Control of generation of arm extensor muscle force in isometric regime of strain of policemen

Abstract

The paper examines the output characteristics of mechanism responsible for generation of the set level of force over the arm extensor. The research was carried out using bench-press test in isometric conditions of strain, and it was carried out at the sample of 150 subjects - the students of Advanced School of Interior Affairs in Zemun - Beograd. During the experimental testing, the subjects were given 5 individual test attempts each, whereas the maximum muscle isometric power was measured during the first attempt FmaxIZO (F30%T, F50%T, F70%T i F90%T), and during the remaining four attempts the force achieved was compared with the set percentage of maximum force Fmax at the level of 30%, 50%, 70% and 90% (F30%o, F50%o, F70%o and F90%o). The other parameters defining the mechanisms of demonstration of isometric muscle force have also been measured such as: the speed of force generation in the unit of time, i.e. explosiveness - RFD, the speed of inclusion of motor units - K and the time required for generation of tested levels of force - t. All mentioned parameters were observed in relation to theoretically set module (level of force), as well as for the realized module (level of force). Testing was carried out by means of hardware-software system used in Diagnostic and Prognosis Laboratory (DPL) for Special Physical Education in the Advanced School of Interior Affairs in Zemun. In order to determine the existence of difference between individual variables a student t-test for pair samples was used. The results of a student t-test showed that there were statistically significant differences (p lt 0.01) between the mean value of the realized force and the mean value of theoretical level of force of FmaxIZO (30%, 50%, 70% and 90%, as mean, big and sub-maximum level of force) for all monitored variables, except for the achieved and realized force for variables F90%T F90%O (p = 0.74) and RFD90% T - RFD90%O (p = 0.22). Generally observed, based on the parameters monitored in the research (set level of force, speed of inclusion of motor units, speed of production of force and force production time), it can be concluded that the control of generation of maximum and set force values, set (achieved) values differ from maximum (theoretical) values. This is important for the methodology of training in Special Physical Education and sport, especially for understanding of mechanisms of neural-muscle adaptation during the training of muscle force.

U radu su ispitivane karakteristike autputa (out-put) mehanizma odgovornog za kontrolu stvaranja zadatog nivoa sile nad mišićima opružača ruku. Istraživanje je ostvareno primenom testa bendž-pres u izometrijskim uslovima naprezanja, a realizovano je nad uzorkom od 150 ispitanika. Ispitanici su tokom eksperimentalnog testiranja ostvarili po 5 pojedinačnih testovnih pokušaja, pri čemu je pri prvom pokušaju merena maksimalna mišićna izometrijska sila FmaxIZO (F30%T, F50%T, F70%T i F90%T), a u preostala četiri je merena ostvarena sila u odnosu na zadati procenat od maksimalne sile Fmax na nivou od 30%, 50%, 70% i 90% (F30%o, F50%o, F70%o i F90%o). Takođe, mereni su i ostali parametri koji definišu mehanizme ispoljavanja izometrijske mišićne sile i to: brzina stvaranja sile u jedinici vreme- na, tj. eksplozivnost - RFD, brzina uključenja motornih jedinica - K i vreme potrebno za generisanje ispitivanih nivoa sile - t. Svi pomenuti parametri su posmatrani u odnosu na teoretski zadat modul (nivo sile), kao i za ostvareni, tj. realizovani modul (nivo sile). Rezultati studentovog t-testa su pokazali da po- stoje statistički značajne razlike (p lt 0.01) između srednje vrednosti ostvarene sile i srednje vrednosti teoretskog nivoa sile od FmaxIZO (30%, 50%, 70% i 90% kao srednjeg, velikog i sub maksimalnog nivoa sile) kod svih praćenih varijabli, osim kod postignute i ostvarene sile kod varijabli F90%T - F90%O (p = 0.74) i RFD90% T RFD90%O (p = 0.22). Generalno, na osnovu parametara koji su praćeni u navedenom istraživanju može se zaključiti da se kontrola generisanja maksimalnih i zadatih iznosa sile, zadate (ostvarene) vrednosti od maksimalnih (teoretskih) razlikuju.