Guest Post: Cardiac Output Training for Strength Athletes

Today's post comes from Erika Hurst, strength coach and owner of Hurst Strength. She's a pretty strong woman and knows her stuff! 

In light of her aerobic training post, SAPT has a Spartan Race team and you can refer to Jarrett's post from this week for more information on how to sign up for training with us!

Steady state aerobic training. It's kind of the red-headed step child of the fitness realm. In the past few years aerobic work, or “cardio”, has been vilified due to misconstrued understanding of research and the rising trend of “HIIT” (high intensity interval training) and other gut-busting activities designed to better condition you.  Who wants to spend 30 minutes sucking wind when you could supposedly accomplish the same thing with a 4 minute circuit?

But what if I told you without a well-developed aerobic system, fuel for your muscles can't be regenerated as quickly, causing your performance to suffer, power output to significantly decrease and no matter how strong you are, you won't have the energy to harness all of your strength.

The terms “cardio” and “conditioning” are oftentimes thrown around interchangeably without much solid understanding of what either really mean.  Because of this, most take a sort of shotgun approach when trying to improve their conditioning – a jog here and there, some sled pushes – I mean as long as you're sweating, panting and your muscles are burning you must be doing it right!

Joel Jamieson describes conditioning as “the result of how well the systems of your body are able to create the energy your muscles need to perform the skills of (your sport) throughout a (competition)” (1). Some sports require a little more power than endurance, others vise-versa, so conditioning needs to be approached and developed accordingly.

There are actually EIGHT different methods for developing a better aerobic base, and not all are slow and longer duration.  The first method is Cardiac Output.

Before we get into the meat and potatoes of how and why to use CO to develop an aerobic foundation, it's important to first understand the three basic energy systems of the body and how they work together to fuel us to sprint, lift, run, crawl, climb, breathe and even walk to the fridge.

            1)   Anaerobic Alactic (ATP-CP) – supplies short-term energy, primary energy source of      first 0-12       seconds of activity.

2)     Anaerobic Lactic (Glycolytic) – supplies intermediate energy, provides for a little        more than a minute.

3)     Aerobic (Oxidative) – supplies long-term energy, capable of providing energy for    hours.

All three energy systems kick on at the onset of activity, but contribute to energy production at different levels based on the duration of the activity being performed, recovery period between each bout, and the number of bouts of activity.

The first two energy systems are anaerobic, meaning they fuel short bursts of high intensity activities like heavy, low rep deadlifts, sprints and hard punches.  They can produce powerful energy fast, but don't have the capacity to do so for extended periods of time.

The aerobic system on the other hand, which fuels slower, longer duration activity, is slow at producing energy, but it can be leaned on for longer periods of time for energy supply. 

What most don't understand about the aerobic system is that it actually refuels the anaerobic systems and prevents you from “gassing” out and losing steam when training, at competitions, on the field or during other activities that require you to exert a high burst of energy in a short period of time.

If you need a little more convincing that you should dedicate some time to your aerobic base, here are a few more benefits:

Increased heart efficiency

When performing aerobic work based on the parameters I'll describe below, blood is being forced into the left ventricle of the heart.  While it's in there it stretches out the heart wall, causing it to get bigger.  A bigger left ventricle means you can pump more blood in and out with each heartbeat, making your heart more efficient – it doesn't have to work as hard or beat as fast.  This results in a lower resting heart rate and more blood and oxygen pumped to your muscles.  Not only is this integral to higher performance, but for general health as well.

Unfortunately, this adaptation can not occur with higher intensity training.


Increased work capacity

With repeated bouts of activity (intervals, sports, etc), you become more and more “aerobic” as duration and fatigue increase.  Without a developed aerobic system you'll gas out sooner when needed to produce repeated high-intensity bouts of activity – slowing down and reducing your power output is your body's only option to keep you going in this situation.

A healthy, strong aerobic system will increase your work capacity, or your ability to perform more high quality work within a training session, on the field or in competition, with less rest and recovery needed to regenerate in between.

If you're a powerlifter or weightlifter this means you'll be able to perform at a higher level during lengthy competitions. If you're an adult looking to lose fat and get in shape, this means you can do more and lift harder without getting tired during training session – making your workouts more metabolic and beneficial.


Improved recovery between sessions and competitions.

It's been heavily rumored that performing slower cardio will make you slower, eat away at your hard-earned muscle and basically shrivel you into a weakling.

Properly planned and executed aerobic development sessions, done in conjunction with lifting heavy and moving fast, will do none of the perceived disadvantages above. Instead, it will actually boost your recovery between strength workouts, reduce soreness and boost your energy, allowing your body to better adapt to the training you’re doing.

Bonus benefits:

Being able to walk up stairs without getting winded, improved mental well-being, improved insulin sensitivity/more efficient use of dietary carbs, shifts autonomic nervous system out of “fight or flight” and into “rest and digest”, reduces arterial plaque formation, reduces body fat stores and boosts longevity.

 How To

Cardiac output entails keeping your heart rate between 120/130-150 beats per minute for 30-90 minutes.  (If you are younger, 130-150bpm, older 120-150bpm).

You can do this with mobility or body weight circuits, light sled pushes/drags, farmers carries, low level skill work, low intensity resistance training, jump rope, biking, easy medicine ball drills, battle rope work, etc. or a circuit combing all of these.

It really doesn't matter what you do for that time block, as long as your heart rate stays in range.  If it goes over, stop and rest until it comes down to range or lower your intensity.

Incorporate CO for 1-3 days per week for 6-8 weeks alongside 2-3 days of strength training.  To track your progress, monitor your resting heart rate.  It should become consistently lower as you expand your aerobic base.

The good news is that once you achieve a wider aerobic base, it is very easy to maintain.


How do you know if you need it?

Honestly, I think most everyone would reap benefits from performing regular cardiac output work. Due to the excessive amounts of stress in our daily lives that results in the chronic over stimulation of our sympathetic (fight or flight) nervous systems, some low-intensity work can definitely help us to counteract that stress response.

Otherwise, the best way to tell if you need to start doing CO besides how fast you fatigue, is via your resting heart rate. If it is in the 60s/70s or higher, you're a candidate.

Whether you are a speed or power athlete, an athlete who plays a more aerobic dominant sport or just a general fitness enthusiast, there's most likely a place in your program for expanding your aerobic base. 

Remember, you're only as strong as your aerobic system.  Take time to build it and you'll have the requisite capacity to perform more high-intensity work to get even stronger, faster and more explosive.


1. Jamieson, Joel. (2009). Ultimate MMA Conditioning. Performance Sports Inc.




Erika Hurst is the owner of Hurst Strength, a private strength and conditioning facility in Wallingford, CT.  She has dabbled in powerlifting and is a firm believer in the power of hauling heavy things and good cheeseburgers.