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Table 3 Between-group analysis and within-group analysis of the primary and secondary outcomes

From: Resistance exercise improves muscle strength, health status and pain intensity in fibromyalgia—a randomized controlled trial

Measures Resistance exercise (experimental) Relaxation therapy (control) Between-group analysis of change
Baseline Post test Post-test- baseline Within-group analysis Baseline Post test Post-test- baseline Within-group analysis
(n = 67) (n = 56) (n = 56) (n = 63) (n = 49) (n = 49)
Mean (SD) Mean (SD) Δ (SD) p value Mean (SD) Mean (SD) Δ (SD) p value p value
Median (min; max) Median (min; max) Δ (min; max)   Median (min; max) Median (min; max) Δ (min; max)
Primary outcome
Isometric knee-extension force, N 330.1 (109.4) 356.2 (118.9) 30.4 (71.9) 0.002 298.8 (107.8) 276.4 (112.9) −8.8 (70.0) 0.644 0.010
326 (111; 643) 342 (105; 663) 31 (−157; 178) 287 (51; 534) 278 (41; 595) −10 (−222; 132)
Secondary outcomes
FIQ total, 0–100 60.5 (14.4) 54.4 (18.2) −5.7 (15.0) 0.009 61.1 (17.3) 59.3 (16.0) 0.1 (12.9) 0.71 0.038
59 (31; 95) 55 (11; 88) −3 (−51; 20) 61 (17; 88) 61 (21; 86) 1 (−34; 25)
Current pain intensity, VAS 49.3 (23.9) 38.6 (25.2) −11.5 (25.1) 0.002 52.4 (18.3) 53.4 (20.0) −1.5 (16.5) 0.63 0.033
50 (5; 100) 31 (0; 95) −13 (−83; 48) 51 (10; 88) 56 (10; 86) −2 (−51; 30)
6MWT, m 556.6 (75.1) 579.7 (73.7) 18.4 (65.1) 0.002 540.7 (64.5) 533.9 (73.1) −5.6 (43.5) 0.51 0.003
566 (360; 766) 582 (340; 762) 24 (−290; 196) 530 (362; 660) 537 (366; 656) 1 (−125; 101)
Isometric elbow flexion force, kg 13.0 (5.4) 14.8 (5.6) 2.4 (3.3) <0.001 10.9 (5.2) 11.7 (5.6) 1.2 (3.3) 0.020 0.020
13 (2; 32) 15 (2; 27) 2 (−5; 12) 10 (2; 24) 12 (3; 27) 1 (−7; 13)
Hand-grip force, N 161.8 (68.7) 181.1 (61.5) 20.1 (36.1) <0.001 139.4 (61.7) 147.2 (66.7) 14.0 (37.9) 0.013 0.49
164 (34; 319) 185 (38; 327) 14 (−32; 158) 134 (40; 311) 146 (39; 327) 9 (−101; 98)
SF36 PCS, 0–100 31.2 (7.9) 34.5 (9.1) 3.3 (7.2) 0.004 29.9 (8.1) 30.7 (8.3) 0.8 (5.7) 0.28 0.11
31 (12; 50) 35 (14; 54) 3 (−13; 18) 30 (10; 50) 30 (17; 47) 1 (−13; 13)
SF36 MCS, 0–100 37.7 (12.2) 42.0 (12.6) 3.3 (10.3) 0.007 39.6 (12.1) 38.8 (12.9) −0.4 (9.5) 0.86 0.054
37 (10; 61) 44 (12; 62) 3 (−23; 35) 42 (16; 59) 41 (13; 61) 0 (−22; 23)
PDI, 0–70 35.3 (12.2) 32.2 (13.1) −3.8 (10.6) 0.006 35.0 (12.5) 35.7 (12.4) 1.4 (9.0) 0.27 0.005
36 (8; 69) 34 (7; 67) −5 (−29; 23) 34 (7; 61) 38 (9; 58) 0 (−19; 21)
CPAQ, 0–120 63.6 (16.1) 69.6 (15.2) 5.7 (13.1) 0.002 62.4 (17.1) 63.4 (19.1) 0.1 (11.8) 0.79 0.043
63 (19; 106) 69 (34; 98) 6 (−27; 46) 61 (15; 107) 60 (30; 113) 2 (−38; 23)
FABQphysical, 0–24 9.7 (6.1) 8.9 (6.1) −0.8 (7.0) 0.36 11.2 (6.1) 10.3 (6.3) −1.3 (5.6) 0.24 0.92
9 (0; 24) 8 (0; 22) −1 (−19;19) 11 (0; 24) 9 (0; 24) 0 (−18;10)
FABQwork, 0–42 17.2 (12.7) 17.8 (13.1) 0.4 (8.9) 0.83 15.9 (12.1) 16.67 (12.5) 1.2 (8.1) 0.54 0.79
16 (0; 42) 16 (0; 42) 0 (−27; 29) 12 (0; 42) 14 (0; 42) 0 (−19; 30)
  1. Missing values at baseline: Resistance exercise group, SF36 PCS and SF36 MCS, n = 1; FABQwork, n = 6, FABQphysical, n = 1; Relaxation therapy group, CPAQ, n = 1; FABQwork, n = 8. Missing post-test values: Resistance exercise group, SF36 MCS and PCS, n = 3; FABQwork, n = 7; FABQphysical, n = 2; Relaxation therapy group, FIQtotal, n = 1; SF36 PCS and MCS, n = 2; FABQwork, n = 9. Significant p values are shown in bold text. 6MWT six-minute walk test, FIQ fibromyalgia impact questionnaire, VAS visual analog scale, SF36 short-form 36, PDI pain disability index, CPAQ chronic pain acceptance questionnaire, FABQ fear avoidance beliefs questionnaire