Speed vs HR when doing intervals/Two marathons close to each other

by Magnus Midtgard
(New York)

Heart rate vs. speed and two marathons close together :

"Hi Marius!

1) When doing the interval sessions, my heart rate (naturally) varies depending on the length of the actual intervals. So for example, when doing the 30x20 sec (20sec recovery) Effort 4 session, I will for example do 10 mph, and even then, my HR is not in Effort 4 before perhaps the 20th interval (and in the end, I am still a long way from reaching effort 5). To me, that seems too late in the session in order for the session to have the desired effect. However, when doing longer effort 4 intervals – for example the first session in week 6 for the 3:15 plan, where there are two 3 min Effort 4 intervals (after doing some quite long Effort 3 intervals), I need to keep the speed limited to 9.4-9.5 min/mile in order not to go into Effort 5. The same applies to Effort 3 sessions – for example the long (15-30 minutes) Effort 3 sessions, I will need to run significantly slower than for example the session with 10x3 min where each 3 minute is 1 min E2, 1 min E3 and 1 min E4.

So the question is: Do I want to follow the speed or the HR when doing the intervals? If it takes too long to get my heart rate up, should I aim for a higher speed on those shorter interval sesions (however always staying in control so I do not end up in too high in the effort zone at the end)?

2) For various reasons, I am thinking of doing both Chicago and New York Marathon the same year. The problem is that they are only 3 weeks apart. I really want to go all in for Chicago (which is the first one), however I also want a good experience for the NY Marathon (those will be my 4th and 5th marathons in a period of 3 years). Is there any way to adapt/build on the 100 Day Plan to achieve this (I will be following the 3:15 or the 3:00 plan)? For example doing a lot of easy running before starting the plan (50-60 miles/week – no hard sessions at all), and then add more easy sessions in the actual plan to have a solid foundation? And what should I be doing the 3 weeks between the two marathons?

Thanks for a great and motivating plan – much appreciated!"

Answer: Hi Magnus and thanks for your question.

1) In terms of speed vs. heart rate and length of the intervals - you are right ; the speed will always be higher on the shorter ones in the same training zone, and it does complicate things slightly. However, you can allow yourself this, without worrying too much about it. You also DO need some time to hit the correct heart rate zones within an interval, and for the shorter interval runs you'll usually spend 20-30 seconds to get there. This is ok. So in these shorter type work, heart rate isn't as good of an predictor and you may want to look more at the speed (should be good into Effort 4 speed if this is the aim of the session) - even though I generally suggest that you EITHER chose heart rate or speed for a given schedule, this is an exception to that.

2) In terms of very close marathons, read this one (see all the answers) You'll see even examples of 3 weeks in between marathons outlined there :) Short time between marathons

I wish you all the best,

kind regards,
Marius