Control of posture with FES systems

One of the major obstacles in restoration of functional FES supported standing in paraplegia is the lack of knowledge of a suitable control strategy. The main issue is how to integrate the purposeful actions of the non-paralysed upper body when interacting with the environment while standing, and the actions of the artificial FES control system supporting the paralyzed lower extremities. In this paper we provide a review of our approach to solving this question, which focuses on three inter-related areas: investigations of the basic mechanisms of functional postural responses in neurologically intact subjects; re-training of the residual sensory-motor activities of the upper body in paralyzed individuals; and development of closed-loop FES control systems for support of the paralyzed joints

The Existence of Shared Muscle Synergies Underlying Perturbed and Unperturbed Gait Depends on Walking Speed

Muscle synergy theory assumes that the central nervous system generates a wide range of complex motor outputs by recruiting muscle synergies with different strengths and timings. The current understanding is that a common set of muscle synergies underlies unperturbed as well as perturbed walking at self-selected speeds. However, it is not known whether this is the case for substantially slower walking. The aim of this study was to investigate whether a shared set of muscle synergies underlies balance recovery responses following inward-and outward-directed perturbations in the mediolateral direction at various perturbation onsets and walking speeds. Twelve healthy subjects walked at three walking speeds (0.4, 0.6, and 0.8 m/s) on a treadmill while perturbations were applied to the pelvis using the balance assessment robot. A set of sixteen EMG signals, i.e., eight muscles per leg, was measured and decomposed into muscle synergies and weighting curves using non-negative matrix factorization. The muscles included were left and right tibialis anterior, soleus, gastrocnemius medialis, gastrocnemius lateralis, rectus femoris, hamstring, gluteus medius, and gluteus maximus. In general, four muscle synergies were needed to adequately reconstruct the data. Muscle synergies were similar for unperturbed and perturbed walking at a high walking speed (0.8 m/s). However, the number of similar muscle synergies between perturbed and unperturbed walking was significantly lower for low walking speeds (0.4 and 0.6 m/s). These results indicate that shared muscle synergies underlying perturbed and unperturbed walking are less present during slow walking compared to fast walking

Synergetic effects of K, Ca, Cu and Zn in human semen in relation to parameters indicative of spontaneous hyperactivation of spermatozoa

We have observed that sperm quality parameters indicative of spermatozoa hyperactivation such are lower “ linearity ” and “ straightness ” , and as showed by this research “ elongation ” , were more pronounced in patients with normal spermiogram compared to the group of men with reduced sperm motility who were undergoing routine in vitro fertilisation. The research encompassed 97 men diagnosed with normozoospermia (n = 20), asthenozoospermia (n = 54) and oligoasthenozoospermia (n = 23). The findings indicate that sperm quality of patients with normal spermiogram diagnosed according to WHO criteria, may be compro- mised by showing premature spontaneous hyperactivation which can decrease the chances of natural conception. We assessed synergistic effects of multiple chemical ele- ments in ejaculated semen to find if premature spontaneous hyperactivation of spermato- zoa can be a sign of imbalanced semen composition especially of elements K, Ca, Cu and Zn. Human semen samples showing low or high baseline status of chemical elements con- centrations were found in samples from all three diagnostic groups. However, correlation of K/Ca and Cu/Zn ratios, taking into account samples from all three groups of men, were neg- ative at statistical significance level p = 0.01. We tested if the negative correlation between K/Ca and Cu/Zn ratio works for greater number of semen samples. We found the negative correlation to be valid for 175 semen samples at statistical significance of p = 0.00002. The ratio of K/Ca and Cu/Zn, i.e. increased concentrations of K and Zn in comparison to concen- trations of Ca and Cu, were associated with a decrease of “ straightness ” in the group of men with normal spermiogram and pronounced spontaneous hyperactivation of spermato- zoa, implying that these elements act in synergy and that the balance of elements and not their absolute concentrations plays the major role in premature spermatozoa hyperactiva- tion in ejaculated semen

Kinematic, Dynamic and EMG Analysis of Drop Jumps in Female Elite Triple Jump Athletes

The purpose of the study was a biodynamic analysis of the kinematic, dynamic and EMG parameters of two types of drop jumps (heights of 25 cm and 45 cm). The sample of measured subjects included four female elite triple jump athletes, with their best results varying from 13.33 to 15.06 meters. The kinematic and dynamic parameters were calculated with the use of a bipedal tensiometric force plate, which was synchronized with nine CCD cameras. A 16-channel electromyography (BTS Pocket, Myolab) was used to analyze the EMG activation of the following muscles: m. erector spinae, m. gluteus, m. rectus femoris, m. vastus medialis, m. vastus lateralis, m. biceps femoris, m. soleus and m. gastrocnemius medialis. In the drop jump from a 25 cm height, the measured subjects achieved the following results: height of jump 43.37±5.39 cm and ground reaction force 2770±411 N. In comparison, results for the drop jump from a 45 cm height were: height of jump 45.22±4.65 cm and ground reaction force 2947±366 N. Vertical velocity of the take-off in the 25 cm drop jump was 2.77±0.19 ms–1 and in the 45 cm drop jump it was 2.86±0.15 ms–1. Observation of the EMG activation revealed the proximal to distal principle of muscle activation at work in both types of drop jumps. In the fi rst phase of the concentric phase the most active muscles were m. gluteus maximus and m. rectus femoris. The greatest activity of m. gastrocnemius medialis and m. soleus was noticed in the last third of the take-off action. Signifi cantly high EMG activation of m. vastus medialis and m. vastus lateralis was already shown in the fl ight phase prior to the feet making contact with the ground

Design of a series visco-elastic actuator for multi-purpose rehabilitation haptic device

<p>Abstract</p> <p>Background</p> <p>Variable structure parallel mechanisms, actuated with low-cost motors with serially added elasticity (series elastic actuator - SEA), has considerable potential in rehabilitation robotics. However, reflected masses of a SEA and variable structure parallel mechanism linked with a compliant actuator result in a potentially unstable coupled mechanical oscillator, which has not been addressed in previous studies.</p> <p>Methods</p> <p>The aim of this paper was to investigate through simulation, experimentation and theoretical analysis the necessary conditions that guarantee stability and passivity of a haptic device (based on a variable structure parallel mechanism driven by SEA actuators) when in contact with a human. We have analyzed an equivalent mechanical system where a dissipative element, a mechanical damper was placed in parallel to a spring in SEA.</p> <p>Results</p> <p>The theoretical analysis yielded necessary conditions relating the damping coefficient, spring stiffness, both reflected masses, controller's gain and desired virtual impedance that needs to be fulfilled in order to obtain stable and passive behavior of the device when in contact with a human. The validity of the derived passivity conditions were confirmed in simulations and experimentally.</p> <p>Conclusions</p> <p>These results show that by properly designing variable structure parallel mechanisms actuated with SEA, versatile and affordable rehabilitation robotic devices can be conceived, which may facilitate their wide spread use in clinical and home environments.</p

Planning and Programming The Fitness Preparation of Football Players : Undergraduate Thesis

Već dugi niz godina nogomet možemo svrstati među najpopularnije sportove u svijetu. Svakim danom imamo sve više igrača, ali i trenera koji samo zajednički mogu napraviti formulu uspjeha. U ovom završnom radu nastojala sam prikazati kako bi trebalo izgledati planiranje i programiranje kondicijske pripreme nogometaša. Opisana je kratka povijest nogometa, anatomija nogometaša te strukturalana analiza nogometa. Istaknula sam pojedine motoričke i funkcionalne sposobnosti koje su od izuzetne važnosti u svakodnevnom napretku. Uz to, opisala sam i neke vježbe koje se mogu izvoditi tijekom ili između sezona kako bi planiranje i programiranje bilo uspješno provedeno. Objasnila sam kako kroz smislenu periodizaciju treba raspodijeliti fokus kroz prednatjecateljsko, natjecateljsko i prijelazno razdoblje. Kroz ovaj završni rad ukazala sam na konstantu potrebu rada i napretka, odnosno nadogradnje u tehnici i taktici nogometa. Svakako je važno spomenuti i utjecaj prehrane, ali i nezaobilazne ozljede s kojima se moraju nositi nogometaši. U suštini, nogomet svakog dana postaje sve zahtjevniji sport i izuzetni su napori s kojima se igrači, koji se profesionalno bave nogometom, susreću tijekom svakodnevnih treninga i čestih utakmica. Samo uz iskusnog trenera koji u svakom trenutku zna što radi, sportaš može dosegnuti svoje granice i zadržati se na vrhu onoliko koliko mu tijelo to dopusti. U svemu treba naći balans pa tako i u nogometnoj igri i treninzima. Balans između trenera, nogometaša, treninga, utakmica, želja, potreba i mogućnosti. Ako se sve to dobro izbalansira, a da se pritom na ne naruši zdravlje, uspjeh je gotovo zagarantiran.Football has been one of the most popular sports in the world for many years. Every day we have more and more football players and coaches who can succeed only if they work together. This thesis tries to show what the planning and programming of fitness training of football players should look like. A short history of football, the anatomy of football players and a structural analysis of football are described. I highlighted certain motor and functional abilities that are extremely important in everyday progress. I have also described some exercises that can be performed during or between seasons to make planning and programming successful. Moreover, I explained how the focus should be distributed through the preparatory, competition and transition period. In this thesis I tried to point out the constant need for work and progress but also the need to upgrade football techniques and tactics. It is also important to mention the importance of diet, but also the inevitable injuries that footballers have to deal with. Football is becoming an increasingly demanding sport and everyday training and frequent matches put an enormous strain on professional football players. Only with the guidance of an experienced coach who knows what he is doing at all times can athletes reach their limits and stay on top of the game as long as their bodies allow. One needs to find a balance in everything, including football and training. A balance between a coach, a footballer, training, matches, desires, needs and opportunities. If all this is well balanced, without compromising one’s health, success is almost guaranteed

Sindrom delecije 22q11.2 u skupini hrvatskih bolesnika

Sindrom delecije 22q11.2 je poremećaj uzrokovan nedostatkom malog dijela dugog kraka kromosoma 22. Regiju 22q11 karakterizira prisutnost tzv. ponavljanja malog broja kopija (engl. LCR, low copy repeats) zbog kojih je ovo područje kromosoma vrlo nestabilno i podložno delecijama/duplikacijama uslijed pogrješnog sparivanja kromosoma tijekom nealelne homologne rekombinacije. Sindrom delecije 22q11.2. Taj sindrom povezuje se sa širokim spektrom poteškoća za pacijenta kao što su: karakteristične dismorfične crte lica, prirođene srčane grješke, anomalije nepca, disfunkcija imunosnog sustava što uključuje i autoimune bolesti, hipokalcijemija, i endokrinološke bolesti kao što su bolest štitnjače ili nedostatak hormona rasta, a javljaju se i gastrointestinalni problemi, teškoće hranjenja, anomalije bubrega, gubitak sluha, epilepsija, koštane abnormalnosti, poteškoće učenja i ponašanja. Simptomi ovog sindroma su različito prisutni, čak i unutar članova iste obitelji. Pojam 22q11.2 delecijski sindrom je krovni pojam koji se koristi za obuhvaćanje svih fenotipova povezanih s delecijom 22q11.2. Nedostatak gena smještenih na 22q11.2 regiji utječe na ranu morfogenezu ždrijela, srca, kostura i mozga. TBX1 je najvažniji gen te regije. U istraživanje uključena je skupina djece s delecijom 22q11.2 kojma je dijagnoza postavljena u razdoblju od 2005.-2018. godine u Klinici za dječje bolesti Zagreb. Cilj istraživanja bio je analizirati skupinu bolesnika s 22q11.2 delecijskim sindromom kako bi se definiralo vrijeme postavljanja dijagnoze i fenotipski spektar u djece dijagnosticirane s ovim mikrodelecijskim sindromom u Hrvatskoj. Delecija 22q11.2 je u 6 ispitanika bila otkrivena MLPA metodom, te se u svih 6 ispitanika procijenila na veličinu približno 3Mb,a kod preostala 3 ispitanika delecija je bila otkrivena CMA metodom, te je jedan ispitanik imao deleciju veličine 2,735kb, a preostala dva ispitanika 2,844kb. Dob postavljanja dijagnoze varira od dojenačke dobi do adolescencije, a u prosjeku je 4-5 godina. Analiza podataka prikupljenih o ispitanicima pokazala je da su kod njih prisutne mnoge anomalije opisane u sklopu 22q11.2 delecije. Od osnovnih obilježja 22q11.2 delecijskog sindroma 67% ispitanika imalo je prirođene srčane grješke, 22% anomalije nepca, 11% hipokalcijemiju, u 44% ispitanika bio je pronađen imunološki poremećaj te 66% ispitanika, koji su bili u predškolskoj i školskoj dobi, imalo je teškoće u upčenju, a u 50% ispitanika mlađih od 5 godina zabilježeno je zaostajanje u razvoju govora, te usporen kognitivni i motorički razvoj. 56% ispitanika imalo je karakteristične crte lica koje se povezuju s 22q11. delecijskim sindromom

Some predictors of work engagement

Cilj ovog istraživanja bio je ispitati postoje li razlike u radnoj angaţiranosti između radnika iz skupine „bijelih― i „plavih― ovratnika, te razlikuje li se struktura prediktora između te dvije skupine zaposlenika. Prediktori su bili temeljne samoevaluacije i tri psihološka stanja iz Teorije karakteristika posla (Hackman i Oldham, 1980). U istraživanju je sudjelovalo po 82 zaposlenika iz svake skupine. Kao što smo i pretpostavili, skupina bijelih ovratnika je pokazala višu razinu radne angažiranosti, u ukupnom rezultatu, ali i na svakoj komponenti, odnosno energičnosti, predanosti i zadubljenosti. Višestrukim hijerarhijskim analizama, utvrđeno je da se razlikuje struktura prediktora za dvije skupine ispitanika. Značajni prediktori za bijele ovratnike su temeljne samoevaluacije, doživljena smislenost i doživljena odgovornost, a za plave ovratnike samo doživljena smislenost.The aim of this study was to test whether there are differences in work engagement between white-collar and blue-collar workers, and if there is a difference in predictors structure for two groups. Predictors were core self-evaluations and three critical psychological states from Job characteristic model (Hackman and Oldham, 1980). The data was collected from 82 workers for each group. As expected, white-collar workers reported higher leves of work engagement, in total result and on each of the component, respectively vigor, dedication and aborption, than blue-collar workers. Multiple hierarchical analyses showed difference between predictors structure for two groups. Significant predictors for white-collar workers are core self-evaluations, experienced meaningfulness and experienced responsibility, and only experienced meaningfulness for blue-collar workers

Planning and Programming The Fitness Preparation of Football Players : Undergraduate Thesis

Već dugi niz godina nogomet možemo svrstati među najpopularnije sportove u svijetu. Svakim danom imamo sve više igrača, ali i trenera koji samo zajednički mogu napraviti formulu uspjeha. U ovom završnom radu nastojala sam prikazati kako bi trebalo izgledati planiranje i programiranje kondicijske pripreme nogometaša. Opisana je kratka povijest nogometa, anatomija nogometaša te strukturalana analiza nogometa. Istaknula sam pojedine motoričke i funkcionalne sposobnosti koje su od izuzetne važnosti u svakodnevnom napretku. Uz to, opisala sam i neke vježbe koje se mogu izvoditi tijekom ili između sezona kako bi planiranje i programiranje bilo uspješno provedeno. Objasnila sam kako kroz smislenu periodizaciju treba raspodijeliti fokus kroz prednatjecateljsko, natjecateljsko i prijelazno razdoblje. Kroz ovaj završni rad ukazala sam na konstantu potrebu rada i napretka, odnosno nadogradnje u tehnici i taktici nogometa. Svakako je važno spomenuti i utjecaj prehrane, ali i nezaobilazne ozljede s kojima se moraju nositi nogometaši. U suštini, nogomet svakog dana postaje sve zahtjevniji sport i izuzetni su napori s kojima se igrači, koji se profesionalno bave nogometom, susreću tijekom svakodnevnih treninga i čestih utakmica. Samo uz iskusnog trenera koji u svakom trenutku zna što radi, sportaš može dosegnuti svoje granice i zadržati se na vrhu onoliko koliko mu tijelo to dopusti. U svemu treba naći balans pa tako i u nogometnoj igri i treninzima. Balans između trenera, nogometaša, treninga, utakmica, želja, potreba i mogućnosti. Ako se sve to dobro izbalansira, a da se pritom na ne naruši zdravlje, uspjeh je gotovo zagarantiran.Football has been one of the most popular sports in the world for many years. Every day we have more and more football players and coaches who can succeed only if they work together. This thesis tries to show what the planning and programming of fitness training of football players should look like. A short history of football, the anatomy of football players and a structural analysis of football are described. I highlighted certain motor and functional abilities that are extremely important in everyday progress. I have also described some exercises that can be performed during or between seasons to make planning and programming successful. Moreover, I explained how the focus should be distributed through the preparatory, competition and transition period. In this thesis I tried to point out the constant need for work and progress but also the need to upgrade football techniques and tactics. It is also important to mention the importance of diet, but also the inevitable injuries that footballers have to deal with. Football is becoming an increasingly demanding sport and everyday training and frequent matches put an enormous strain on professional football players. Only with the guidance of an experienced coach who knows what he is doing at all times can athletes reach their limits and stay on top of the game as long as their bodies allow. One needs to find a balance in everything, including football and training. A balance between a coach, a footballer, training, matches, desires, needs and opportunities. If all this is well balanced, without compromising one’s health, success is almost guaranteed