| Course participants (n = 216), mean (range) | Controls (n = 454), mean (range) | |
| Age (years) | 38.5 (19–59) | 34.3 (17–59) |
| Seniority (duration of employment in the trade: years) | 16.7 (0–45) | 13.1 (0–45) |
| Seniority with the same employer | 10.4 (0–45) | 7.6 (0–38) |
| BMI (weight/height2) | 25.7 (19–41) | 25.2 (17–39) |
| Weight (kg) | 83.4 (57–140) | 82.0 (53–120) |
| Height | 180 (166–207) | 180 (164–198) |