Rethinking High-Intensity Interval Training for Conditioning

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High intensity interval training (HIIT) has become a popular conditioning method. However, Gassers, Shuttle Runs and Tabata intervals might not be the best option for your sport. Read on to find out why.

The Science Behind Conditioning

Energy comes from different sources depending on length and intensity of movement. Each major energy system is activated when movement begins, but some more than others depending on the nature of the work. The traditional breakdown between energy systems is:

  • Aerobic - long duration (typically longer than 3 minutes), moderate intensity exercise fueled by oxygen
  • Anaerobic - short duration, maximal effort activity fueled by stored energy

However, this split doesn't explain enough, because the anaerobic system is further broken down into two parts:

  • Alactic Anaerobic - short-term energy (10-15 seconds) fueled by ATP-CP
  • Lactic Anaerobic - mid-term energy (60-90 seconds) fueled by glycolysis

For approximately the first 15 seconds, the alactic anaerobic system is pumping hard. Beyond this point, if intensity remains high, the lactic anaerobic pathway becomes the primary energy producer. This is what causes the burning sensation in muscles, and it is the primary energy system behind HIIT training. If activity continues, the aerobic system begins to take over.

So, calling something "anaerobic" isn't specific enough. Throwing a baseball is anaerobic. So is performing as many Squat Jumps as possible in one minute. But they are very different.

Capacity and Power

A single bout of explosive effort—like a 100-meter sprint—followed by a long period of rest is based on alactic anaerobic power. It's a one-and-done quick effort. However, football and other team sports require repeated sprints and efforts over extended periods of time with intermittent rest.

Team-sport athletes are faced with unique demands. They need top-end power and the capacity to sustain it over the length of a game. For example, a pitcher with amazing alactic power might hit triple digits on the radar gun, but his speed will quickly decrease if he doesn't have capacity.

Importance of Aerobic Training

If you truly want to condition for your sport, you need to train both the alactic and aerobic systems. This will dramatically improve recovery between plays.

A recent study put soccer players through a total of ten six-second sprints, with thirty seconds of rest between them. There was a 27 percent drop in power from the first to last sprint. Compare this to the standard 20 seconds on and 10 seconds off HIIT interval. It doesn't even come close. Soccer involves about two to four seconds of sprinting followed by 90 seconds of low-intensity jogging. This means that 70 percent of a soccer match is performed under aerobic conditions.

How to Develop the Aerobic System

Distance running is a form of aerobic training, but not all aerobic training is distance running. Whether it's running, calisthenics, jumping rope or circuit training, aerobic conditioning occurs when the heart rate hovers between 130 and 150 beats per minute.

One of the best forms of aerobic training is tempo runs, taken from Charlie Francis. Instead of sprinting at max speed, jog at 60 to 70 percent of your max until your heart rate reaches the upper aerobic threshold. Rest until your heart rate returns to the lower end of the threshold, and repeat.

Sample Program

Day 1: Alactic Power

  • 40-yard sprints with 2-3 minutes of rest between reps
  • Perform until you start slowing down. Specifically, there should be no more than a 10 percent drop in speed.

Day 2: Aerobic Capacity

  • With twenty minutes on a clock, begin a relaxed and loose jog
  • Maintain speed until you start breathing heavily, then slow down to a walk
  • When you feel almost recovered (not completely recovered), jog again
  • Ebb and flow between 50 to 70 percent of your max effort, and never let your heart rate fall out of the 120 to 150 range.
Learn more about building your conditioning through STACK's Conditioning Guide.


Oetter, E. (2011). "Research review: energy systems, interval training, & rsa." [Web log message]. Retrieved from

Osgnach, C., et al. (2010). 'Energy cost and metabolic power in elite soccer: A new match analysis approach." Medicine & Science in Sports & Exercise, 42(1), 170-178.3)

Gaitanos, G.C., et al. (1993). "Human muscle metabolism during intermittent maximal exercise." Journal of Applied Physiology, 75(2), 712-9.

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