Phil Mosley shows you how to improve your triathlon running speed without it impacting your swim and bike training

Triathlon Run Training: More Speed, Less FatigueWouldn’t life be lovely and simple if all you did was running? Each week you could include two speed sessions and a long run into your training routine. Perhaps throw in a few maintenance runs as well and Robert’s your dad’s brother. Job done. You would soon be cheerily knocking minutes off those PBs.

Unfortunately it’s not quite that simple for triathlon. Long runs and interval speed sessions take their toll on our bodies, often requiring a good 48 hours to fully recover from, sometimes even more. Sure, you could do them regularly, but they might leave you too tired to swim and cycle hard the following day. You’ll improve your running, but you could soon lag behind on the other two disciplines.

One solution is to incorporate regular fartlek running, also more politely known as “the Swedish natural method”, into your training regime. These workouts give some of the benefits of structured interval training without causing you quite so much fatigue.

The result is that you’ll have more energy and motivation to work hard during your subsequent swim and bike workouts. Let me explain how those clever Swedes do it.

Fartlek involves running according to how you feel, playing with various intensities as you go. This means occasionally running at low intensity levels and occasionally at higher ones. You can vary the terrain too, so you might run on the streets one day and on undulating trails the next. If you’re having a bad day you can just keep the intensity low. And if you feel great, you could always do a few more high intensity efforts during the run. It’s all about whatever works best for you on that given day.

This means you need to listen to your body rather than sticking blindly to a pre-set workout. So if you feel shattered after three hard reps, you can jog home without feeling guilty. You will still get the increase in leg-speed without digging yourself a big hole that takes two days to climb out of.

However, in the final eight to 10 weeks before race day it’s a good idea to swap a weekly fartlek session for a more structured workout that mimics the demands of your race. For instance, an Olympic-distance triathlete might do 6-10x1km efforts at 10km race pace (with three-minute rests). Just make sure you take ample recovery time during this phase of training when the intensity is higher, or all your hard work could be undone.

Make it work for you: three fartlek sessions to improve your running speed


Run 40mins at a maintainable steady pace. Once warmed up, do 3 – 6 x 60secs efforts as fast as you feel capable of. Keep going at a maintainable pace between the efforts. Start the next 60secs fast effort when you feel ready.


Run 30mins at a maintainable, steady pace. Once fully warmed up, do a 5min effort as hard as you feel capable of. Carry on at a maintainable, steady pace. Depending on how you feel, you can shorten or lengthen the fast effort.


Run 60mins at a maintainable pace. Once warm, include fast efforts of: 1min, 2mins, 3mins, 2mins, 1min – all as hard as you feel capable of. Carry on at a steady pace between each and take as much recovery time as you need.