Low vs. High-Intensity Conditioning: Which Is Better For You?

May 11, 2023

The conditioning landscape in combat sports is changing. For over a decade (and currently), Joel Jamieson’s Ultimate MMA Conditioning has been the go-to resource for prescribing cardiovascular training for fighters.

I’ve implemented his methods extensively, and it is a great, simplistic way to start if you want a stripped-back method for building your gas tank. This has further extrapolated into the zone 2 craze of hours of low-intensity cardio.

But new research and application are making their way into combat sports with unheard-of changes in physiology creating world and national champion fighters. Is it time to move away from energy system development and focus on muscle physiology and work outputs?

Why Emphasize Low-Intensity Conditioning?

When I mention emphasizing low intensity, I’m referring to a polarized model where you train below and above outputs you’d perform during combat sports training. In this instance, it’d be low-intensity steady-state cardio or extensive tempo training and high-intensity alactic power or sprint interval training.

I typically don’t only prescribe low-intensity cardio without sprint interval training unless it’s for a short period to make easy progress without much stress. In this case, alactic power is developed with power-based exercises in the gym.

But why this emphasis on low-intensity conditioning?


It’s all about physiology. That is what the polarized approach leans into—maximizing physiological adaptations. With low-intensity cardio exercise, we are targeting predominantly central adaptations to the heart.

Here we maximize the ability to deliver oxygen to the working muscles, which long-term aerobic exercise does [2]. Typically, athletes with high VO2max values demonstrate high stroke volumes (the ability to pump more blood per heartbeat) [1].

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When comparing polar opposite sporting demand athletes, endurance vs. strength sports, we see endurance athletes have much lower resting heart rates and better heart function to pump blood to the working muscles [3][4].

This ability to pump more blood is led by eccentric left ventricular hypertrophy. Or, in layman’s terms, a bigger heart chamber to pool more blood to be pumped. It is said that low-intensity conditioning drives this adaptation with hours of zone 1 and 2 cardio.

However, after diving into the research, I don’t believe it’s isolated to low-intensity conditioning (I will be updating my conditioning articles with this new information). The research I cited above compared endurance and strength sport athletes, which have polar opposite training objectives.

You’re not lifting weights or doing conditioning in isolation as a combat athlete. Further, if maximizing end-diastolic volume (filling the left ventricle with as much blood as possible before ejection) is how we enhance eccentric left ventricular hypertrophy, this can be achieved with different conditioning intensities.

To extrapolate endurance vs. strength sports athletes to saying low-intensity cardio is the reason wouldn’t be sound. Especially since it’s difficult to find this intensity that maximizes stroke volume [5][9].

Under the energy system model of conditioning, prioritizing low-intensity conditioning builds the aerobic base. It does. But after a while, it loses its effectiveness [6][7].

And the volumes you’d have to reach to continue to improve with a low-intensity approach are long-endurance athlete volumes. As a combat athlete, you don’t have time to do this. Does this make low-intensity conditioning useless?

No. But we may need far less than traditional endurance training volumes.

Low Stress

The second reason for a low-intensity or polarized approach is the lower stress of exercise. We can move the progression needle inch by inch without impacting other training sessions like important technical training.

Essentially, we are doing just enough to make progress but not too much to speed it up. It’s a long-term mindset instead an instant-reward approach.

Especially since it may take a high frequency of low-intensity conditioning over longer periods to continue progressing [8].

But the question becomes, how “fit” do we need to be, and can we get enough low-intensity conditioning from technical training? At what point does doing low-intensity aerobic conditioning not give us any further benefits?

A Non-Energy System Conditioning Paradigm Shift

I’ll preface this section by saying it is heavily influenced by Andrew Usher and Dr. John Babraj’s research which you can hear on the podcast below:

I’ve been talking a lot recently about shifting from an energy systems model to a work output model regarding conditioning development. I believe I’ve managed to piece together and further evolve my conditioning philosophy to be more than energy systems.

This section will be fleshing out for your and my own benefit. Instead of wondering how we can maximally develop each energy system, should we be wondering how to maximize peripheral adaptations and the muscle’s oxidative ability?

The reason for this line of thinking is whether VO2 max is the limiting factor for performance. Among groups of similar performance and longer distances above 3000 m of running, VO2max does not predict performance [10].

Instead, it’s the ability to remain economical with movement at sub-maximally intensities. Does this make aerobic capacity not important for combat sports? No. But its importance may be overstated, and further enhancing central adaptations may not be the key driver for better conditioning for combat sports.

For example, athletes with higher VO2maxs recover faster after intense bouts of exercise [11]. But other ways exist to improve VO2 max without staying “aerobic.” VO2 max intervals are one way where you maximize the time spent training at VO2 max.

Another is through high-intensity interval training (HIIT) and sprint interval training (SIT). One study in particular shows VO2peak to max out after 3 weeks of either 4 – 6 x 15 – 30 sec maximal sprints with 2 mins active recovery, but time to exhaustion during the endurance time trial continued to improve to the end of the 9-week intervention [12].

This indicates we can still improve aerobic conditioning without improvements in VO2 max. Instead, SIT can improve the muscle’s oxidative capacity to reduce fatigue. So, what does this mean for combat sports?

Low vs. High-Intensity Conditioning Approach For Combat Sports

Sprint Interval Training Combat Sports

Your training goals and life schedule will dictate the approach you take. For the hobbyist enjoying combat sports as a way to stay active, do what you enjoy. In most cases, combat training will be your conditioning for the week, and you may have other activities you enjoy.

For the hobbyist who wants to look great naked, you may lean towards lower-intensity conditioning to save energy for lifting weights, as that will have the most significant impact on your physique. But for the competitive combat athlete, it gets a little murky.

The idea of taking a purely SIT approach is you’re getting enough low-intensity activity through technical skills training. Some of you might be as you train every day for 1-2 hours to cover all your skills.

In this instance, you might not need extra low-intensity conditioning as you get the volume through technical combat training. Further, we can still improve VO2 max through SIT! You may be better served doing SIT starting with power-based intervals (longer rest) twice a week and moving to endurance-based intervals (shorter rest) as you get close to a fight.

Here are a couple of examples from Andrew Usher’s Sprint Protocols available in the SSOF Underground:

Power: 6 x 15-sec w/90-sec rest

Endurance: 10 x 10-sec w/20-sec rest

Perform these on a spin bike and turn the resistance knob 2.5 times or until you feel a decent resistance.

But there’s something to consider when taking a pure SIT or HIIT approach to your conditioning. Your muscle fiber type distribution plays a role in recovery. Athletes who are predominately slow twitch recover faster after high-intensity exercise, whereas fast twitch-dominant fighters may take over 5 hours to recover [13].

If you are fast twitch dominant and rely heavily on sprint training, you may dig yourself deeper into a hole as the week progresses with added technical training.

How do you know if you are fast or slow twitch dominant? Outside of lab or field tests, you can use observation. While not entirely accurate, you likely have some idea. Are you a springy, bouncy, explosive fighter with above-average muscle mass who needs to conserve energy in a fight? You’re probably fast twitch dominant.

Some good examples across the spectrum would be Yoel Romero, Tank Davis, Alex Pereira, and Jordan Burroughs.

Are you a workhorse who can grind opponents with a relentless work rate but lack explosive ability? You’re probably slow twitch dominant. Some good examples would be Khabib Nurmagomedov, Nate Diaz, and Gordan Ryan.

But most of you will be in the middle having close to an even mix of fast and slow twitch muscle fibers. For the fast twitch dominant fighters, you may look to take a lower-intensity approach to conditioning.

It will allow you to build the capacity to vacuum excess lactate (which a HIIT and SIT approach can also do) without digging yourself into a hole with fatigue. An HIIT and SIT approach would work tremendously for slow twitch dominant fighters since you recover much faster.

For the intermediate fiber type fighter, you can lean towards a HIIT approach and use low-intensity conditioning as a “recovery” exercise.


Both approaches to conditioning work. It may depend on your physical traits and how much technical training you perform throughout the week. VO2 max may not be as important as we initially believed to combat sports performance, and therefore, a higher-intensity conditioning approach may be warranted.

However, fast twitch-dominant fighters may be weary of how much high-intensity conditioning they do due to extended recovery times.


1. Lundby, C., Montero, D., & Joyner, M. (2017). Biology of VO2max: looking under the physiology lamp. Acta Physiologica220(2), 218-228.

2. Lee, B. A., & Oh, D. J. (2016). The effects of long-term aerobic exercise on cardiac structure, stroke volume of the left ventricle, and cardiac output. Journal of exercise rehabilitation12(1), 37.

3. Vinereanu, D., Florescu, N., Sculthorpe, N., Tweddel, A. C., Stephens, M. R., & Fraser, A. G. (2002). Left ventricular long-axis diastolic function is augmented in the hearts of endurance-trained compared with strength-trained athletes. Clinical science103(3), 249-257.

4. Mihl, C., Dassen, W. R. M., & Kuipers, H. (2008). Cardiac remodeling: concentric versus eccentric hypertrophy in strength and endurance athletes. Netherlands Heart Journal16, 129-133.

5. Buchheit, M., & Laursen, P. B. (2013). High-intensity interval training, solutions to the programming puzzle: Part I: cardiopulmonary emphasis. Sports medicine43(5), 313-338.

6. Hickson, R. C., Hagberg, J. M., Ehsani, A. A., & Holloszy, J. O. (1981). Time course of the adaptive responses of aerobic power and heart rate to training. Medicine and science in sports and exercise13(1), 17-20.

7. Londeree, B. R. (1997). Effect of training on lactate/ventilatory thresholds: a meta-analysis. Medicine and science in sports and exercise29(6), 837-843.

8. Laursen, P. B., & Jenkins, D. G. (2002). The scientific basis for high-intensity interval training. Sports medicine32(1), 53-73.

9. Vieira, S. S., Lemes, B., de Carvalho, P. D. T., de Lima, R. N., Bocalini, D. S., Junior, J. A., … & Serra, A. J. (2016). Does stroke volume increase during an incremental exercise? A systematic review. The Open Cardiovascular Medicine Journal10, 57.

10. Legaz-Arrese, A., Munguía-Izquierdo, D., Nuviala, A. N., Serveto-Galindo, O., Urdiales, D. M., & Masía, J. R. (2007). Average VO2 max as a function of running performances on different distances. Science & sports22(1), 43-49.

11. Seiler, S., Haugen, O., & Kuffel, E. (2007). Autonomic recovery after exercise in trained athletes: intensity and duration effects. Medicine and science in sports and exercise39(8), 1366.

12. Lievens, E., Klass, M., Bex, T., & Derave, W. (2020). Muscle fiber typology substantially influences the time to recover from high-intensity exercise. Journal of applied physiology128(3), 648-659.

About the author 

James de Lacey

I am a professional strength & conditioning coach that works with professional and international level teams and athletes. I am a published scientific researcher and have completed my Masters in Sport & Exercise Science. I've combined my knowledge of research and experience to bring you the most practical bites to be applied to your combat training.


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