Journal of Sports Science and Medicine
Journal of Sports Science and Medicine
ISSN: 1303 - 2968   
Ios-APP Journal of Sports Science and Medicine
Androit-APP Journal of Sports Science and Medicine
©Journal of Sports Science and Medicine (2018) 17, 223 - 228

Research article
Relationship between Achilles Tendon Stiffness and Ground Contact Time during Drop Jumps
Mohamed Abdelsattar1, Andreas Konrad2, , Markus Tilp2
Author Information
1 Faculty of Physical Education Mansoura University, Egypt
2 Graz University, Austria

Andreas Konrad
✉ Institute of Sports Science, University of Graz, Mozartgasse 14, A-8010 Graz, Austria
Publish Date
Received: 19-10-2017
Accepted: 02-03-2018
Published (online): 14-05-2018
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The purpose of this study was to investigate the relationship between Achilles tendon stiffness and ground contact time (GCT) during drop jumps. The property of “springiness” and a short GCT during the movement is required in several types of sports. Therefore, a stiff tendon might be advantageous due to the quick force transmission from the muscle to the bone. Hence, a secondary aim was to relate Achilles tendon stiffness with squat jump (SJ) and counter movement jump (CMJ) performance, respectively. Nineteen physically active healthy males (mean ± SD: 26.7 ± 3.9 years, 1.77 ± 0.07 m, 76.5 ± 6.7 kg) participated in this study. Subjects were asked to perform squat jumps and counter movement jumps to determine jump height, and drop jumps were undertaken on a force plate to determine GCT. We then simultaneously measured isometric maximum voluntary contraction (MVIC) of the plantar flexors with a dynamometer and recorded the elongation of the tendon with ultrasound; hence, we could calculate tendon stiffness. The results show a correlation between GCT and Achilles tendon stiffness (r = -0.50) and MVIC (r = -0.48), respectively. Achilles tendon stiffness was not significantly correlated with squat jump and counter movement jump height, respectively. According to the results, we can confirm the main hypothesis that a stiff Achilles tendon tends to result in a shorter GCT during drop jumps. However, Achilles tendon stiffness does not appear to be a key determinant in jumping performance.

Key words: Isometric maximum voluntary contraction, ultrasound, dynamometer, squat jump, counter movement jump

           Key Points
  • Significant correlation between Achilles tendon stiffness and ground contact time.
  • Significant correlation between isometric maximum voluntary contraction and ground contact time.
  • No correlation between Achilles tendon stiffness and other jumping tests (squat jump and counter movement jump).
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