Description of study sample
| Number of men | 5489 |
| Mean age at baseline (SD) | 18.2 (0.5) |
| Mean time to follow-up (SD, range) | 17.2 years (8.4, 1–35) |
| Mean hand grip* (SD) | 617 (98) |
| Mean elbow flexion* (SD) | 385 (83) |
| Mean knee extension* (SD) | 567 (116) |
| Muscle strength (%) | |
| Low | 1371 (25.0) |
| Average | 2747 (50.0) |
| High | 1371 (25.0) |
| BMI (%) | |
| <18.5 | 477 (8.7) |
| 18.5–24.9 | 4498 (81.9) |
| 25–29.9 | 448 (8.2) |
| >30 | 66 (1.2) |
| Type of interview (%) | |
| In person | 4349 (79.2) |
| By telephone | 1140 (20.8) |
| Pain in back/hips (%) | |
| Yes | 1645 (30.0) |
| Of which severe | 321 (5.8) |
| No | 3842 (70.0) |
| Missing | 2 (0.0) |
| Pain in neck/shoulders (%) | |
| Yes | 1562 (28.5) |
| Of which severe | 246 (4.5) |
| No | 3925 (71.5) |
| Missing | 2 (0.0) |
| Pain in arms/legs (%) | |
| Yes | 1243 (22.6) |
| Of which severe | 196 (3.6) |
| No | 4243 (77.3) |
| Missing | 3 (0.0) |
| Pain, independent of location (%) | |
| Yes | 2847 (51.9) |
| Of which severe | 576 (10.5) |
| No | 2639 (48.1) |
| Missing | 3 (0.0) |
| Smoking status (%) | |
| Yes | 827 (15.1) |
| No | 4662 (84.9) |
| Level of education (%) | |
| Compulsory | 589 (10.7) |
| Secondary | 2889 (52.6) |
| Higher | 2011 (36.6) |
| Physical activity (%) | |
| Practically none | 583 (10.6) |
| Now and then | 1613 (29.4) |
| Regularly | 2077 (37.8) |
| Regularly strenuous | 1216 (22.2) |
*In Newton.
BMI, body mass index; SD, standard deviation.