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Table 2 Subgroup descriptions and post hoc analysis

From: Subgroups of lumbo-pelvic flexion kinematics are present in people with and without persistent low back pain

  SubGroup 1 SubGroup 2 SubGroup 3 SubGroup 4 Difference between subgroups
Percentage of total cohort (n = 266) 50% (n = 133) 27.4% (n = 73) 15.4% (n = 41) 7.1% (n = 19)  
 Percentage (and number) of people with LBP in each sub group cluster 26.3% (35) 71.2% (52) 82.9% (34) 100.0% (19)  
 Posterior probability of belonging to each cluster 0.95 ± 0.10 0.91 ± 0.13 0.97 ± 0.08 0.97 ± 0.11  
Post hoc analysis – demographics
 Age 36.5 ± 13.6 3 37.5 ± 13.7 42.1 ± 14.8 38.1 ± 13.5 Yes
 Sex (female) 60.9% 57.5% 56.1% 47.3% No
Pain behaviour (for LBP people only)
 Pain intensity using numerical rating scale (0–10 scale) 5.2 ± 1.4 5.1 ± 1.3 5.6 ± 1.8 5.3 ± 1.5 No
 ‘Flexion aggravates, Extension eases’ pain score (0–48 scale) a 12.8 ± 7.3 4 14.5 ± 8.0 4 16.4 ± 8.8 4 22.7 ± 8.4 1,2,3 Yes
 Activity limitation (0–100 scale) 31 ± 17 4 38 ± 20 42 ± 22 48 ± 26 1 Yes
 Percentage of LBP people with leg pain b 36.3% 2,4 52.0% 1,4 21.8% 4 76.5% 1,2,3 Yes
Lumbo-pelvic flexion kinematic parameters
 Trunk Peak ROM (o) 111 ± 12 2,3,4 97 ± 17 1,3,4 89 ± 16 1,2,4 77 ± 20 1,2,3 Yes
 Lumbar Peak ROM (o) 51 ± 9 3 54 ± 10 3,4 30 ± 8.5 1,2,4 47 ± 14 2,3 Yes
 Pelvic ROM (o) 60 ± 11 2,4 44 ± 5 1,4 59 ± 15 2,4 31 ± 11 1,2,3 Yes
 Percentage of lumbar contribution to trunk flexion (%) 47 ± 7 2,3,4 57 ± 10 1,3 35 ± 9 1,2,4 60 ± 9 1,3 Yes
 Flexion relaxation response 0.00 ± 0.00 2,3,4 0.04 ± 0.05 3,4 0.48 ± 0.50 1,2 0.72 ± 0.55 1,2 Yes
 Duration of trunk flexion (sec) 2.31 ± 0.63 2,3,4 3.11 ± 1.11 1 2.87 ± 0.70 1 4.10 ± 1.83 1 Yes
 Pelvic time-lag at start of movement (sec)c + 0.17 ± 0.14 2,4 + 0.42 ± 0.31 1,3 + 0.13 ± 0.24 2,4 + 1.10 ± 1.34 1,3 Yes
 Pelvic time-lag at 20o of movement (sec)c + 0.22 ± 0.30 2,4 + 0.86 ± 0.53 1,4 - 0.55 ± 0.8 4 + 2.04 ± 1.74 1,2,3 Yes
  1. Superscript numbers represent subgroups i.e. 3 = Subgroup3 and indicate a significant difference between the column named subgroup and the superscripted subgroup
  2. aA study-specific, non-validated questionnaire based on directional pain responses where flexion aggravates and extension eases (see Appendix)
  3. bPercentage calculated by number of people with leg pain in each subgroup over number of people with LBP in each subgroup
  4. cpositive numbers indicate a time-lag (delay) of pelvic movement, i.e. the lumbar spine moves first then the pelvis begins to move, lagging behind lumbar movement (at start and at 20o of lumbar and pelvic flexion). Negative numbers indicate a time-lag for the lumbar spine, i.e. the pelvis moves or achieves 20o of flexion earlier than the lumbar spine achieving 20o