Cumulative Spine Loading - Fundamentals and Assessment Tools for Occupational Ergonomics - page 307

100

90

Hansson et al.
Brinckmann et al.

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60

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0

0 500 1000 1500 2000 2500 3000 3500 4000 4500

Cycles

FIGURE 13.5 Logarithmic trend lines fit to the data demonstrating the nonlinear relationship between magnitude
of compressive loading and cycles to failure. (From Brinckmann, P., Biggemann, M., and Hilweg, D., Clin. Biomech.,3
(Suppl. 1), pp. s1-s23, 1988; Hansson, T.H., Keller, T.S., and Spengler, D.M., J. Orthop. Res., 5, pp. 479-487, 1987.)

discussed earlier in the chapter supports this relationship for bone in compression (Caler and Carter,
1989) and muscle tendon (Wang et al., 1995; Wren et al., 2003). This lack of a single cumulative
loading failure threshold was substantiated in work that examined the in vitro generation of interverteb-
ral disc herniations from combined loading (Callaghan and McGill, 2001). Varying levels of compression
were applied in conjunction with repetitive flexion

extension motions. The cumulative compression to
injury was affected by the magnitude of the load applied (Figure 13.7).

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60

y = 0.0119x + 0.117
R 2 = 0.9508

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Cycles

FIGURE 13.6 The linear relationship of cumulative loading sustained to failure based on the data.
(From Brinckmann, P., Biggemann, M., and Hilweg, D., Clin. Biomech., 3 (Suppl. 1), pp. s1-s23, 1988.)