Friday Fartlek Run: Threshold Alternating 400’s

This is a very hard threshold workout that will develop your ability to sustain a fast pace. This training session  is perfect for all runners, as well as triathletes.

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.

Threshold Alternating 400’s

  • 10min WU Level II;
  • ?x 400m Level IV, 400m Level IV(ish) ;
  • 10min CD Level II;
  • 10min Stretching

Start the workout with a Warm Up (WU) of ten minutes easy running at Level II.

The main set involves running as many 400m repetitions as possible at Level IV alternating running easier laps ~10 seconds (per 400m slower). Do as many as you can until you can no longer maintain the 400m pace for two consecutive faster reps.

To ensure you run this session at an appropriate intensity, make sure you set your Pace Zones from either a 5km or a 10km zone (click the links to find out how to set your training paces using the Pace Zone Index (PZI)). Convert your kilometre pace to a 400m target time by dividing it by 2½. Note: If you do the hard laps too fast and/or the easier laps too slow, you’ll defeat the purpose of this session and won’t get the benefit.

For example: if your PZ6 (Level IV) pace was between 4:00 & 4:08 min/km this equates to between 1:36 & 1:39 per 400m for your fast 400m; your slower 400m’s will be 10sec slower than this i.e. between 1:46 & 1:49 per 400m.

Another example: if your PZ6 (Level IV) pace was between 5:59 & 6:12min/km this equates to between 2:24 & 2:29 per 400m for your fast 400m; your slower 400m’s will be 10sec slower than this i.e. between 2:34 & 2:39 per 400m.

Conclude the intervals with ten minutes running at Level II for your Cool Down (CD).

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 coachray@coachray.nz 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 Run: 4x 5min Threshold Runs

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