Mile reps - a recovery experiment

I thought I'd post Thursday night's mile reps session. It was an encouraging session in terms of my pace, but it was also an experiment, as I was recovering by jogging until my HR dropped to 125bpm. This was as a result of a discussion I'd had about a recommendation in 'The Coach' magazine about waiting until your HR has dropped to 120bpm during recoveries.

The discussion was that 120bpm seemed a bit low considering that most people jog at a higher rate than that. Everyone has a different max HR anyway, so why make a blanket recommendation of an asolute heart rate? I remembered, during a roastingly hot summer's 8*1000m session, using 125bpm as a mark for recovery, so decided to try using this level as a recovery experiment for the night's mile reps.

So the plan was to jog between each of the 4 1-mile reps and go again once my HR had dropped to 125bpm. Here are the results:

6:47 max HR 150bpm 1:31 recovery
6:49 max HR 154bpm 1:51 recovery
6:51 max HR 154bpm 1:36 recovery
7:06 max HR 149bpm 1:15 recovery (taken after the last rep prior to the warm down)

The last one was a bit slow: I think I could have done it quicker if properly motivated - I was running on my own at the end - I'm in a bit of a no mans land pace-wise at the moment. It's noticeable how the lower effort of the last rep required less recovery.

During the recoveries my HR was dropping quite quickly after an initial plateau, so 120bpm recoveries wouldn't actually be that much longer. I was knackered by the last rep though: I really felt I needed longer recoveries - our standard club session is to take 3 minutes recovery. Despite the increasingly tough efforts though, my recovery seemed the same each time.

On the Runner's World forum, 'Slow-Coach' did some research into recommendations for HR during recovery. Here is her reply:

A bit of lunchtime Googling revealed a range of prescriptions as to what your HR should go down to during the recovery as follows:

Brianmac.com: 100-110 bpm
Sportsmedicine.com: 100-110 bpm
Marc Grosso (US coach): 120 bpm
Powers and Healy, 2001; Fox, Bowers and Foss, 1993 and Reilly et al: 120-140 bpm
Ackland and Reid, 1994: Training HR - 50 bpm
Gerschler: effort at 170-180 bpm; recovery at 120-140.

These last authorities are cited on a couple of sites.

However, no-one says why a particular value is necessary.
My theory would be that the recovery HR should depend on the age-related maximum of the individual and the intensity of the effort. So the "Training HR - 50 bpm" is the closest fit to that I think. But it depends on which energy system one is trying to train. I think if it's the lactate system one should keep the recoveries shorter (i.e. restart at a higher % of your max), than if it's the ATP system. But there is no real guidance I could see on Google.

So the jury's out then. I think, as ever, HR is just one more source of input into a session. I think its main use is to ensure you are getting sufficient recovery; it's not a reason for cutting your recovery in my opinion. If you find that your HR isn't dropping so much in later efforts then take longer recovery to ensure you recover to the same HR as previous efforts. What the recovery target should be is anyone's guess, but maybe 'Training HR - 50 bpm' is a good guide. As 'Slow-Coach' says though, different sessions may require different recovery levels as lactate training requires a shorter recovery than sprint intervals.