Effects of Foot-Core Training on Foot-Ankle Kinematics and Running Kinetics in Runners: Secondary Outcomes From a Randomized Controlled Trial.

This study investigated the effectiveness of an 8-week foot-core exercise training program on foot-ankle kinematics during running and also on running kinetics (impact loads), with particular interest in biomechanical outcomes considered risk factors for running-related injuries in recreational runners. A single-blind, randomized, controlled trial was conducted with 87 recreational runners randomly allocated to either the control (CG) or intervention (IG) group and assessed at baseline and after 8 weeks. The IG underwent foot-core training 3 times/week, while the CG followed a placebo lower-limb stretching protocol. The participants ran on a force-instrumented treadmill at a self-selected speed while foot-segment motion was captured simultaneously with kinetic measurements. After the intervention, there were statistically significant changed in foot biomechanics, such as: IG participants strike the ground with a more inverted calcaneus and a less dorsiflexed midfoot than those in the CG; at midstance, ran with a less plantarflexed and more adducted forefoot and a more abducted hallux; and at push-off, ran with a less dorsiflexed midfoot and a less adducted and more dorsiflexed hallux. The IG runners also had significantly decreased medial longitudinal arch excursion (p = 0.024) and increased rearfoot inversion (p = 0.037). The 8-week foot-core exercise program had no effect on impact (p = 0.129) and breaking forces (p = 0.934) or on vertical loading rate (p = 0.537), but it was positively effective in changing foot-ankle kinematic patterns."

Predictive Effect of Well-Known Risk Factors and Foot-Core Training in Lower Limb Running-Related Injuries in Recreational Runners: A Secondary Analysis of a Randomized Controlled Trial.

BACKGROUND: Running carries the risk of several types of running-related injuries (RRIs), especially in the lower limbs. The variety of risk factors and the lack of strong evidence for several of these injury risks hinder the ability to draw assertive conclusions about them, hampering the implementation of effective preventive strategies. Because the etiology of RRIs seems to be multifactorial, the presence of RRI risk factors might influence the outcome of therapeutic strategies in different ways. Thus, further investigations on how risk and protective factors influence the incidence and prevention of RRIs should be conducted. PURPOSE: To investigate the predictive effect of well-known risk factors and 1 protective factor-foot-core training-on the incidence of lower limb RRIs in recreational runners. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Middle- and long-distance recreational runners (N = 118) were assessed at baseline and randomly allocated to either an intervention group (n = 57) or a control group (n = 61). The intervention group underwent an 8-week (3 times/wk) foot-core training program. Participants were followed for a year after baseline assessment for the occurrence of RRIs. Logistic regression with backward elimination of variables was used to develop a model for prediction of RRI in recreational runners. Candidate predictor variables included age, sex, body mass index, years of running practice, number of races, training volume, training frequency, previous RRI, and the foot-core exercise training. RESULTS: The final logistic regression model included 3 variables. As previously shown, the foot-core exercise program is a protective factor for RRIs (odds ratio, 0.40; 95% CI, 0.15-0.98). In addition, older age (odds ratio, 1.07; 95% CI, 1.00-1.14) and higher training volume (odds ratio, 1.02; 95% CI, 1.00-1.03) were risk factors for RRIs. CONCLUSION: The foot-core training was identified as a protective effect against lower limb RRI, which can be negatively influenced by older age and higher weekly training volume. The predictive model showed that RRIs should be considered a multivariate entity owing to the interaction among several factors. REGISTRATION: NCT02306148 (ClinicalTrials.gov identifier).

Accuracy and correlation between skin-marker based and radiographic measurements of medial longitudinal arch deformation.

Static and dynamic measurements of the medial longitudinal arch (MLA) in the foot are critical across different clinical and biomechanical research fields. While MLA deformation can be estimated using skin-markers for gait analysis, the current understanding of the correlates between skin-marker based models and radiographic measures of the MLA is limited. This study aimed at assessing the correlation and accuracy of skin-marker based measures of MLA deformation with respect to standard clinical X-ray based measures, used as reference. 20 asymptomatic subjects without morphological alterations of the foot volunteered in the study. A lateral X-ray of the right foot of each subject was taken in monopodalic upright posture with and without a metatarsophalangeal-joint dorsiflexing wedge. MLA angle was estimated in the two foot postures and during gait using 16 skin-marker based models, which were established according to the marker set of a validated multi-segment foot kinematic protocol. The error of each model in tracking MLA deformation was assessed and correlated with respect to standard radiographic measurements. Estimation of MLA deformation was highly affected by the skin-marker models. Skin-marker models using the marker on the navicular tuberosity as apex of the MLA angle showed the smallest errors (about 2 deg) and the largest correlations (R = 0.64-0.65; p < 0.05) with respect to the radiographic measurements. According to the outcome of this study, skin-marker based definitions of the MLA angle using the navicular tuberosity as apex of the arch may provide a more accurate estimation of MLA deformation with respect to that from radiographic measures.

Subgroups of Foot-Ankle Movement Patterns Can Influence the Responsiveness to a Foot-Core Exercise Program: A Hierarchical Cluster Analysis.

The purpose of this study is to identify homogenous subgroups of foot-ankle (FA) kinematic patterns among recreational runners and further investigate whether differences in baseline movement patterns can influence the mechanical responses to a foot-core exercise intervention program. This is a secondary analysis of data from 85 participants of a randomized controlled trial (clinicaltrials.gov - NCT02306148) investigating the effects of an exercise-based therapeutic approach focused on FA complex. A validated skin marker-based multi-segment foot model was used to acquire kinematic data during the stance phase of treadmill running. Kinematic features were extracted from the time-series data using a principal component analysis, and the reduced data served as input for a hierarchical cluster analysis to identify subgroups of FA movement patterns. FA angle time series were compared between identified clusters and the mechanical effects of the foot-core exercise intervention was assessed for each subgroup. Two clusters of FA running patterns were identified, with cluster 1 (n = 36) presenting a pattern of forefoot abduction, while cluster 2 (n = 49) displayed deviations in the proximal segments, with a rearfoot adduction and midfoot abduction throughout the stance phase of running. Data from 29 runners who completed the intervention protocol were analyzed after 8-weeks of foot-core exercises, resulting in changes mainly in cluster 1 (n = 16) in the transverse plane, in which we observed a reduction in the forefoot abduction, an increase in the rearfoot adduction and an approximation of their pattern to the runners in cluster 2 (n = 13). The findings of this study may help guide individual-centered treatment strategies, taking into account their initial mechanical patterns.

Foot Core Training to Prevent Running-Related Injuries: A Survival Analysis of a Single-Blind, Randomized Controlled Trial.

BACKGROUND: Running-related injuries (RRIs) are a pervasive menace that can interrupt or end the participation of recreational runners in this healthy physical activity. To date, no satisfactory treatment has been developed to prevent RRIs. PURPOSE: To investigate the efficacy of a novel foot core strengthening protocol based on a ground-up approach to reduce the incidence of RRIs in recreational long-distance runners over the course of a 1-year follow-up. STUDY DESIGN: Randomized controlled trial; Level of evidence, 1. METHODS: The participants, 118 runners, were assessed at baseline and randomly allocated to either an intervention group (n = 57) or a control group (n = 61). The intervention group received an 8-week training course focused on the foot-ankle muscles, followed by remotely supervised training thereafter. Assessments consisted of 3 separate biomechanical evaluations of foot strength and foot posture and a weekly report on each participant's running distance, pace, and injury incidence over 12 months. RESULTS: The control group participants were 2.42 times (95% CI, 1.98-3.62) more likely to experience an RRI within the 12-month study period than participants in the intervention group (P = .035). Time to injury was significantly correlated with Foot Posture Index (P = .031; r = 0.41) and foot strength gain (P = .044; r = 0.45) scores. This foot exercise program showed evidence of effective RRI risk reduction in recreational runners at 4 to 8 months of training. CONCLUSION: Recreational runners randomized to the new foot core strengthening protocol had a 2.42-fold lower rate of RRIs compared with the control group. Further studies are recommended to better understand the underlying biomechanical mechanisms of injury, types of injuries, and subgroups of runners who might benefit maximally. REGISTRATION: NCT02306148 (ClinicalTrials.gov identifier).

Repeatability of skin-markers based kinematic measures from a multi-segment foot model in walking and running.

Skin-markers based multi-segment models are growing in popularity to assess foot joint kinematics in different motor tasks. However, scarce is the current knowledge of the effect of high-energy motor tasks, such as running, on the repeatability of these measurements. This study aimed at assessing and comparing the inter-trial, inter-session, and inter-examiner repeatability of skin-markers based foot kinematic measures in walking and running in healthy adults. The repeatability of 24 kinematic measures from an established multi-segment foot model were assessed in two volunteers during multiple barefoot walking and running trials by four examiners in three sessions. Statistical Parametric Mapping (1D-SPM) analysis was performed to assess the degree of shape-similarity between patterns of kinematic measurements. The average inter-trial variability across measurements (deg) was 1.0 ± 0.3 and 0.8 ± 0.3, the inter-session was 3.9 ± 1.4 and 4.4 ± 1.5, and the inter-examiner was 5.4 ± 2.3 and 5.7 ± 2.2, respectively in walking and running. Inter-session variability was generally similar between the two motor tasks, but significantly larger in running for two kinematic measures (p < 0.01). Inter-examiner variability was generally larger than inter-trial and inter-session variability. While no significant differences in frame-by-frame offset variability was detected in foot kinematics between walking and running, 1D-SPM revealed that the shape of kinematic measurements was significantly affected by the motor task, with running being less repeatable than walking. Although confirmation on a larger population and with different kinematic protocols should be sought, attention should be paid in the interpretation of skin-markers based kinematics in running across sessions or involving multiple examiners.

Effects of a foot strengthening program on foot muscle morphology and running mechanics: A proof-of-concept, single-blind randomized controlled trial.

OBJECTIVES: To investigate the effects of a foot training program on muscle morphology and strength as well as running biomechanics in healthy recreational runners. DESIGN: Proof-of-concept, single-blind randomized controlled trial. SETTINGS: Runners were allocated to a control (CG) or an intervention (IG) group. The intervention focused on strengthening the intrinsic foot muscles and their activation during weight-bearing activities. All participants were assessed at baseline and after 8-weeks. PARTICIPANTS: Twenty-eight healthy recreational long-distance runners not habituated to minimalist running shoes or barefoot running. MAIN OUTCOMES MEASURES: Outcomes were hallux and toes strength; foot function, cross-sectional area and volume of the abductor hallucis (ABH), abductor digiti minimi (ABV), flexor digitorum brevis (FDB), and flexor hallucis brevis; medial longitudinal arch range of motion and stiffness; vertical and antero-posterior propulsive impulses during running. RESULTS: Compared to the CG, an increase was found in the IG for the volume of all muscles investigated and for vertical propulsive impulse during running. Correlations were found between vertical propulsive impulse and volume of ABH(r = 0.40), ABV(r = 0.41), and FDB(r = 0.69). CONCLUSION: The foot exercise protocol effectively increased intrinsic foot muscle volume and propulsive forces in recreational runners. This shows that intrinsic muscle strengthening affects running mechanics and suggests that it may improve running performance.

Reliability of medial-longitudinal-arch measures for skin-markers based kinematic analysis.

The medial-longitudinal arch (MLA) is perhaps the most important feature characterizing foot morphology. While current skin-markers based models of the MLA angle used in stereophotogrammetry allow to estimate foot arch shape and deformation, these do not always appear consistent with foot anatomy and with standard clinical definitions. The aim of this study was to propose novel skin-markers based measures of MLA angle and investigate their reliability during common motor tasks. Markers on the calcaneus, navicular tuberosity, first metatarsal head and base, and on the two malleoli were exploited to test eight definitions of MLA angle consistent with foot anatomy, both as angles between two 3-dimensional vectors and as corresponding projections on the sagittal plane of the foot. The inter-trial, inter-session and inter-examiner reliability of each definition was assessed in multiple walking and running trials of two volunteers, tested by four examiners in three sessions. Inter-trial variability in walking was in the range 0.7-1.2 deg, the inter-session 2.8-7.5 deg, and the inter-examiner in the range 3.7-9.3 deg across all MLA definitions. The Rizzoli Foot Model definition showed the lowest inter-session and inter-examiner variability. MLA measures presented similar variability in walking and running. This study provides preliminary information on the reliability of MLA measurements based on skin-markers. According to the present study, angles between 3-dimensional vectors and minimal marker sets should be preferred over sagittal-plane projections. Further studies should be sought to investigate which definition is more accurate with respect to the real MLA deformation in different loading conditions.

Effects of a therapeutic foot exercise program on injury incidence, foot functionality and biomechanics in long-distance runners: Feasibility study for a randomized controlled trial.

BACKGROUND: The goal was to examine the feasibility of a randomized controlled trial (RCT) on the effect of a therapeutic foot-ankle training program to prevent injury in long-distance runners. First, we evaluated (i) the access to participants and recruitment success; (ii) participants' satisfaction and adherence to the program; (iii) the effect of the training program to improve foot muscle strength and change foot biomechanics; and, second, we used the collected data for a post hoc sample size calculation. METHODS/DESIGN: We randomized 31 healthy long-distance recreational runners to either an 8-week foot-ankle muscle strength-training program (intervention) or a stretching protocol (control). The recruitment rate was the number of eligible participants per week of recruitment; recruitment success, the ratio between scheduled baseline visits and initially eligible participants. Participant satisfaction was assessed by a questionnaire, and adherence to the training program was recorded in a Web-based software, both at the 8-week mark. Program effect was assessed by hallux and toe muscle strength using a pressure platform, foot muscle cross-sectional area using magnetic resonance imaging and foot kinematics during running using 3D gait analysis; assessments were done at baseline and after 8 and 16 weeks. A post hoc power analysis was performed on foot strength and the biomechanical data was collected. RESULTS: In two weeks of recruitment, 112 initially eligible subjects were screened, 81 of whom were deemed eligible and 31 had a baseline study visit, giving a recruitment rate of 40.5 subjects/week and recruitment success of 28%. Participants' adherence was 97%, and satisfaction scored a median >3 out of 5 on a Likert scale on all questions. The cross-sectional area of the abductor hallucis (P = 0.040) and flexor digitorum brevis (P = 0.045) increased significantly at 8 weeks in the intervention group. The post hoc sample sizes for almost all the strength and biomechanical parameters were below those of the 112 subjects calculated as the original sample size for clinical outcome (running-related injury). CONCLUSION: Results show that this RCT is feasible, given an accessible study population that is willing to participate and that perceives the training program as positive and adheres to the program. The training program leads to several positive outcomes on muscle strength that justifies assessing clinical outcomes in this RCT.

Protocol for evaluating the effects of a therapeutic foot exercise program on injury incidence, foot functionality and biomechanics in long-distance runners: a randomized controlled trial.

BACKGROUND: Overall performance, particularly in a very popular sports activity such as running, is typically influenced by the status of the musculoskeletal system and the level of training and conditioning of the biological structures. Any change in the musculoskeletal system's biomechanics, especially in the feet and ankles, will strongly influence the biomechanics of runners, possibly predisposing them to injuries. A thorough understanding of the effects of a therapeutic approach focused on feet biomechanics, on strength and functionality of lower limb muscles will contribute to the adoption of more effective therapeutic and preventive strategies for runners. METHODS/DESIGN: A randomized, prospective controlled and parallel trial with blind assessment is designed to study the effects of a "ground-up" therapeutic approach focused on the foot-ankle complex as it relates to the incidence of running-related injuries in the lower limbs. One hundred and eleven (111) healthy long-distance runners will be randomly assigned to either a control (CG) or intervention (IG) group. IG runners will participate in a therapeutic exercise protocol for the foot-ankle for 8 weeks, with 1 directly supervised session and 3 remotely supervised sessions per week. After the 8-week period, IG runners will keep exercising for the remaining 10 months of the study, supervised only by web-enabled software three times a week. At baseline, 2 months, 4 months and 12 months, all runners will be assessed for running-related injuries (primary outcome), time for the occurrence of the first injury, foot health and functionality, muscle trophism, intrinsic foot muscle strength, dynamic foot arch strain and lower-limb biomechanics during walking and running (secondary outcomes). DISCUSSION: This is the first randomized clinical trial protocol to assess the effect of an exercise protocol that was designed specifically for the foot-and-ankle complex on running-related injuries to the lower limbs of long-distance runners. We intend to show that the proposed protocol is an innovative and effective approach to decreasing the incidence of injuries. We also expect a lengthening in the time of occurrence of the first injury, an improvement in foot function, an increase in foot muscle mass and strength and beneficial biomechanical changes while running and walking after a year of exercising. TRIAL REGISTRATION: Clinicaltrials.gov Identifier NCT02306148 (November 28, 2014) under the name "Effects of Foot Strengthening on the Prevalence of Injuries in Long Distance Runners". Committee of Ethics in Research of the School of Medicine of the University of Sao Paulo (18/03/2015, Protocol # 031/15).

Children with visual impairments may have altered joint movement: an observational case-control study / Niños con deficiencia visual pueden tener la amplitud de movimiento articular alterada: un estudio observacional tipo caso-control / Crianças com deficiência visual podem ter a amplitude de movimento articular alterada: um estudo observacional tipo caso-controle

To assess the articular range of motion in children with congenital visual impairment. Were evaluated 75 children between five and twelve years old, 49 with normal visual acuity and 26 visually impaired. Two evaluators performed the measure of active and passive range of motion by goniometry of shoulder and hip in all axes of motion. All examiners made a test of correlation between data obtained, to determine the inter-rater reliability, using the intraclass correlation coefficient (ICC). In individuals with visual impairments was statistically significant difference, with higher range of motion in individuals with visual impairments to medial and lateral rotation of shoulder and hip lateral rotation. Were found: high correlation in the inter-rater reliability (ICC>0.70) for 9 (22.5%) groups of articular range of motion, moderate correlation (0.7>ICC>0.5) for 25 (62.5%) groups and low correlation to 6 (15%) groups ranges of motion. Sampled children with congenital visual impairment showed greater joint mobility for rotational range of motion of the shoulder and hip than children with normal visual acuity, although they have also shown lower values for articular range of motion in abduction and extension in shoulders.

Se evaluó la amplitud de movimiento articular en niños con deficiencias visuales congénitas. Se evaluaron a 75 niños con edades entre 5 y 12 años, siendo 49 con acuidad visual normal y 26 con deficiencia visual. Dos evaluadores realizaron la medición de la amplitud de movimiento articular activa y pasiva mediante goniometría del hombro y de la cadera, en todos los ejes de movimiento. Todos los evaluadores realizaron un test de correlación entre los datos obtenidos para la determinación de la fiabilidad interevaluador, por medio del coeficiente de correlación intraclase (ICC). En los individuos con deficiencia visual hubo diferencia estadísticamente significativa, con mayores valores de amplitud de movimiento para la rotación medial y lateral del hombro y rotación lateral de la cadera. Fueron encontradas: alta correlación de fiabilidad interevaluadores (ICC>0,70) para 9 (22,5%) grupos de amplitud de movimiento articular, correlación moderada (0,7>ICC>0,5) para 25 (62,5%) grupos y baja correlación para 6 (15%) grupos de amplitudes de movimiento. Los niños incluidos en la muestra con deficiencia visual congénita presentaron mayor movilidad articular para las amplitudes de movimiento de rotación del hombro y de la cadera que los niños sin deficiencias visuales, aunque también presentaron valores más bajos para la amplitud de movimiento articular de abducción y extensión de hombros.

Avaliou-se a amplitude de movimento articular em crianças com deficiências visuais congênitas. Foram avaliadas 75 crianças entre 5 e 12 anos de idade, sendo 49 com acuidade visual normal e 26 portadoras de deficiência visual. Dois avaliadores realizaram a medida da amplitude de movimento articular ativa e passiva, pela goniometria do ombro e quadril, em todos os eixos de movimento. Todos os avaliadores realizaram um teste de correlação entre os dados obtidos, para determinação da confiabilidade interavaliador, por meio do coeficiente de correlação intraclasse (ICC). Nos indivíduos com deficiência visual houve diferença estatisticamente significativa, com maiores valores de amplitude de movimento para rotação medial e lateral de ombro e rotação lateral de quadril. Foram encontradas: alta correlação na confiabilidade interexaminador (ICC>0,70) para 9 (22,5%) grupos de amplitude de movimento articular, correlação moderada (0,7>ICC>0,5) para 25 (62,5%) grupos e baixa correlação para 6 (15%) grupos de amplitudes de movimento. As crianças amostradas com deficiência visual congênita apresentaram maior mobilidade articular para as amplitudes de movimento rotacional do ombro e quadril que as crianças sem comprometimentos visuais, embora tenham apresentado também menores valores para amplitude de movimento articular de abdução e extensão de ombros.

Brazilian-Portuguese translation and cross cultural adaptation of the activities-specific balance confidence (ABC) scale.

BACKGROUND: The Activities-specific Balance Confidence (ABC) scale was developed to quantify the self-perceived level of confidence in performing specific activities without losing balance or becoming unsteady. The ABC scale has been adopted in clinical practice and in research, although cross-cultural differences may impose difficulties in its use. OBJECTIVE: To translate, cross-culturally adapt and verify the intra- and inter-rater reliability of the Brazilian-Portuguese version of the ABC scale and describe the self-perceived balance confidence of elderly Brazilian people. METHOD: The ABC scale was translated and culturally adapted. To verify the intra- and inter-rater reliability, 40 elderly individuals with ages ranging from 60 to 88 years were interviewed. The scale was administered by two raters on the same day and readministered after seven days by rater 1. To test the reliability, we used the intraclass correlation coefficient (ICC). RESULTS: Six items from the ABC scale were considered culturally, semantically or regionally inappropriate and were modified. The intra-rater reproducibility was excellent (ICC=0.94), and the inter-rater reproducibility was very good (ICC=0.80). The self-perception of balance in specific activities of the elderly was considered very good, with an average of 81.7 and scores ranging from 61.2 to 96.7. CONCLUSION: The ABC scale was translated and culturally adapted for the Brazilian population and presents good intra- and inter-rater reliability. The self-perceived balance confidence in elderly Brazilian people evaluated with the ABC scale is moderate.

Brazilian-Portuguese translation and cross cultural adaptation of the activities-specific balance confidence (ABC) scale

BACKGROUND: The Activities-specific Balance Confidence (ABC) scale was developed to quantify the self-perceived level of confidence in performing specific activities without losing balance or becoming unsteady. The ABC scale has been adopted in clinical practice and in research, although cross-cultural differences may impose difficulties in its use. OBJECTIVE: To translate, cross-culturally adapt and verify the intra- and inter-rater reliability of the Brazilian-Portuguese version of the ABC scale and describe the self-perceived balance confidence of elderly Brazilian people. METHOD: The ABC scale was translated and culturally adapted. To verify the intra- and inter-rater reliability, 40 elderly individuals with ages ranging from 60 to 88 years were interviewed. The scale was administered by two raters on the same day and readministered after seven days by rater 1. To test the reliability, we used the intraclass correlation coefficient (ICC). RESULTS: Six items from the ABC scale were considered culturally, semantically or regionally inappropriate and were modified. The intra-rater reproducibility was excellent (ICC=0.94), and the inter-rater reproducibility was very good (ICC=0.80). The self-perception of balance in specific activities of the elderly was considered very good, with an average of 81.7 and scores ranging from 61.2 to 96.7. CONCLUSION: The ABC scale was translated and culturally adapted for the Brazilian population and presents good intra- and inter-rater reliability. The self-perceived balance confidence in elderly Brazilian people evaluated with the ABC scale is moderate. .