Razvoj programske podrške za sveobuhvatnu analizu varijabli dobivenih mjerenjima pomoću tenziometrijske platforme

This technical note summarizes the development of a software solution aimed at data acquisition and analyses and results reporting on the tests performed on a force plate. In the introduction, the history of force plate development is reviewed, followed by a description of the process of ground reaction force measurement data acquisition and parameterization. The second part is a short description of five groups of the force plate based tests used to evaluate human movement: (i) static balance, (ii) dynamic balance, (iii) locomotion and body transfer, (iv) fast alternating movements, and (v) strength and power tests. This is followed by the main part in which we present a technical solution, describe the software’s conceptual structure by test modules, point out the most important functions and graphically present a concise overview of the tests that the software is designed to handle. We conclude with ideas for further development and future directions.Ovaj tehnički rad objašnjava razvoj softverskoga rješenja za prikupljanje i analizu podataka te oblikovanje izvješća o rezultatima testova provedenih na tenziometrijskoj ploči. U uvodu je predstavljen pregled povijesti razvoja tenziometrijskih platforma, nakon čega slijedi opis postupaka za prikupljanje i parametrizaciju rezultata mjerenja sile reakcije podloge. Drugi dio je kratak opis pet skupina testova na tenziometrijskim pločama za procjenu ljudskoga kretanja: (i) testovi statičke ravnoteže, (ii) testovi dinamičke ravnoteže, (iii) testovi lokomocije i aktivnosti transfera tijela, (iv) testovi brzih alternativnih pokreta i (v) testovi snage. Nakon toga slijedi glavni dio u kojemu je predstavljeno tehničko rješenje i koncepcijska modularna struktura softvera. Istaknute su glavne funkcije, a grafički su predstavljeni, u pregledu, svi testovi koje aplikacija podržava. Na kraju su istaknute neke ideje o daljnjemu razvoju i budućoj praktičnoj primjeni ovdje predstavljene programske podrške

Razvoj programske podrške za sveobuhvatnu analizu varijabli dobivenih mjerenjima pomoću tenziometrijske platforme

This technical note summarizes the development of a software solution aimed at data acquisition and analyses and results reporting on the tests performed on a force plate. In the introduction, the history of force plate development is reviewed, followed by a description of the process of ground reaction force measurement data acquisition and parameterization. The second part is a short description of five groups of the force plate based tests used to evaluate human movement: (i) static balance, (ii) dynamic balance, (iii) locomotion and body transfer, (iv) fast alternating movements, and (v) strength and power tests. This is followed by the main part in which we present a technical solution, describe the software’s conceptual structure by test modules, point out the most important functions and graphically present a concise overview of the tests that the software is designed to handle. We conclude with ideas for further development and future directions.Ovaj tehnički rad objašnjava razvoj softverskoga rješenja za prikupljanje i analizu podataka te oblikovanje izvješća o rezultatima testova provedenih na tenziometrijskoj ploči. U uvodu je predstavljen pregled povijesti razvoja tenziometrijskih platforma, nakon čega slijedi opis postupaka za prikupljanje i parametrizaciju rezultata mjerenja sile reakcije podloge. Drugi dio je kratak opis pet skupina testova na tenziometrijskim pločama za procjenu ljudskoga kretanja: (i) testovi statičke ravnoteže, (ii) testovi dinamičke ravnoteže, (iii) testovi lokomocije i aktivnosti transfera tijela, (iv) testovi brzih alternativnih pokreta i (v) testovi snage. Nakon toga slijedi glavni dio u kojemu je predstavljeno tehničko rješenje i koncepcijska modularna struktura softvera. Istaknute su glavne funkcije, a grafički su predstavljeni, u pregledu, svi testovi koje aplikacija podržava. Na kraju su istaknute neke ideje o daljnjemu razvoju i budućoj praktičnoj primjeni ovdje predstavljene programske podrške

Quantification of Inter-Limb Symmetries With Rate of Force Development and Relaxation Scaling Factor

The inter-limb (a)symmetries have been most often assessed with the tests that quantify the maximal muscle capacity. However, the rapid force production and relaxation during submaximal tasks is equally important for successful sports performance. This can be evaluated with an established rate of force development and relaxation scaling factor (RFD-SF/RFR-SF). The aims of our study were (1) to assess the intra-session reliability of shortened RFD-SF/RFR-SF protocol and its absolute and symmetry outcome measures, (2) to compare the main absolute RFD-SF/RFR-SF outcome measures (slopes of RFD-SF and RFR-SF: kRTD–SF and kRFR–SF, theoretical peak RFD/RFR: TPRFD and TPRFR) across gender and sports groups, and (3) to compare inter-limb symmetries across gender and sports groups for main outcome measures (kRFD–SF, kRFR–SF, TPRFD, and TPRFR). A cross-sectional study was conducted on a group of young health participants (basketball and tennis players, and students): 30 in the reliability study and 248 in the comparison study. Our results showed good to excellent relative and excellent absolute reliability for the selected absolute and symmetry outcome measures (kRFD–SF, kRFR–SF, TPRFD, and TPRFR). We found significantly higher absolute values for kRFD–SF and TPRFD in males compared to females for the preferred (kRFD–SF: 9.1 ± 0.9 vs. 8.6 ± 0.9/s) and the non-preferred leg (kRFD–SF: 9.1 ± 0.9 vs. 8.5 ± 0.8/s), while there was no effect of sport. Significantly lower symmetry values for kRFR–SF (88.4 ± 8.6 vs. 90.4 ± 8.0%) and TPRFR (90.9 ± 6.8 vs. 92.5 ± 6.0%) were found in males compared to females. Moreover, tennis players had significantly higher symmetry values for kRFR–SF (91.1 ± 7.7%) and TPRFR (93.1 ± 6.0%) compared to basketball players (kRFR–SF: 88.4 ± 8.7% and TPRFR: 90.9 ± 6.7%) and students (kRFR–SF: 87.6 ± 8.7% and TPRFR: 90.5 ± 6.7%). Our results suggest that the reduced RFD-SF/RFR-SF protocol is a valuable and useful tool for inter-limb (a)symmetry evaluation. Differences in symmetry values in kRFR–SF and TPRFR (relaxation phase) were found between different sports groups. These may be explained by different mechanisms underlying the muscle contraction and relaxation. We suggest that muscle contraction and relaxation should be assessed for in-depth inter-limb symmetry investigation

Vpliv nenadne razbremenitve sile v vodoravni smeri na stabilnost pri Taijiquan

Taiji quan (TJQ) je borilna veščina, ki poskuša razvijati čim bolj učinkovito gibanje v borbi. Njegov osnovni namen je, da poskušamo zmanjšati nasprotnikovo stabilnost in ga prisiliti k izgubi ravnotežja medtem, ko sami ravnotežja ne izgubimo. Namen raziskave je bil primerjati stabilnost pri nenadni vodoravni razbremenitvi med skupino udeležencev, ki redno vadi TJQ in sicer vadbo v dvoje in skupino, ki s tako obliko vadbe ni imela še nobenih izkušenj. V vsako skupino je bilo vključenih 7 oseb. V študiji smo uporabili dvojno ploščo za merjenje sil na podlago in mehanizem za vodoravno obremenitev s sprožilcem za nenadno razbremenitev. Merjenca smo obtežili z 7,5 kg utežjo tako, da je sila nanj delovala vodoravno v višini njegovih bokov. Merili smo spreminjanje sile navpično na podlago in premik centra pritiska v smeri naprej-nazaj, po nenadni razbremenitvi. Primerjali smo največji amplitudi obeh parametrov in izračunali hitrost in pospešek gibanja v smeri naprej-nazaj. Rezultati so pokazali, da je skupina, ki vadi TJQ, proizvedla veliko manjše spremembe sile navpično na podlago, kot kontrolna skupina. Razmerje med amplitudama je bilo 115+-49 N proti 182+-88 N (p=0,002). Nasprotno se je pri premiku centra pritiska v smeri naprejnazaj izkazalo, da med obema skupinama ni večjih razlik, razmerje je 0,189+-0,038 m proti 0,194+-0,051 (p=0,564). Z obremenitvijo v vodoravni smeri nismo neposredno vplivali na spremembo navpične sile na podlago, zato lahko predvidevamo, da so bile spremembe te sile posledica refleksnega mišičnega odziva. Skupina, ki vadi TJQ, se je odzvala z manjšimi silama v navpični smeri, iz česar lahko sklepamo, da je imela boljšo kontrolo nad držo in tudi boljšo stabilnost.Taiji quan (TJQ) is a martial art that tries to develop the most efficient movement in battle. Its primary purpose is to try to reduce the opponent\u27s stability and force him/her to lose balance, without losing his own balance. The purpose of this study was to compare the stability after sudden horizontal release between a group of participants who practice TJQ regularly and another group whose participants have no experience of TJQ. Each group consisted of 7 people. We used the double force plate to measure forces on the ground and a mechanism to apply the load to the participant horizontally with a trigger for sudden release of the load. The participant was loaded witha 7.5 kg weight. The direction of the force was horizontal at the height of hips. We measured the change of vertical ground reaction force (Fz), and the shift of center of pressure (COP) in anterior - posterior direction (A-P). We compared the maximum amplitude of both parameters and calculated the velocity and acceleration of movement in the direction of A-P after the sudden release of the load. The results showed that the group who practices TJQ produced a much smaller change in ground reaction force Fz than the control group. The relationship between the amplitude was 115+-49 N N vs. 182+-88 N (p = 0.002). By contrast, we didn\u27t find significant difference between the two groups in movement of the COP, the ratio was 0.189+-0.038 m vs. 0.194+-0.051 m (p = 0.564). The load in the horizontal direction didn\u27t directly affected the vertical force on the ground, so we can assumed that the changes of this force are consequence of reflex muscle response. The response of the TJQ group was significantly smaller, from which we can conclude, that it had better postural control and better stability

Biomehanika i energetika vožnje bicikla uzbrdo: pregled istraživanja

The winners of the major cycling 3-week stage races (i.e. Giro d’Italia, Tour de France, Vuelta a Espana) are usually riders who dominate in the uphill sections of the race. Amateur cyclists, however, will often avoid uphill terrain because of the discomfort involved. Therefore, understanding movement behavior during uphill cycling is needed in order to find an optimum solution that can be applied in practice. The aim of this review is to assess the quality of research performed on biomechanics and the energetics of uphill cycling. Altogether we have analyzed over 40 articles from scientific and expert periodicals that provided results on energetics, pedal and joint forces, economy and efficiency, muscular activity, as well as performance and comfort optimization during uphill cycling. During uphill cycling, cyclists need to overcome gravity and in order to achieve this, some changes in posture are necessary. The main results from this review are that changes in muscular activity are present, while on the other hand pedal forces, joint dynamics, and cycling efficiency are not substantially altered during seated uphill cycling compared to cycling on level terrain. In contrast, during standing uphill cycling, all of the previously mentioned measures are different when comparing either seated uphill cycling or level terrain cycling. Further research should focus on outdoor studies and steeper slopes.Pobjednici najvećih biciklističkih 3-tjednih etapnih utrka (npr. Giro d’Italia, Tour de France, Vuelta a Espana) su najčešće biciklisti koji dominiraju u segmentima utrke s usponima. Amaterski biciklisti, pak, često izbjegavaju uzbrdice zbog neugodnosti koju vožnja uzbrdo izaziva. Zbog toga je nužno poznavati i razumjeti kretanje tijekom vožnje bicikla uzbrdo da bi se izabralo optimalno motoričko ponašanje koje se može primijeniti u praksi. Cilj je ovoga rada ocijeniti kvalitetu istraživanja o biomehanici i energetskim zahtjevima bicikliranja uzbrdo. Ukupno smo analizirali 40 članaka iz znanstvenih i stručnih časopisa koji su istražili energetiku, sile pedaliranja i sile u zglobovima, ekonomičnost i učinkovitost mišićne aktivnosti te optimizaciju izvedbe i udobnosti tijekom vožnje bicikla uzbrdo. Za vožnje po uzbrdici biciklisti moraju svladati gravitaciju, a da bi u tome uspjeli, potrebne su određene promjene u položaju tijela. Glavni rezultat ovog preglednog rada jest zaključak da se mišićna aktivnost mijenja tijekom vožnje bicikla uzbrdo u sjedu usporedbi s vožnjom po ravnom terenu, dok se s druge strane, sile na pedalama, dinamika zglobova i učinkovitost vožnje ne mijenjaju značajno. Suprotno tome, tijekom vožnje bicikla uzbrdo u stojećem položaju sve ranije spomenute mjere su različite od onih zabilježenih u vožnji bicikla uzbrdo u sjedu ili u vožnji po ravnom terenu. Daljnja istraživanja trebala bi se usmjeriti na istraživanja provedena u vanjskim uvjetima i na strmijim usponima

Validity and reliability of the Daily Activity Behaviours Questionnaire (DABQ) for the assessment of 24-h movement behaviours among adolescents

Measurement of the time spent in sleep, sedentary behaviour, and physical activity across the full 24-h day (i.e. 24-h movement behaviours) is essential for time-use research among adolescents. However, selfreported questionnaires for the assessment of 24-h movement behaviours are scarce. The aim of this study was to examine the validity and reliability of recently developed Daily Activity Behaviours Questionnaire (DABQ) for the assessment of time spent in sleep, sedentary behaviour, light physical activity, and moderateto-vigorous physical activity among adolescents. A convenience sample of 59 high-school students (34 female, age range: 15–18 years) was recruited. Participants were asked to complete a web-based DABQ at two occasions (two-weeks apart) to examine test-retest reliability of the DABQ, and to wear activPAL accelerometer to examine convergent validity of the DABQ. The test-retest reliability correlation coefficients (ICC) for the durations of sleep, sedentary behaviour, light physical activity, and moderate-to-vigorous physical activity were 0.49, 0.64, 0.51, and 0.66, respectively. Convergent validity correlation coefficients (Spearman’s ρ) were 0.51, 0.38, 0.25, and 0.53, respectively. Our findings are comparable with the reliability and validity of most existing sleep, sedentary behaviour, or physical activity questionnaires among adolescents. However, DABQ is one of the first validated questionnaires that resonates with the emerging 24-h movement paradigm. The observed reliability and validity are indicating satisfactory measurement properties of the DABQ to be used in time-use research among adolescents

Reaktionsänderungen auf transkraniale magnetische Stimulation während wiederholten isometrischen Kontraktionen

Ten healthy male students (age 22.1+2.3 years), without neurological disorders, volunteered for the study. Muscle fatigue of the first dorsal interosseus muscle was studied during repeated isometric voluntary contractions until exhaustion. Transcranial magnetic stimulation was used to elicit motor-evoked potentials and mechanical responses in the exercised muscle. The averages of 6 responses were analyzed pre-exercise, every 25 contractions during the exercise and during the recovery phase. The average of isometric contractions until the fatiguing of a subject was 175 repetitions. During the protocol, amplitudes of mechanical as well as electrophysiological responses changed significantly (P<.001 and P<.002, respectively). A potentiation of the electrophysiological responses was prominent only at the beginning of the task while twitch force remained increased until the final fatiguing. Both measures were depressed after the task termination. However, diminishment of electromyographic responses remained more prominent. During the recovery phase twitch force fully recovered, while electrophysiological potentials remained depressed (P<.05). During and after the fatiguing task, modulations of mechanical and electrophysiological responses to transcranial magnetic stimulation were not parallel. Additional qualitative analysis of the electrophysiological responses revealed a systematic shift from biphasic responses in pre-tests to polyphasically shaped ones during the fatigue and recovery phase. This phenomenon could indicate a shift from monosynaptic to oligosynaptic corticospinal projections which could namely cause temporally different recruitment of the motor units. The modulatory mechanism is most probably of supraspinal origin while F wave as a measure of peripheral excitability did not show significant modifications through the experiment.Uvod Posljednjih petnaest godina neki istraživači koriste transkranijalnu magnetsku stimulaciju kako bi istražili kortikospinalne mehanizme umora. Njihovi izvještaji ne slažu se oko modifikacije motoričkih evociranih potencijala za vrijeme i nakon produžene mišićne aktivnosti. Naše je istraživanje stoga osmišljeno kako bi se ispitala promjena neurofizioloških i mehaničkih odgovora na transkranijalnu magnetsku stimulaciju za vrijeme ponavljane iscrpljujuće izometričke kontrakcije. Status perifernih modulatornih mehanizama testiran je valovima M i F. Metoda Eksperiment je proveden na deset zdravih studenata (u od dobi od 22±2.3 godine) bez ikakvih neuroloških poremetnji. Mišićni umor prvog dorzalnog interkostalnog mišića proučavao se za vrijeme ponavljane voljne izometričke kontrakcije (ponavljane kontrakcije u trajanju 6 sekundi s pauzom u trajanju 4 sekunde). Ispitanici su ovu aktivnost izvodili sve dok su bili sposobni proizvoditi mišićnu silu veću od 60% njenog početnog maksimuma. Transkranijalna magnetska stimulacija korištena je kako bi se dobio motorički evocirani potencijal i mehanički odgovori u aktivnom mišiću. U prosjeku je šest odgovora analizirano prije vježbe, te svaka 25. kontrakcija za vrijeme vježbe i u fazi oporavka. Rezultati Prosječan broj izometričkih kontrakcija prije nastupanja umora kod ispitanika bio je 175 ponavljanja. Za vrijeme vježbe, amplitude mehaničkih, kao i električnih odgovora značajno su se mijenjale (p<.001 i p<.002). Potencijal elektrofizioloških odgovora bio je istaknut samo na početku zadatka dok je sila kontrakcije još bila visoka sve do nastupanja konačnog umora. Obje su se mjere smanjile nakon završetka zadatka. Ipak, smanjenje elektromiografskih odgovora bilo je veće. U fazi oporavka sila kontrakcije se u potpunosti oporavila, dok je elektrofiziološki potencijal i dalje ostao smanjen (p<.05). Rasprava i zaključak Za vrijeme i nakon umarajućeg zadatka, modulacija mehaničkih i elektrofizioloških odgovora na transkranijalnu magnetsku stimulaciju nije tekla paralelno. Dodatna kvalitativna analiza elektrofizioloških odgovora pokazala je sistematičan prijelaz sa bifazičnog odgovora, zabilježenog u mjerenju prije testa, na polifazičan odgovor koji se javlja u fazi umaranja i oporavka. Ovaj fenomen može ukazivati na prijelaz s monosinaptičkih na oligosinaptičke kortikospinalne projekcije što, naime, može uzrokovati vremenski različitu selekciju i aktivaciju motoričkih jedinica. Amplituda vala M, dobivena stimulacijom ulnarnog živca zgloba šake nakon produžene ponavljane umarajuće voljne izometričke kontrakcije, nije se značajno razlikovala od iste dobivene stimulacijom primijenjenom prije ovog iscrpljujućeg protokola. Val F, kao mjera periferne pobuđenosti, nije pokazao značajne modifikacije za vrijeme eksperimenta. Na temelju dobivenih rezultata moguće je isključiti utjecaj perifernih faktora na ove modulacije. Mehanički odgovori na transkranijalnu magnetsku stimulaciju nisu striktno odražavali elektrofiziološke evocirane potencijale, štoviše, ponašali su se potpuno različito u nekim točkama mjerenja. Za ukupni obrazac evociranih odgovora najvjerojatnije su odgovorni kortikalni mehanizmi. Čini se da je razina pobuđenosti evociranih odgovora snažno pod utjecajem aferentnog ulaza. Nesrazmjer između mehaničkih i elektrofizioloških odgovora mogao bi se objasniti modulacijom cervikalnog propriospinalnog sustava te mehaničkim objašnjenjem povezanim s ulogom mišićne čvrstoće u produkciji sile mišićnog trzaja.10 gesunde Studenten (im Alter 22.1+2.3 Jahre) ohne neurologische Störungen nahmen an der Studie freiwillig teil. Die Ermüdung des ersten dorsalen zwischen den Knochen liegenden Muskels wurde während wiederholten isometrischen freiwilligen Kontraktionen bis zur Erschöpfung untersucht. Die transkraniale magnetische Stimulation wurde angewandt, um motorisch-provozierte Potenziale und mechanische Reaktionen im betreffenden Muskel zu bekommen. Die durchschnittlichen Werte von 6 Reak-tionen wurden vor der Übung analysiert, nach jeder 25sten Kontraktion, sowie während der Übung und während der Erholungsphase. Die durchschnittlichen isometrischen Kontraktionen bis zur Ermüdung des Probanden betrugen 175 Wiederholungen. Im Laufe des Protokolls änderten sich wesentlich die Amplituden der mechanischen und der elektrophysiologischen Reaktionen (P<.001 und P<.002). Die Potentiation von elektrophysiologischen Reaktionen war nur am Anfang der Aufgabe zu merken, während die erhöhte Reaktionskraft bis zur endgültigen Erschöpfung blieb. Die beiden Werte nahmen nach der Aufgabe ab. Die Abnahme der elektromyographischen Reaktionen war aber auffälliger. Während der Erholungsphase wurde die Reaktionskraft völlig zurückgewonnen, aber die elektrophysiologischen Potenziale blieben niedrig (P<.05). Während und nach der Aufgabe waren die Modulationen von mechanischen and elektrophysiologischen Reaktionen auf transkraniale magnetische Stimulation nicht parallel. Eine zusätzliche Qualitätsanalyse elektrophysiologischer Reaktionen brachte zum Vorschein eine systematische Änderung von biphasischen Reaktionen vor den Tests zu polyphasischen Reaktionen während der Ermüdungs- und Erholungsphase. Dieses Phänomen könnte auf die Änderung von monosynaptischen zu oligosynaptischen kortikospinalen Projektionen hindeuten, was nämlich zur Folge eine zeitlich verschiedene Rekrutierung motorischer Einheiten haben könnte. Der Modulatormechanismus ist höchstwahrscheinlich supraspinalen Ursprungs, während die F Welle, als eine Größe der peripheren Erregbarkeit, keine wesentlichen Modifikationen während des Experiments aufzeigte