Table 1 Outcome measurements of the study
| Â | Measurement |
|---|---|
Primary outcome: | |
 Low back pain | Pain intensity: Visual analogue scale (VAS; 0–100 mm) during past month [46] (0 = no pain, 100 = worst possible pain) |
Secondary outcomes: | |
 Pain interfering with work | Subscale from the RAND 36 Health Survey [47]; 0–100 (0 = worst pain and extreme difficulties, 100 = no pain and no difficulties) |
 Movement control of the low back | MCI test battery [48] consisting of four tests: 1) the waiter’s bow (flexion of the hips in the upright standing position without movement of the lower back), 2) dorsal tilting of the pelvis, 3) sitting knee extension, and 4) prone-lying active knee flexion [49] |
Physical fitness: | |
 Aerobic fitness | 6MWT; maximal walking distance (metres) in 6 min [50] |
 Muscular strength and endurance | Modified push-ups [51], dynamic sit-ups [52], one-legged squats [51] |
Work-related factors: | |
 Work-induced lumbar exertion | Perceived exertion in the low back after a typical working day [53]. NRS 1–5; 1 = no exertion … 5 = high exertion. Ratings were split into two groups: 1 + 2 = no exertion, 3–5 = moderate to high exertion |
 Physical functioning in nursing tasks | Ability to manage with heavy, task-specific nursing duties, including patient transfer: Sum score of NRS 0–10 with eight selection points: 0 = no difficulties … 80 = does not manage at all [42] |
 Tiredness, sleepiness, and difficulties in recovering from work | Sum score from four questions: 4 = no tiredness or sleepiness and recovering well from work … 18 = long-term, daily tiredness and sleepiness, and not recovering from work [53] |