Tuesday, May 10, 2016

Intervals: What Are You Really Training?

Here's a question I recently asked my friend and go-to on exercise physiology Marc Lewis regarding intervals and aerobic training. His answer made a ton of sense, and I think it's something a lot of trainers and coaches may not be aware of. #themoreyouknow


Hi Marc,

I have some questions about aerobic training. If I did hard battle rope waves for about 10 seconds, stopped to rest, my heart rate peaked at 150, and I continued to rest until it went back down to 120, then repeated in a similar fashion for several minutes, could I call that "cardiac output" training? Or not cardiac output since it’s not steady state, but still “aerobic” training?

Basically, I’m wondering if you can still call it aerobic if an anaerobic system predominates during those 10 seconds — even though you don’t work long enough for your heart rate to get above the aerobic zone.

Would it be more akin to "cardiac output" or “aerobic" if the exertion level were lower and the work periods were longer so that the climb up to 150 took longer than 10 seconds and the work-to-rest ratio favored more work than rest?



Hi Travis,

Will an anaerobic system predominate? It will for the first couple of rounds, but will quickly become aerobic in nature. This is the issue when people design "anaerobic" intervals that do not provide enough rest time between sets. Their anaerobic intervals quickly become aerobic training and they are neglecting the actual energy systems they are attempting to train, while their objective intensity quickly decreases (i.e. must reduce speed, load, or whatever that measure is).  

Cardiac output training (i.e. aerobic training) does not have to be thought of in the box of continuous training or in a box of low intensity training. We are trying to elicit adaptations based on the utilization of aerobic metabolism and volume loading in the heart. If you are engaging in training that elicits a target heart rate around that 120-150 beat per minute range (with some variation depending on training status, age, etc.), then you are training aerobically.

If you are doing hard battle ropes for 10 seconds and then back on after a 30, 40, or 50 second rest, but your heart rate isn't recovering below 120-130 before you start again, then you are NOT doing anaerobic work. It's physiologically impossible for the anaerobic system to predominate for that extended period of time without restoring its ATP stores and producing energy oxidatively.

Hope that makes sense!

For more from Marc on interval training, click the link below: 

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