EMPHASIZE EXTENDING THE KNEES IN A GRAB START
De Jesus, Karla, de Jesus, K., Roesler, H., Fernandes, R. J., & Vilas-Boas, J. P. (2013). Joint rotations during swimming grab start technique performance. Medicine & Science in Sports & Exercise, 45(5), Supplement abstract number 2937.
This study compared the value and time of peak extensor angular velocity of the hip, knee, and ankle joints during the grab start technique of experienced swimmers (N = 8). Ss performed three maximal repetitions of a grab start over a 15 m distance. The starts were 3D recorded with four above water synchronized cameras. A starter device produced the signal and a light signal on the video system. The peak angular velocity of the right hip, knee, and ankle joints extension and time were assessed in each of the three trials. The grab start was divided into block and flight phases and each angular velocity curve was normalized to the combined phase times.
The knee showed greater peak extensor angular velocity values than the hip and ankle joints with a large effect size. Similar hip, knee, and ankle time values were observed for peak extensor angular velocity with a small effect size, and the three joints were maximally extended during the block phase. No temporal lower limb rotation sequence was observed.
Implication. The knee joint was the major contributor to the ballistic take-off in the grab start. When executing a grab start, extending the knees as quickly as possible should be emphasized.
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