Parameter interdependence and success of skeletal muscle modelling

In muscle and movement modelling it is almost invariably assumed that force actually exerted is determined by several independent factors. This review considers the fact that length force characteristics are not a relatively fixed property of muscle but should be considered the product of a substantial number of interacting factors. Level of activation and recruitment are influential factors in relation to aspects of muscle architecture. For the level of activation effects of its short term history (potentiation, fatigue in sustained contractions) have to be taken into account and are reviewed on the basis of recent experimental results as well as available literature. History is also an important determinant for the effect of length changes. This concept is introduced on the basis of recent experimental evidence as well as available literature. Regarding effects of muscle architecture, the concepts of primary and secondary distribution of fibre mean sarcomere length are introduced as well as effects of muscle geometry for mono- and bi-articular muscles on those distributions. Implications for motor control are discussed and the need for intramuscular coordination indicated

Fatigue Induced Changes in Muscle Strength and Gait Following Two Different Intensity, Energy Expenditure Matched Runs

Purpose: To investigate changes in hip and knee strength, kinematics, and running variability following two energy expenditure matched training runs; a medium intensity continuous run (MICR) and a high intensity interval training session (HIIT). Methods: Twenty (10F, 10M) healthy master class runners were recruited. Each participant completed the HIIT consisting of six repetitions of 800 meters with a 1:1 work: rest ratio. The MICR duration was set to match energy expenditure of the HIIT session. Hip and knee muscular strength were examined pre and post both HIIT and MICR. Kinematics and running variability for hip and knee, along with spatiotemporal parameters were assessed at start and end of each run-type. Changes in variables were examined using both 2 x 2 ANOVAs with repeated measures and on an individual level when the change in a variable exceeded the minimum detectable change (MDC). Results: All strength measures exhibited significant reductions at the hip and knee (P < .05) with time for both run-types; 12% following HIIT, 10.6% post MICR. Hip frontal plane kinematics increased post run for both maximum angle (P < 0.001) and range of motion (P = 0.003). Runners exhibited increased running variability for nearly all variables, with the HIIT having a greater effect. Individual assessment revealed that not all runners were effected post run and that following HIIT more runners had reduced muscular strength, altered kinematics and increased running variability. Conclusion: Runners exhibited fatigue induced changes following typical training runs, which could potentially increase risk of injury development. Group and individual assessment revealed different findings where the use of MDC is recommended over that of P values

Ethnic minority organisations in Russia and Poland: a comparison challenge

This article proposes a framework for classifying ethnic minority organisations based on a broad combination of discursive and non-discursive criteria rooted in their political opportunities profile. One diasporic and one non-diasporic organisation were chosen for Russia and Poland, respectively. Diasporicity is understood according to William Safran’s criteria and Rogers Brubaker’s triadic configuration. The Russian study cases are Komi Voityr and the Russian Polish Congress; the Polish, the Silesian Autonomy Movement and the Belarussian House. The analysis of their status, activities, domestic and external political impact, localisation and role in the ‘triadic configuration’ has shown that the four cases are ethnic minority associations, and their legal status and scope of activities differ significantly. Their domestic political opportunities are rather scarce. Out of the four cases, just one organisation is an active part in Brubaker’s classical triadic configuration; its role is not traditional, ascribed to the respective ‘angle’. Although both Russian associations enjoy an official status, their activities are limited to the cultural, memorial and linguistic domains, primarily at the national level. In Poland, both associations act internationally as advocacy groups, and their activities are not confined to culture and language. Far from being universally applicable, the proposed classification framework can still add to the comparative ethnic politics toolkit

Methodological and anatomical modifiers of Achilles tendon moment arm estimates implications for biomechanical modelling: Implications for biomechanical modelling

This thesis was submitted for the degree of Doctor of Philosophy and was awarded by Brunel University.Moment arms are important in many contexts. Various methods have been used to estimate moment arms. It has been shown that a moment arm changes as a function of joint angle and contraction state. However, besides the influence of these anatomical factors, results from recent studies suggest that the estimation of moment arm is also dependent on the methods employed. The overall goal of this thesis was to explore the interaction between the methodological and anatomical influences on moment arm and their effect on estimates of muscle-tendon forces during biomechanical modelling. The first experiment was a direct comparison between two different moment arm methods that have been previously used for the estimation of Achilles tendon moment arm. The results of this experiment revealed a significant difference in Achilles tendon moment arm length dependent on the moment arm method employed. However, besides the differences found, results from both methods were well correlated. Based on these results, methodological differences between these two methods were compared across different joint angles and contraction states in study two. Results of experiment two revealed that Achilles tendon moment arms obtained using both methods change in a similar way as a function of joint angle and contraction state. In the third experiment, results from the first two experiments were used to determine how methodological and anatomical influences on Achilles tendon moment arm would change muscle-tendon forces during the task of submaximal cycling. Results of the third experiment showed the importance of taking the method, ankle angle and contraction state dependence of Achilles tendon moment arm into account when using biomechanical modelling techniques. Together, these findings emphasis the importance of carefully considering methodological and anatomical modifiers when estimating Achilles tendon moment arm

Muscle fiber typology substantially influences time to recover from high-intensity exercise

Human fast-twitch muscle fi- bers generate high power in a short amount of time but are easily fatigued, whereas slow-twitch fibers are more fatigue resistant. The transfer of this knowledge to coaching is hampered by the invasive nature of the current evaluation of muscle typology by biopsies. Therefore, a noninvasive method was developed to estimate muscle typology through proton magnetic resonance spectroscopy in the gastrocnemius. The aim of this study was to investigate whether male subjects with an a priori-determined fast typology (FT) are character- ized by a more pronounced Wingate exercise-induced fatigue and delayed recovery compared with subjects with a slow typology (ST). Ten subjects with an estimated higher percentage of fast-twitch fibers and 10 subjects with an estimated higher percentage of slow-twitch fibers underwent the test protocol, consisting of three 30-s all-out Wingate tests. Recovery of knee extension torque was evaluated by maximal voluntary contraction combined with electrical stimulation up to 5 h after the Wingate tests. Although both groups delivered the same mean power across all Wingates, the power drop was higher in the FT group (—61%) compared with the ST group (—41%). The torque at maximal voluntary contraction had fully recovered in the ST group after 20 min, whereas the FT group had not yet recovered 5 h into recovery. This noninvasive estimation of muscle typology can predict the extent of fatigue and time to recover following repeated all-out exercise and may have applications as a tool to individualize training and recovery cycles. NEW & NOTEWORTHY A one-fits-all training regime is present in most sports, though the same training implies different stimuli in athletes with a distinct muscle typology. Individualization of training based on this muscle typology might be important to optimize per- formance and to lower the risk for accumulated fatigue and potentially injury. When conducting research, one should keep in mind that the muscle typology of participants influences the severity of fatigue and might therefore impact the results

Foreign direct investments distribution in the Russian Federation: do spatial effects matter?

In this paper we explore the hypothesis of spatial effects in the distribution of Foreign Direct Investments (FDI) across Russian regions. We make use of a model, which describes FDI inflows as resulting from an agglomeration effect (the level of FDI in a given region depends positively on the level of FDI received by the regions in its neighbourhood) and remoteness effect (the distance of each Russian regions from the most important outflows countries). Considering a panel of 68 Russian regions over the period 2000-2004 we find that the two effects play a significant role in determining FDI inflows towards Russia. The two effects are also robust to the inclusion of other widely used explanatory variables impacting the level of FDI towards countries or regions (e.g. surrounding market potential, infrastructures, investment climate)

Maximize muscle mechanical output during the stretch-shortening cycle--the contribution of preactivation and stretch load

It is well documented that the stretch-shortening cycle (SSC), the most common muscle behavior, enhances muscle mechanical output. Stretch load and muscle preactivation level have been suggested as the two important factors regulating mechanical output. The purpose of this series studies is to systematically examine influences of the preactivation and the stretch load on muscle mechanical output during SSC. In the First study, a two dimensional lower extremity dynamic model was used to evaluate the influence of the approach on mechanical output. The peak summed power during the push-off phase demonstrated a quadratic trend across heights and appeared to be driven primarily by the ankle joint response. When an approach was used summed peak power was approximately 10% greater, regardless of the number of steps. In the Second study, we investigated muscle activity of seven major low extremity muscles during drop jumps. The surface EMG activities were full-wave rectified and averaged (aEMG) during the pre-activation (50ms before touchdown), downward and pushoff phases. The results showed that the aEMG of most tested muscles during the preactivation phase and the downward phase increased with more steps of the approach. This increase did not change the antagonist-agonist coactivation ratio, therefore would not attribute to knee joint injury. On the other hand, no aEMG changes were found with different drop heights. In the Third study, stretch load and preactivation were used as inputs for a muscle model to calculate muscle force, muscle velocity and muscle power. This model quantified how the different preactivation level and stretch load (velocity) affect the muscle mechanical output. Results showed that for low preactivation levels, increasing preactivation level could significantly increase gain in height for all stretch velocities we tested, but increasing stretch velocity may decrease the gain in height; for high preactivation levels, further increasing preactivation level may not increase gain in height. Over all, increasing preactivation enhances mechanical output due to increased active state level during SSCs; when preactivation is high, increasing stretch load enhances mechanical output due to increased positive work. Stretch load needs a high preactivation level to maximize the mechanical output

Modelling and in vivo evaluation of tendon forces and strain in dynamic rehabilitation exercises: a scoping review

Objectives Although exercise is considered the preferred approach for tendinopathies, the actual load that acts on the tendon in loading programmes is usually unknown. The objective of this study was to review the techniques that have been applied in vivo to estimate the forces and strain that act on the human tendon in dynamic exercises used during rehabilitation. Design Scoping review. Data sources Embase, PubMed, Web of Science and Google Scholar were searched from database inception to February 2021. Eligibility criteria Cross-sectional studies available in English or Spanish language were included if they focused on evaluating the forces or strain of human tendons in vivo during dynamic exercises. Studies were excluded if they did not evaluate tendon forces or strain; if they evaluated running, walking, jumping, landing or no dynamic exercise at all; and if they were conference proceedings or book chapters. Data extraction and synthesis Data extracted included year of publication, study setting, study population characteristics, technique used and exercises evaluated. The studies were grouped by the types of techniques and the tendon location. Results Twenty-one studies were included. Fourteen studies used an indirect methodology based on inverse dynamics, nine of them in the Achilles and five in the patellar tendon. Six studies implemented force transducers for measuring tendon forces in open carpal tunnel release surgery patients. One study applied an optic fibre technique to detect forces in the patellar tendon. Four studies measured strain using ultrasound-based techniques. Conclusions There is a predominant use of inverse dynamics, but force transducers, optic fibre and estimations from strain data are also used. Although these tools may be used to make general estimates of tendon forces and strains, the invasiveness of some methods and the loss of immediacy of others make it difficult to provide immediate feedback to the individuals.This work is part of a government-funded project supported by the University Teaching Training Programme (FPU) of the Ministry of Science, Innovation and Universities of Spain. Grant number: FPU17/00161. The University of Malaga has supported this study with the contribution of funds to support its publication in open access

Passive and Reflexive Categories in Languages of the Volga Region : An Areal Typological Study

All of the Volga region languages investigated in this study (Mordvin, Mari, and Chuvash) have a rich derivational morphology. In general linguistics terms, they all have a passive classified as a reflexive passive. The relationship between the derivative and the root verb is described using the valence roles of case grammar. The role of the first, or primary, actant is crucial in defining all the different meanings of the derived verbs in question. The main roles used to express the first actants are: AGENTIVE, ACTOR, NEUTRAL, EXPERIENCER, and FORCE. In Mordvin, passive sentences contain a special polyfunctional derivative suffix, -v-, which also renders the automative, reflexive, perfective and unintentional meaning, as well as dynamic modality. Besides the -v-, the rare and almost forgotten -t-, shares most of these meanings. Moreover, in many respects, these suffixes show parallel development. Contemporary speakers use these t-verbs to express unpleasant feelings and negative physiological states. t-derivatives can also be used to describe weather conditions as the only constituent part of a sentence, but this use is marginal. These two usages bring the t-derivatives close to the impersonal in the Indo-European languages. Furthermore, Mari and Chuvash have very similar suffixes, the reflexive-passive -ǝlt- or -Alt-, and the passive -l- and the reflexive -n-, respectively. Their passives do not permit an agent, and automative meanings are common, as are reflexives. My material proves that both Chuvash suffixes can have identical meanings. Interestingly, in all three languages, zero meaning occurs with intransitive root verbs. Finally, meteorological verbs in 14 Uralic languages were studied from a syntactic perspective. Some verbs have zero valence, others display a more or less semantically faded subject, while others feature an object. With causative transitive verbs, the prevailing restriction seems to be that either a subject or an object is possible, but both are not. Earlier, it was assumed that the sentence type V is Uralic, but according to my findings it is absent in some of the Samoyed languages and that the SV or VS type is more widely known. The introduction provides background information on the history of the Volga region and the many alternative ways of expressing passive and related meanings in the Uralic languages. An agent in a passive sentence is rare, and thus special attention is given to its expression. It seems obvious that the agent has been completely absent in passive sentences in the Uralic and Turkic languages. Many of these languages, however, have now developed an agent under the influence of the Indo-European languages. Furthermore, the construction with a dummy subject has started to spread and now occurs in the Saami and Finnic languages.Kaikilla tutkimukseen kuuluvilla Volgan seudun kielillä: mordvalla, marilla ja t uvassilla verbien morfologia on runsas lukuisine johtimineen. Myös niiden kaikkien passiivi on samaa tyyppiä, yleisen kielitieteen termein: refleksiivinen passiivi. Johdosten ja kantaverbien suhdetta on kuvattu sijakieliopin valenssiroolien avulla. Mordvan passiivilauseet muodostetaan v-johtimen avulla. Tällä johtimella on monia muitakin merkityksiä: automatiivinen, refleksiivinen, ei-intentionaalinen ja perfektiivinen, sillä voidaan ilmaista myös dynaamista modaalisuutta. Paitsi v-johdinta on mordvassa toinenkin, harvinainen ja miltei unohtunut -t-, jolla on melkein kaikki samat merkitykset. Monessa suhteessa näiden suffiksien kehitys on ollut rinnakkaista. Nykyiset mordvan kielten puhujat käyttävät t-johdoksia enimmäkseen epämiellyttävien tunteiden ja kielteisten fysiologisten tilojen ilmaisemiseen. t-johdoksia voidaan käyttää myös säätilojen kuvaamiseen jopa lauseen ainoana jäsenenä, mutta tämä on harvinaista. Nämä kaksi funktiota tuovat t-johdokset lähelle indoeurooppalaisten kielten impersonaaleja. Marilla ja t uvassilla on hyvin samanlaiset suffiksit, marin refleksiivis-passiivinen -ǝlt- tai -Alt-, t uvassin passiivinen -l- ja refleksiivinen -n-. Näiden kielten passiiveissa agentti ei ole sallittu, automatiiviset ja refleksiiviset merkitykset ovat yleisiä. Keräämäni aineiston perusteella molemmilla t uvassin johtimilla on samat merkitykset. Kaikista kolmesta kielestä löytyy lisäksi intransitiivisista kantaverbeistä 0-merkitys. Myös 14 uralilaisen kielen meteorologisia verbejä on tutkittu lauseopilliselta kannalta. Joidenkin verbien valenssi on 0, joten ne muodostavat lauseen yksinkin. Joskus subjekti on semanttisesti haalistunut, joskus objekti on läsnä. Usein transitiivisten verbien kanssa näyttää vallitsevan sellainen rajoitus, että vain subjekti (S) tai objekti voi olla läsnä, eivät molemmat. Aiemmin oletettiin, että pelkästä predikaattiverbistä koostuva lause (V) olisi uralilainen, mutta tutkimukseni paljastavat, että sen levinneisyys ei ulotu kaikkiin samojedikieliin. Sen sijaan tyyppi SV tai VS on kaikkialla tunnettu. Johdanto-osio valaisee Volgan seudun historiaa sekä uralilaisten kielten monia tapoja ilmaista passiivia ja muita sentapaisia merkityksiä. Erityistä huomiota kiinnitetään passiivilauseen agentin ilmiasuun. Nykyäänkin agentti on melko harvinainen sekä uralilaisissa että turkkilaisissa kielissä. Moniin niistä sellainen on kehittynyt indoeurooppalaisten kielten vaikutuksesta. Myös muodolliseen subjektiin verrattava vieraaseen vaikutukseen perustuva rakenne on alkanut levitä lännesta, sitä tavataan nyt saamelaisissa ja itämerensuomalaisissa kielissä

Utvrđivanje utjecaja bilateralnog deficita na izvedbu skoka s pripremom kod vrhunskih sprintera

The purpose of the present study was to investigate the bilateral deficit (BLD) in elite sprinters and examine the relationship between the BLD and sprint start performance. Twelve male elite sprinters (age: 22.41±3.39 years, 100m personal best: 10.82±.25s) performed sprint starts, two- and one-leg counter- -movement jumps (CMJ). A system of eight CCD cameras with a frequency of 200 Hz was used for the 3D kinematic measurements of CMJ. The ground reaction forces of sprint starts and vertical jumps were measured unilaterally and bilaterally by means of two independent and synchronized force platforms. Significantly lower values of force production of the front leg in the double start compared to the force production in the single start indicated the existence of a phenomenon similar to the bilateral deficit (BLD). The main findings of the present study were that: 1) lower values of BLD in the CMJ are related to higher peak force production of the rear leg in the double start of the sprint start (r=-.630; p=.000), 2) lower BLD in the CMJ is also related to higher total impulse of force on the blocks (r=-.550; p=.000) and 3) BLD values in CMJ are higher in elite sprinters compared to team sport athletes examined in the previous studies. The BLD measured in CMJ is a good indicator of a lower performance in the sprint start. As a consequence, the sprinters with higher BLD produced a lower total impulse of force on the blocks and lower block velocity, which are related to the overall 60m and 100m sprint performance.Cilj ovog istraživanja bio je utvrđivanje bilateralnog deficita (BLD) kod vrhunskih sprintera i istraživanje relacija između BLD i izvedbe niskog starta. Dvanaest vrhunskih muških sprintera (starih: 22.41±3.39 godina, osobni rekord u sprintu na 100 m: 10.82±.25 s) izvodili su niski start, te jednonožne i objenožne skokove s pripremom (CMJ). Sustav od osam CCD kamera frekvencije 220 Hz koristio se za 3D kinematičko mjerenje skokova s pripremom. Sile reakcije podloge sprinterskih startova i vertikalnih skokova mjerene su unilateralno i bilateralno pomoću dvije nezavisne i sinkronizirane tenziometrijske platforme. Statistički značajno slabije vrijednosti manifestiranja sile prednje noge kod objenožnog starta u usporedbi s manifestiranjem sile kod jednonožnog starta uputile su na postojanje fenomena koji je sličan fenomenu bilateralnog deficita. Glavni rezultati ovog istraživanja su: 1) niže vrijednosti bilateralnog deficita kod skoka s pripremom povezane su s očitovanjem veće vršne sile stražnje noge kod objenožnog starta (r=-.630; p=.000); 2) manji BLD kod skoka s pripremom je također povezan s većim ukupnim impulsom sile na startni blok (r=-.550; p=.000) i 3) vrijednosti BLD kod skoka s pripremom su veće kod vrhunskih sprintera u usporedbi sa sportašima iz sportskih igara testiranih u dosadašnjim istraživanjima. Vrijednosti BLD izmjerene pri izvedbi skoka s pripremom su vrlo dobri pokazatelji slabije izvedbe sprinterskog starta. U skladu s navedenim rezultatima provedenog istraživanja sprinteri s većim BLD proizveli su manji ukupan impuls sile na startni blok i nižu brzinu izlaska iz bloka, što je izravno povezano sa slabijim rezultatom sprinta na 60 i 100 metara