As humans we always want information displayed as – Do This Not That. Eat This Not That. It’s easy. It’s clear and let’s face it nuances don’t sell. Over the last few decades we have been sold High Intensity Interval Training (HIIT) hard.

The research is fairly clear that HIIT overpowers steady state cardiovascular training in weight loss, fat loss, and in promoting healthy changes in blood sugar and insulin sensitivity. This all makes sense given the mechanisms of action, but it is not the end of the story or the only side. Those who despise steady state cardio now say – nope, never need it again. Deuces. (This tends to happen with a lot of things, but the best example is stretching. The people that don’t like to stretch but who need it the most don’t do it, and the people that love it tend to do too much)

I used to be a HIIT Jedi. Everything I ever did with myself and clients was in intervals. My justification was the research on fat loss. I was also an early disciple of Boyle and I bought into the ideology that we need only work inside the intervals of our sport or perhaps a little longer…but not too much! There is no debating that football players work in short bursts of activity. The average NFL play is 5-15 seconds. The most a baseball player is ever likely to run is 60 yards or about 6 to 7 seconds. Thus, the contemporary strength coach has had the mentality that speed and power athletes don’t need chronic cardio. Which is true they don’t, but they do need movement and cardiac output work. Yet, this Interval Philosophy has now been extrapolated to everyone ever. Why would I go for a hike or move throughout the day when I can just get this whole thing done in 4 minutes of negative rest intervals of Tabata. Party.

The problem isnt HIIT, it is that we aren’t building or maintaining the foundation to really use HIIT well and recover from it. HIIT is powerful. Potent. But so is cardiac output work. In fact if given the choice of whether to move throughout the day or have a structured exercise regimen, one should always chose movement. It trumps structured exercise in the research as far as longevity and health, and is much more in tune with how we have evolved into being.


So what are the benefits of HIIT?


Concentric Hypertrophy of the Heart  – Increased stroke volume


EPOC – Increased After Burn


Time Efficient


Weight Loss


Increased Insulin Sensitivity – Glycogen Depletion


Opioid High – Feels Soooo Good


Improved Buffering Capacity (Lactate)


Improved Anaerobic Capacity & Power if programmed correctly.


Increased Muscular Hypertrophy (Circuit Training)


What are the negatives?


Concentric Hypertrophy of the Heart – Limits blood volume. (If overdosed can cause excess acidosis leading to damage.)


Promotes the idea that you can just sit or stand still the rest of the day – Lack of time spent in movement exploration (Stuck in 2D?)


Sympathetic Driver – Over prescription can exhaust the endocrine system.


CNS Fatigue – Taps emotional energy (lingering fatigue can affect motor learning and strength)


Destroys Mitochondria – Heart and Muscle Fibers


Randomness – very few know how to progress this type of work well


Sacrifices in Movement Quality in Highly Fatigued States


Now what are the benefits of Cardiac Output or Movement Work at low heart rate ranges (120-130bm) for 30-40 min?


* this zone is generally a lot lower than the endurance hobbyists who creep up far too high and live in what is called the dead zone of training or Zone 3 and 4 for Ben Greenfield Disciples out there.


Eccentric Hypertrophy of the Heart – Increases the stretch reflex of the heart. Less energy used per beat.


Increased Capillarization


Increased Mitochondrial Density


Parasympathetic Driver


Improved Oxygen Utilization Within The Muscles


Increased Aerobic Capacity


Increased Recovery Between Sets or Intervals


Increases Recovery Between Workouts


Reduces Resting Heart Rate


Can Increase Time to Fatigue During Skill Acquisition – More focused training


What are the negatives of Cardiac Output or Movement Work?


Let’s Be Honest – Boredom – Few use their imaginations


Can Eat Up at Muscle – if done in excess and without added resistance training


Can Disrupt Endocrine Function – if done in excess and without added resistance training


Can Negatively Affect Hypertrophy and Strength – if done incorrectly


Increased Chances of Overuse Injuries, If Kept to a Single Modality


Over the last decades we have moved from the chronic cardio epidemic of the 80s and 90s to the currently regime of HIIT and self destruction. We believe the pendulum is swinging back towards people gaining an understanding and using sound principles to decide the dose and variety of conditioning that fits them best. But no matter what you choose, Cardiac Output Work is equally powerful and there aren’t a lot of negatives related to programming 3D movement in low heart rate zones. AKA accumulating steps and triplanar work throughout the day.

Yes, running from a lion is important and leaves you with a flood of opiates in the brain, but equally so is foraging, playing, and dancing. This big industrialized engine of a world has made us far more efficient, but has it ever made us healthier? The answer to that question is looking more and more to be a resounding no. HIIT is not black and white and without movement, it is probably dangerous and unproductive in a long term view.

Is it better than nothing? Depends on the Athlete.

Is it better than moving throughout the day? No way.

Is combining both in an educated manner the way to go? F@#$ Yes.


By: Ben House, Ph.D. Candidate, FDN, fNMT and Aaron Davis, CSCS