Effect of a rocker non-heeled shoe on EMG and ground reaction forces during gait without previous training

Unstable shoes have been designed to promote "natural instability" and during walking they should simulate barefoot gait, enhancing muscle activity and, thus, attributing an advantage over regular tennis shoes. Recent studies showed that, after special training on the appropriate walking pattern, the use of the Masai Barefoot Technology (MBT) shoe increases muscle activation during walking. Our study presents a comparison of muscle activity as well as horizontal and vertical forces during gait with the MBT, a standard tennis shoe and barefoot walking of healthy individuals without previous training. These variables were compared in 25 female subjects and gait conditions were compared using ANOVA repeated measures (effect size:0.25). Walking with the MBT shoe in this non-instructed condition produced higher vertical forces (first vertical peak and weight acceptance rate) than walking with a standard shoe or walking barefoot, which suggests an increase in the loads received by the musculoskeletal system, especially at heel strike. Walking with the MBT shoe did not increase muscle activity when compared to walking with the standard shoe. The barefoot condition was more effective than the MBT shoe at enhancing muscle activation. Therefore, in healthy individuals, no advantage was found in using the MBT over a standard tennis shoe without a special training period. Further studies using the MBT without any instruction over a longer period are needed to evaluate if the higher loads observed in the present study would return to their baseline values after a period of adaptation, and if the muscle activity would increase over time. (C) 2012 Elsevier B.V. All rights reserved.

Effectiveness of a long-term use of a minimalist footwear versus habitual shoe on pain, function and mechanical loads in knee osteoarthritis: a randomized controlled trial

Background: Recent studies have shown an important reduction of joint overload during locomotion in elderly women with knee osteoarthritis (OA) after short- term use of minimalist shoes. Our aim is to investigate the chronic effect of inexpensive and minimalist footwear on the clinical and functional aspects of OA and gait biomechanics of elderly women with knee OA. Methods/Design: Fifty-six elderly women with knee OA grade 2 or 3 (Kellgren and Lawrence) are randomized into blocks and allocated to either the intervention group, which will use flexible, non-heeled shoes-Moleca (R)-for six months for at least six hours daily, or the control group, which could not use these shoes. Neither group is undergoing physical therapy treatment throughout the intervention period. Moleca (R) is a women's double canvas, flexible, flat walking shoe without heels, with a 5-mm anti-slip rubber sole and a 3-mm internal wedge of ethylene vinyl acetate. Both groups will be followed for six months and will be assessed at baseline condition, after three months, and after six months (end of intervention). All the assessments will be performed by a physiotherapist that is blind to the group allocation. The primary outcome is the pain Western Ontario and McMaster Universities Osteoarthritis (WOMAC) score. The secondary outcomes are global WOMAC score; joint stiffness and disability WOMAC scores; knee pain with a visual analogue scale; walking distance in the six-minute walk test; Lequesne score; amount and frequency (number of days) of paracetamol (500 mg) intake over six months; knee adduction moment during gait; global medical assessment score; and global patient auto-assessment score. At baseline, all patients receive a diary to record the hours of daily use of the footwear intervention; every two weeks, the same physiotherapist makes phone calls to all patients in order to verify adherence to treatment. The statistical analysis will be based on intention to treat analysis, as well as general linear models of analysis of variance for repeated measure to detect treatment-time interactions (alpha = 5%). Discussion: This is the first randomized, clinical trial protocol to assess the chronic effect of minimalist footwear on the clinical and functional aspects and gait biomechanics of elderly women with knee osteoarthritis. We expect that the use of Moleca (R) shoes for six months will provide pain relief, reduction of the knee adduction moment when walking, and improve joint function in elderly women with knee OA, and that the treatment, thus, can be considered another inexpensive and easy-to-use option for conservative OA treatment.

Attenuation of foot pressure during running on four different surfaces: asphalt, concrete, rubber, and natural grass

The practice of running has consistently increased worldwide, and with it, related lower limb injuries. The type of running surface has been associated with running injury etiology, in addition other factors, such as the relationship between the amount and intensity of training. There is still controversy in the literature regarding the biomechanical effects of different types of running surfaces on foot-floor interaction. The aim of this study was to investigate the influence of running on asphalt, concrete, natural grass, and rubber on in-shoe pressure patterns in adult recreational runners. Forty-seven adult recreational runners ran twice for 40 m on all four different surfaces at 12 +/- 5% km . h(-1). Peak pressure, pressure-time integral, and contact time were recorded by Pedar X insoles. Asphalt and concrete were similar for all plantar variables and pressure zones. Running on grass produced peak pressures 9.3% to 16.6% lower (P < 0.001) than the other surfaces in the rearfoot and 4.7% to 12.3% (P < 0.05) lower in the forefoot. The contact time on rubber was greater than on concrete for the rearfoot and midfoot. The behaviour of rubber was similar to that obtained for the rigid surfaces - concrete and asphalt - possibly because of its time of usage (five years). Running on natural grass attenuates in-shoe plantar pressures in recreational runners. If a runner controls the amount and intensity of practice, running on grass may reduce the total stress on the musculoskeletal system compared with the total musculoskeletal stress when running on more rigid surfaces, such as asphalt and concrete.

Effects of replica running shoes upon external forces and muscle activity during running

Twelve participants ran (9 km . h(-1)) to test two types of running shoes: replica and original shoes. Ground reaction force, plantar pressure and electromyographic activity were recorded. The shoes were tested randomly and on different days. Comparisons between the two experimental conditions were made by analysis of variance (ANOVA) test (P <= 0.05). The time to first peak, loading rate of the first peak and impulse of the first 75 ms of stance were significantly different between the shoes (P <= 0.05), revealing an increase of impact forces for the replica shoes. The peak plantar pressure values were significantly higher (P <= 0.05) when wearing replica shoes. During running, the contact area was significantly smaller (P <= 0.05) for the replica shoe. The electromyographic activity of the analysed muscles did not show changes between the two shoes in running. These findings suggest that the use of replica running shoes can increase the external load applied to the human body, but may not change the muscle activity pattern during locomotion. This new mechanical situation may increase the risk of injuries in these movements.

The Nuss procedure made safer: an effective and simple sternal elevation manoeuvre

The Nuss procedure requires the creation of a substernal tunnel for bar positioning. This is a manoeuvre that can be dangerous, and cardiac perforation has occurred in a few cases. Our purpose was to describe two technical modifications that enable the prevention of these fatal complications. A series of 25 patients with pectus excavatum were treated with a modification of the Nuss procedure that included the entrance in the left haemithorax first, and the use of the retractor to lift the sternum, with the consequent lowering displacement of the heart. These modified techniques have certain advantages: (i) the narrow anterior mediastinum between the sternum and the pericardial sac is expanded by pulling up the sternum; (ii) the thoracoscopic visualization of the tip of the introducer during tunnel creation is improved; (iii) the rubbing of the introducer against the pericardium is minimized; (iv) the exit path of the introducer can be guided by the surgeon's finger and (v) haemostasis and integrity of the pericardial sac can be more easily confirmed. We observed that with these manoeuvres, the risk of pericardial sac and cardiac injury can be markedly reduced.

URANS calculations for smooth circular cylinder flow in a wide range of Reynolds Numbers: solution verification and validation

The flow around circular smooth fixed cylinder in a large range of Reynolds numbers is considered in this paper. In order to investigate this canonical case, we perform CFD calculations and apply verification & validation (V&V) procedures to draw conclusions regarding numerical error and, afterwards, assess the modeling errors and capabilities of this (U)RANS method to solve the problem. Eight Reynolds numbers between Re = 10 and Re 5 x 10(5) will be presented with, at least, four geometrically similar grids and five discretization in time for each case (when unsteady), together with strict control of iterative and round-off errors, allowing a consistent verification analysis with uncertainty estimation. Two-dimensional RANS, steady or unsteady, laminar or turbulent calculations are performed. The original 1994 k - omega SST turbulence model by Menter is used to model turbulence. The validation procedure is performed by comparing the numerical results with an extensive set of experimental results compiled from the literature. [DOI: 10.1115/1.4007571]

Reliability in kimono grip strength tests and comparison between elite and non-elite Brazilian jiu-jitsu players

Background and Study Aim: The grip strength endurance is important for Brazilian Jiu-Jitsu (BJJ). Thus, the aims of this study were: a) to test the reliability of two kimono grip strength tests named maximum static lift (MSL) and maximum number of repetitions (MNR) and b) to examine differences between elite and non-elite BJJ players in these tests. Material/Methods: Thirty BJJ players participated into two phases: "A" to test reliability and "B" to compare elite and non-elite. In phase A, twenty participants performed the MSL and, 15 min later, the MNR in two occasions with 24-h interval. In phase B, ten other BJJ practitioners (non-elite) and ten athletes (elite) performed the same tests. The intraclass correlation coefficient (ICC) two way fixed model (3,1), Bland-Altman plot and the limits of agreement were used to test reliability, correlation between the tests were evaluated by Pearson correlations and independent T test (P<0.05) was utilized to compare elite vs. non-elite. Results: The ICC was high for repeated measurements on different days of phase A (MSL: r=0.99 and MNR: r=0.97). Limits of agreement for time of suspension were -6.9 to 2.4-s, with a mean difference of -2.3 s (CI: -3.3 to -1.2-s), while for number of repetitions the limits of agreement were -2.9 to 2.3-rep, with a mean difference of -0.3-rep (CI: -0.9 to 0.3-rep). In phase B, elite presented better performance for both tests (P<0.05) compared to non-elite (56 +/- 10-s vs. 37 +/- 11-s in MSL and 15 +/- 4-rep vs. 8 +/- 3-rep in MNR). Moderate correlation were found between MSL and MNR for absolute values during test (r=0.475; p=0.034), and retest phases (r=0.489; p=0.029), while moderate and high correlations in the test (r=0.615; p=0.004) and retest phases (r=0.716; p=0.001) were found for relative values, respectively. Conclusions: These proposed tests are reliable and both static and dynamic grip strength endurance tests seem to differentiate BJJ athletes from different levels.

TRANSITIVITY AND ROTATION SETS WITH NONEMPTY INTERIOR FOR HOMEOMORPHISMS OF THE 2-TORUS

We show that if f is a homeomorphism of the 2-torus isotopic to the identity and its lift (f) over tilde is transitive, or even if it is transitive outside the lift of the elliptic islands, then (0,0) is in the interior of the rotation set of (f) over tilde. This proves a particular case of Boyland's conjecture.

Experimental study on vortex-induced motions of a semi-submersible platform with four square columns, Part I: Effects of current incidence angle and hull appendages

An experimental study on Vortex-Induced Motion (VIM) of the semi-submersible platform concept with four square columns is presented. Model tests were carried out to check the influence of different headings and hull appendages (riser supports located at the pontoons; fairleads and the mooring stretches located vertically at the external column faces; and hard pipes located vertically at the internal column faces). The results comprise in-line, transverse and yaw motions, as well as combined motions in the XY plane, drag and lift forces and spectral analysis. The main results showed that VIM in the transverse direction occurred in a range of reduced velocity 4.0 up to 14.0 with amplitude peaks around reduced velocities around 7.0 and 8.0. The largest transverse amplitudes obtained were around 40% of the column width for 30 degrees and 45 degrees incidences. Another important result observed was a considerable yaw motion oscillation, in which a synchronization region could be identified as a resonance phenomenon. The largest yaw motions were verified for the 0 degrees incidence and the maxima amplitudes around 4.5 degrees. The hull appendages located at columns had the greatest influence on the VIM response of the semi-submersible. (C) 2012 Elsevier Ltd. All rights reserved.

Effect of a propeller duct on AUV maneuverability

A number of autonomous underwater vehicles, AUV, are equipped with commercial ducted propellers, most of them produced originally for the remote operated vehicle, ROV, industry. However, AUVs and ROVs are supposed to work quite differently since the ROV operates in almost the bollard pull condition, while the AUV works at larger cruising speeds. Moreover, they can have an influence in the maneuverability of AUV due to the lift the duct generates in the most distant place of the vehicle's center of mass. In this work, it is proposed the modeling of the hydrodynamic forces and moment on a duct propeller according to a numerical (CFD) simulation, and analytical and semi-empirical, ASE, approaches. Predicted values are compared to experimental results produced in a towing tank. Results confirm the advantages of the symbiosis between CFD and ASE methods for modeling the influence of the propeller duct in the AUV maneuverability. (C) 2012 Elsevier Ltd. All rights reserved.

Water-assisted Flow of Heavy Oil in a Vertical Pipe: Pilot-scale Experiments

The use of the core-annular flow pattern, where a thin fluid surrounds a very viscous one, has been suggested as an attractive artificial-lift method for heavy oils in the current Brazilian ultra-deepwater production scenario. This paper reports the pressure drop measurements and the core-annular flow observed in a 2 7/8-inch and 300 meter deep pilot-scale well conveying a mixture of heavy crude oil (2000 mPa.s and 950 kg/m3 at 35 C) and water at several combinations of the individual flow rates. The two-phase pressure drop data are compared with those of single-phase oil flow to assess the gains due to water injection. Another issue is the handling of the core-annular flow once it has been established. High-frequency pressure-gradient signals were collected and a treatment based on the Gabor transform together with neural networks is proposed as a promising solution for monitoring and control. The preliminary results are encouraging. The pilot-scale tests, including long-term experiments, were conducted in order to investigate the applicability of using water to transport heavy oils in actual wells. It represents an important step towards the full scale application of the proposed artificial-lift technology. The registered improvements in terms of oil production rate and pressure drop reductions are remarkable.

Monsplasty for Women After Massive Weight Loss

Ptosis with excess skin in the pubic area is a very common deformity in patients after massive weight loss. This deformity requires adequate surgical treatment whether combined with abdominoplasty or not. The enlarged pubogenital area may lead to psychosocial distress and impaired quality of life. A series of 23 women with a mean age of 39.5 years who previously underwent bariatric surgeries and later presented with pubogenital ptosis underwent monsplasty. The preoperative surgical markings and the surgical technique presented are easily reproducible. In this prospective study, the surgical outcomes were assessed by questionnaires applied to the patients, who scored the following parameters: movement dynamics, aesthetic appearance, sexual performance, improved hygiene, and use of clothing items. Four of the parameters assessed (movement dynamics, aesthetic appearance, hygiene, and use of clothing items) showed clear improvement, with scores ranging from good to very good. A small percentage of the patients (13%) reported fair improvement in sexual performance. The findings showed monsplasty to be a simple and reproducible technique with favorable outcomes and low morbidity rates.

The role of wake stiffness on the wake-induced vibration of the downstream cylinder of a tandem pair

When a pair of tandem cylinders is immersed in a flow the downstream cylinder can be excited into wake-induced vibrations (WIV) due to the interaction with vortices coming from the upstream cylinder. Assi, Bearman & Meneghini ( J. Fluid Mech. , vol. 661, 2010, pp. 365–401) concluded that the WIV excitation mechanism has its origin in the unsteady vortex–structure interaction encountered by the cylinder as it oscillates across the wake. In the present paper we investigate how the cylinder responds to that excitation, characterising the amplitude and frequency of response and its dependency on other parameters of the system. We introduce the concept of wake stiffness , a fluid dynamic effect that can be associated, to a first approximation, with a linear spring with stiffness proportional to Re and to the steady lift force occurring for staggered cylinders. By a series of experiments with a cylinder mounted on a base without springs we verify that such wake stiffness is not only strong enough to sustain oscillatory motion, but can also dominate over the structural stiffness of the system. We conclude that while unsteady vortex–structure interactions provide the energy input to sustain the vibrations, it is the wake stiffness phenomenon that defines the character of the WIV response