To HIIT or not to HIIT


My parents are steady drinkers they drink most days, it’s their generation, they have a six pm drink, Mum- vodka, Dad-whisky, wine with the evening meal, and sometimes a nightcap.
My generation think that’s weird & pointless, often abstaining from alcohol until a day in the week when they go… out out. It can be any day really, but often a Thursday and Saturday where they will drink everything their stomachs and wallets allow them to - lager, wine, spirits, shots…..the works, and they will not stop until they pass out, are asked to leave, or the body rejects it all through the mouth.

We, in the UK, love Intensity, and it’s not just alcohol we love applying it to, but also exercise. We all want to be fit yesterday, and the way we try to achieve that is to wage an all-out war on the body by ‘going hard or going home’, and having the motto ‘no pain no gain’. Clients often judging the quality of their workout solely on whether they can’t walk properly the next day.

I’m not here to slag off HIIT, of course, there is merit to be given and often in a lot of people’s workouts there is a serious need for intensity, but I’m trying to get the point across that it isn’t a method that should supersede and dominate others, and that it could be limiting your performance and goals if you do so.

People often say to me “I’m into HIIT” when I discuss what cardio they do. Once you peel back the surface I often find that they aren’t really into HIIT (it’s too intense ;), but they like the concept of it because they don’t have to run/jog for a long period of time, and like the idea that you only have to work out for 2mins a day to reap the benefits.

If you are unconditioned and workout with a new and increased intensity then perhaps initially you will make some gains, a new stimulus on the body with some consistency will cause an adaptation, but these gains will soon plateau quickly. I used the word perhaps in the previous sentence, as caution needs to be taken especially if the person participating is unfit and sedentary. Should we really be taking someone who has had no-intensity exposure straight into high intensity? Medically that is not a good idea, not just from cardiac perspective, but also because of the high impact forces through joints, tendons, and connective tissues that are not conditioned to the high energy calisthenic circuit session which HIIT is typically dished out in.

That’s also my next point too, often seeing HIIT applied in environments where its either got no programming to it, and is loosely thrown into the last 5 mins of a session for a quick finisher. Although I’ve used the latter in some of my sessions, my point is that if you aren’t making your goals and gains in your workouts then this could be the problem. It boils down to what I call ‘Mindless Motion’ a sort of ‘free for all’ jump around for a few minutes, where the outcome sort after is mainly fatigue. If your goal, outcome, and training protocol for a workout is fatigue, then that is what you get..…..fatigue.


Yes, the body will expend some energy, and get fitter if the intensity is higher than what the participant is typically used to, but over a 2minute period no one in any sports performance bracket or who is vaguely fit will benefit from consistently doing the same set of exercises randomly thrown together, without any progression or programming. The workout often lacks the specifics and time to concentrate on either strength, or cardio. There is a lack of monitoring and measuring that should steer the next session to vary load or volume to progress from the previous session. The format in a lot of HIIT sessions seems to be to move around without specifics to get the heart rate up leaving the body unsure of what it needs to adapt to.

Another potential problem is that the body needs recovery after training. Going back to my reference at the start - linking todays workouts and binge drinking – I have many clients come to see me and tell me how they are now ready to train and that they want do 5-6 (hard) sessions a week. I try to convince them that it’s not the exercise that’s going to produce the gains they require, but the rest. Exercise is the catalyst, it’s the stressor on the body that breaks down the muscles and fibres. The following rest and recovery, involving sleep and good nutrition, is where the gains are made, and the body builds itself back up by fixing the muscles fibres making them bigger & stronger, and upgrading the systems of the body that have been affected by the exercise. Without the rest and recovery, daily increased intensity and exercise, will not give the body the chance to adapt, and will instead often give you pain & injury as a clue to rest up.

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Overtraining and overreaching are becoming more and more of a problem due to this intensity trap, and not monitoring & programming training efficiently where the priority should lean towards recovery over volume is the reason.

The LSD vs HIIT debate often fails to go into the specifics of each adaptation to warrant a serious debate. Boxers have been using LSD (long slow duration running) effectively for centuries, so should HIIT now replace that method of cardio?
I was taught to argue the benefits for both and that one doesn’t supersede the other in effectiveness due to the different stressors, and therefore adaptations it has on the cardiac system.

High intensity exercise requires the heart to beat at much higher rates typically >160bpm. The heart therefore is beating very quickly and this type of stress strengthens the walls of the heart making it stronger. It develops aerobic power and the ability to sustain the heart rate for longer.

On the other-hand continuous jogging allows more blood flow into the heart in what is called ‘eccentric cardiac hypertrophy’ which means increased blood flow into the heart grows the left ventricle making it larger. The low intensity & increased blood capacity causes the heart to work less to deliver the same amount of blood, and it develops the capillary network that supplies O2 and nutrients to the muscles.

It also works the aerobic system which has been shunned in a lot of sports these days, with people touting that the majority of sports actually fall into the anaerobic zone (energy system that operates without the need for oxygen i.e at higher intensities) so aerobic work and training is no longer applicable. Those that believe this, often fail to realise that it’s the aerobic system that replenishes and recovers the anaerobic systems during low intensity or rest. Failure to increase and advance the aerobic system means you tap into the anaerobic system too quickly into exercise and because of that you will fatigue more easily. Adapting and increasing the aerobic system is what will make your fitness, endurance, and ability to recover better.

So, which is better LSD or HIIT…..neither…. as they both cause different stressors to the heart, which from a fitness and athletic standpoint are both necessary for good conditioning.

In the sports performance world, you rarely train someone to consistently go all out, switch off, and just increase power and speed for as long as possible. For example, you teach the boxer to conserve energy and to control it. Because movement efficiency is related to the energy systems and therefore your energy expenditure. Poor technique, movement, and breathing leaks energy, and therefore power & performance. This is why there is such a big difference between fitness and conditioning. You often see MMA fighters or boxers in the ring and they just don’t perform at the highest level. It’s very short-sighted to think that they didn’t train to go 12 rounds, or their fitness was poor. These athletes’ fitness levels are often at the top of their game in regards to VO2 max, cardiac output, and strength & power – but the specific conditioning for the event was off, and that has to do with many additional factors (another article).

As usual I got my wife to read this, for her thoughts, a dangerous practice for me as normally with one wise sentence she has the ability to shutdown my entire article. Her reaction to this one was “I think you are missing the point for most people, HIIT during a boot-camp is a fun, and social group activity that lots of people enjoy doing to keep fit.” And of course she is right, it is fun, I also use it, it is effective due to its intensity, & it’s useful for those that are time short and without equipment. But, what I’m trying to get across is that it isn’t a new scientific phenomenon designed to replace other forms of cardio. Despite what Michael Mosley in his BBC documentaries reports (he’ll be the first to admit that he hates exercise and so exercise methods that show promise doing the least amount of physical exertion he happily advocates.) Leaving people thinking that this is the only exercise they should be doing. For the beginners or unfit peeps new to exercise HIIT is often too much, and for the intermediate or advanced fitness enthusiast the lack of programming, specificity, and shortness of the workouts, along with too much random variety could be the reason for not making any gains.

Consistency beats intensity every time ;).