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Marathon Training: DNF’ing a Long Run – Is It Sometimes Better To Cut It Short?

I hate cutting workouts short. I’m a numbers guy, and when I have a target distance for a workout I like to hit it. However, one of the lessons I’ve learned over the past few years is that sometimes it’s better to cut a workout short when things just aren’t feeling right. Today was one of those days.

Coach Caleb had me scheduled to run 18 miles today. I’m nearing the end of this marathon training cycle, and my taper begins next week, so today’s 18 miler and one more 21 miler next weekend were the final two really long workouts. I left the house this afternoon with a bit of apprehension since I was feeling tired, and after just a few miles I knew the run was going to be a struggle. My legs did not want to move.

I pushed on, hoping to just go easy and finish off the workout, but at the top of a big hill at mile 8 it was clear that my legs were shot. I felt like I was at mile 24 of a marathon, and it took immense effort just to keep putting one foot in front of the other.

My biggest struggle in a situation like this is mental. I get down on myself if I can’t finish a workout, and I start to worry about how I’m going to handle the race if I can’t complete 18 miles just four weeks out. It’s irrational since I’ve already had a really solid 18 miler, and a decent 20, but I have the thoughts nonetheless.

My recourse today was to focus on the purpose of the workout. The goal of a long run like this is to get me mentally prepared to run 26.2, and to get my legs physically prepared to handle the rigors of the distance. Running long forces them to continue working when tired, and that simulates the late stages of the race.

What I kept telling myself as I considered my options was that even if I cut the run short I would achieve the goal of running on tired legs. In fact, my legs were tired almost from the start, and 13 miles on tired legs might be just as good as 18 on fresh legs. I identified the three factors that were making me miserable:

1. I ran 20 miles last Sunday, then did a hard 10 miler with a fartlek in the middle on Wednesday. The 10 miler was a challenge after the 20, and I knew my legs were already fatigued earlier in the week.

2. I went to a Taekwondo class yesterday morning for the first time in a few weeks. Master Jung had us doing some intensive sparring practice, and I’m pretty sure I’ve never done any exercise quite as intense as TKD sparring. My legs were sore afterward, and the soreness lingered into today (my peroneals, hamstrings, and hip adductors in particular were all barking). I paid the price for not keeping up with my TKD workouts.

3. It was hot today. Mid-70’s F and sunny might not seem hot to some, but we had a particularly long winter in New England and I am not acclimated to running in anything remotely warm yet. I think this was only the second time this year that I’ve run in temps above 70. It takes me about 3 weeks to acclimate to warmer weather, and I’m just not there yet.

Considering the above was enough to help me overcome the mental challenge of deciding to cut the run short. I opted to shoot for 13 miles. That would give me enough time to shower and eat something before heading off to meet my 5K team (I ran another 2.5 with them). I managed 13.5 before giving in, and it was probably the single hardest run I have done this training cycle. As I sit here writing this, my legs are still completely shot. I got in 42 miles for the week, so not far off my planned total, but it does still hurt just a bit to have not gotten today’s run done. However, my thinking is that going the full 18 might have set me back for the entire week to come, so hopefully shortening things today will pay off over the next few workouts.

Caleb sent me my workouts for the week this morning:

For next week (April 29-May 5):

  • Easy Miles: 5, single run
  • Strength Routines: Taekwondo
  • Workout 1 (Tuesday/Wednesday): 11 miles total.  2 miles easy, then transition into 8 miles @ target MP. Since you are running conservatively in VT, you could run a moderate effort for this 8-mile section, or go all the way to PR MP if you are feeling frisky. After the longer MP segment, run 1 mile SLOW to cool down.
  • Workout 2 (Thursday/Friday): 9 miles, easy aerobic with 8 x 30 seconds strides after mile 7.
  • Long (Saturday/Sunday): 21 total miles. Run 10 miles at normal easy long run pace. Stop and put on your marathon race shoes, then run 3 x 3-mile @ MP (again, either moderate effort or shoot for PR MP) with 1 mile easy in between MP segments. So, you will finish the workout with the last 3 miles at MP. This is to simulate the late-race feeling as much as possible. Fuel on planned marathon intervals throughout this long workout.  I also like to wear my race day singlet and shorts for this run, to make it as much of a dress rehearsal as possible.

My challenge right now is to figure out if how I felt today was indeed simply a result of the three factors listed above. I’m very wary of overtraining myself into misery given that I’ve had a pretty rapid mileage buildup this cycle, and I’d rather run the race on less mileage and fresh legs than more mileage and dead legs. I’m pretty confident that my aerobic fitness and speed are where they need to be, it’s my legs that I’m worried about. You can expect that I’ll be looking to Caleb for guidance!

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About Peter Larson

This post was authored by Peter Larson. Pete is a biology teacher, track/soccer coach, and dad (x3) with a passion for running, soccer, and science. If you'd like to learn a little bit more about who I am and what I do, click here, or visit

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