DETERMINATION OF INERTIA ELEMENTS FOR THE LOWER LIMBS

INTRODUCTION: For kinematic and dynamic studies of the lower limbs, using a three dimensional model is useful. Such models allow one to determine segment movements and forces acting on joints. Inverse Dynamic Analysis can be used to calculate the biomechanical loads applied (Elftman,1939). The reliability of the results depends on the degree of accuracy of the kinematic and anthropometric data (Kingma et al.,1996).The purpose of this paper is to explain a simple way to determine inertia elements of the lower limbs using anthropometric data available in the literature. METHODS: Body mass and stature are the only anthropometric parameters known for a subject. Body segment inertia parameters are obtained from cadavers and we use here de Leva (1996) segmental data for males to perform our calculations. We consider each segment of the lower limb (foot, shank and thigh) as rigid and independent. The model supposes a knowledge of the relative mass and the spatial coordinates of at least three points for each segment. A mathematical method is developed in order to obtain data which take into account the individual characteristics of the subjects. For each segment we have to determine three successive elements:- the localization of the center of mass,- a coordinate system assigned, - an inertia matrix assigned. RESULTS: The main difficulty is to place the markers properly on subjects. A simple test, allowing distance determination between markers, was proposed previously to further calculations. The mathematical model is developed in such a way as to be easily used. Conclusions: These simple-to-use methods presuppose a reducing hypothesis. We assume that for each joint a geometrical center exists. This point lies on the longitudinal axis of the segments and has a fixed three dimensional position relative to the segments forming the joint. The localization of the ‘joint center’ is not referenced to the sagittal and transversal axis. We use data reported by de Leva (1996). This supposes that the lower limb is a standard limb, reducing accuracy for subjects with some pathological segment orientation or for young, old and female subjects. As the error introduced by using inappropriate segment parameters could be substantial, the choice of the biomechanical model, as well as the optimal measurement method, is absolutely necessary to obtain for example a good evaluation of the forces acting on the different joints

INFLUENCE OF REST PERIOD ON ELECTRICAL STIMULATION EFFICIENCY

INTRODUCTION: Electrical stimulation (ES) is now widely used as a modality of strengthening in healthy subjects and highly trained athletes. Most of the previous studies have reported that training by ES induces strength gains (Portmann, 1991; Fredon & Poumarat, 1995). Pulse parameters and stimulus regimens are well documented, especially for frequency of stimulation and electrode localization (Ferry & Poumarat, 1994; Ferry et al., 1994). There is a lack of information on training protocols. These should include periodic rest periods to minimize muscle fatigue and maintain an adequate level of contraction during the training session. The aim of this paper is to clarify the effect of rest periods on muscular performance

MECHANICAL STRESS ON KNEES DURING HALF-SQUAT EXERCISES

INTRODUCTION Articular forces and moments have been found to be affected by the lifting technique in ergonomics (Trafirnow et al., 1993) and in weight-training (Poumarat et al.,1989).While these researchers have improved our understanding of biomechanical aspects of lifting as related to the spine and the lower extremities, most of them remain related to either static orquasi-static conditions. The purpose of this study was to determine the mechanical stress on the knee joint using a 3-D dynamic model. MATERIALS AND METHODS Three male volunteer students participated in the study. They were asked to perform three different sets of 10 half-squat exercises: no load, 100% and 120% of total body mass of the subject additional weight. To determine kinematic data, the movement of the half-squat exercises was recorded using the Mac Reflex optoelectronic system (4 cameras) with markers on the left lower extremity at the fust metatarsal, the external rnalleolus, the external lateral femoral condyle and the greater trochanter. A six components force-plate (AMTI) provided kinetic data. Compressive and the shear forces acting on the thigh at the knee joint were calculated where; Fx represents the compressive force; Mx, the external rotatory moment of the thigh; Fy, the medio-lateral shear force; My, the extension moment of the thigh; Fz, the antero-posterior shear force; and Mz, the abductor moment of the thigh. The resultant knee force, in all subjects, increases when lifted load increases. A similar increase in the resultant moment at the knee joint was found. These pic values were calculated for a knee angle of 108. The medio-lateral shear force (Fy) was not affected by the load. However, during the middle phase of the exercise, the mtero-posterior shear force increased from 0.72 to 0. 88 times body weight when lifted mass increased from 1 to 1.20 times body weight. For the compressive component (Fx), no clear variation as a function of load was found in this study in all subjects. Even for the heaviest load (120% body weight), no increase in forces and moments was recorded from the first to the last repetition of one set. CONCLUSION The results of this study demonstrated that mechanical stress acting on knee joint in half-squat exercise increased with lifted barbell. For knee force components, load was found to affect only the antero-posterior shear force. The medio-lateral shear force was independent of this variable. Force and moment values were affected by REFERENCES Poumarat, G., Dabonneville, M., Chandezon, R., & Roddier, P. (1989). Les squats: Forces induites sur I'articulation du genou et sur L5 S 1 en fonction des postures adoptCes. CinCsiologie, 69-74. Trafimow, J.H., Schipplein, O.D., Novak, G.H.,& Andersson, G.B.J. (1993). The effects ofquadriceps fatigue on the technique of lifting. Spine, 18,364-367

Adult scoliosis can be reduced through specific SEAS exercises: a case report

<p>Abstract</p> <p>Background</p> <p>It has been known since many years that scoliosis can continue to progress after skeletal maturity: the rate of progression has shown to be linear, and it can be used to establish an individual prognosis. Once there is progression there is an indication for treatment: usually it is proposed a surgical one. There are very few papers on an alternative rehabilitation approach; since many years we propose specific SEAS exercises and the aim of this study is to present one case report on this approach.</p> <p>Case presentation</p> <p>All radiographs have been measured blindly twice using the same protractor by one expert physician whose repeatability error proved to be < 3° Cobb; the average measurement has been used. In this case a 25 years old female scoliosis patient, previously treated from 14 (Risser 1) to 19 years of age with a decrease of the curve from 46° to 37°, showed a progression of 10° Cobb in 6 years. The patient has then been treated with SEAS exercises only, and in one year progression has been reverted from 47° to 28.5°.</p> <p>Conclusion</p> <p>A scoliosis curve is made of different components: the structural bony and ligamentous components, and a postural one that counts up to 9° in children, while it has not been quantified in adults. This case shows that when adult scoliosis aggravates it is possible to intervene with specific exercises (SEAS) not just to get stability, but to recover last years collapse. The reduction of scoliotic curve through rehabilitation presumably does not indicate a reduction of the bone deformity, but rely on a recovery of the upright postural collapse. This reduction can decrease the chronic asymmetric load on the spine and, in the long run, reduce the risks of progression.</p

Unique presentation of a giant mediastinal tumor as kyphosis: a case report

<p>Abstract</p> <p>Introduction</p> <p>Although posture distortion is a common problem in elderly patients, spinal deformity caused by a thymoma has not been previously reported. Thymomas are slowly growing tumors that predominantly cause respiratory symptoms.</p> <p>Case presentation</p> <p>We report the case of an 83-year-old woman who was admitted with a giant mediastinal mass that had caused progressive spinal distortion and weight loss to our department. The clinical and laboratory investigations that followed revealed one of the largest thymomas ever reported in the medical literature, presenting as a mass lesion placed at the left hemithorax. She underwent complete surgical excision of the tumor via a median sternotomy. Two years after the operation, she showed significant improvement in her posture, no pulmonary discomfort, and a gain of 20 kg; she remains disease free based on radiographic investigations.</p> <p>Conclusions</p> <p>In this case, a chronic asymmetric load on the spine resulted in an abnormal vertebral curvature deformity that presented as kyphosis.</p

The Complete Genome Sequence of Mycoplasma bovis Strain Hubei-1

Infection by Mycoplasma bovis (M. bovis) can induce diseases, such as pneumonia and otitis media in young calves and mastitis and arthritis in older animals. Here, we report the finished and annotated genome sequence of M. bovis strain Hubei-1, a strain isolated in 2008 that caused calf pneumonia on a Chinese farm. The genome of M. bovis strain Hubei-1 contains a single circular chromosome of 953,114 bp with a 29.37% GC content. We identified 803 open reading frames (ORFs) that occupy 89.5% of the genome. While 34 ORFs were Hubei-1 specific, 662 ORFs had orthologs in the M. bovis type strain PG45 genome. Genome analysis validated lateral gene transfer between M. bovis and the Mycoplasma mycoides subspecies mycoides, while phylogenetic analysis found that the closest M. bovis neighbor is Mycoplasma agalactiae. Glycerol may be the main carbon and energy source of M. bovis, and most of the biosynthesis pathways were incomplete. We report that 47 lipoproteins, 12 extracellular proteins and 18 transmembrane proteins are phase-variable and may help M. bovis escape the immune response. Besides lipoproteins and phase-variable proteins, genomic analysis found two possible pathogenicity islands, which consist of four genes and 11 genes each, and several other virulence factors including hemolysin, lipoate protein ligase, dihydrolipoamide dehydrogenase, extracellular cysteine protease and 5′-nucleotidase

Reversal of childhood idiopathic scoliosis in an adult, without surgery: a case report and literature review

<p>Abstract</p> <p>Background</p> <p>Some patients with mild or moderate thoracic scoliosis (Cobb angle <50-60 degrees) suffer disproportionate impairment of pulmonary function associated with deformities in the sagittal plane and reduced flexibility of the spine and chest cage. Long-term improvement in the clinical signs and symptoms of childhood onset scoliosis in an adult, without surgical intervention, has not been documented previously.</p> <p>Case presentation</p> <p>A diagnosis of thoracic scoliosis (Cobb angle 45 degrees) with pectus excavatum and thoracic hypokyphosis in a female patient (DOB 9/17/52) was made in June 1964. Immediate spinal fusion was strongly recommended, but the patient elected a daily home exercise program taught during a 6-week period of training by a physical therapist. This regime was carried out through 1992, with daily aerobic exercise added in 1974. The Cobb angle of the primary thoracic curvature remained unchanged. Ongoing clinical symptoms included dyspnea at rest and recurrent respiratory infections. A period of multimodal treatment with clinical monitoring and treatment by an osteopathic physician was initiated when the patient was 40 years old. This included deep tissue massage (1992-1996); outpatient psychological therapy (1992-1993); a daily home exercise program focused on mobilization of the chest wall (1992-2005); and manipulative medicine (1994-1995, 1999-2000). Progressive improvement in chest wall excursion, increased thoracic kyphosis, and resolution of long-standing respiratory symptoms occurred concomitant with a >10 degree decrease in Cobb angle magnitude of the primary thoracic curvature.</p> <p>Conclusion</p> <p>This report documents improved chest wall function and resolution of respiratory symptoms in response to nonsurgical approaches in an adult female, diagnosed at age eleven years with idiopathic scoliosis.</p

Effects of eccentric phase velocity of plyometric training on the vertical jump

Abstract The aim of this study was to compare the effects of plyometric training performed with rapid or slow stretch contraction on jump performance and muscle properties. Thirty males between the ages of 19 and 22 volunteered for the 8-week experiment. Subjects were divided into the following three groups: training group 1 (TG1), training group 2 (TG2), and control group (CG). Each of the two experimental groups underwent a unique training regimen. For the first group (TG1, n = 12): from a standing position the subject flexed his knees to a 90° angle with velocity standardized and controlled at 0.4 m/s and immediately performed a leg extension as quickly as possible. For the second group (TG2, n = 12): from a standing position, the subject flexed his knees to a 90° angle with velocity standardized at 0.2 m/s and then performed a leg extension as quickly as possible. Each exercise consisted of six sets of ten repetitions with a barbell on the shoulders at 70 % of the maximal isometric force (1 RM). The 70 % load was modified at two-week intervals by evaluating a new 1 RM. Exercises were performed four times a week over the eight-week period. The third group (CG, n = 6), served as the control group. Maximal isometric force (MVC), maximal concentric force, squat jump (SJ) and counter movement jump (CMJ) exercises were performed before and after the training program. Subjects were filmed (100 Hz) and each jump was divided into three phases: eccentric phase (ECC), transition phase (TR) and concentric phase (CON). Surface EMG was used to determine the changes in the electromyographic (EMG) activity before and after the training program. There was an increase in leg extension force, velocity and electrical activity for SJ and CMJ for the two training groups (p < 0.05). However, TG1 showed a significant advantage in CMJ performance as well as a significant decrease in TR compared to the TG2 (p < 0.05). The results of this study show that when plyometric training is performed with rapid stretch contraction the CMJ jump height increases and the TR decreases

A PCR for the detection of mycoplasmas belonging to the Mycoplasma mycoides cluster: application to the diagnosis of contagious agalactia.

Contagious agalactia is a mycoplasmal infection caused by Mycoplasma agalactiae, Mycoplasma mycoides subsp. mycoides LC, M. mycoides subsp. capri, Mycoplasma capricolum subsp. capricolum and Mycoplasma putrefaciens. Identification of the causative organisms is usually performed by isolation and classical biochemical and serological tests, though this is a lengthy and cumbersome process for mycoplasmas. Specific PCR assays have been developed for the identification of Mycoplasma agalactiae and M. putrefaciens. For members of the M. mycoides cluster existing PCR tests are based on the amplification of highly conserved genes coding for ribosomal proteins, hence a possibility of cross-reactions. The gene glk, coding for a glucokinase, that is found in this cluster is very distantly related to any other bacterial glucokinase described so far. It was therefore chosen as target to design a new PCR test. The validation was performed independently in three laboratories in France and India using over 100 mycoplasma strains of various geographical origins. All strains belonging to the M. mycoides cluster were detected by amplification of the expected PCR product (428 bp) while no amplification was obtained from M. agalactiae strains. Our results demonstrate the universality of this PCR in spite of the great heterogeneity found within this cluster. This new tool may be of great help for the implementation of control measures directed towards contagious agalactia