TABLE 2.

Compressive loads to replicate physiological loading

	Applied load (N)		Stress (L4L5)
	L3L4	L4L5	MPa
Lying supine	100	106	0.06
Sitting slouched	270	286	0.16
Sitting relaxed	460	488	0.27
Standing	500	530	0.29
Sitting with actively straightening back	550	583	0.32
Mid‐range during walking	590	625	0.34
Holding 20 kg close to body	1100	1166	0.64

Note: in vitro testing by Dreiscarf et al determined the load needed to replicate intradiscal pressures as measured by Wilke et al. ¹²⁹ , ¹⁵³ Values reported by Dreiscarf et al were used as the baseline values for L₃‐L₄ and L₄‐L₅ discs (bold values). Data from Wilke et al were used to calculate the relative difference in activity. Finally, the applied stress for the L₄‐L₅ disc was calculated by using an average disc area of 1826 mm². ⁹⁹ , ¹²¹