Motor coordination during gait after anterior cruciate ligament injury: a systematic review of the literature

AbstractTo investigate the state of art about motor coordination during gait in patients with anterior cruciate ligament (ACL) injury. Searches were carried out, limited from 1980 to 2010, in various databases with keywords related to motor coordination, gait and ACL injury. From the analysis of titles and applying the inclusion/exclusion criteria 24 studies were initially selected and, after reading the abstract, eight studies remained in the final analysis. ACL deficient patients tend to have a more rigid and less variable gait, while injured patients with ACL reconstruction have less rigid and more variable gait with respect to healthy individuals. The overall results suggest the existence of differences in motor coordination between the segments with intact and those with injured knee, regardless of ligament reconstruction. ACL injured patients present aspects related to the impairment of the capability to adapt the gait pattern to different environmental conditions, possibly leading to premature knee degeneration. However, the techniques used for biomechanical gait data processing are limited with respect to obtaining information that leads to the development of intervention strategies aimed at the rehabilitation of that injury, since it is not possible to identify the location within the gait cycle where the differences could be explained

APPLICATION OF PRINCIPAL COMPONENT ANALYSIS IN THE STUDY OF TASKS WITH DIFFERENT MECHANICAL CONSTRAINTS

This study aims to compare the lower limb kinematics between two landing tasks, using the Principal Component Analysis (PCA) and parametric techniques. Ten male volleyball athletes performed bilateral vertical jumps with single leg or double leg landings. Hip, knee and ankle kinematics were used in the analysis. Statistical analysis was performed in the principal components coefficients (PCC) retained in the PCA and in the parametric variables. Only the first PCC presented differences in the three joints. The minimum peak showed differences in the ankle and knee, the maximum peak was different in the knee and hip and the mean angular displacement showed differences in the three joints. PCA described the differences presented by the parametric variables allowing the identification of the location where the variance between the landing tasks could be better explained

Accuracy of the WHO’s body mass index cut-off points to measure gender- and age-specific obesity in middle-aged adults living in the city of Rio de Janeiro, Brazil

Introduction. Obesity is defined by the World Health Organization (WHO) as a disease characterized by the excessive accumulation of body fat. Obesity is considered a public health problem, leading to serious social, psychological and physical problems. However, the appropriate cut-off point of body mass index (BMI) based on body fat percentage (BF%) for classifying an individual as obese in middle-aged adults living in Rio de Janeiro remains unclear. Materials and methods. This was a prospective cross-sectional study comprising of 856 adults (413 men and 443 women) living in Rio de Janeiro, Brazil ranging from 30-59 years of age. The data were collected over a two year period (2010-2011), and all participants were underwent anthropometric evaluation. The gold standard was the percentage of body fat estimated by bioelectrical impedance analysis. The optimal sensitivity and specificity were attained by adjusting BMI cut-off values to predict obesity based on the WHO criteria: BF% >25% in men and >35% in women, according to the receiver operating characteristic curve (ROC) analysis adjusted for age and for the whole group.Results. The BMI cut-offs for predicting BF% were 29.9 kg/m2 in men and 24.9 kg/m2 in women. Conclusions. The BMI that corresponded to a BF% previously defining obesity was similar to that of other Western populations for men but not for women. Furthermore, gender and age specific cut-off values are recommended in this population

RELIABILITY OF KINEMATIC MEASUREMENTS DURING TREADMILL RUNNING

This study aimed at determining the within- and between-day reliability of kinematic data during treadmill running. Seventeen young adult male recreational runners were evaluated in a treadmill running test. Nine reflective markers were placed on the right leg and kinematic data were collected twice on the first day (within-day reliability) and once on the second day (between-day).The peak values of the knee flexion, dorsiflexion, plantiflexion and eversion during stance and knee flexion during swing were evaluated. Higher reliability was observed in within-day (ICC > 0.94, lower CV, typical error and limits of agreement) compared to between-day. The eversion presented the lowest ICC (0.79) in between-day and heteroscedastic error in the within-day measurements. The results indicated that evaluated kinematic data were reliable during running in treadmill

ELECTROMYOGRAPHY OF TRUNK MUSCLES IN TIME-FREQUENCY DOMAIN DURING CORE STABILITY EXERCISES

The aim of this work was to compare the electromyogram (EMG) of trunk muscles, in the time-frequency domain, among core exercises. The EMG of 17 men was recorded by electrodes placed on external oblique (EO), rectus abdominis (RA), lumbar erector spinae (LES) and multifidus (MT) muscles. Short-time Fourier transform was performed and instantaneous median frequency (MedFreq) was calculated and averaged. MedFreq of the EO and RA were significantly higher (p < 0.0001) during double leg back bridge exercise. Contrarily, LES and MT showed significant higher (p < 0.0001) MedFreq during frontal and left side bridge. Antagonist muscles showed greater MedFreq than agonist muscles. This may be explained by the low-pass filtering effect of the adipose tissue, which could attenuate the increase of high frequencies EMG energy of agonist muscles

Teste de força de preensão manual: estudo da fadiga mioelétrica do flexor radial do carpo e flexor superficial dos dedos

Um protocolo de força de preensão manual (FPM) em degraus de intensidade foi empregado para estudo da fadiga dos músculos flexor radial do carpo (FRC) e flexor superficial dos dedos (FSD) por meio do registro da força de preensão sustentada. Foi feita a análise do sinal eletromiográfico de superfície destes músculos no domínio do tempo e da frequência de 2kHz. Foi utilizado um dinamômetro eletrônico e um conversor analógico-digital de 16 bits. Participaram deste estudo 12 indivíduos saudáveis, ativos e destros, com média de idade 21,53 ± 1,26 anos, percentual de gordura 7,76 ± 3,53%, peso corporal 74,9 ± 10,36 kg e estatura 180,69 ± 7,14 cm. Os indivíduos realizaram o teste de contração isométrica voluntária máxima (CIVM) da mão dominante seguido do protocolo de degraus submáximos em 20%, 40% e 60% da CIVM por 10 segundos cada. O processamento dos sinais envolveu a filtragem passa banda e o cálculo dos valores de raiz média quadrática (RMS) e frequência mediana (FM) em cada degrau de contração submáxima. A análise de variância "two-way" foi aplicada para os valores de RMS e FM. O teste proposto não gerou queda do rendimento de força nos degraus submáximos estabelecidos e a instauração do processo de fadiga do FSD. Por outro lado, o FRC apresentou sinais de fadiga mioelétrica sugerindo o processo de falência da FPM. Estes dados sugerem que a fadiga mioelétrica dos flexores dos dedos durante a FPM é um processo tardio à fadiga dos estabilizadores do punho. O protocolo em degrau de 60% parece desencadear o processo de fadiga mioelétrica do músculo FRC, mas não do FSD, baseado na análise da ativação muscular nos domínios do tempo e frequência.A test protocol of handgrip strength in steps was used in order to study the fatigue of the flexor carpi radialis (FRC) and the flexor digitorum superficialis (FSD) muscles with signal processing in the time and frequency domains. It was used an electronic hand grip dynamometer, and a 16-bits analog-digital converter. The sampling frequency was 2 kHz. The study included 12 healthy subjects, active and right-handed, mean age 21.53 ± 1.26 years, body fat percentage 7.76 ± 3.53%, weight 74.9 ± 10.36 kg and height 180. 69 ± 7.14 cm. The subjects performed the test of maximal voluntary contraction (CIVM) of the dominant hand and then, submaximal protocol of ten seconds steps of 20%, 40% and 60% of CIVM. The proposed test didn't generate a drop on strength performance on the established submaximal steps, as well as the fatigue process establishment of FSD. On the other hand, the FRC showed myoelectric fatigue signs, suggesting stabilizing wrist collapse. These data suggest that myoelectric fatigue of the finger flexors during handgrip is a late process compared to wrist stabilizing fatigue. The protocol in 60% step seems to trigger the myoelectric fatigue muscle process of the FRC but not the FSD, based on analysis of muscle activation in time and frequency domains