| Difficult Run to Opwijk | 3,865.41 mi (6,220.78 km) |
| Difficult Run to Ostend | 3,807.81 mi (6,128.08 km) |
| Difficult Run to Oud-Heverlee | 3,888.39 mi (6,257.77 km) |
| Difficult Run to Oud-Turnhout | 3,888.60 mi (6,258.10 km) |
| Difficult Run to Oudenaarde | 3,844.74 mi (6,187.52 km) |
| Difficult Run to Oudenburg | 3,812.12 mi (6,135.01 km) |
| Difficult Run to Oupeye | 3,931.13 mi (6,326.54 km) |
| Difficult Run to Overijse | 3,884.29 mi (6,251.17 km) |
| Difficult Run to Overpelt | 3,908.56 mi (6,290.22 km) |
| Difficult Run to Paal | 3,903.43 mi (6,281.96 km) |
| Difficult Run to Peer | 3,912.24 mi (6,296.15 km) |
| Difficult Run to Pepinster | 3,941.94 mi (6,343.94 km) |
| Difficult Run to Peruwelz | 3,852.51 mi (6,200.02 km) |
| Difficult Run to Perwez | 3,899.86 mi (6,276.22 km) |
| Difficult Run to Philippeville | 3,900.22 mi (6,276.79 km) |
