What is high intensity training?

16 January 2018


 What is high-intensity training, and how does it work?


Chris Smith wanted to hear more about HIT from sport scientist Dan Gordon...

Dan - Okay. This is the big hot topic at the moment in terms of training. This is the notion that we can get fitter faster, and it’s really come about because there was some work done out in the US and Canada where it was quite obvious that people were saying the biggest impediment to being able to do exercise was a lack of time. Historically we’ve understood that interval training is actually a really potent stimulation for biological adaptation because you’ve got a high intensity block and low intensity block, so you can accomplish more than you would if you were doing low intensity exercise. There’s a real rationale for doing this.

The issue that comes with HIT is that I think there’s a lot of misunderstanding about what HIT training is. If we go back a little bit into the late 90s/early 2000s HIT was promoted as doing 30 seconds of maximum intensity exercise with about a 30 second recovery. Do it four times, three times a week and, low and behold, after four weeks we’ve got a biological adaptation.

Chris - It sounds too good to be true?

Dan - And it probably is too good to be true. I think a lot of the issues lie in the vast majority of the studies that have been done have been in controlled conditions. They’ve only been done over short periods of time and they tend to be done with a population group that you don’t really want to try them on which is students who are already relatively physically active.

Actually, what we do understand is that interval training does work. If you look at elite athletes they will do intervals, but the key is that intervals only work if you’ve put the foundations in. To get to that high intensity work, we’ve got to have done low intensity, cardiovascular work, because the key to intervals working is the recovery. If you can’t recover between the interval in the end what happens is that, in essence, you lose any of that biological gain.

Then it becomes really interesting because now we’ve got what’s called SIT. SIT is where the science has been fudged which is oh well, we didn’t really mean 30 seconds, that’s not what this kind of training is into now. They’re all into this really really short 10 seconds of exercise and 30 second recovery. I’m less convinced by this because if we think about that in terms of…

Chris - Tell me the regime then? If I wanted to do SIT training what would I do?

Dan - If you wanted to do SIT training you would come in and we would set a resistance up on the bike, which is probably about 7½% of your body mass. Then we would say to you that you are now going to sprint as hard as you can for 10 seconds and I’m now going to give you about 20 seconds recovery. I’m going to ask you to do that 10 times and then you’re going to do that three times a week. The evidence that’s come out from this, there’s some studies that have come out that showed improvement, and when I say improvement we’re talking about improvement in maximal oxygen uptake, which is our index of cardiorespiratory fitness after doing just 6 sessions.

Chris - That sounds like it’s good for muscle function. What about my blood pressure? Taking exercise to lower my blood pressure, taking exercise to reduce my risk of diabetes, stroke and heart disease. What about those impacts?

Dan - This is where it becomes really fascinating because there a lot of studies that are suggesting that if you do HIT/SIT training that it can reduce the incidence of type 2 diabetes. Suddenly the alarm bells go off in your head and you start thinking… really? And we’re talking about 8 to 12 weeks of exercise.

I just don’t think the science adds up. If I’m doing 10 seconds of training and I’m training the high-energy phosphates, the use of ATP and phosphocreatine. Although I’ve got a recovery in between those blocks the majority of the work is short duration so I can never quite make how that comes round to actually improving cardiovascular fitness. I can understand how doing intervals which are at a lower intensity but a much longer duration. If we took about 4 to 5 minute duration intervals, which is what Mo Farah would be doing then it works, and you can understand then how the blood pressure is reduced because you’re getting that engagement in central cardiovascular drive. But doing these very short intensity efforts, I’m less inclined to believe the fad.

Chris - So stick to a sensible regime that you know you can stick to so you can keep a routine and just the mantra ‘some exercise is better than no exercise’ is probably the rule of the day, isn’t it?

Dan - Yes, it really is, yeah.


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