High Intensity Interval Training (HIIT) has been the darling of the fitness scene for a few years now. Fundamentally, it involves repetitions of short bursts of intense, ‘maximal effort’ exercise, like sprinting; usually for anywhere between 20 to 40 seconds.
The theory behind HIIT is very appealing. By working out at your top level of exertion, you burn more calories in a short space of time than other workouts. What’s more, studies show that your metabolism stays in a heightened state for up to 24 hours after you’ve finished. Time-pressed office workers can get a workout in their lunch break, and then continue to burn off fat once they’re back at their desk.
And in practice, HIIT can have impressive results. It’s an effective tool for increasing cardiovascular fitness, sculpting your physique and increasing metabolic rate. Hence why HIIT classes are popping up all over the place. People have become accustomed to turning up to a class with loud music and dark lighting, just like a night club – and leaving in the same state: barely able to walk.
However … I have a big bone to pick with HIIT, which is that there’s often no focus on form or technique in these classes, even though it’s now prescribed as the go-to form of exercise for everyone. Instead, the measure of a good HIIT sessions seems to be how ‘destroyed’ you feel after a class. It’s inevitable that problems arise from this ‘all pain for gain’ approach.
A study recently published in the American Journal of Medicine found instances of a condition called rhabdomyolysis, which is normally associated with military training camps, among newcomers to HIIT. Sufferers experience pain due to intracellular muscle constituents breaking down and leaking into their blood stream. It is as though their muscles are ‘melting’; left unchecked, the syndrome can lead to kidney damage.
Researchers found a number of case studies of patients who went to A&E departments with symptoms of rhabdomyolysis following their first spin classes.
The issue is simply that people are doing workouts that they’re not conditioned for. There is no emphasis on flexibility, mobility or activation in many HIIT classes; yet all are incredibly important in keeping the body fit and healthy as you age.
What’s more, I regularly see people “smashing” multiple HIIT classes a day, 5-6 days per week. HIIT should not be done more than three times per week (at most), because it is so strenuous. It puts an incredible strain on your nervous system, joints and muscles; especially if you are overweight and unfit.
The HIIT approach to exercise has gone OTT. It’s entering unsustainable territory.
HIIT’s rise in popularity is symptomatic of what is wrong with the fitness industry as a whole: a brazen disregard of the fundamentals, and a detrimental “one size fits all” mentality. Having trained 100s of clients in my five years as a personal trainer, the biggest issues most people have are a lack of flexibility, mobility and core strength, on top of muscle activation issues. All of the above lead can lead to chronic injuries and are further exacerbated by HIIT.
Office workers are particularly at risk here. Sitting at a desk for eight hours a day can cause all sorts of joint and muscle issues. To then go and put so much strain on your muscles and joints is a recipe for disaster. Furthermore, 40 minutes of intense activity does not cancel out 8-10 hours of sitting down on a daily basis.
What will make a difference to your fitness is incorporating movement throughout the day. It’s not difficult: set an hourly reminder to get up from your desk and walk around the office for five minutes; choose (or maybe accept!) to stand on your commute; take the stairs and avoid the lift or escalator. Try taking your trainers to work and get off 1 or 2 stops early on your way back, to walk or run the rest of the way home.
My belief is that everyone should try to train like athletes do. I don’t mean the same training frequency and intensity as athletes, I mean the mentality and the approach. Having trained as a competitive sprinter for four years, I learned to take every aspect of my life into account: sleep, rest days, nutrition and weaknesses. I learnt to listen to my body. Some days I would wake up feeling tired and fatigued, so on those days I wouldn’t train hard. I would do something less intense and focus on recovery.
Remember: burning calories isn’t the be all and end all of fitness and good health. Yes, HIIT may burn more calories than any other form of exercise, but it’s no use if it leads to injury or illness. Overtraining is a real danger: it can ruin your immune system, cause insomnia, affect your appetite and release cortisol, which in turn can make you more likely to put on fat.
I’m not saying that HIIT isn’t an effective form of exercise, because it really is. BUT it’s important to understand who should/shouldn’t be doing it and note that everyone is different. What benefits one person doesn’t necessarily benefit the next.
If you are looking to get back into exercise for the first time in a while, it would be a lot more beneficial to start with some low impact cardiovascular exercises like walking, cycling or rowing, while adding flexibility and mobility practices to your daily routine. Do this for a couple of months to condition your body, and then start with the HIIT, once or twice a week.