1. Delayed onset of electromyographic activity of vastus medialis obliquus relative to vastus lateralis in subjects with patellofemoral pain syndrome 
Sallie M. Cowan, GradDip, Kim L. Bennell, PhD, Paul W. Hodges, PhD, Kay M. Crossley, GradDip, Jenny McConnell, GradDip, MBiomedEng 
Archives of Physical Medicine and Rehabilitation 
Volume 82, Issue 2, Pages (February 2001)
DOI: /apmr
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

2. Fig. 1 Surface EMG electrode placement for the VMO and VL.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

3. Fig. 2
EMG data of a representative subject from the (A) control and (B) PFPS group in the concentric phase of the stair-stepping task. Note in the control subject the onset of the VMO and VL occur at approximately the same time, whereas in the subject with PFPS the onset of the VL occurs before VMO.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

4. Fig. 3
EMG data of a representative subject from the (A) control and (B) PFPS group during the eccentric phase of the stair-stepping task. Note in the control subject the onset of the VMO and VL occur almost synchronously, whereas in the subject with PFPS the onset of the VL occurs before VMO.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

5. Fig. 4
Mean difference in EMG onsets of the VMO and VL for the PFPS and control groups in the concentric and eccentric phases of the stair-stepping task. The midpoint of each line indicates the mean EMG onset timing difference. The SD of the mean is also indicated. Note in the control subjects the average EMG onset of the VMO and VL occurs almost at the same time in both phases of stair stepping. In contrast, the EMG onset of the VMO occurs after that of the VL in both the concentric and eccentric phases of the stair-stepping task in the subjects with PFPS.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

6. Fig. 5
Percentage of subjects in which the EMG onset of the VMO preceded, followed, or occurred at the same time as the VL in the PFPS and control subjects. In both phases of stair stepping, the onset of the VL was more likely to precede the VMO for subjects in the PFPS group than for the control group. (□), VMO onset > 10ms before VL; (▩), VMO onset occurs within 10ms of VL; (▩), VL onset occurs > 10ms before VMO.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /apmr )
Copyright © 2001 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions