improvement in balance measures for older adults.

Effects of a knee extension constraint brace on lower extremity movements after ACL reconstruction.

BACKGROUND: Patients have high reinjury rates after ACL reconstruction. Small knee flexion angles and large peak posterior ground reaction forces in landing tasks increase ACL loading. QUESTIONS/PURPOSES: We determined the effects of a knee extension constraint brace on knee flexion angle, peak posterior ground reaction force, and movement speed in functional activities of patients after ACL reconstruction. PATIENTS AND METHODS: Six male and six female patients 3.5 to 6.5 months after ACL reconstruction participated in the study. Three-dimensional videographic and force plate data were collected while patients performed level walking, jogging, and stair descent wearing a knee extension constraint brace, wearing a nonconstraint brace, and not wearing a knee brace. Knee flexion angle at initial foot contact with the ground, peak posterior ground reaction force, and movement speed were compared across brace conditions and between genders. RESULTS: Wearing the knee extension constraint brace increased the knee flexion angle at initial foot contact for each activity when compared with the other two brace conditions. Wearing the knee extension constraint brace also decreased peak posterior ground reaction force during walking but not during jogging and stair descent. CONCLUSIONS: Although the knee extension constraint brace did not consistently reduce the peak posterior ground reaction force in all functional activities, it consistently increased knee flexion angle and should reduce ACL loading as suggested by previous studies. These results suggest the knee extension constraint brace has potential as a rehabilitation tool to alter lower extremity movement patterns of patients after ACL reconstruction to address high reinjury rates.

Comparison of gluteus medius muscle electromyographic activity during forward and lateral step-up exercises in older adults.

BACKGROUND: Step-up exercises often are suggested for strengthening the hip abductor muscles and improving balance in older adults. Little is known, however, about whether the forward or lateral version of these exercises is best for activating the hip abductor muscles. OBJECTIVE: The purpose of this study was to examine the electromyographic (EMG) amplitude of the gluteus medius (GM) muscles bilaterally during forward and lateral step-up exercises. DESIGN: The study design involved single-occasion repeated measures. METHODS: Twenty-seven community-dwelling adults (7 men and 20 women) with a mean (SD) age of 79.4 (8.0) years performed forward and lateral step-up exercises while the surface EMG activity of the GM muscles was recorded bilaterally. Pressure switches and dual forceplates were used to identify the ascent and descent phases. Subjects were instructed to lead with the right lower extremity during ascent and the left lower extremity during descent. Differences in normalized root-mean-square EMG amplitudes with exercise direction (forward versus lateral) and phase (ascent versus descent) were examined by use of separate repeated-measures analyses of variance for the right and left lower extremities. The alpha level was set at .05. RESULTS: Gluteus medius muscle EMG activity was significantly greater for lateral than for forward step-up exercises for the left lower extremity during the ascent phase and for both lower extremities during the descent phase. In addition, right GM muscle EMG activity was significantly greater during ascent than during descent for both exercise directions. LIMITATIONS: Study limitations include use of a convenience sample and collection of limited information about participants. CONCLUSIONS: Step-up exercises are effective in activating the GM muscle, with lateral step-up exercises requiring greater GM muscle activation than forward step-up exercises. Further study is needed to determine whether exercise programs for hip abductor muscle strengthening in older adults should preferentially include lateral over forward step-up exercises.

Balance measures for discriminating between functionally unstable and stable ankles.

PURPOSE: To identify force plate measures that discriminate between ankles with functional instability and stable ankles and to determine the most accurate force plate measure for enabling this distinction. METHODS: Twenty-two subjects (177 +/- 10 cm, 77 +/- 16 kg, 21 +/- 2 yr) without a history of ankle injury and 22 subjects (177 +/- 10 cm, 77 +/- 16 kg, 20 +/- 2 yr) with functional ankle instability (FAI) performed a single-leg static balance test and a single-leg jump-landing dynamic balance test. Static force plate measures analyzed in both anterior/posterior (A/P) and medial/lateral (M/L) directions included the following: ground reaction force (GRF) SD; center-of-pressure (COP) SD; mean, maximum, and total COP excursion; and mean and maximum COP velocity. COP area was also analyzed for static balance. A/P and M/L time to stabilization quantified dynamic balance. Greater values of force plate measures indicated impaired balance. A stepwise discriminant function analysis examined group differences, group classification, and accuracy of force plate measures for discriminating between ankle groups. RESULTS: The FAI group had greater values than the stable ankle group for A/P GRF SD (P = 0.027), M/L GRF SD (P = 0.006), M/L COP SD (P = 0.046), A/P mean COP velocity (P = 0.015), M/L mean COP velocity (P = 0.016), A/P maximum COP velocity (P = 0.037), M/L mean COP excursion (P = 0.014), M/L total COP excursion (P = 0.016), A/P time to stabilization (P = 0.011), and M/L time to stabilization (P = 0.040). M/L GRF SD and A/P time to stabilization had the greatest accuracy scores of 0.73 and 0.72, respectively. CONCLUSION: Although 10 measures identified group differences, M/L GRF SD and A/P time to stabilization were the most accurate in discriminating between ankle groups. These results provide evidence for choosing these GRF measures for evaluating static and dynamic balance deficits associated with FAI.