Let's talk anaerobic endurance. Most people know anaerobic endurance training by it's much shorter name, HIIT (High Intensity Interval Training). Anaerobic simply translates to “without oxygen”. This means your body is performing at a level that is too intense for your aerobic system to keep up with, so it quickly shifts to it's anaerobic system to keep producing the energy that your working muscles demand. Any activity that requires less than 2-minutes to complete before resting is considered an anaerobic activity.

So if you are not using oxygen for energy, what are you using? Glycogen! For those of you who would prefer to discuss this in simple terms, glycogen is basically carbohydrates or sugar. The goal of training your anaerobic system to is move fast, powerfully, and as intense as you can for the time duration you are aiming for. For example, if you were doing 30-second sprints, you would try to maintain the fastest pace possible for the entire 30-second period rather than running fast for 10-seconds and jogging the last 20-seconds. Now that you know the basics, this is where HIIT comes in to play.

After you have built your aerobic endurance over the course of several weeks, it's time to supplement your program with one day per week of HIIT to keep your progress moving smoothly. While aerobic endurance training speeds your recovery time, decrees blood pressure and resting heart rate, improves circulation and will prepare you to complete more effective HIIT, it does not improve your overall speed and power as well as HIIT does.

If you want to BE FASTER, you have to GO FASTER! I have had several athletes who could run a 5k in around 23-minutes, but no matter how hard they tried they just could not get their time lower even with proper aerobic conditioning. I asked them how often to included interval work in their program, and not surprisingly, they said none! “We are not sprinters …” they would protest. So what! Even sprinters do one long run per week to keep their aerobic fitness levels in tact, so why would not an endurance athlete want to improve their anaerobic fitness levels? Variety is key, so I made them begin HIIT sessions once per week for two weeks, then twice per week for the following two weeks.

Much to their surprise, after 4-weeks of adding one, then two HIIT sessions into their cardio programs, their 5K time had been shaved down! Improvement ranged between 1-3 minutes shaved off their times after only 4-weeks. If you are a runner, you know that is a very significant time decrease. In a race, increasing by 30-seconds would make most runners ecstatic, but 1-3 minutes? These athletes were totally sold.

Alright so let's get to the nitty-gritty that everyone wants to know, what is the program I gave them? Well … here it is!

Weeks One and Two: Complete Once per Week

Weeks Three and Four: Complete Twice per Week

  • 5-minute warm-up at 75% maximum heart rate (bike, running, elliptical, does not matter – always 75% MHR!)
  • 20-minute HIIT workout: Run / bike / elliptical as hard and fast as you can for 30 seconds
  • After 30 seconds, slow your pace down significantly (walk, pedal slower, elliptical slower)
  • Keep an eye on your heart rate monitor. Look for when your heart rate falls BELOW 70% MHR
  • GUN IT for another 30 seconds!
  • Repeat this as many times as possible for the 20-minute duration
  • 5-minute cool-down at 60% MHR
  • Stretch !!

You may be wondering why I do not prescribe a specific time frame for rest. When you want to track how efficient your heart is becoming, you look towards your recovery rate. A beginner may take several minutes to return back below 70% MHR after a 30-second sprint, whereas an advanced trainee may only take 30-60 seconds to return below 70% MHR. Therefore, sometimes the beginner may only complete 6 sprints in the 20-minute time frame, where as the advanced trainee may complete 12 sprints in the 20-minute time frame.

Track your progress by counting how many 30-second sprints you completed in the 20-minute time frame! If you got 6 this week, and 7 two weeks later, your anaerobic conditioning is improving! But do not forget, training your aerobic endurance will help speed up how fast your heart slows down as well, so do not get carried away with your HIIT and totally neglect your aerobic training!

In Good Health,

Steve Hunter