Training for an ultramarathon is time consuming and a small injury can ruin your schedule. But changing your plans to include two shorter but tough sessions in a weekend is a great way to replicate that tired leg feeling.

I headed out for two 21km runs over the notoriously tough Twins as I wind up to my first 100km race, the Vibram Hong Kong 100, in January.

I spoke to two runners – two time Hardrock 100 finisher Andre Blumberg, and Irish national runner Brian McFlynn – to find out why I was putting myself through this torture.

Watch: Back-to-back training for the HK100

  • Practicalities

Blumberg said that back-to-back sessions are sometimes just easier to fit in your schedule. Not everyone can head out on to the trails at the weekend for 10 hours. But, by splitting it up, you still practise on tired legs as you head out for day two, but you have time for your pesky obligations and family.

  • Injuries

McFlynn said that running back-to-back sessions lets him fit volume into his programme but has far less risk of injury than slogging it out on the trails in one long go.

  • Mental training

Getting motivated for the second day can be harder than just pushing through a long run. This is great for training mental fortitude that you’ll need during the race. Blumberg said you can make it more mentally challenging by doing the first of your two sessions straight after work on a Friday, when you are already mentally spent from the office.

  • Don’t take it lightly

Just because you are splitting up your sessions, doesn’t mean you should underestimate them. They are still tough, especially in hot or humid weather. “I have quit on back-to-back runs before because I haven’t taken into account the weather,” McFlynn said.

  • Still go on long runs

“They both have a time and place,” said Blumberg. There are some things you just cannot replicate on shorter runs, like nutrition or if your gear fits properly.

  • Enjoy it and reward yourself

“Enjoy the runs as much as possible, inevitably the distance will come into play and will result in a good effort,” McFlynn said. He added you should reward yourself with a big meal at the conclusion of your training. “But save the post-run beer until after the second day.”