Mobility of all lumbar levels plotted versus disc height during axial rotation for (A) range of motion (ROM), (B) lax zone (LZ), and (C) stiff zone (SZ) for males and females. Note the negative correlations for male segments (ROM: r = −0.244, P = .018; LZ: r = −0.230, P = .026; SZ: r = −0.125, P = .228), and positive correlations for female segments (ROM: r = 0.120, P = .333; LZ: r = 0.119, P = .336; and SZ: r = 0.237, P = .054). Used with permission from Barrow Neurological Institute.