An argument for Polarized Training.
In today’s post we'll cover polarized training. What it is, what supporting evidence there is to suggest its efficacy, and how you can implement it in your training.
To put it simply, polarized training is alternating between low and high intensity. Hard effort one day, a controlled truly easy effort the next. This allows for more total training volume since low intensity work is less damaging to the body, it can increase your ability to recover from your hard efforts, and addresses energy systems that are undertrained in high intensity only training- primarily the aerobic system. - study(aerobic training/mitochondria)
I gotta come clean, I have struggled with polarized training in the past. Even when the intent of given workouts in my programming was clearly to be low intensity I would often brush that off and push hard anyway. I grew up in a training environment that was different than today. In high school I ran distance and our team held tightly to a Steve Prefontaine quote "any thing over 7:00 mile pace is a waste of time" Another idea that was common among us was that "long slow distance makes long slow runners". It's common sense logic, if you train harder you'll get more out of the training. Unfortunately the data says otherwise. - study(polarized training)
Variability of intensity matters. Hard can’t be hard if its always the same intensity.
When we have a "more is more" mentality we often do a significant portion of our training at MODERATE intensity. Not easy, and not truly hard. If you're going "hard" every day, maybe Monday or your first training day of the week is hard, but by day two or three are you even able to give a truly hard effort? Local muscular fatigue and overall central nervous system fatigue build up quickly with hard/moderate efforts and the overall intensity of these "hard" sessions drops.
Contrast is important. If you go at a 9 out of 10 rate of perceived effort on Monday then go at a 3-5/10 effort Tuesday you allow your body to recover from the truly hard effort Monday, you still get training volume in on Tuesday even at a lower intensity and you work in a different heart rate range that allows for different physiological adaptations.
Benefits of developing the aerobic system.
When training at a lower intensity specifically zone 2 or low zone 3(lets call it 120-140 bpm, this is approximate and not going to be accurate for all readers) your body primarily uses fat oxidation for fuel. You train your aerobic fat metabolism reducing reliance on glycogen stores(utilized during anaerobic or “hard” efforts). This improves the ability to sustain prolonged activity and helps your burn more fat.
Mitochondrial Biogenesis and efficiency. Zone 2 is the most effective intensity for building mitochondrial density(mitochondria are the powerhouse of the cell, training here will make more of them) and improving oxidative phosphorylation efficiency. So not only will you increase the amount, but you'll make them more efficient. - study(mitochondrial adaptations)
How can I implement this?
At the elite level, the volume of total exercise can be so high that many athletes are doing 80% of their work in an easy range and 20% at high intensity. For amateurs and your common gym fiend you could alternate hard/easy and still reap a lot of these rewards.(study on Polarized training for untrained individuals) This will require a heart rate monitor(chest strap preferred but wrist mounted ok).
On your hard days, go hard. 7-9/10 RPE scale. Always in control, but pushing the pace. For metabolic conditioning or aerobic work your heart rate may be in zone 4 or 5 here depending on the workout. For strength work use the RPE Scale as your heart rate will likely remain low throughout.
On your easy days, keep your hr between 120-140 or 60-70% of your max heart rate during metabolic conditioning or aerobic work.
For your strength work keep loads below 70% of your 1RM or below 7/10 RPE.
Don't expect immediate results
One of the reasons high intensity training became so dominant in the fitness space is that it shows better results in short time domains(most studies are conducted in 4-12 weeks). High intensity training(anaerobic) relies on stored fuels (ATP-PC, glycolysis) for short, high-intensity bursts. It builds strength, power, and muscle size quickly because muscle fibers are under direct mechanical stress and hormonal signals for growth are strong.
Aerobic training- aerobic adaptations, however, involve changes in heart and lung efficiency, capillary density, and mitochondrial production — these processes that take months to fully develop.
I am not urging you to toss out high intensity training, it works and I'm a huge proponent of it. I'm urging you to polarize your training, develop an often underutilized energy sytem. Recover more effectively from your high intensity bouts while reaping the rewards of more and more efficient mitochondria.