Aluísio Otávio Vargas Ávila

The Relationship between Running Economy and Biomechanical Variables in Distance Runners.

In this study, we analyzed the relationship between running economy (RE) and biomechanical parameters in a group running at the same relative intensity and same absolute velocity. Sixteen homogeneous male long-distance runners performed a test to determine RE at 4.4 m.s-1, corresponding to 11.1% below velocity at the ventilatory threshold. We found significant correlations between RE and biomechanical variables (vertical oscillation of the center of mass, stride frequency, stride length, balance time, relative stride length, range of elbow motion, internal knee, ankle angles at foot strike, and electromyographic activity of the semitendinosus and rectus femoris muscles). In conclusion, changes in running technique can influence RE and lead to improved running performance.

Comparação de protocolos para determinação do ângulo de pronação subtalar

INTRODUCTION: Many studies have analyzed the maximum subtalar pronation without any concern over the choice of model for determining this variable. OBJECTIVE: To compare the maximum subtalar pronation and its moment of occurrence during the stance phase, determined based on two mathematical models consisting of two and four reference points, respectively. METHOD: Sixteen runners participated in two running economy tests on a treadmill at speeds of 16 and 17 km.h-1. RESULT: The study showed significant differences in oxygen consumption between the speeds adopted, contrary to the values of maximum subtalar pronation and their moments of occurrence, which did not show any significant differences between the speeds, regardless of the mathematical model adopted. Comparing the two mathematical models, the values of maximum subtalar pronation showed significant differences, regardless of speed. However, the moments of occurrence of maximum subtalar pronation showed no significant differences. CONCLUSION: The measure of maximum subtalar pronation is influenced by the mathematical model adopted. However, the moment of occurrence of maximum subtalar pronation during the stance phase is independent of the model.

Avaliação biomecânica das fraturas intra-articulares do calcâneo e sua correlação clínica radiográfica

The present study had an objective to perfom a clinical, radiographic and biomechanical evaluation in patients with calcaneal fractures submitted to open reduction with internal fixation. The sample consisted of 22 patients - 20 male and 2 female with an average age of 40,95 (±11,63) years old. The authors have done radiographic evaluation of the pre and post operatory of Bochler and Gissane angles; furthermore, they used a CT scanning for Sanders classification of calcaneal fractures. The plantar pressure distribution was analyzed with F-scanning system. The results of the intra-articular calcaneal fractures were clinically satisfactory, showed average punctuation with 75,5 in AOFAS criterion. The surgical reduction in a better angle of Bochler and Gissane. The study showed statistical differences between the forefoot and rearfoot concerning the the contact area, average preassure and strength in the injured foot. The figures found to this parameter were bigger in the rearfoot than the forefoot. The trajectory of pressure (COP) was shorter in the fractured foot than in the normal foot. The correlation between the angle of Gissane after the reduction and the second peak of force was found, showing as better as the reduction of this angle, the better is the impulsion. It was also found the correlation between the punctuation between AOFAS and the first peak of force, showing as better is the clinical result the better is the foot supporter.

BIOMECHANICS AND HISTOLOGICAL ANALYSIS IN RABBIT FLEXOR TENDONS REPAIRED USING THREE SUTURE TECHNIQUES (FOUR AND SIX STRANDS) WITH EARLY ACTIVE MOBILIZATION

Objective: Analyzing suture time, biomechanics (deformity between the stumps) and the histology of three groups of tendinous surgical repair: Brazil-2 (4-strands) which the end knot (core) is located outside the tendon, Indiana (4-strands) and Tsai (6-strands) with sutures technique which the end knot (core) is inner of the tendon, associated with early active mobilization. Methods: The right calcaneal tendons (plantar flexor of the hind paw) of 36 rabbits of the New Zealand breed (Oryctolagus cuniculus) were used in the analysis. This sample presents similar size to human flexor tendon that has approximately 4.5 mm (varying from 2mm). The selected sample showed the same mass (2.5 to 3kg) and were male or female adults (from 8 ½ months). For the flexor tendons of the hind paws, sterile and driven techniques were used in accordance to the Committee on Animal Research and Ethics (CETEA) of the University of the State of Santa Catarina (UDESC), municipality of Lages, in Brazil (protocol # 1.33.09). Results: In the biomechanical analysis (deformity) carried out between tendinous stumps, there was no statistically significant difference (p>0.01). There was no statistical difference in relation to surgical time in all three suture techniques with a mean of 6.0 minutes for Tsai (6- strands), 5.7 minutes for Indiana (4-strands) and 5.6 minutes for Brazil (4-strands) (p>0.01). With the early active mobility, there was qualitative and quantitative evidence of thickening of collagen in 38.9% on the 15th day and in 66.7% on the 30th day, making the biological tissue stronger and more resistant (p=0.095). Conclusion: This study demonstrated that there was no histological difference between the results achieved with an inside or outside end knot with respect to the repaired tendon and the number of strands did not affect healing, vascularization or sliding of the tendon in the osteofibrous tunnel, which are associated with early active mobility, with the repair techniques applied.

Vertical ground reaction force analysis during gait with unstable shoes

Introduction Footwear is no longer just an accessory but also a protection for the musculoskeletal system, and its most important characteristic is comfort.Objectives This study aims to identify and to analyze the vertical ground reaction force in barefoot women and women with unstable shoes.Methodology Five women aged 25 ± 4 years old and mass of 50 ± 7 kg participated in this study. An AMTI force plate was used for data acquisition. The 10 trials for each situation were considered valid where the subject approached the platform with the right foot and at the speed of 4 km/h ± 5%. The instable shoe of this study is used in the practice of physical activity.Results The results showed that the first peak force was higher for the footwear situation, about 5% and significant differences between the barefoot and footwear situation. This significant difference was in the first and second peaks force and in the time of the second peak.Conclusion The values showed that the footwear absorbs approximately 45% of the impact during gait.

Internal tibia rotation during gait

15 min. Three different downhill conditions were performed one after the other (one very technical and very steep: DTS, one with rocks and steep: DRS and one not technical and not steep: Deasy) during which subjects were equipped with an accelerometer placed on the shin (Fox system, Hikob, Villeurbanne, France, 500 Hz) and with a portable plantar pressure device (Pedar System, Novel Electronics, Munich, Germany, 100 Hz). Peak accelerations at the tibia (PTA in g) were calculated from acceleration signals. From the portable plantar pressure device, the 2D localisation of the centre of pressure (CP) was calculated at the moment of first contact with the ground (Figure 1), i.e. the barycentre of all the pressure values of each sensor.

INTRA ARTICULAR CALCANEAL FRACTURES: A CLINICAL AND BIOMECHANICAL ANALYSIS.

Objective: Verify the variables of plantar pressure distribution of patients submitted to surgical procedure for calcaneal fracture, and correlate them with two different surgical approaches. Method: The authors studied 15 patients between 20 and 53 years of age (average 40.06 yrs.) who had intra-joint calcaneal fractures, submitted to surgical treatment by means of two different approaches: the lateral and the sinus tarsi. The authors checked the plantar pressure distribution by correlating these variables with the two different surgical approaches. The plantar pressure distribution was assessed using the Pedar System (Novel, Gmbh, Munich, Germany), by checking the maximum peak of the hindfoot and forefoot pressure on the affected and the normal sides. Results: the mean maximum pressure of the hindfoot plantigram in both approaches showed no statistical difference (t=0.11; p=0.91), as well as the mean maximum pressure of the forefoot plantigram (t=-0,48; p=0,64). Conclusion: The authors have concluded that there were no significant statistical differences between the average maximum peak of the hindfoot and forefoot pressure on the affected side as compared to the normal side, and these variables have showed no differences when compared to the surgical approach used.