Table 2.
Participant outcomes and results of the primary analysis.
| Measures | Immediate group, mean (SD) | Delay group, mean (SD) | Adjusted difference in mean change at T0-T1 | ||||||||
| Baseline (T0; n=26) | 13 weeks (T1; n=24) | 26 weeks (T2; n=22) | 39 weeks (T3; n=20) | Baseline (T0; n=25) | 13 weeks (T1; n=24) | 26 weeks (T2; n=22) | 39 weeks (T3; n=23) | Mean difference (95% CI) | P value | ||
| Time in MVPAa,b (min) | 31.0 (37.3) | 37.7 (30.5) | 37.0 (32.3) | 34.0 (25.2) | 71.3 (99.8) | 49.4 (63.6) | 74.6 (102.1) | 54.8 (66.2) | 13.1 (1.6 to 24.5) | .03 | |
| Time in purposeful activityc (min) | 11.1 (19.5) | 13.3 (20.0) | 13.7 (18.8) | 12.8 (16.8) | 42.1 (80.2) | 23.1 (37.1) | 36.5 (62.6) | 22.0 (42.3) | 1.6 (−3.0 to 6.1) | .50 | |
| Daily steps | 6294.0 (3418.0) | 7133.3 (3603.3) | 6381.6 (3492.0) | 5845.3 (2575.5) | 7030.1 (3921.6) | 6232.7 (3086.1) | 8162.3 (6642.3) | 7445.1 (4713.2) | 1106.5 (−19.9 to 2232.9) | .05 | |
| Sedentary timed (min) | 567.5 (183.1) | 531.4 (173.5) | 492.5 (156.6) | 502.8 (135.3) | 551.1 (234.9) | 558.3 (224.9) | 499.5 (248.9) | 483.1 (225.4) | −29.5 (−75.8 to 16.7) | .21 | |
| Knee Injury and Osteoarthritis Outcome Score (0-100; higher=better) | |||||||||||
| Symptoms | 68.5 (10.7) | 69.3 (12.7) | 65.4 (45.8) | 68.4 (16.3)e | 65.7 (12.3) | 66.9 (14.9)f | 72.2 (16.8)g | 72.5 (13.3)g | −1.4 (−7.8 to 4.9) | .66 | |
| Pain | 72.6 (13.5) | 73.1 (15.3) | 72.5 (18.3) | 72.1 (19.8)e | 65.1 (13.7) | 65.9 (15.6)f | 74.8 (15.4)g | 72.8 (13.2)g | 2.5 (−4.2 to 9.5) | .49 | |
| Activity of daily living | 75.5 (14.7) | 75.0 (13.1) | 77.7 (18.9) | 74.8 (20.7)e | 72.2 (15.8) | 70.3 (16.9)f | 80.3 (13.1)g | 80.0 (14.0)g | 2.8 (−3.3 to 8.8) | .37 | |
| Sports and recreation | 47.9 (23.7) | 47.1 (22.4) | 50.5 (30.1) | 51.6 (30.4)e | 46.8 (25.4) | 52.5 (22.7)f | 62.5 (22.5)g | 55.8 (26.3)g | −3.8 (−14.9 to 7.2) | .50 | |
| Quality of life | 44.0 (16.0) | 48.7 (17.5) | 49.4 (15.7) | 49.3 (19.1)e | 47.5 (16.0) | 46.9 (13.6)f | 54.7 (14.7)g | 54.4 (14.6)g | 1.4 (−5.0 to 7.9) | .66 | |
| Partners in Health (0-96; higher=better) | 76.8 (11.0) | 76.7 (11.5) | 78.9 (9.0) | 81.0 (7.0)e | 78.0 (12.0) | 81.6 (9.6)f | 82.6 (9.3)g | 82.6 (10.0)g | −2.3 (−6.6 to 1.9) | .28 | |
| Patient Health Questionnaire-9 (0-27; lower=better) | 5.2 (4.6) | 4.0 (3.0) | 3.6 (3.3) | 4.2 (4.1)e | 5.4 (5.3) | 4.7 (4.9)f | 4.5 (5.2)g | 4.5 (5.3)g | −0.4 (−1.7 to 0.8) | .47 | |
| Self-Reported Habit Index (1-7; higher=stronger habit) | |||||||||||
| Sitting at work subscale | 5.0 (1.4) | 5.2 (1.6) | 4.7 (2.1) | 5.0 (1.9)e | 4.5 (2.1) | 4.4 (2.0)f | 4.3 (2.1)g | 4.1 (2.1)g | 0.7 (0.2 to 1.2) | .004 | |
| Sitting at leisure subscale | 4.8 (1.1) | 5.1 (1.1) | 5.0 (1.1) | 5.5 (1.1)e | 5.1 (1.4) | 4.7 (1.6)f | 4.4 (1.9)g | 4.7 (1.7)g | 0.7 (0.2 to 1.2) | .006 | |
| Walking subscale | 4.3 (1.8) | 4.4 (1.6) | 4.6 (1.8) | 4.7 (1.8)e | 4.8 (2.0) | 4.6 (2.0)f | 4.8 (1.6)g | 4.6 (1.8)g | 0.3 (−0.3 to 0.9) | .27 | |
| Theory of Planned Behavior Questionnaire (1-7; higher=more positive) | |||||||||||
| Attitude toward physical activity | 6.0 (0.6) | 5.9 (0.7) | 6.0 (0.5) | 6.0 (0.5)e | 6.1 (0.6) | 6.1 (0.7)f | 6.2 (0.6)g | 6.1 (0.7)g | −0.1 (−0.4 to 0.2) | .63 | |
| Subjective norm | 6.2 (0.6) | 6.2 (0.8) | 6.1 (0.8) | 6.2 (1.1)e | 6.3 (0.8) | 6.2 (0.7)f | 6.3 (0.8)g | 6.3 (0.7)g | 0.2 (−0.1 to 0.5) | .13 | |
| Perceived control | 5.8 (1.0) | 5.6 (1.4) | 5.6(1.5) | 5.7 (1.4)e | 6.1 (0.7) | 5.8 (1.2)f | 6.2 (1.0)g | 6.2 (0.9)g | 0.1 (−0.6 to 0.8) | .80 | |
| Intention | 6.2 (0.8) | 5.9 (1.0) | 5.7 (1.1) | 5.8 (0.8)e | 6.3 (0.8) | 6.4 (0.6)f | 6.4 (0.6)g | 6.3 (0.9)g | 0.1 (−0.1 to 0.3) | .22 | |
aMVPA: moderate-to-vigorous physical activity.
bMVPA was performed at ≥3 metabolic equivalent of tasks and in bouts ≥10 min.
cPurposeful activity was performed at ≥4 METs and in bouts ≥10 min.
dSedentary behavior was performed at ≤1.5 METs in bouts ≥20 min.
en=19.
fn=22.
gn=24.