Trunk muscle responses to demands of an exercise progression to improve dynamic spinal stability1  Krista L. Clarke Davidson, MSc, Cheryl L. Hubley-Kozey, PhD  Archives of Physical Medicine and Rehabilitation  Volume 86, Issue 2, Pages 216-223 (February 2005) DOI: 10.1016/j.apmr.2004.04.029

Fig 1 (A) An example of the entire sequence is illustrated in panels 1 through 6. The only difference among levels is panel 4, and the differences are illustrated (B) for levels 2 to 5. The initial instructions for all levels were: “Place your fingertips on each side of your abdomen just under your ribcage, and pull your abdomen in and up toward your chest as if to tuck your stomach under your ribcage” (panel 1). The right foot is lifted off the floor until the hip is flexed to 90°, and in contact with the wooden frame (panel 2). The left leg is then lifted to the same position (panel 3). The leg-extension phase is shown in panel 4. For all levels, the legs are then flexed back to the 90° hip angle position until contact is made with the wooden frame (panel 5). The left leg (panel 6), then the right leg, are lowered to the starting position (panel 1). (B) The differences for the leg-extension phase for each level. In level 2, the right leg extends as the heel lightly slides until the leg is fully extended, then the leg is flexed back to the original 90° hip angle position (level 2 panel). Level 3 is the same as level 2, except the foot does not touch the table until the leg is fully extended. Then the leg is lifted and flexed back to the 90° hip angle position. In level 4, both feet are lowered to lightly touch the table, and the heels slide along the table until legs are fully extended. Then the subject slides both legs back to the 90° hip angle position. In level 5, both feet are lowered without touching the table until the legs are fully extended; they are then set down on the table. The legs are then lifted and flexed back to the 90° hip angle position. All exercises were performed to a count of 8. Archives of Physical Medicine and Rehabilitation 2005 86, 216-223DOI: (10.1016/j.apmr.2004.04.029)

Fig 2 The event marker provided a voltage change for each event to divide the total exercise into 3 phases. Phase 1 is the leg-lifting phase, phase 2 is the leg-extension phase (including hip and knee extension and flexion), and phase 3 is the leg-lowering phase. Abbreviations: R, right; F, foot; L, left; T, thigh. Archives of Physical Medicine and Rehabilitation 2005 86, 216-223DOI: (10.1016/j.apmr.2004.04.029)

Fig 3 Interaction plots for (A) abdominal muscle sites and (B) trunk extensor muscle sites. ∗Level 2 differs statistically from levels 3, 4, and 5; †level 3 differs statistically from levels 4 and 5; ‡level 3 differs statistically from level 5; ∥level 4 differs statistically from level 5 (P<.001 for abdominals, P<.002 for trunk extensors). All of the abdominal muscle sites had similar differences, as indicated in panel A, whereas the erector spinae and multifidus did not, as indicated in panel B. Archives of Physical Medicine and Rehabilitation 2005 86, 216-223DOI: (10.1016/j.apmr.2004.04.029)