FOOTNOTES

46 Bret Contreras’ data

47 “RA, EO and TrA act at optimal force-generating length in the midrange of lumbar spine flexion, where IO can generate approximately 90% of its maximum force.” (Brown et. al, 2010)

48 Monfort (1998), Bankoff & Furlina (1984)

49 Tarnanen et al. (2008)

50 Kendall et. al (1971) point out that normally downward movement of the arms, or shoulder extension “requires fixation by abdominal muscles. [However,] when abdominal weakness exists, however, fixation for the downward pull or push of the arm may be provided by the back muscles. For example, if a patient is placed in a supine position and given resistance to a downward pull of both arms, normal abdominal muscles will contract to fix the thorax firmly toward the pelvis. However, if extensive abdominal weakness is present, the back will arch from the table, and the thorax will pull away from the pelvis until it is firmly fixed by extension of the thoracic spine. The arching of the back stretches the abdominal muscles, and they may appear firm under tension. The examiner must be careful not to mistake this tautness for firmness due to actual contraction of the muscles.”

51 “Bilateral weakness of external obliques decreases the ability to flex the vertebral column and tilt the pelvis posteriorly… The posterolateral fibers of the external oblique are elongated as the thoracic spine flexes during the trunk curl. These fibers of the external oblique help to draw the posterior rib cage toward the anterior iliac crest, and in so doing, they tend to extend, not to flex, the thoracic spine...” (Kendall et al., 2005)

52 “Weakness of the external oblique is common in persons performing excessive sit-up exercises because the posterolateral fibers of the external oblique elongate during the trunk curl.” (Kendall et al., 2005)

53 Chek (1992)

54 Ratov (1972, 1987, 1994), Yevseyev & Rykunov (1984)

55 Belsky (2003)

56 “The rectus abdominis muscle… is relatively inactive [in supine leg raises]; it secures the pelvis and increases the intraabdominal pressure. It begins to shorten only when the legs are raised high enough. At this point, however, the moment of force gravity, pulling the legs down, is relatively slight. Since the initial pressure on the discs is rather high and the activity of the abdominal wall muscles is not significant… this exercise is not especially valuable… Leg raising in a hanging position is much more effective (here the rectus abdominis contracts when the moment of gravity of the legs reaches its maximum), but it is feasible only for trained persons.” (Zatsiorsky, 1995)