This 50K plan is designed for the intermediate runner who has a history of ultramarathon, marathon, or half-marathon events, has been running consistently for a few months, and is currently comfortable with 10 miles, or about 90 minutes of steady running. As most 50Ks are off-road events, the plan assumes the goal race is on trail, with a moderate amount of elevation gain - 3000 to 5000 feet of climbing through the race.
If you’re new to trails, that’s okay! Preferably, you would have access to run at least two of your weekly training days on trail, or dirt roads, with some hills. For most of the long days, try to find trails that are somewhat similar to the race course, but again, if that is not logistically possible you can still get adequate training on rolling, urban routes (or treadmills).