HIIT It or Quit It?
In the 1990s, two key pieces of research headed by Dr. Izumi Tabata and Dr. Angelo Tremblay on high-intensity interval training (HIIT) were the impetus for a dramatic shift in the way people perform "cardio." Long, slow jogs were quickly replaced by nausea-inducing, high-intensity intervals.
Since HIIT is relatively new in the research world, we don't yet know what, if any, long-term health ramifications could come from consistently putting the body into metabolic acidosis. But there are some strong indicators suggesting that if you need a puke bucket next to you during a HIIT workout it might contribute to heart arrhythmias and damage your otherwise healthy muscle proteins. Not good.
For years, I was as guilty as any performance coach for elevating the popularity of HIIT. Those workouts take less time, and the fatigue they create definitely makes you feel like you did something beneficial. But over the last year I've switched back to lower-intensity cardio workouts for my clients. I noticed two essential improvements:
- They felt better overall, meaning they had more energy during the day and slept better at night.
- They recovered faster from their weight-training workouts.
Long-duration cardio performed at a low intensity upregulates hormones and neurotransmitters that are conducive to the recovery state. Conversely, the high-threshold motor unit recruitment and joint strain that accompanies HIIT is like adding another weight training session, which can often drain the athlete's recovery capacity.
But if you're anything like me, the idea of jogging on a treadmill for 45 minutes is as appealing as eating dinner in a gas station bathroom.
Furthermore, if you're an explosive athlete, it's likely that spending hours each week doing leisurely jogs, or pedaling an exercise bike, will lead to muscle fiber conversions that make you slower and weaker. Your hip and knee extensors need to be as fast-twitch as possible to keep your vertical jump, deadlift, and sprint velocity at their peak.
So what can you do to get the benefits of long-duration cardio without the boredom and muscle fiber conversions? Kickboxing.
Kickboxing targets all the elements any athlete should want:
- It builds athleticism because it challenges your balance, agility, and reflexes.
- By constantly switching between punches and kicks, you're not overworking any single muscle group, minimizing muscle fiber conversions.
- You don't need to be good at kickboxing for it to be an effective cardio-booster.
- It's anything but boring.
Find a reputable kickboxing coach that can show you a few combinations to practice at home (shadowboxing) or with a punching bag. The key is to do it at an intensity you can sustain for 30 minutes or more.
How do you know if you're working at the right intensity? I recommend the heart rate formula popularized by endurance expert, Dr. Phil Maffetone: 180 minus your age.
So a 30 year-old guy should perform the vast majority of his cardio at a heart rate of around 150 beats per minute. Let's call it 145-155 beats per minute if you're fit, or 140-150 if you're not. At that range you'll get maximum oxygen uptake, which is your primary goal, while avoiding metabolic acidosis.