I think there's some masochism inside all of us. At least when it comes to suffering through conditioning and cardio. It's why high intensity work is so popular, and the association seems pretty clear - work hard, embrace the suck, get results. And to some degree that does happen.
But only using high intensity conditioning, or using it too frequently, is going to lead you nowhere fast. It's a lesson I learned through my own conditioning, as well as writing programs for my clients. Both myself and (most of) my clients loved sweating, breathing hard, and getting smoked. But I couldn't figure out why some people weren't getting better, and why they weren't improving markers of fitness (lowering their resting heart rate, increasing their heart rate variability, increasing VO2 max, decreasing musculoskeletal pain).
That's because I had fallen for what I like the call the "Tabata fallacy." Tabata, of course, is the method of high intensity that was born from this study. It examined one group that did only moderate intensity workouts (~70% of their VO2 max) and another group that did high intensity, short intervals (~170% of their VO2 max!). As one might expect, the high intensity group saw improvements in their anaerobic capacity - their ability to work hard over a 2-3 minute period followed by a very long rest.
The high intensity group also saw an improvement in their VO2 max over the first three weeks of the study. VO2 max demonstrates your ability to keep working for an extended period of time, and it's highly correlated with longer life spans.
The problem? The study was six weeks long. And I'm not sure about you, but I love plateaus about as much as a swift slap to my face.
As the paper reads:
After 3 weeks of training, the VO2max had increased significantly by 5 ± 3 ml·kg-1·min-1. It tended to increase in the last part of the training period, but no significant changes were observed.
Unfortunately, this study has been poorly extrapolated across the fitness industry. High intensity work now has the reputation of always being more efficient than low or moderate intensity, when that's simply not the case.
The moderate intensity group (70% of their VO2 max) saw a constant improvement each week, not just the first three weeks. That's because building up your own conditioning is always about the long game. This group was able to properly build up their aerobic energy system, which takes consistent time and effort. Anyone who tells you differently is trying to sell you something.
So rather than going as hard as you can every time you condition, set the following priorities:
1. Use specific goals. To ensure you're continually improving, set specific times or physiological results to see if your program is working. These metrics could be anything: decreasing your resting heart rate by 3-5 beats, increasing your heart rate variability by an average of 5, or knocking 15 seconds off your running or bike times. Just like building strength, setting goals will make you more focused.
2. Train the aerobic system first and more often. As I've written about here, the aerobic system is the straw that stirs the drink. A robust aerobic system helps you last longer while you're conditioning by taking the brunt of the work, and it helps your body recover between exercises. Further, aerobic work turns on our parasympathetic system (rest and digest) helping you fight systemic inflammation and making you feel better.
The catch - of course - is that moderate intensity is the best way to target your aerobic system, and training it 2-5 times/week is optimal. This could mean a brisk walk 30-45 minutes; get-ups and swings for 30 minutes; and my personal favorite - 18 miles on the Air Assault bike in 54 minutes.
3. Use high intensity workouts minimally. Despite what I've said above, high intensity conditioning does serve a great purpose but only if you use it with care. Higher intensity work needs to have a corresponding drop in volume - the number of reps, time, distance, etc. Otherwise, you're setting yourself up for failure or injury.
This is where I've grown most as a coach over the past few years. Rather than giving people what they want - high intensity at the end of a session - I've been giving moderate intensity throughout. It hasn't always been easy, as I have to actively pull most of my clients back from going too hard.
But I wouldn't have it any other way.