FOOTNOTES

19 Kendall et al. (1971)

20 Juker et al. (1998)

21 Kendall et al. (2005)

22 Bret Contreras comments: “A glute contraction protects against shear through tension of the thoracolumbar fascia, which has excellent leverage for anti-flexion (Sullivan, 1989). It is my belief that this is a huge reason why powerlifters could round back deadlift without blowing out discs; their strong glutes contract hard, which tenses the TLF, which counteracts a significant portion of the flexion moment. (Vleeming et al., 1995)”

23 O’Sullivan et al. (1997)

24 Tesh et al. (1987), McGill (1998), McGill (2001)

25 Semyonov (1968)

26 While breath holding is enough to work the obliques, it takes sharp cough like exhalations to get the six-pack’s attention. From Basmajian & DeLuca (1985): “When the subjects… were made to strain or to bear down” with the breath held, the external obliques and the internal obliques (lower parts) contracted to a degree that was directly related to the effort, but rectus abdominis, in contrast, was very quiet. (Floyd & Silver, 1950) This was later confirmed by Ono (1958)… de Sousa & Furlani (1974)… found exuberant activity by the recti bilaterally during a cough. So there is a difference, apparently, between the reactions of the recti to the increase of intra-abdominal pressure from “bearing down” and sharp, short increase of coughing.”

27 McGill (2009)

28 Zakharyants (1962)

29 Verkhoshansky & Siff (2009)

30 Herrington (2011). The data is for the “normal asymptomatic population”.

31 Herrington (2011)

32 Prof. Stuart McGill was kind enough to add his commentary:

Here is a summary of spine motion or non-neutral postures. If the spine is under load, the discs will succumb faster if they are bent (non-neutral postures). If the load is lower this is not much of a concern. So any “pulsing” of muscle activity will be better tolerated when the spine is closer to neutral. Having stated that, motion while loaded is more risky than locking the spine in a non-neutral posture when under load. Consider picking up an Atlas stone from the ground—deep squat and full spine flexion—but the torso is wrapped around the stone in a flexed but isometric grip on the stone. This is less risky than moving the spine under such a great load.

I also make the distinction between those that have back injury and those who have never had an injury—many do not get this distinction but you certainly do. If there is an injury history it must be managed and a lot of our strategies are to manage the injury and remain functional. So I will be insistent for the flexion intolerant back that they have to avoid this at all costs—yet for others it is not so important. As always—these are individual considerations.

Also, the tolerable volume of training is modulated by the spine posture. Repeated bending of the spine reduces the tolerable volume—for example one could tolerate much more volume in “stir the pot” on a ball vs situps. But as you point out the idea is to train less for better athleticism—your synopsis on this is about the best I have read—very well done!

33 While Russian researchers do not question the fact that isometrics build strength (Vorobyev, 1977), they consider it only a supplementary strength training modality (Zatsiorsky, 1996). Isometrics should constitute only 10% of the strength training volume (Vorobyev & Slobodyan, 1977). A mix of muscle work regimes needs to be employed in order to continue improving results (Semyonov & Chudinov, 1963; Petrov & Chudinov, 1966).

34 Shields & Heiss (1997), Drysdale et al. (2004), Urquhart et al. (2005)

35 Workman et al. (2008)

36 McGill (2006)

37 Sarti et al. (1996), Willet et al. (2001)

38 Lipetz & Gutin (1970), Guimaraes et al. (1991)

39 Kendall et al. (1971)