journal.pone.0190903.pdf (6.57 MB)

Sex differences in muscle morphology of the knee flexors and knee extensors

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posted on 07.02.2018, 17:00 by Fearghal Behan, Thomas M. Maden-Wilkinson, Matthew Pain, Jonathan Folland
Introduction Females experience higher risk of anterior cruciate ligament (ACL) injuries; males experience higher risk of hamstring strain injuries. Differences in injury may be partially due to sex differences in knee flexor (KF) to knee extensor (KE) muscle size ratio and the proportional size of constituent muscles. Purpose To compare the absolute and proportional size, and mass distribution, of individual KE and KF muscles, as well as overall size and balance (size ratio) of these muscle groups between the sexes. Methods T1-weighted axial plane MR images (1.5T) of healthy untrained young males and females (32 vs 34) were acquired to determine thigh muscle anatomical cross-sectional area (ACSA). Maximal ACSA (ACSAmax) of constituent muscles, summated for KF and KE muscle groups, and the KF:KE ratio were calculated. Results Females had 25.3% smaller KE ACSAmax (70.9±12.1 vs 93.6±10.3 cm2; P<0.001) and 29.6% smaller KF ACSAmax than males (38.8±7.3cm2 vs 55.1±7.3cm2; P<0.001). Consequently, females had lower KF:KE ACSA ratio (P = 0.031). There were sex differences in the proportional size of 2/4 KE and 5/6 KF. In females, vastus lateralis (VL), biceps femoris long-head (BFlh) and semimembranosus (SM) were a greater proportion and sartorius (SA), gracilis (GR) and biceps femoris short-head (BFsh) a smaller proportion of their respective muscle groups compared to males (All P<0.05). Conclusion Sex differences in KF:KE ACSAmax ratio may contribute to increased risk of ACL injury in females. Sex discrepancies in absolute and proportional size of SA, GR, VL and BFlh may contribute further anatomical explanations for sex differences in injury incidence.

Funding

Arthritis Research UK Centre for Sport, Exercise and Osteoarthritis

History

School

  • Sport, Exercise and Health Sciences

Published in

PlosOne

Volume

13

Issue

1

Pages

e0190903 - e0190903

Citation

BEHAN, F. ... et al, 2018. Sex differences in muscle morphology of the knee flexors and knee extensors. PLOS ONE, 13 (1), e0190903.

Publisher

Public Library of Science © The Authors

Version

VoR (Version of Record)

Publisher statement

This work is made available according to the conditions of the Creative Commons Attribution 4.0 International (CC BY 4.0) licence. Full details of this licence are available at: http://creativecommons.org/licenses/ by/4.0/

Publication date

2018-01-23

Notes

This is an Open Access Article. It is published by Public Library of Science under the Creative Commons Attribution 4.0 International Licence (CC BY). Full details of this licence are available at: http://creativecommons.org/licenses/by/4.0/

eISSN

1932-6203

Language

en

Licence

Exports