Weeks 4 and 5: Fine Tune Your Regimen
If you hope to complete a 5K obstacle race in 40 minutes, you should be able to run a 10K over rough terrain in about 80 minutes by the end of week five. Note: This time is likely quite different from your normal race time, but remember that your usual running pace is not realistic for an obstacle race. Add at least 25 to 50 percent to your usual time.
Consider whether you can or can't do this to decide which training plan you should follow for weeks four and five:
1. If have yet to hit this pace, make that your goal and focus these two weeks.
2. If you're happy with your endurance, add speed work or hill repeats to one or two of your runs.
For both plans, continue to strength train and work on weak areas. Increase strength-training sessions from two workouts a week to three if you have time.
More: 10 Excercises to Prep You For an Obstacle Course Race
Week 6: Take It Easy
A short obstacle race will demand so much increased energy that you'll feel like you're competing in a much longer race. For this reason, reduce mileage and ease up on the strength training in the last week before your race. In the same way that long-distance athletes taper leading up to a half or full marathon, give your body a little rest so that you show up on race day with as much energy as possible.
The Plan
Don't skip a whole week of workouts; cut total mileage by 30 percent and limit your strength sessions to one or two light bodyweight circuits. Also, take this time to make your race-day plan, which should include getting rest the night before as well as hydrating and fueling two to three hours before the starting gun goes off.
More: How to Taper to Boost Performance
Get more half-marathon racing tips and advice.