Dragan Mirkov, Aleksandar Nedeljković
University of Belgrade - Faculty of Medicine, Faculty of Sports and Physical Education.

indent Abstract
The subject of this research is examination of sensitivity of isometric power test (Fmax) and certain tests for evaluation of the speed of power development (tests BRS), at the changes caused by strength training. Upon familiarization with the experimental prerequisites, 8 tests (experimental group) before and after the intensive six week strength training, had a task to develop as fast as possible the maximal isometric powers of flexors and extensors in the elbow joint. The remaining 13 examinees were also tested prior to and after the period of six weeks, but without training between two tests. Apart form maximal power (Fmax) three different criteria for evaluation of BRS were conducted from the noted time function of power signal: time interval from the moment when the achieved level was equal to 30% Fmax to the moment when the level of 70% Fmax (T30%-7o%) was achieved, the maximum of the first source o the power signal in time (PDF) as well as the maximum of the power source in time relativized by the maximal power (RDF/Fmax). Comparing the results prior to and after the test in the experimental group for flexors, as a consequence of training, the significant improvement of Fmax and RFD was noted while there was a negligent effect on the remaining constants. Also, none of the results in post testing (extensors), upon the repeated measurement, did not differ from those obtained in pre-testing. The connection of Fmax with RFD and T30-70% with RFD/ Fmax was statistically significant. When it was compared to the results obtained at the extensors, it was noted that the middle value Fmax and RFD are greater at flexors while RFD/Fmax and T30%-70% were not significantly different. The reliability of the repeated measurement (pre/post-test) measured by 'intraclass' correlation factors, was greater at flexors than at extensors. The reliability of most of the tests at flexors was estimated as good (ICC coefficients in the interval from 0.6 to 0.8). The obtained results suggest that besides Fmax even RFD is sensitive to changes provoked by the applied type of training, while RDF/F i.e. T30%-70% are not. Although between pre and post test 6 weeks passed, the reliability of Fmax and RFD remained satisfactory.