Relative muscle contribution of lower extremity muscles during
isokinetic single leg squat in patients following reconstruction of the
anterior cruciate ligament
Affiliations: [a] Department of Physical Therapy, University of Social
Welfare and Rehabilitation Sciences, Tehran, Iran | [b] Department of Physical Therapy, School of
Rehabilitation, Tehran University of Medical Sciences, Tehran, Iran | [c] Department of Physical Therapy, School of
Rehabilitation Sciences, Iran University of Medical Sciences, Tehran,
Iran | [d] Department of Biomechanics, Islamic Azad University of
Tehran Central Branch, Tehran, Iran | [e] Department of Physical Therapy, Musculoskeletal
Rehabilitation Research Center, Faculty of Rehabilitation, Ahwaz Jundishapour
University of Medical Sciences, Ahwaz, Iran | [f] Department of Orthopedic Surgery, School of Medicine,
Iran University of Medical Sciences, Tehran, Iran | [g] Department of Physical Therapy, Rehabilitation
Research Center, School of Rehabilitation Sciences, Iran University of Medical
Sciences, Tehran, Iran
Note: [] Corresponding author: Ali Ashraf Jamshidi, Department of
Physical Therapy, School of Rehabilitation Sciences, P.O. Box
15875-4391, Tehran 1545913187, Iran. Tel.: +98 021 2222 7124; Fax: +98 021 2222
0946; E-mail: Jamshidi.a@IUMS.ac.ir
Abstract: BACKGROUND: The single-leg squat (SLS) is a common
strengthening exercise after anterior cruciate ligament reconstruction (ACLR)
surgery. The multi-joint nature of squatting may allow patients to shift the
demand from the target muscle group to its synergies, thus reducing the
strengthening effect of the SLS exercise. OBJECTIVE: To compare the
muscular contribution in the involved and uninvolved side of the ACLR patients
and both sides of the ACLR patients with the matched control group during SLS
exercise. METHOD: Seventeen athletic men with unilateral ACL
reconstruction and 16 athletic healthy men participated. Integrated
Electromyography was used to calculate the relative contributions of, Vastus
Medialis (VM), Vastus Lateralis (VL), rectus femoris (RF), Gluteus maximus
(GMax) and Soleus (SOL) muscles to SLS performance and squat peak force was
measured with a Biodex System 3 isokinetic dynamometer. RESULTS: The VM muscle contribution was significantly lower and the VL and GMax contribution
was higher on the involved side of the ACLR patients compared to their
uninvolved side and the control group. The SLS peak force was significantly
lower on the involved side compared to the uninvolved side. CONCLUSION: The increased VL and GMax muscle contribution might be a
compensatory mechanism for the reduced VM contribution on the involved side.
Keywords: Electromyography, anterior cruciate ligament, single leg squat, isokinetic
