Strategies That Improve Paralyzed Human Quadriceps Femoris Muscle Performance During Repetitive, Nonisometric Contractions  Maikutlo B. Kebaetse, PT, PhD, Samuel C. Lee, PT, PhD, Therese E. Johnston, PT, MS, Stuart A. Binder-Macleod, PT, PhD  Archives of Physical Medicine and Rehabilitation  Volume 86, Issue 11, Pages 2157-2164 (November 2005) DOI: 10.1016/j.apmr.2005.06.011 Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig 1 (A) Work, (B) average power, and (C) peak power for a typical subject produced during each contraction when stimulating the muscle with each protocol. An arrow represents the switch to the 66-Hz train. For this subject (subject 7), the C20+66, C33+66, and C66 protocols produced 56+14, 43+8, and 36 contractions, respectively. Note the higher initial values and more rapid decline in performance for the C66 versus the C33 and C20 and the greater augmentation with the 66-Hz train after the C20 than after the C33. For the C20+66 and C33+66 protocols, the breaks in data at the end of the C20 or C33 represent the 2 contractions that failed to meet the 40° target. The responses to these nonsuccessful contractions were not plotted. Archives of Physical Medicine and Rehabilitation 2005 86, 2157-2164DOI: (10.1016/j.apmr.2005.06.011) Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig 2 Mean number of successful contractions for each single frequency (C20, C33, C66) and combined frequencies (C20+66, C33+66) for FES users (E-STIM) and nonusers. NOTE. Values are mean ± standard error (SE). Archives of Physical Medicine and Rehabilitation 2005 86, 2157-2164DOI: (10.1016/j.apmr.2005.06.011) Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig 3 The number of successful contractions produced by each single frequency and frequency combination. NOTE. Values are mean ± SE. *P≤.05 between the C20+66 and each of the single frequencies or combination tested; †P≤.01 between the C20+66 and each of the single frequencies or combination tested; ‡P≤.01 between the C66 and the C20 or C33 frequencies. Archives of Physical Medicine and Rehabilitation 2005 86, 2157-2164DOI: (10.1016/j.apmr.2005.06.011) Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig 4 Time to target, work, average power, and peak power produced by each protocol during the first and last successful contractions of the C20, C33, and C66 frequencies (initial frequencies – responses shown to the left of the vertical dotted line) during the first contractions of the 66-Hz trains after the C20 and C33 trains, during the last contraction of the C66 protocol, and during the last contractions of 66-Hz trains after the C20 and C33 trains (responses shown to the right of the vertical dotted line). NOTE. Values are mean ± SE. *P≤.05 between the C20+66 protocol and each of the other 2 protocols; †P≤.05 between the C20+66 protocol and each of the other 2 protocols; ‡P≤.01 between responses from the C33+66 protocol and responses from the C66 protocol. Archives of Physical Medicine and Rehabilitation 2005 86, 2157-2164DOI: (10.1016/j.apmr.2005.06.011) Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions

Fig 5 Initial work and rate of decline of initial work for the C20, C33, and C66 single frequencies. The last contraction of the single frequencies shows that a minimum amount of work was required to produce a successful excursion, irrespective of frequency. The rate of decline of initial work was greatest for the C66, C33, and C20 frequencies. A successful excursion was produced as long as the amount of work exceeded minimum work. Archives of Physical Medicine and Rehabilitation 2005 86, 2157-2164DOI: (10.1016/j.apmr.2005.06.011) Copyright © 2005 American Congress of Rehabilitation Medicine and the American Academy of Physical Medicine and Rehabilitation Terms and Conditions