1. Enhancing Muscle Force and Femur Compressive Loads Via Feedback-Controlled Stimulation of Paralyzed Quadriceps in Humans 
Shauna Dudley-Javoroski, PhD, PT, Andrew E. Littmann, MA, PT, Shuo-Hsiu Chang, PhD, PT, Colleen L. McHenry, BSE, Richard K. Shields, PhD, PT 
Archives of Physical Medicine and Rehabilitation 
Volume 92, Issue 2, Pages (February 2011)
DOI: /j.apmr
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

2. Fig 1
Schematic representation of the active-resisted stance experimental paradigm. The force transducer measures the posterior force during the isometric activation of the quadriceps. The biomechanical calculation of compressive (Fc), shear (Fs), and quadriceps force (Fq) is detailed by Frey Law and Shields.12 The model uses the subject's height, weight, and hip/knee position to resolve the compression and shear forces at the distal femur, expressed as a percentage of the subject's BW.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

3. Fig 2
Representative example of CONST (A) and FDBCK (B) bouts. Representatives of all frequencies are plotted (20, 24, 28, 32, 36, 40, 44, and 48Hz) in the FDBCK bout. The corresponding contractions for the CONST bout are also depicted.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

4. Fig 3
Representative example of a 48-Hz FDBCK contraction, showing the instantaneous force values associated with each of the 100 stimulus pulses. The dotted line illustrates the within-train force decline slope for pulses 30 to 100.
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

5. Fig 4
Mean (SE) normalized quadriceps force (A), normalized mean force (B), and fatigue index (C) during repetitive stimulation. Percentages to the right of the plots in (A) and (B) correspond to the value of contraction 60. *Greater than corresponding CONST bout (P<.05).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions

6. Fig 5
Modeled femur compressive load, expressed as a percentage of BW (%BW). *Significant difference between FDBCK and CONST for bout 1 (P<.05). †Significant difference between FDBCK and CONST for bout 2 (P<.05).
Archives of Physical Medicine and Rehabilitation  , DOI: ( /j.apmr )
Copyright © 2011 American Congress of Rehabilitation Medicine Terms and Conditions