IMMEDIATE EFFECTS OF POST-ISOMETRIC RELAXATION AND STATIC STRETCHING ON QUADRICEPS MUSCLE DURING VERTICAL JUMP IN VOLLEY BALL AND BASKETBALL PLAYERS

Background and Aim: In today sports such as volleyball and basketball, Vertical Jump is considered as important component that enhance the performance of athlete. The aim of this study was to determine the effect of muscle energy technique on vertical jump performance in volleyball and basketball players. Methodology: This Randomized Clinical Trial was conducted at Islamic International University Islamabad. Twenty-nine athletes of age 18 – 35 playing basketball and volley as part time/domestic level were included. Post isometric relaxation technique was applied on group A (n=15) and static stretching was applied on group B (n=14). Surface electromyography activity of quadriceps and abdominal muscle was recorded, Stable time, airtime and vertical jump height were measured using two-axis force platform and vertical jump height was measured by motion sensor. Measurements were taken at baseline and immediately after applying interventions to both groups. Data entry and analysis were done by using software SPSS version 22. Results:   Of the 29 athletes, 15 were in the group A and 14 were in the group B. Immediate assessment of vertical jump height was not significantly improved by post-isometric relaxation relative to static stretching (p=0.594). Muscle recruitment, ground reaction and vertical jump height improved apparently after post isometric relaxation but not significantly. Conclusion: It appears that post isometric relaxation and static stretching of quadriceps shows no significant difference in vertical jump height.

Performance Analysis and Enhancement of Phased-Mimo Radar and Frequency Diverse Array Radar

Multiple-input-multiple-output (MIMO) radar and frequency diverse array (FDA) radar have gained significant attention from researchers community due to their numerous advantages over the phased-array radars. The distinguishing features of MIMO radar and FDA radar are waveform diversity and frequency diversity, respectively, while their phased-array counterpart lacks any such diversity. The hybridization form of MIMO and phased-array radars, called phased-MIMO radar, has also attracted the researchers attention due to its capability of combining the benefits of both. In this dissertation, phased-MIMO radar with closely spaced antennas and FDA radar with small inter-antenna frequency offset have been studied. To analyse the performance of radar, ambiguity function has proved to be a useful foundation. We have formulated ambiguity functions of phased- MIMO and FDA radars and derived their important mathematical properties. We have shown that FDA radar can promise better range resolution as compared to that of phased-array radar. For FDA we have proposed two novel schemes of inter-antenna frequency offset. Firstly, it is the time-dependent frequency offset as compared to the constant offset in the existing FDA. With the proposed idea a range-dependent beampattern can be synthesized with the maximum constantly illuminating the given target location. This is in contrast to the time-modulated beampattern with constant frequency offset. Secondly, we have proposed non-uniform (logarithmically increasing) frequency offset as compared to the uniform offset in the existing FDA. The proposed frequency offset promises a beampattern with a maximum only at the given target location. On the contrary, beampattern of FDA with uniform frequency offset exhibits multiple maxima in the visible range. The proposed schemes can provide a strong foundation for the development of modern radars capable of scanning the space more intelligently. We have investigated the proposed schemes only for linear array but they can be extended to planar arrays to scan the space in three dimensions.