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JOURNAL
OF
SPORTS SCIENCE &
MEDICINE
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Research
article
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ANTHROPOMETRIC, GAIT AND STRENGTH CHARACTERISTICS OF KENYAN DISTANCE RUNNERS |
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Pui W. Kong1 
and Hendrik de Heer2 |
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1Department of Kinesiology and 2Department of Psychology, University of Texas at El Paso, Texas, USA |
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© Journal of Sports Science and Medicine (2008) 7, 499 - 504 Search Google Scholar for Citing Articles |
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| ABSTRACT | |||
| This study intended to take a biomechanical approach to understand
the success of Kenyan distance runners. Anthropometric, gait and lower extremity
strength characteristics of six elite Kenyan distance runners were analyzed.
Stride frequency, relative stride length and ground contact time were measured
at five running speeds (3.5 - 5.4 m/s) using a motion capture system. Isometric
knee extension and flexion torques were measured at six angles and hamstrings
and quadriceps (H:Q) ratios at three angular velocities were determined
using an isokinetic dynamometer. These runners were characterized by a low
body mass index (20.1 ± 1.8 kg·m- 2), low percentage body fat (5.1 ± 1.6%)
and small calf circumference (34.5 ± 2.3 cm). At all running speeds, the
ground contact time was shorter (p < 0.05) during right (170 - 212 ms)
compared to left (177 - 220 ms) foot contacts. No bilateral difference was
observed in other gait or strength variables. Their maximal isometric strength
was lower than other runners (knee extension: 1.4 - 2.6 Nm·kg-1, knee flexion:
1.0 - 1.4 Nm·kg-1) but their H:Q ratios were higher than athletes in other
sports (1.03 ± 0.51 at 60o/s, 1.44 ± 0.46 at 120o/s, 1.59 ± 0.66 at 180o/s). The slim limbs of Kenyan distance runners may positively contribute
to performance by having a low moment of inertia and thus requiring less
muscular effort in leg swing. The short ground contact time observed may
be related to good running economy since there is less time for the braking
force to decelerate forward motion of the body. These runners displayed
minor gait asymmetry, though the difference may be too small to be practically
significant. Further investigations are needed to confirm whether the bilateral
symmetry in strength and high H:Q ratios are related to genetics, training
or the lack of injuries in these runners.
Key words: Stride length, stride frequency, ground contact time, isometric torque, hamstrings to quadriceps ratio, asymmetry. |
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