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Friday, March 2, 2001

Biomechanical, neuromuscular differences found in knee flexion

A study of kinetic, kinematic and strength variables of female and male basketball and volleyball players during two landing tasks suggests both biomechanical and neuromuscular variables differ between genders during landing.

The results of the study in poster exhibit 19 shows males had greater amount of knee flexion subsequent to impact. The study authors say the larger flexion displacement serves to attenuate impact forces reducing loads imposed on the joint. Absence of this controlled knee flexion in females may be related to the weaker quadriceps, resulting in an abrupt stiffening of the knee. These factors may be related to the pathoetiology of ACL injuries in female athletes.

Twenty-two athletes performed single leg landing (20 cm) and forward hop (45 percent body height) tasks. An electromagnetic tracking device synchronized with a forceplate provided knee (flexion) and hip (flexion, rotation, abduction) kinematic data and vertical ground reaction force (vGRF) data, respectively. Two kinematic variables, maximum angular displacement (MAD) and time to maximum angular displacement (TMAD), were calculated for each angle. MAD was defined as the difference between ground contact and peak angles attained immediately following ground contact. The maximum force and time to maximum force was calculated from vGRF data after normalizing to body mass. Peak torque/body mass measured isokinetic strength at 60 degrees/sec.

Across both tasks, males demonstrated significantly (p<0.05) higher MAD (knee flexion). Additionally, females demonstrated significantly (p<0.05) lower TMAD (knee flexion) and higher TMAD (hip rotation) for both landing tasks. Females revealed significantly (p<0.05) lower quadriceps peak torque/body mass. No significant (p>0.05) differences were revealed for vGRF variables.

Coauthors are Scott M. Lephart, PhD, Pittsburgh, Pa.; Cheryl M. Ferris, ATC, Pittsburgh, Pa.; Bryan L. Riemann, PhD, Greensboro, N.C.; Joseph B. Myers, ATC, Pittsburgh, Pa.; and Freddie H. Fu, MD, Pittsburgh, Pa.

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2001 Academy News March 2 Index B

Last modified 20/February/2001 by IS