Absract for Role of Arm Motion in the Standing Long Jump
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Ashby, B.M., Heeggaard, J.H.(2002). Role of arm motion in the standing long jump. Journal of Biomechanics, 35 1631-1637
Purpose
The purpose of this study was to discover the role and use of arm motion on the performance of the standing long jump and if it improves the distance of the jump. The study also investigated the additional benefits of the use of arms in balancing the body for optimal landing and different forces during the take off phase.
Methods
The subjects were three unskilled male adults varying in age approximately from 21 to 37 years, with an average mass of 72.3 +/- 13.0 kg and height of 1.81+/- 0.03 m. Warm up for a few minutes was instructed to the subjects prior to the jumps. Subjects jumped off a force platform on a verbal signal as far as possible (independent variable) six times each time with control variables being the usage of their arms and without using their arms (hand was held in front of abdomen). A 3-D passive motion captive system was used to with four cameras, passive reflective markers, a force platform and a computer software with a linear transform equations that transformed projections into 3-D position of each marker in space. The markers were applied to skin and shoe at all the main joints involved in the movement of standing long jump. The jumping distance was calculated by measuring the displacement of the toe marker from the initial position to the ending position. This developed a 2-D link model on the computer and the center of gravity and the distance was thus calculated along with the take off velocity (after disregarding the drag force) for comparisons between the two variables.
Results
The results revealed that the subjects jumped approximately 21.2% of by 36cm further with the free arm movement than when the arm movement was restricted. So the subjects with the arm movement had an increased take of velocity at the center of gravity by 12.7 %. For the ground reaction forces in the vertical direction, the arm movement made no significant difference but when the arm movement was restricted it did decrease the horizontal ground reaction force with peak values were 15.4% greater in free arm movement than in the restricted arm movement. The center of gravity was greater initially at 0.4s before take off in the subjects with the free hand movement but it decreased in magnitude to around 0.15s before it returned to zero (pitching forward) at take off. But in the restricted arm positions the movement increased again causing the subject to pitch backward which ultimately decreased