Evaluation of mechanical properties of the arm muscles when the complex movements are performed

[S. P. Srećković]

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Fizičko vaspitanje i sport - Nauke fizičkog vaspitanja , sporta i rekreacije / Physical Education and Sport - Science of Physical Education, Sports and Recreation

Mehaničke osobine mišića - sila, snaga i brzina, su predmet istraživanja primenjene fiziologije i humane lokomocije već decenijama unazad a me u najznačajnijim istraživanjima su zavisnost mišićne sile i snage u odnosu na brzinu bilo da se posmatraju pri skraćenju pojedinačnog mišića ili pri izvo enju složenih motoričkih zadataka. Ova svojstva se nazivaju relacija sila-brzina (F-V relacija) i relacija snaga-brzina (P-V relacija). Treba imati na umu da pošto je snaga proizvod sile i brzine, obrazac posmatrane F-V relacije direktno odre uje obrazac P-V relacije. Sa povećanjem ispoljene sile mišića mogućnost za ispoljavanje brzine njegovog skraćenja se smanjuje i obratno. Ovaj odnos sile i brzine u prvobitnim istraživanjima je predstavljen kao nelinearni (približno hiperboličan). Me utim novije studije su pokazale da bi njihov odnos dobijen primenom spoljašnjih opterećenja pri izvo enju složenih motoričkih zadataka mogao biti predstavljen približno linearno. Iako ove studije po pitanju oblika dobijenih F-V relacija pokazuju priličnu doslednost ipak ostaje pitanje u kojoj meri su linearne F-V i parabolične P-V relacije povezane. To se jasno može videti na mišićima ruku i ramenog pojasa. Tako e ostaje otvoreno pitanje pouzdanosti i validnosti njihovih parametara, kao i konkurentne validnosti dobijenih parametara. Iz tih razloga ciljevi studije su bili: (1) da se proceni linearnost i jačina F-V, kao i jačina proisteklih P-V relacija; (2) da se proceni pouzdanost parametara F-V i P-V relacija; (3) da se uporede parametri varijabli dobijenih iz prosečnih i maksimalnih vrednosti; (4) da se proveri konkurentna validnost dobijenih parametara sa direktno izmerenim vrednostima sile, brzine i snage. Da bi se rešili navedeni problemi testirana je relativno homogena grupa od 12 ispitanika koji su na Smit mašini vršili izbačaj sa grudi sa opsegom 20 kg do 70 kg (6 opterećenja). Pri tome je dobijen niz prosečnih i maksimalnih vrednosti za silu i brzinu koji su omogućavali primenu različitih regresionih modela na F-V i pripadajuću P-V relaciju. Iz linearne F-V relacije dobijeni su parametri sile (F0), brzine (V0) i snage (P0), kao i parametar nagiba relacije (α). Iz parabolične P-V relacije dobijen je parametar maksimalne snage (Pmax). Pored parametara relacija ispitanicima je izvršena direktna procena maksimalne sile pri potisku sa grudi kroz test jedno maksimalno ponavljanje (1RM) na istoj Smit mašini kao i direktna procena maksimalne brzine i maksimalne snage pri bacanju medicinke (od 450 g i 3 kg). Rezultati studije pokazuju da su F-V relacije približno linearne i visoko povezane, za individualne podatke sile i brzine, bilo da su uzete kao prosečne (r = 0,985) ili maksimalne (r = 0,988) vrednosti...

Mechanical properties of muscles - force, power and velocity, have been research subjects of applied physiology and human locomotion for decades now, and among the most important are dependence of muscle force and the power on the velocity, of either muscle shortening or when performing complex multi-joint tasks. These properties are referred to as the force-velocity (F-V) and power-velocity (P-V) relationship. It should be noted that since power is a product of force and velocity, the pattern of the observed F-V relationship directly determines the P-V relationship pattern. With increase of the manifested muscle force, a possibility for manifesting velocity of its shortening is decreased and vice versa. In seminal studies, this force and velocity relationship has been known as non-linear (approximately hyperbolic). However, recent studies have shown that their relationship, obtained by application of external loads when performing complex multi-joint tasks, could be presented as approximately linear. Although these studies regarding the shape of obtained F-V relationships have been fairly consistent, it still remains questionable to what extent both linear F-V and parabolic P-V relationships are associated. We can clearly see that in the arm and shoulder muscles. Furthermore, an open question remains regarding reliability and validity of their parameters, as well as concurrent validity of the obtained parameters. For those reasons, the aims of the study were: (1) to evaluate linearity and strength of F-V, as well as the strength of the associated P-V relationship; (2) to assess the reliability of F-V and P-V relationship parameters; (3) to compare variable parameters obtained from average and maximum values; (4) to check the concurrent validity of obtained parameters with directly measured values of force, velocity and power. To address the stated problems, a relatively homogeneous group of 12 subjects was tested on the Smith machine, on the loaded bench press throws, with the range of 20 kg to 70 kg (6 loads). A series of average and maximum force and velocity values was obtained and these data allowed applying various regression models to the F-V and associated P-V relationship. Linear F-V relationship provided parameters of force (F0), velocity (V0) and power (P0), as well as the relationship slope parameter (α). Parabolic P-V relationship provided maximum power parameter (Pmax). Besides the relationship parameters, direct assessment of the maximum force with bench press through a test of one maximum repetition (1RM) was performed on the subjects, on the same Smith machine, as well as direct evaluation of maximum velocity and power with medicine ball throw tests (from 450 g to 3 kg)...

regresija, izbačaj sa grudi, snaga, pouzdanost, validnost, testiranje

Regression, Bench press throw, Strength, Reliability, Validity, Testing

796.012(043.3)

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