Dear CrossFit, Add Heart Rate Training To Explode Your Performance

Building on my post about periodizing CrossFit, I want to explore an idea for adding heartrate training into the sport. Just to give a bit of background, I’ve been a professional rowing coach for many years at various levels (high school to elite), and specific aerobic training is critical to our performance. I’d like to see if heart rate training can be a benefit to CrossFit.

NOTE: Glassman on the definition of fitness and training, where he rips on heart rate training…full videos if you have a Journal account. John McBrien also addresses this on a conceptual level in this Journal video: CrossFit Endurance, Intro to Programming.

To kick this off, we need a quick primer on the energy systems and how they apply to training. There are three energy systems: aerobic, anaerobic, and ATP-CP. Common knowledge, right? But, what you may or may not know is that the energy systems break down into smaller bands–by bands I’m referring to % of heart rate max (HRM)–and each of these bands can and should be trained. Most importantly, all three of the energy systems are intertwined and need to be trained in specific ways in order to get the most benefit.

Check this page for several heart rate max calculators.

Before I get crazy about energy systems, I have to say this. In my opinion, to be truly fit, you absolutely have to train the energy systems intelligently and methodically, just like you would train for increasing strength in a methodical fashion. To ignore it or do it haphazardly leads to poor results.

Here they are:

ATP-CP: I’m going to refer to this as one system. ATP-CP is what powers you for the first 5-8 seconds of an explosive exercise. In rowing, we use this on starts and sprints. In CrossFit, we burn through our CP during the first few reps of an intense set. So, when I’m doing 30 reps of Grace, the first couple of reps use the immediate on-demand energy of the ATP-CP system. This also has little aerobic impact and causes minimal fatigue. That changes quickly after the first couple of reps.

ATP = Adenosine Triphosphate, CP = Creatine Phosphate.

Anaerobic: Once the CP stores from above are depleted, the body goes to stored glucose for ATP. The breakdown of glucose results in the production of lactate, and lactate is what causes fatigue. You can break down the anaerobic system into two bands, lactate tolerance and transport.

  • Lactate Tolerance (LT): 90-100% of HRM. Workout could be 4 x 60″ at race intensity.
  • Transport (TR): 85-90% of HRM. Typical workout might be 5 x 4′ at high intensity.

Aerobic: The aerobic energy system uses proteins, fats and carbohydrate (glycogen) for resynthesising ATP. The aerobic system can be broken down into three bands, which I’ll refer to as low, medium and high. For any endurance or power endurance sport, the aerobic energy system is key to performance because it provides anywhere from 50% to 80%+ of your energy. In a typical 2000 meter rowing race, the Olympic distance, 50% of the race is supplied by your aerobic system. That’s a massive amount and you simply wouldn’t be competitive unless you trained this energy system to a high level.

  • Low: Long, slow, and steady pressure at 55 to 70% of max heart rate. This places demands on muscle and liver glycogen. Benefits include capillarization, that is the growing of capillaries which deliver blood to your muscles. A workout for low aerobic might be running for 60′ straight at a low heart rate.
  • Medium: 70-80% of HRM. Places demands on the system to cope with lactate production. Working out at this level assists with the removal and turnover of lactate and the body’s ability to tolerate greater levels of lactate. Here we’re talking about 30-45′ of work at a medium intensity level.
  • High:  80-85% of HRM. Lactate levels become high as these workouts border on anaerobic. 20′ or so of intense aerobic work. This is also known as anaerobic threshold or AT.

How Does This Apply to Crossfit?

Okay, now that we have the energy systems established, a few things should become apparent.

All workouts have an aerobic component and almost all CrossFit workouts use all three systems (aerobic, anaerobic, ATP-CP). Even the shortest CF workouts, say a 3:00 Fran if you’re good, requires a high level of aerobic efficiency. You can’t do 90 reps of thrusters and pullups in less than three minutes without aerobic capacity. I would estimate that 50-60% of the energy supplied during Fran comes from the aerobic energy system. The longer the workout is, the more it slides into the aerobic realm. Remember Open WOD 11.5, the 20′ cardio disaster with power cleans, toes-2-bar, and wall balls? That’s probably 75% aerobic.

We rarely train the lower end aerobic system, or rarely train it optimally. If you only do WOD’s, when was the last time you worked out at a steady pace for 60′ with your heart rate in the 140’s?

As I said in my previous post, CrossFit is now a legitimate sport with a world championship and a competitive season, and elite CrossFitters are basically pro athletes. In my mind, there’s no question that a structured training plan that addresses aerobic and anaerobic efficiency as well as strength and skill are keys to maximum performance, especially for the top CrossFitters.

What Are Some Ways To Adjust Training?

If you’re serious about competing and want to train everything, and by everything I mean all of your energy systems plus strength plus skill to be the fittest athlete possible, how do you it?

What I do personally to train the lower end aerobic bands is add in longer runs, bikes, and rows at low intensity (low heart rates) outside of the gym. This gets me my aerobic base. Since I also train for competitive rowing, this training translates very well to the CrossFit gym. What most people say about me is that I’m good at “metcons,” that is I’m good at body weight WODs that require high aerobic capacity. Basically, my aerobic system is well trained.  The heavier strength stuff, not so much 😉

I think some of the top CrossFit athletes are training their other energy systems inadvertently, by going on longer runs and bikes as extra workouts because they like doing other sports.

There is another route you can take that I believe would be more effective at training your energy systems and making it specific to CrossFit. Here are a couple of ideas:

1. Do a regular CrossFit WOD, but stay in a specific heart rate range. This would require wearing a heart rate monitor or checking your pulse. This works best for longer WODs. Using Open WOD 11.5 as an example, you would could stay in a heart rate range of 135-140 the entire time, thus working the medium aerobic band. Consider reducing the weight (less weight = less impact aerobically) and increase the workout time to 30′. So, a varaint would look like this:

30′ AMRAP, 5 power cleans (95/65) , 10 T2B, 15 wall balls (15/10), heart rate ~135-140

Notice I added in heart rate to the workout description. Now you’re getting in specific aerobic training and also doing a CrossFit WOD.

2. Do lots of reps at lower weight in a specific movement for intervals with rest. We do a ton of this in rowing. An example here would be:

3 x 5′ of thrusters @ 45#, with 5′ of rest in between, pace is Transport.

The goal here is to stay in the Transport band, ie heart rate 85-90% HRM, to work that band. Customize the weight to achieve that. Doing thrusters, which is a common CrossFit movement and builds up other movements (front squat, press, etc) also builds skill via multiple repetitions.

You could even do this type of workout with a complex Olympic movement, say overhead squats or snatches with low weight (bar). It’s not the funnest thing in the world but it’s effective and builds skill and muscular endurance.

3. Do two or more WODs in a day, with either #1 or #2 above as your first WOD and then a normal, balls-to-the-wall WOD as the second WOD. That way you’re getting in the aerobic training and also getting in the competition WOD where heart rate spikes up into the 180s.

I think a lot of top Crossfitters are training like this, where they work out for 3-4 hours in a day, but only say 20-30′ of that volume is at race pace. The rest of it is lower heart weight lifting, skills development, and aerobic development.

Those are just a couple of ideas for adding another layer to your training and optimizing your fitness. In a future post, I’ll layout a sample training plan that gives some specific workouts and what the benefits are. Comments and feedback are welcome.


  • Mike

    Very interesting! Do you have any espcific workouts?

  • manatee2000

    Another well thought out article.


    great article. I’m just learning about the different energy systems in hopes of being a personal trainer/L1 trainer; and I also Crossfit. I’m convinced, all training should revolve around improving particular energy systems. Doing so will only make you a better overall athlete/crossfitter. I will definitely implement this philosophy in my programming.