Table 1 Baseline participant characteristics
|  | Non-LBP (n = 20) | Episodic LBP (n = 23) | Persistent LBP (n = 57) |
|---|---|---|---|
Age in years, mean (SD, range) | 31 (SD 11, 19–57) | 35 (SD 13, 18–59) | 37 (SD 12, 18–58) |
Sex | 7 female (35%), 13 male (65%) | 14 female (61%), 9 male (39%) | 28 female (49%), 29 male (51%) |
LBP intensity on 0–10 NRS, median (IQR, range) | |||
Current LBP | – | 1.0 (IQR 2.0, 0–4) | 3.0 (IQR 3.0, 0–7) |
Average LBP in previous 24 h | – | 2.0 (IQR 3.0, 0–6) | 5.0 (IQR 2.5, 1–8) |
Worst LBP in previous 24 h | – | 3.0 (IQR 4.0, 0–7) | 6.0 (IQR 2.5, 1–10) |
Best LBP in previous 24 h | – | 0.0 (IQR 1.0, 0–2) | 1.0 (IQR 3.0, 0–7) |
Duration of LBP problems | – | ≥10 years: 10 (43.5%) | ≥10 years: 25 (43.9%) |
3–9 years: 7 (30.4%) | 3–9 years: 17 (29.8%) | ||
1–2 years: 4 (17.4%) | 1–2 years: 13 (22.8%) | ||
3–11 months: 2 (8.7%) | 3–11 months: 2 (3.5%) | ||
Pain Catastrophizing Scale score (0–52), mean (SD, range) | 6.3 (SD 6.8, 0–26) | 13.4 (SD 9.8, 0–40) | 14.2 (SD 9.5, 0–40) |
PROMIS Anxiety T-score, mean (SD, range) | 49 (SD 8.6, 39.1–71.3) | 51.7 (SD 9.2, 39.1–71.3) | 54.5 (SD 8.7, 39.1–74.1) |
Intervention group | – | 12 SMT (52%), 11 sham (48%) | 28 SMT (49%), 29 sham (51%) |
Guess for intervention group | – | 18 real (78%), 5 not real (22%) | 40 real (70%), 17 not real (30%) |
Calf PPT (kg/cm2), median (IQR) | 4.0 (IQR 3.7) | 3.5 (IQR 3.3) | 3.8 (IQR 3.6) |
Lumbar PPT (kg/cm2), median (IQR) | 5.5 (IQR 4.1) | 4.1 (IQR 4.6) | 4.4 (IQR 4.6) |
Shoulder PPT (kg/cm2), median (IQR) | 3.1 (IQR 2.6) | 2.3 (IQR 2.3) | 2.6 (IQR 2.4) |
Hand TS (0–100 NRS), median (IQR) | 2.6 (IQR 13.2) | 5.0 (IQR 13.7) | 5.2 (IQR 9.5) |
Feet TS (0–100 NRS), median (IQR) | 10.9 (IQR 20.1) | 8.3 (IQR 19.7) | 10.8 (IQR 14.7) |