What is a Low Running Heart Rate?

What counts as a "low heart rate" while running? If you go by feel or effort, it's easy to run harder than you think. Often we'll move into that middle heart rate zone that is neither easy nor hard--a no man's zone. It doesn't foster recovery and it also doesn't build fitness and speed like it should. Too hard for health, but not hard enough for real speed development (lactate threhold or VO2max). I've been a big fan of keeping my running aerobic and developing that easy fat-burning zone. But what is that zone? What maximum heart rate is easy and aerobic? Where does fat-burning move to mostly carb-burning?

In the past, I've been fond of promoting the Maffetone style of low heart rate training. Pretty simple formula for determing your maximum aerobic heart rate: 180-age. Very simple, and minor, adjustments can be made based on your individual exercise, health, and injury history. You do all of your runs at or below that heart rate. I've used it, on and off, for several years. It's kept me injury-free and likely improved my base aerobic fitness. But I never stay with it for too long. Its boring. It's not fun. It does not maximize your running potential. It doesn't prepare you for most running events. And, it does not seem to have any scientific backing. Lots of anecdotes, but no research. It may work for some people, but I do not think it's the best low heart rate training program for most people. I have given up on it...mostly due to its very limited zone of training and lack of connection to standard physiological metrics of exercise and running (lactate threshold, VO2max, maximum heart rate, etc). Plus, it takes a lot of the fun out of running. Running should be fun, right?

I firmly believe in lots of easy running to build aerobic fitness and a strong running foundation. And to stay injury-free. What other "low heart rate training" options are available? There are none that promote purely an aerobic zone. But, there are many that support and encourage the majority of your running to be at an aerobic (low heart rate and "easy") level. They are normally tied to your lactate threshold (see this short post for determining your LT). My favorites are Matt Fitzgerald and Joe Friel (they both have excellent books too--see end of this blog post). The "easy zones" max out around 89% of your lactate threshold. It gives you a much higher maximum aerobic heart rate than Maffetone. My Maffetone HR max would be 180-49=131. My Friel and Fitzgerald top-end aerobic HR is about 144.

Also, those zones tied to LT allow for progress over time as you become fitter and your LT moves higher. Individual differences are maintained, changes over time are incorporated into the formula, and it's based on real science. If you look at what many coaches (Arthur Lydiard, Roy Benson, etc) would define as "easy/recovery pace" based on heart rate reserve, it would be about 65-70%--for me that is 141-148. Middle of that easy heart rate reserve zone ends up being the Friel and Fitzgerald upper limit of "easy." Numbers seem to converge on a single area that is aerobic and easy. For me, that's around 144.  This is my new maximum easy/recovery zone heart rate.

How's this new heart rate zone working for me? Well, I've only tried it once, and it was wonderful.  I ran a 7-mile route by effort trying to keep it easy and my watch HR alarm went off only three times--always at the top of a hill. I walked briefly (15-30 seconds) and my heart rate fell back into the zone. 98% was at or below the 144 heart rate. All good. After the run was over, I felt excellent.  After a shower and breakfast, I still felt good. With the extremely low Maffetone HR, I never really felt good.  It was always OK. During the run I'd be frustrated with the slow pace and after the run I wouldn't have that sense of accomplishment. I believe this new easy zone will work out better for me. I'll stay injury-free and disciplined, but also improve my fitness and feel proud of my training. Win, win.

Another bonus with the new low heart rate approach? Coach Riddle approves of this 89% of lactate threshold being my top-end of easy running. Excellent. Always good to keep the Riddler happy.

For full heart rate running zones, based on lactate threshold, try these two excellent books:

80/20 Running: Run Stronger and Race Faster by Training Slower (Matt Fitzgerald, 2014)

Total Heart Rate Training: Customize and Maximize Your Workout Using a Heart Rate Monitor (Joe Friel, 2006)

After I have about 6-8 weeks in the purely aerobic (easy) zone, I'll start to incorporate a modest amount (10-20%) of harder workouts as prescribed by Friel and Fitzgerald. Target race for all this training?  Tunnel Hill 50-miler in November.