Question for all the knowledgeable multisport athletes.

I am going to be competing in 2 duathlons and one mini triathlon this upcoming spring/summer. The most running I will be doing in either of those races is two 4km runs during one of the duathlons.

So my question is, when it comes to training, does it make sense to train for longer than a 5km run? I've done one 10k training run, was that a waste of time??

I always build up to longer than i need too, so when it comes to race time I can well and truely do the distance.

Most plans (and experts) won't have you running up to the full distance. For example, the furthest I ran for my half marathon was 11 miles. But with such a short distance I don't think you'd harm yourself or anything... though you may be better served doing speed workouts than run longer than 4 km.

Depends on your goals.

If you want to finish, I think that a long training run of 10k would probably be all you need to do.

If you want to do well, I think a long run would depend on the mileage you are doing but probably longer than 10k by a bit.

so how do I figure out the optimal training distance?

Hmmm... that's a tough question. For the very best of runners, it seems to be 100 miles/week give or take 25ish.

For the average Joe who is trying to get better, I think that about 30-35 miles per week is a good goal. In my experience it seems to be the point where you can get all the quality running in that a person would need and you see a lot of "return" on the investment. I think beyond the 30-35 mile per week range up to about 60 miles per week you continue to see a good, but decreasing, return on investment.

Under 40 miles per week, I usually recommend a long run of 25% of total weekly run volume. A typical week in the 30-35 mile/week range for me would be something like:

Monday 6 mile run
Tuesday 7 miles - 2 mile warm up, 3 minute repeats "hard", 4 times with 3 minutes rest/light jog in between each repeat.
Wednesday rest
Thursday 2 miles - 1-2 mile warm up, tempo(pretty hard) of 15-40 minutes, cool down if necessary
Friday rest
Saturday 9 mile long run easy
Sunday 4 miles easy

32 total weekly miles. Long run of 8 miles. 2 "hard" days, one with a shorter duration/higher intensity, another with a longer duration/lower intensity but still hard. A couple of easy days.

When increasing mileage, take it slow and easy. Build up a few miles per week at a time.

For that of a short distance you should probably be doing alot of speed work/intervals, instead of focusing on longer runs. You need to be able to run short distances at a high speed, probably above you're aerobic threshold, vs a longer distance at a moderate pace. Plus, if you spend alot of time running you will take away time you could be training on the bike, which will also increase your aerobic fitness.

Focus on doing BRICKS!!!!!!!

+1. Won't help if you have a killer run if you are starting way back in the pack after T2 because your swim and bike legs sucked. This is triathlon the emphasis on TRI

Always remember you can't win a triathlon in the water or on the bike - you have to finish first on the run. So your goal needs to be not to lose on the swim or the bike and save enough energy to close the deal on the run.

Try looking on Runner's World website. They seem to have a training plan for any distance. Imo there is nothing wrong with doing some 10k's... it's not exactly a long distance and your duathalon will be 8k in total. Speed work will key though

Cheers!