The metabolic cost of running

There is something that has been bothering me for years. I run slow. Until now I have clung to the belief that if I train well I will go faster. Hardly a day passes without me seeing a post from Runners World or Triathlete Magazine promising as much. Run these intervals. Run in the hills. Work on your core. If it is not about my body, it is about my shoes. Better shoes make you faster. So they say.

I must admit that over the last five years, in spite of a busy training schedule, I have not gotten any faster. 

In his book Fast After 50 Joe Friel makes a compelling case that senior athletes need more recovery time. He has worked out a thoughtful framework that distributes effort across three key intensity levels while paying close attention to recovery. I’ll refer to these levels as Very High (VH), Moderately High (MH), and Long Slow Distance (LSD). If you are curious, VH corresponds to VO2Max intervals, or what some cyclists refer to as sprints. MH are lactate threshold intervals, what cyclists like to call sweet spot. LSD is what it has been forever, the long run and long ride. By the way, swimming is an odd animal that does not fit in well with discussions about intensities and fatigue. For now I am focused on running and cycling.

In the framework Friel creates he tries to spread out these three key workouts, to give the athlete adequate time to recover. The outline I follow goes like this: Tuesday, VH, Thursday, MH, and Sunday, LSD. The in-between days are recovery days. That means not long and not hard, or just rest. 

Added to this are strength training (ST) days, twice a week. These count as recovery days because the work he has you do is purposefully not aerobic. High loads, low reps.

Here is how my week starts to take shape:

There is another facet to this, how much of each type of workout to use. It’s covered in the book, but I’ll postpone that discussion for another time. Again, in the above schedule “Rest” can mean a swim, an easy ride, or complete rest. Weekday workouts last thirty minutes to an hour, whereas the LSD workout needs to be longer, with bike rides lasting longer than runs.

Always remember one inviolate rule: The older we are, the more recovery time we need. Sooner or later we reach the point where one day between key workouts is not enough to allow for a proper execution of those key workouts. Friel offers a solution but admits it won’t work for everyone. The solution? The above table represents a seven day mesocycle. A nine day mesocycle allows a second rest day after Monday and Wednesday. If that sounds like a great idea, consider that the workout schedule will no longer align with a standard week. It is worth considering by senior athletes who are retired.

Training for triathlon means distributing workouts in three disciplines across this framework. Every athlete training for triathlon knows there is never enough time to train well in all three. My solution is to schedule a run intensive week followed by a bike intensive week. I always do the Tuesday VH workout on the bike, as it benefits all three disciplines. The MH and LSD workouts are more activity specific, although much of the endurance built on the bike carries over to the run. I use a three week cycle. The third week begins with a few easy days, followed by testing. The LSD workout depends on my overall focus for that period of time. Currently my focus is running.

Remember what I said about more running makes you faster? No run coach would say that three runs a week are all you need. At best that will sustain your current run fitness. Every time I finish a good run workout I find myself thinking about how I should do more of those. Sure. Like, when?

In my previous blog I wrote about my heart condition. I ran that 10k as hard as possible, pushing myself far beyond my comfort zone, in order to prove to myself that I could do more, and to provoke the elusive arrhythmia that spoiled my last two marathons. In fact, I am quite certain that my misbehaving heart has spoiled other races as well, in particular my Ironman races. 

This time I carried my Kardia EKG, and my cardiologist was able to use the strip I took at the finish to diagnose my arrhythmia as PACs, premature atrial contractions. Uncomfortable, scary, but benign. PACs are a little like a calf cramp. They won’t kill you, but they make running fast a challenge.

As an aside here, dear old TrainingPeaks rewarded my effort with an increase in my run LTHR. A big increase. My ego was thrilled! There is widespread agreement that the best source for zone setting data is a race, so I decided to play along. I did a run last Wednesday where I held my heart rate at the border between zones 1 and 2 (at the LT1 point, for those who care) and used that to calibrate my Stryd run power zones. I have only done one run at the new settings, but I must admit I didn’t die.

So I’m looking at my race results feeling good about pushing myself into heart rate zones I never knew I had and trying to understand what that means to my upcoming Ironman races. The optimist in me, aided by a big dose of denial, thinks I can have a terrific run. Then reality kicks in - or is it just my pessimist side? - and I realize that even when I am going all in I am too slow. Slower than a lot of people walking beside me. 

One thing you will always hear triathlon coaches say is to hold back on the bike and save something for the run. Go out too hard on the bike and you will be walking. 

Strong cyclists will almost always be tempted to use their bike leg as a “weapon.” This is a serious mistake because difficulties in the run are very costly in terms of time lost. Most often 5-10 min. on the bike can be the difference between being able to put together a solid run and having to walk. Your fastest race will result from adopting a conservative bike strategy and putting any surplus energy into the second half of the run.

(From Going Long, by Joe Friel and Gordon Byrn, Ch. 15.)

In every triathlon I have raced I have followed this advice. Don’t overcook the bike. This isn’t a bike time trial. You have to run off the bike. For me, this just doesn’t help. I am so slow just running, like last Sunday, that saving anything on the bike just prolongs my bike leg.

A couple of recent Fast Talk podcasts discussed heart issues in athletes. One was specifically on heart remodeling, and one was an answer to a listener’s question about arrhythmias. Those led me to a book co-authored by one of the podcast hosts, Cris Case, titled The Wayward Heart. Most of the content is written by John Mandrola, MD, a cardiac electrophysiologist and active athlete who’s bike racing was curtailed by A-Fib. 

I had just reached the chapter on treatments when I got my diagnosis. Here are some highlights from that chapter:

• The adrenergic nervous system, where the fight-or-flight response happens, can trigger PACs. (Think adrenaline, sometimes referred to as the sympathetic nervous system.)
• All stress can increase adrenergic nervous system activity.
• Knowing that PACs are harmless can reduce the stress caused by them.
• A high training load causes stress, which can aggravate PACs.
• Recovery (rest and sleep) reduces stress, so insufficient recovery can aggravate PACs.

Now consider this:

• To improve my running I should run more.
• There are not enough days in the week (seven day mesocycle) to train properly in all three disciplines.
• I work full time, so a nine day mesocycle is not practical.
• I should reduce training volume, especially high intensity workouts (VH and MH), to reduce the likelihood of PAC episodes.

In Chapter 5 of Jason Coop’s excellent book, Training Essentials for Ultrarunning, he talks about the metabolic cost of running vs. walking. His primary focus is on hills, the idea being that when the athlete starts running uphill they slow down, and at some point they will be more efficient (use less energy) walking. But I also know that many ultrarunners, and many amateur marathoners, experience something similar on flat ground. It has happened to me many times. I reach a point where I can still run, but so slowly that everyone around me is walking and I might be better off walking, too. That’s where I was last Sunday.

Koop cites research done on a large, global population which concluded that the average preferred walking rate is 16:45 to 18:00 min/mi. He does not say if that is while trying to catch a train, or strolling through the woods. The only qualifier is comfort, so I’m guessing something in between. Then he goes on to say that the average preferred transition speed to go from walking to running is around 13:30. 

Three things jump out right away for me. First, I walk way slower than that, down around 20:00 min/mi. Second, there is a large gap between comfortable walking and a preferred running speed. Third, my easy run pace is a lot slower than 13:30, down around 17:00. In fact, my easy run pace is in the average preferred walking pace.

Taking all of the above into account, I have arrived at what seems like an obvious conclusion. In a long course triathlon I should plan on walking the run. This is not a plan to win my age group or a Kona ticket. My goal is to finish the race in spite of my wonky heart. I am assuming that, knowing what I know now, this should provide me the best chance of finishing.

The muscle movements for walking are different from running. To improve my walking pace I will need to set aside some workout time for walking. To be clear, my goal is not to become a race walker. But I guess something like that.

Actually I do not plan on dropping all of my running. The optimist in me believes that if I increase my cadence and stride length a bit I might find a sweet spot where I run more efficiently. From Koop’s book that would be better than 13:30 min/mi. Who knows, I might be able to run a little on race day. And framework and arrive at something I can live with. Time will tell.

If nothing else, coaching is about solving problems that interfere with an athlete's ability to have the race they want. That is what this is all about. I hope that I can use the lessons I am learning now to help others achieve their goals. In long course endurance events you are not competing against the other athletes. Your only competitor is yourself.

and arrive at something I can live with. Time will tell.

If nothing else, coaching is about solving problems that interfere with an athlete's ability to have the race they want. That is what this is all about. I hope that I can use the lessons I am learning now to help others achieve their goals. In long course endurance events you are not competing against the other athletes. Your only competitor is yourself.