Friday Fartlek Run – Alternating VO2 400s

This is a hard VO2 Max workout that develops your ability to sustain your top end race speed and enhance your ability to suffer. It is similar to last weeks workout in concept and it perfect for all runners, as well as triathletes, especially those running up to 10km in distance.

Each week I will be posting the Friday Fartlek Run Sessions that you can do to enhance your running. Fartlek is a Swedish term that is often used by runners and it means speed-play. See a previous post about training intensity (levels) to know how hard to work.

Alternating VO2 Max 400’s

  • 10min Level II WU;
  • Alternate running 400m repetitions at Level V Pace and then 10 seconds per 400m slower, complete as many repetitions as possible until you can no longer maintain the 400m pace for two consecutive reps;
  • 10min Level II CD;
  • 10min Stretching

The warm up (WU) should be done at an intensity that is steady but not over consuming at Level II for ten minutes.

The main set is made up of running laps at the athletic track. Run one 400m lap at Level V (your VO2 Max or PZ8 pace), ease off slightly and run the next 400m lap 10 seconds slower. Keep alternating between these two paces until you can no longer maintain the pace for two laps in a row, which won’t be very long compared to last weeks workout.

For example: if your VO2 Max or PZ8 pace was between 4:23 & 4:32min/km this equates to between 1:45 & 1:49 per 400m for your fast 400m; your slower 400m’s will be 10sec slower than this i.e. between 1:55 & 1:59 per 400m.

Another example: if yourVO2 Max or PZ8 pace was between 5:42 & 5:54min/km this equates to between 2:16 & 2:21 per 400m for your fast 400m; your slower 400m’s will be 10sec slower than this i.e. between 2:26 & 2:31 per 400m.

The Cool Down (CD) is at a low intensity jogging (Level II) for a minimum of ten minutes.

Finish with 10 minutes stretching to assist with the recovery.

If you would like further advice feel free to contact me.

I am the Head Coach & Director of Qwik Kiwi – Endurance Sports Consultant.

I specialise in assisting first timers and recreational athletes to achieve their sporting goals. I can be contacted at and 021 348 729.

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If you enjoyed this workout, here is a similar session I published 12 months ago.

Friday Fartlek Session: Sisyphus Session

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