Coach Ray

Training for Excellence, with Excellent Training

Fartlek Session
Run Sessions Triathlon Training

Friday Fartlek Run – Alternating Threshold 400s

This is a hard threshold workout that develops your ability to sustain your threshold pace and enhance your ability to suffer. Perfect for all runners, as well as triathletes, especially those running up to 10km or half marathon 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 Threshold 400’s

  • 10min Level II WU;
  • Alternate running 400m repetitions at Level IV 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 fifteen minutes.

The main set is made up of running laps at the athletic track. Run one 400m lap at Level IV (your threshold 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.

For example: if your Threshold 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 your Threshold 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 fifteen 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.

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Ray has competed in triathlons from sprint to ironman distance (both IM Taupo and Challenge Wanaka). Consequently he is aware of the importance of balancing training with lifestyle, thus complimenting other important aspects of an athlete’s life (family, work, study commitments etc…). • Entering your first triathlon? • Stepping up to a longer distance? • Looking to go faster? • Wanting to turn previous negatives into positives? Ray has coached athletes to achieve these and more. Training programmes are accessible online, so athletes can be located anywhere and still reap the benefits of Ray’s coaching. Contact him to discuss how he can assist you to achieve your goals.
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