The following is taken from my Personal Training Q&A Group
Q) Interesting comments there, Nick.
However I find this a little hard to believe, but only because I am so used (like everyone else) to the current established ways of thinking when it comes to cardio training.
I see what you and the Japanese writer are saying, but I’d like to know why the body responds in that manner when you exercise intensely for very short bursts, compared to moderate – or even high load intensity (but not maxing out) – for longer periods of time. Has it got anything to do with the body’s use of/production of ATP?
Secondly, what are the best forms of exercise to perform when attempting this interval training? Occasionally I do sprint training in the pool and I am essentially doing this, would it produce similar results or am I better off focusing on running/biking?
A) Why does it work? They theorise that its because the body doesn’t have a chance to settle and start conserving energy as it does in a steady state workout, so your entire system is made to work that much harder and you therefore get a far more significant metabolic adaptation. Plus it’s just so much more intense. There is an old saying that you can go hard or you can go long, but you can’t do both.
As for the ATP question – not to get too technical here but you are not really using ATP as your energy system with this type of work as much as you are using CP (creatine phosphate). 10 seconds of all out effort tends to use up ATP – CP in what is known as an anaerobic alactic power system, whereas the 20 seconds that this programme dictates utilises your anaerobic alactic capacity and that tends to rely on CP alone for fuel. These high energy fuel sources are the main sources of energy for this sort of work initially, but then as the workout progresses it also becomes more classically reliant upon your anaerobic lactic power and capacity, and uses glycogen as fuel.
What you need to get your head around with this system is that it is NOT so much about calories burned during exercise (its so short how could it be). Rather it is all about calories burned AFTER exercise through the massive metabolic shifts it can stimulate.
What exercises are best? The best is the one described in the article, but you can try to adapt it to anything that will allow you to exercise major muscle groups with brief bouts of all out intensity. I don’t like most people doing it via sprints as almost everyone runs with poor biomechanics and severely underestimates how hard running can be on the body. Especially for women who as a sex suffer from 6 times the number of ACL knee injuries as their male counterparts simply due to less efficient angle of their femur (thigh bone) running from the knee into wider hips.