Efficiency of protection of human rights in non unitary entities by means of uniformly applied sets of norms

This thesis attempts to deal with the question of whether the protection of the fundamental rights of the citizens of the Member States of the European Community should be entrusted to a uniformly applied set of norms. In other words, it discusses whether the legal area of human rights should be subjected to the process of integration that has been characteristic of the development of the European Community in the last fifty years. In doing so, the thesis initially introduces the principles of efficiency and uniformity and presumes that efficiency of protection of human rights exists when protection is afforded by means of uniformly applied sets of norms, whereas inefficiency exists when protection is fragmented. The validity of these presumptions is then tested on two non unitary entities, the European Community and the United States of America. This is done by means of an analysis of the whole spectrum of the protective measures available in these entities, which includes the uniformly applied sets of norms for each one of them, the European Convention on Human Rights, as regards the European Community, and the Bill of Rights of the American Constitution, as regards the United States of America. As a result of this analysis the thesis questions the validity of the two presumptions initially made. Indeed in Europe, where the protection of the human rights of the individual is significantly fragmented, there are no indications that this protection is inefficient. In the United States of America, on the other hand, where the protection of the rights of individual is overwhelmingly bestowed upon the uniformly applied provisions of the federal Bill of Rights, efficiency problems seem to exist

Commentary on child-adult differences in muscle activation - A review

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THE EFFECT OF PENNATION ANGLE CHANGES DURING CONTRACTION ON THE ESTIMATED TRICEPS SURAE MOMENT

INTRODUCTION: Forward dynamics simulations are important tools in biomechanics research but the accuracy of the muscle model parameters (such as pennation angle, optimal fiber length, force-velocity relationship, etc.) is critical for realistic force and joint moment estimations. The pennation angle in particular determines the efficiency of force transmission to the tendon. The purpose of this study was to investigate changes in the modeled triceps surae complex and its predicted maximum moment using a computer based musculoskeletal model when incorporating in vivo measured pennation angle values. METHODS: The Software for Interactive Musculoskeletal Modeling (SIMM) (Delp et al., 1990) was used to obtain the triceps surae maximum isometric moment at ankle angles of -15o (dorsiflexion), 0o (neutral ankle position), +150 and +300 (plantarflexion). Moments were estimated using pennation angle values a) based on literature pennation angle data used normally in the SIMM model and b) from in vivo pennation angle measurements. Pennation angle measurements were taken using ultrasonography (Esaote Biomedica, Italy) from gastrocnemius medialis, gastrocnemius lateralis and soleus in six males during maximum isometric plantarflexions using an electromechanical dynamometer (Lido Active, Loredan Biomedical, USA) at ankle angles of -15o, 0o, +15o and +30o. RESULTS: The estimated triceps surae moment using cadaveric pennation angle data were approximately 122 Nm, 85 Nm, 17 Nm and 0 Nm at ankle angles of - 15o, 0o, +15o and +30o respectively. The corresponding estimated moments taken incorporating the experimentally observed pennation angles in the model were approximately 106 Nm, 72, Nm, 17 Nm and 0 Nm. Substantially overestimated moment values at ankle angles of -15o (15%) and 0o (18%) were obtained when using cadaveric pennation angle data from the literature compared with the model moment predictions taken incorporating in vivo pennation angle data. CONCLUSIONS: The findings of this study suggest that a realistic model estimation of the moment generating capacity around a joint requires the incorporation of changes in the muscle pennation angle occurring during contraction. REFERENCES: Delp, S., Bleck, E., Zajac, F., Bollini, G. (1990). An Interactive, Graphics-Based Model of the Lower Extremity to Study Orthopaedic Surgical Procedures. IEEE Transactions on Biomedical Engineering 37, 757-767

In vivo measurements of muscle specific tension in adults and children

This article is available open access through the publisher’s website at the link below. Copyright @ 2009 The Authors.To better understand the effects of pubertal maturation on the contractile properties of skeletal muscle in vivo, the present study investigated whether there are any differences in the specific tension of the quadriceps muscle in 20 adults and 20 prepubertal children of both sexes. Specific tension was calculated as the ratio between the quadriceps tendon force and the sum of the physiological cross-sectional area (PCSA) multiplied by the cosine of the angle of pennation of each head within the quadriceps muscle. The maximal quadriceps tendon force was calculated from the knee extension maximal voluntary contraction (MVC) by accounting for EMG-based estimates of antagonist co-activation, incomplete quadriceps activation using the interpolation twitch technique and magnetic resonance imaging (MRI)-based measurements of the patellar tendon moment arm. The PCSA was calculated as the muscle volume, measured from MRI scans, divided by optimal fascicle length, measured from ultrasound images during MVC at the estimated angle of peak quadriceps muscle force. It was found that the quadriceps tendon force and PCSA of men (11.4 kN, 214 cm2) were significantly greater than those of the women (8.7 kN, 152 cm2; P 0.05) between groups: men, 55 ± 11 N cm−2; women, 57.3 ± 13 N cm−2; boys, 54 ± 14 N cm−2; and girls, 59.8 ± 15 N cm−2. These findings indicate that the increased muscle strength with maturation is not due to an increase in the specific tension of muscle; instead, it can be attributed to increases in muscle size, moment arm length and voluntary activation level

Interplay between body stabilisation and quadriceps muscle activation capacity.

The study aimed to distinguish the effect of stabilisation and muscle activation on quadriceps maximal isometric voluntary contraction (MVC) torque generation. Nine subjects performed (a) an MVC with restrained leg and pelvis (Typical MVC), (b) a Typical MVC with handgrip (Handgrip MVC), (c) an MVC focusing on contracting the knee extensors only (Isolated knee extension MVC), and (d) an MVC with unrestrained leg and pelvis (Unrestrained MVC). Torque and activation capacity between conditions were compared with repeated measures ANOVA and dependent t-tests. EMG (from eleven remote muscles) was compared using Friedman's and Wilcoxon. Typical MVC (277.2±49.6Nm) and Handgrip MVC (261.0±55.4Nm) were higher than Isolated knee extension MVC (210.2±48.3Nm, p<0.05) and Unrestrained MVC (195.2±49.7Nm, p<0.05) torque. Typical MVC (83.1±15.9%) activation was higher than Isolated knee extension MVC (68.9±24.3%, p<0.05), and both Typical MVC and Handgrip MVC (81.8±17.4%) were higher than Unrestrained MVC (64.9±16.2%, p<0.05). Only flexor carpi radialis, biceps brachii, triceps brachii and external oblique muscles showed EMG differences, with Isolated knee extension MVC consistently lower than Typical MVC or Handgrip MVC. Stabilisation of the involved segments is the prime concern allowing fuller activation of the muscle, reinforcing the need for close attention to stabilisation during dynamometry-based knee joint functional assessment

Is human Achilles tendon deformation greater in regions where cross-sectional area is smaller?

The Achilles is a long tendon varying in cross-sectional area (CSA) considerably along its length. For the same force, a smaller CSA would experience higher tendon stress and we hypothesised that these areas would therefore undergo larger transverse deformations. A novel magnetic resonance imaging-based approach was implemented to quantify changes in tendon CSA from rest along the length of the Achilles tendon under load conditions corresponding to 10, 20 and 30% of isometric plantar flexor maximum voluntary contraction (MVC). Reductions in tendon CSA occurring during contraction from the resting condition were assumed to be proportional to the longitudinal elongations within those regions (Poisson's ratio). Rather than tendon regions of smallest cross-sectional area undergoing the greatest deformations, the outcome was region-specific with the proximal (gastrocnemius) tendon portion showing larger transverse deformations upon loading compared to the distal portion of the Achilles (P<0.01). Transverse tendon deformation only occurred in selected regions of the distal Achilles tendon at 20% and 30% of MVC, but in contrast occurred throughout the proximal portion of the Achilles at all contraction levels (10, 20 and 30% of MVC; P<0.01). Calculations showed that force on the proximal tendon portion was ∼60% lower, stress ∼70% lower, stiffness ∼30% lower and Poisson's ratio 6-fold higher compared to the distal portion of the Achilles tendon. These marked regional differences in mechanical properties may allow the proximal portion to function as a mechanical buffer to protect the stiffer, more highly stressed, distal portion of the Achilles tendon from injury

The Achilles tendon is mechanosensitive in older adults: adaptations following 14 weeks versus 1.5 years of cyclic strain exercise.

The aging musculoskeletal system experiences a general decline in structure and function, characterized by a reduced adaptability to environmental stress. We investigated whether the older human Achilles tendon (AT) demonstrates mechanosensitivity (via biomechanical and morphological adaptations) in response to long-term mechanical loading. Thirty-four female adults (60-75 years) were allocated to either a medium-term (14 weeks; N=21) high AT strain cyclic loading exercise intervention or a control group (N=13), with 12 participants continuing with the intervention for 1.5 years. AT biomechanical properties were assessed using ultrasonography and dynamometry. Tendon cross-sectional area (CSA) was investigated by means of magnetic resonance imaging. A 22% exercise-related increment in ankle plantarflexion joint moment, along with increased AT stiffness (598.2±141.2 versus 488.4±136.9 N mm(-1) at baseline), Young's modulus (1.63±0.46 versus 1.37±0.39 GPa at baseline) and about 6% hypertrophy along the entire free AT were identified after 14 weeks of strength training, with no further improvement after 1.5 years of intervention. The aging AT appears to be capable of increasing its stiffness in response to 14 weeks of mechanical loading exercise by changing both its material and dimensional properties. Continuing exercise seems to maintain, but not cause further adaptive changes in tendons, suggesting that the adaptive time-response relationship of aging tendons subjected to mechanical loading is nonlinear