What is the easiest distance to race?

Jeff and I before this year's Lincoln half.

The short, quick answer is this: None.  Each distance has it's own pros and cons.  And each distance has it's own strategy and recipe for success.  Here are my thoughts on some of the most popular racing distances:

The 5k

I recently read Lauren Fleshman's article on the 5k (here), and couldn't agree more.  The 5k gets this unfortunate stereotype of being an "easy" race.  I couldn't tell you how many times I have heard something similar to this: "You're running a 5k this weekend?! That should be so easy for you since your so used to running marathons!" False.  The 5k for me is 20 minutes of the hardest running I can muster on that given day.  You go out as hard as you can, and you finish as hard as you can.  Although race day hydration and nutrition remain important, you don't have to change your entire routine.  You don't have to take in calories during a 5k.  Is it easy to train for? This depends on your goals.  If you are running simply to finish a 5k, then probably not.  You can easily get by on running 3ish times per week.  However, if you goal is to compete or run a new PR, then hard work is part of the prerequisite. 400 repeats are a great workout for 5k success.  I'm also a big believer in mile repeats for any distance.  Now, the 5k may not be for you if you're looking to lose weight.  Give or take, the 5k probably burns close to 300 calories total...which is like one or two cookies.

The 10k

Arguably, this is the hardest distance I race.  I basically employ the same racing strategy here as I do in the 5k: start hard, finish hard.  This race, though, requires more toughness around miles 3 and 4...you've been working really hard for quite awhile, and there is still a lot to go. 40-60 minutes of HARD running.  I always think that courses with a little variety are better for the 10k...I can think about staying strong up a hill by pumping my arms, taking shorter steps, and driving my knees upward.  I can think about letting go and allowing gravity do it's work as I run downhill.
  Once again, this distance can be what you want it to be.  If you want to PR, there is a lot of work involved.  (Here's where mile repeats start to really benefit your fitness level.)  If you're looking for a good workout or calorie burner, this is your ticket.  600 calories burned? Now we're talking.   This race will hurt while you're running, but you should be able to recover relatively quickly.  Training will not take over your life.

The Half Marathon

This is such an incredibly popular distance. Why?  It is always a challenge...BUT it's a challenge that practically all of us are capable of IF we put in the training.  What does training look like?  Running very consistently for 12-16 weeks as you gradually build yourself up to 13.1 miles.  I have had the best results (and felt the best during the race) when I have training over the race distance.  Last year, I did a 15 miler about a month out from the Lincoln half.  However, I think you can get by with a 10 miler being the longest run.  (Once again, this depends on what your goals are for your race.)  I am also a believer in adding calories to this race.  I usually take 2 gels during the race at miles 6 and 10.
This race requires serious strategy and discipline....you need to go out hard, but in a "sustainable" way.  Remember--you're going to be out there for a long time...and there are still four long miles left after mile 9.  Training for this race is probably your best bet if weight loss is a goal.

The Marathon

Marathons are hard.  Always.  They are not double the difficulty of a half, but 10x harder.  There is a lot of sacrifices to be made when you're training for a half.  Training plans range from 16-20 weeks and you'll most likely go to be early the night before a long run (missing social engagements).  Nutrition and fueling are vitally important to success in this event...training requires a large calorie intake, as does the race itself.  I take in about 500-600 calories during the actual race. Though it seems like the opposite should be true, you will most likely not lose weight during this training cycle.  One needs to be very aware of their fitness level going into the race so they're able to start out at the right pace.  I am much better at this now...I have had several races where I've blazed though the first half in 1:45 only to finish in 4:24.  (You can make guesses as to how awful this feels...)
The marathon is not a distance I really enjoy, which I'm sure is evident from this not-so-pretty picture I've painted.  I have always struggled at this distance and have yet to run a really great marathon. So why have I done so many if I don't really like them?  What is SO great about 26.2?  It's a great accomplishment...even more so when you PR or your race goes perfectly.  And there is something about pushing your body to the breaking point and knowing full well that you are capable of great things.

Each race distance offers its own challenges and quirks.  What is your favorite distance?