SPRINTING, SWIMMING AND VOLLEY BALL PUSH OFF IN GENERATING IMPULSE-MOMENTUM ACTION * Hashem Kilani, Mohammad Abu Al-Tuieb** & Maher Al-Kilani** *Sultan Qaboos University, College OF Education, PHED, Muscat, Oman **Hashemite University, College of Sport Sciences, Zarqa, Jordan The purpose of this study was to investigate the relationship between impulse and change of momentum in three types of ground take-off. Three athletes from the swimming, sprinting and volleyball national teams executed three trials from an AMTI force platform synchronized with video capturing system of starting take-off. APAS software was used for further analysis. Results indicate that the swimmers and the sprinter are less capable of getting equal impulse relationship to the change of momentum due to deviation of reaction forces into the desired motion. KEY WORDS: impulse- momentum, sprinting and swimming take-off. INTRODUCTION: In most sport situations, a push-off by feet is required to produce forces into the desired direction of a motion. The push-off is a function of force action through time history which should be optimized to produce a quality of momentum. The acceleration of a body parallel and directly proportional to the net force (F) acting on the body is in the direction of the net force, and is inversely proportional to the mass (m) of the body i.e., F = ma (Second Newton’s law). This impulse produced should be equal to the momentum outcome especially at the start of sprinting and swimming. However, the vertical jumping take-off in volleyball for example, also requires a force against the ground so that reaction forces is equal to that action but into the opposite direction, are equal in magnitude and opposite in direction (Third Newton’s Law). Therefore, any deviation of reaction forces into the desired motion or any absorption of the force produced by the body system assumed to affect the momentum into the desired reaction. A distribution of the 3 reaction forces may alter the optimum movement in comparing the execution of push-off between sprint start, swimming start and vertical jump in volleyball. In sprinting, the percentage contribution of the starting block as a fast reaction time to the acceleration phase was recorded up to 76%. (Milan et al, 1998) In swimming, the good start contributes 25% of the total time for the 25-yard race, 10% of the total time for the 50-yard race, and 5% of the total time for the 100-yard race. Although improving the start reduces the time of the race at least 10% of a second. (Kilani & Zeidan, 2004; Adrian & Cooper, 1995) The mastery of some skills in volleyball such as serving punch, blocking defense, and the smashing offense require a high-performance vertical jump. This needs a great potential of the lower extremity leg power making a good balance and produce appropriate impulse to generate an appropriate momentum. This, in turn allows athletes in the three skills mentioned above to perform the highest vertical velocity during their take-off, resulting in a bounce higher and longer flight time (Jadidi & Kilani, 2010). The direction of the force must coincide with the direction of body push-off at sprinting, swimming and vertical jump in volleyball. This principle can be achieved with minimum torque and moments at ankle joints (Hay, 1993). The purpose of this study was to compare some of the biomechanical variables due to impulse momentum relationship at push-off between sprinting start, swimming start and vertical jumping strike in volleyball. METHOD: The best three players were selected intentionally from the national teams of sprinting, swimming and beach volleyball in Jordan to serve in this study. In Table 1 they were filmed using a digital video camera (Sony) (25-Hz) from the sagittal plane of their execution from an AMTI force platform synchronized with APAS system for analyses. The force platform was mounted on the block start for the swimming matching the angle of the