Vertical force distribution between lower limbs in different lunge techniques

The lunge exercise is considered a bilateral and multi-joint exercise; in this way, each lower limb presents different force distributions in different techniques and body positions. The purpose of this study was to measure the vertical force distribution between lower limbs in different lunge exercises. Thirty-two young, resistance-trained (male=27, 27±6 years, 174.6±9.6 cm, 79.1±14.2 kg; female=7, 24±4 years, 165.2±2.6 cm, 67.1±13.5 kg) performed 3 different lunge techniques on the floor [traditional (TL), partial (PL), and long (LL)] and two on the step [Rear-Foot-Elevated Lunge (RFEL) and RFEL at 50% (RFEL50)] in two static positions (upper and lower) in a randomized, counterbalanced fashion. For the assessment of the vertical force, two portable force plates were positioned under the anterior and posterior lower limb for all lunge techniques. Factorial ANOVA was used to test differences between exercises (TL, PL, LL, RFEL, and RFEL50), limbs and moments. An alpha of 5% was used. In conclusion, lunge techniques as the TL, PL, and LL presented differences in force between legs and positions, however similarities between techniques, and might be applied for different sports under unilateral conditions. Lunges with step (RFEL or RFEL50) presented high asymmetry between lower limbs and emphasis on the anterior leg.

Homogenization of cohesive fracture in masonry structures

We derive a homogenized mechanical model of a masonry-type structure constituted by a periodic assemblage of blocks with interposed mortar joints. The energy functionals in the model under investigation consist of (i) a linear elastic contribution within the blocks, (ii) a Barenblatt’s cohesive contribution at contact surfaces between blocks, and (iii) a suitable unilateral condition on the strain across contact surfaces, and are governed by a small parameter representing the typical ratio between the length of the blocks and the dimension of the structure. Using the terminology of [Formula: see text]-convergence and within the functional setting supplied by the functions of bounded deformation, we analyze the asymptotic behavior of such energy functionals when the parameter tends to zero, and derive a simple homogenization formula for the limit energy. Furthermore, we highlight the main mathematical and mechanical properties of the homogenized energy, including its non-standard growth conditions under tension or compression. The key point in the limit process is the definition of macroscopic tensile and compressive stresses, which are determined by the unilateral conditions on contact surfaces and the geometry of the blocks.

A Multi-Scale Model of Soft Imperfect Interface with Nonlocal Damage

The aim of this paper is to propose a model of bonded interface including nonlocal damage and unilateral conditions. The model is derived from the problem of a composite structure made by two adherents and a thin adhesive. The adhesive is damaged at microscopic level and is subjected to two regimes, one in traction and one in compression. The model of interface is derived by matched asymptotic expansions. In this paper, two cases corresponding to the two regimes are discussed. Moreover, this model can be considered as a model of contact with adhesion and unilateral constraint. At the end of the paper, a simple numerical example is presented to show the evolution of the model.

Retrospective Analysis of Plantar Fascia by Ultrasound Imaging in Patients with Plantar Fasciitis

Background: We compared diagnostic ultrasound images of the plantar fascia with available patient histories for symptomatic patients previously diagnosed as having plantar fasciitis. Plantar fascia thickness and depth, the prevalence of perifascial hypoechoic lesions, and injury timelines in patients were reviewed. Methods: Images and histories for 126 symptomatic patients were collected from a patient database. We documented plantar fascia depth and thickness and the visualization of hypoechoic perifascial lesions. After image analysis, the obtained plantar fascia thickness measurements were compared with various patient attributes for possible relationships, including age, weight, and body mass index. In addition, plantar fascia thickness measurements were separated based on injury timeline as well as symptomatic/asymptomatic foot for patients with unilateral conditions to check for significant differences between subgroups. These were, in turn, compared with a control group of 71 individuals with no heel pain or diagnosis of plantar fasciitis. Results: Overall, mean ± SD symptomatic thickness (n = 148) was 6.53 ± 1.56 mm. Mean ± SD symptomatic depth (n = 136) was 13.36 ± 2.14 mm. For the control group, mean ± SD thickness was 3.20 ± 0.66 mm and depth was 10.30 ± 2.00 mm. Comparison of thickness based on injury timeline showed two significant differences: acute injuries (≤3 months) are significantly thicker than chronic injuries (>3 months), and only acute symptomatic thicknesses are significantly different from their asymptomatic thickness counterparts. Age, weight, and body mass index did not show significant correlations to thickness. Analysis of ultrasound images showed that 93% of symptomatic feet had hypoechoic lesions. Conclusions: Injury timeline and the presence of hypoechoic lesions may play important roles in patient discomfort, diagnosis, and treatment of plantar fasciitis.

Imperfect interfaces with graded materials and unilateral conditions: theoretical and numerical study

In this paper a composite body is considered. This body is made of three solids: two linear elastic adherents and a piecewise linear thin adhesive. The composite occupies a bounded domain depending naturally on a small parameter [Formula: see text], which is the thickness, assumed constant, of the adhesive. Classically, it is possible to derive an interface imperfect law using asymptotic expansions as the thickness [Formula: see text] tends to zero. In this work, the material in the interphase is assumed to be graded, i.e. its elasticity properties vary along the thickness. Moreover, an unilateral condition is considered to avoid penetrations. A first result of the paper is that it is possible to apply the above methodology based on asymptotic expansions to this kind of material. Then, a finite element method is introduced to solve the initial problem (with three layers) and the limit problem (with two layers in imperfect contact). Various types of graded materials are numerically analyzed. In particular, different types of stiffness distributions are studied in detail.

Comparison of bilateral and unilateral contractions between swimmers and nonathletes during leg press and hand grip exercises

The bilateral limb deficit (BLD) is defined as the reduction in force production during bilateral compared with summed unilateral contractions of homologous muscles. The underlying mechanism for the BLD has been elusive to determine. The purpose of this study was to examine the presence of the BLD during maximal isometric leg press and handgrip exercises in female swimmers (n = 9, mean age = 20.1 ± 1.3 years) and nonathletes (n = 9, mean age = 21.7 ± 1.3 years) to gain further insight into this phenomenon. Force and electromyography (EMG) measures were collected from participants under bilateral and unilateral conditions for handgrip and leg press exercises. Bilateral limb ratios (BLR) were calculated for swimmers (BLRS) and nonathletes (BLRNA). A deficit was found for swimmers and nonathletes in leg force (BLRS = 79.84% ± 13.09% and BLRNA = 81.44% ± 19.23%) and leg EMG (BLRS = 88.45% ± 15.41% and BLRNA = 94.66% ± 13.62%); however, no BLD was seen in hand force (BLRS = 98.30% ± 11.21% and BLRNA = 95.91% ± 11.04%) and hand EMG (BLRS = 102.42% ± 11.20% and BLRNA = 103.30% ± 16.50%). Furthermore, no significant differences were found between groups for leg force, leg EMG, hand force, and hand EMG. In conclusion, a BLD was detected for both groups during bilateral isometric leg press. This suggests that while the BLD may be affected by neural influences, there may other factors involved such as postural stability requirements to perform the exercise.