Science on high intensity interval training: HIIT, or SHIIT?

Let me pose you a question: would you rather go down to the video store (if it hasn’t yet gone bankrupt) to hire a DVD, or stream it from the comfort of your own home? You’ve probably answered: the comfort of your own home, unless of course you get all nostalgic about walking down the street to hire discs. I know I do!

Okay, okay, now let me pose you a further question: would you rather spend one hour exercising, or 30 minutes? Stop, don’t answer that just yet. What if I were to say that both workouts would give you equivalent results? Unless you’re a time wasting enthusiast, pain junky, or DOMS devotee you’re probably going to answer 30 minutes. Well a new (old) exercise regiment known as high intensity interval training (HIIT) is offering just that.

Yes, if you believe one of the internet’s many great fitness prophets, then you will be aware that HIIT is the shit! Slow endurance training is the DVD for hire and HIIT is Netflix, which is of course, the shit. So is HIIT truly the shit, or should you beware of false fitness prophets?

What is HIIT?

Before I answer your previous question. What is HIIT? Simply put, HIIT involves performing intervals of highly intense exercise followed by either complete rest, or low intensity exercise. The high intensity-low intensity combination seems to be the more popular of the two currently.

How about an example? Sure, here’s one. Let’s say running is your game. Your HIIT may involve a ratio of a one minute sprint, to 45 seconds of slow jogging, repeated for a total of 15 minutes. It certainly doesn’t have to follow this exact ratio, or duration and these variables change greatly from protocol to protocol, that was simply an example. I should note, however, that scientific data to date has found minimal difference between different interval ratios thus far (9).




Why HIIT might be the shit?

HIIT is proposed to lead to multiple complex physiological changes to the skeletal muscle system that promote fat burning efficiency and preference, and more efficient oxygen utilisation. In turn, this is proposed to: make you skinnier, fitter and it will likely give you the ability to fly! But probably not the last one.

Science and HIIT (SHIIT):

Of course theory means little unless it translates to real world, real life changes. So, does it? Spoiler, it generally does.

Aerobic health:

A review paper analysing studies on individuals suffering from various different lifestyle diseases found HIIT to be effective. Specifically, cardiovascular fitness, as measured by Vo2 max, was 9% higher when individuals performed HIIT as opposed to moderate intensity continuous exercise (1). Another large scale review paper on scientific studies to date found HIIT to improve: aerobic fitness level more so than normal, moderate intensity exercise in both sedentary and active individuals. But it was only as effective as continuous exercise training in athletic persons (2). If that wasn’t enough science for you, a third study found HIIT to improve aerobic fitness as well as moderate intensity continuous exercise in a relatively fit group of people (3). This basically tells us that the lower your fitness level is, the better you will respond to HIIT and if you only want to do one sort of training, HIIT will be more effective than continuous training for aerobic fitness. Conversely, if you’re really fit and only want to do one form of exercise, then HIIT is as good as continuous moderate intensity exercise for aerobic fitness.

Muscles, muscles, muscles:

What about those muscles? Can you skip the separate weight sessions and do an all in one HIIT session? Well, the scientific data is very limited on this. But the one study that does exist on this topic, found that when having an active rest period was compared to having complete rest, complete rest won. Yes, complete rest led to greater work output, which in turn would likely mean improved: muscle mass, strength, power, looking shredded bro (4)! This makes sense and says that resistance training HIIT will likely provide you with some nice adaptations, but not as good as traditional weight training where proper rest between sets is taken.

Weight loss:

What about weight loss then? The data ain’t crystal clear on this. One study found HIIT boxing was better than continuous brisk walking at improving body fat percentage (5). Another study found participants had a decreased waist circumference following HIIT, but not following moderate intensity continuous exercise (6). Yet, in complete contrast, continuous moderate intensity exercise was found to decrease trunk fat more so than HIIT in another study (7). All in all, the science isn’t certain on whether HIIT or continuous training is best for weight loss. But if you base your workout on the number of calories you’re burning, based on average heart rate or a similar method, then you should be no worse off than performing continuous exercise, as average heart rate tends to be higher for HIIT and stays elevated for longer following exercise.

Adherence:

If HIIT is quicker to do, then you’d think people would do it more and stick to it. And they do! High intensity interval training led to a greater level of adherence (89% vs 71%) than moderate intensity continuous training (8). Grouse!

Is it healthful? 

Ladies and gentlemen, HIIT is the shit! Or at least it is pretty darn good and very relevant to our time-centric society:

• HIIT is likely as good as endurance exercise for aerobic fitness and if you’re of a low fitness level it’s probably better.
  
  
•  Resistance training HIIT won’t get you as ripped as traditional resistance training with structured rest periods. But it’s probably not a great deal worse.
  
  
• HIIT will lead to at least equivalent weight loss to continuous moderate intensity exercise in a shorter period of time, likely due to an elevated average heart rate.
  
  
• HIIT generally leads to higher adherence, so you’re more likely to stick with it.

Our verdict :Highly healthfull. If you’re time poor and unfit, HIIT’s the most effective way to turn things around. Although if time is less of a factor and you really want to optimise your health you should combine HIIT, anaerobic exercise and aerobic exercise as part of a proper periodised program. Especially, if you have sport related goals.

I hope this has been healthful!

Isithealthful

I hold a Doctor of Physiotherapy, Bachelor of Exercise Science and am a qualified personal trainer. I have extensive clinical and research experience and a strong passion for all things health. This has driven me to write the blog: Is it healthful, in order to analyse sound scientific research to determine if a product, service or intervention is healthful, or simply a waste of money or time.

 
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Keeping a pledge to fitness resolutions for a new year new beginning 2014

Two heads are always better than one, so grab a friend to exercise with. The support and motivation will go a long way towards achieving results. – AFP

A new year signals a new beginning, but are fitness resolutions necessary when most people can’t sustain them?

RESOLUTIONS are never easy to keep, especially fitness ones.

Every year-end, I hear these mantras from at least a dozen people: lose weight, get toned, enrol in yoga, run faster, muscle up, eat less...

It’s like a pledging ritual, but without proper planning and implementation. Only one, at most two, will doggedly stick to the resolve. Hats off to them.

Most people gear up to hit the gym come Jan 1, follow through for the first couple of months, hit a roadblock (most likely from laziness, muscle soreness or injuries), and eventually, slide off the commitment ladder. This is also the period when gyms, as well as wellness and slimming centres, offer huge promotions to entice new clients.

Don’t be fooled or gullible enough to fall into this trap unless you know you have the perseverance to succeed.

Resolutions seem possible at the start of the year, but become impossible as the days and months whiz past. Or, you’ve set unrealistic expectations. Habits and behaviours require time to change, so don’t be too tough on yourself.

One of my Pilates students has told me countless times that his intention is to lose his belly fat. He’ll point to a macho guy at the gym and say, “I want to look like that.”

Not wanting to engage in a lengthy discussion about body types, every year, I’ll advise him on a workout regime he can adhere to. He’ll pump iron, run on the treadmill, and attend classes diligently the first few weeks.

Then poof!, he disappears, citing work, travel, weather and family issues. By year-end, he’ll reappear, pinch his spare tyre and exclaim, “Look at this!”

I’ll look and smile knowingly. This scenario has continued for the past five years. Buddy, I can’t help you if you don’t help yourself.

So this year, why not do something different before embarking on your fitness goals?

First, sit on the couch and get your cravings out of the way. Yeah, that’s right. Allow yourself to binge to your heart’s desire to usher in the New Year. Put your feet up, snack on your favourite food – junk included, and sip your preferred drink, while watching the telly.

It’ll feel good for a while, but pretty soon, you’ll be sick of the over-indulgence and yearn for a more meaningful activity.

When you have mental clarity, focus on a fitness programme that is attainable. Ditch the impossible resolutions (e.g. losing 20 kilos in six months), but take your health and self-improvement goals one baby step at a time.

Unlike food, the endorphins released during exercise leave you feeling high for a longer time. Not only does it boost your mood, it also helps you get in shape.

Have you heard of anyone feeling depressed after a round of exercise? Fatigued, yes, but they’re rarely down in the dumps.

Physical activity doesn’t have to be complicated, so here are some tips for a healthy start:

Always warm up before starting a physical activity

Warming up is essential to prepare the body for energetic activity and reduce the risk of injury. The purpose is to ease both the mind and body from a state of rest into a state of strenuous activity.

A warm-up routine should consist of a 10-minute cardio workout, such as skipping or brisk walking, and five to 10 minutes of gentle loosening exercises, which produces a light sweat (for example, rotation of the ankle, wrists, shoulders and hips).

Increasing the core and muscle temperatures helps to make muscles loose and supple. Besides increasing the heart rate and boosting blood flow, warm-ups supply oxygen to the muscles and prepare the body for action.

Walk, walk and walk

If you have limited finances or lack time to join the gym, go brisk walking, weather permitting. Avoid taking lifts, but walk up the stairs, walk to the shops, walk around the park or walk to your colleague’s cubicle instead of phoning or sending her/him an Intranet message.

Walking has multiple benefits, including helping against heart disease, high blood pressure and type 2 diabetes.

Work out with a friend

Two heads are always better than one, so grab a friend to exercise with. The support and motivation will go a long way towards achieving results. And with the crime rate these days, it’s better to have a companion, especially if you’re doing an outdoor workout.

Commit to early morning exercise

Everyone needs an extra minute of sleep, but if you can rise early and squeeze in at least 30 minutes for exercise, you’ll be more likely to keep to your regime.

Plus, once you get the exercise bit out of the way, you’ll also have plenty of energy left for the rest of the day.

Combine cardio and strength training

Instead of allocating separate days for cardio and strength training, combine both. Do a two-minute cardio routine and add two strength moves (e.g. crunches and push-ups). Repeat the cardio and add two more strength moves (e.g. squats and tricep dips).

Not only does it help with muscle retention, but it also promotes a faster metabolic rate and enhances lipolysis, speeding up the rate of fat loss.

Cool down and stretch

Cooling down is equally as important as warming up, though many people fail to realise this and jump into the next activity immediately.

Cooling down restores the body to a pre-exercise state in a controlled manner, helps the body repair itself, and can lessen muscle soreness the following day. Gentle walking for five to 10 minutes is good to recover the heart’s resting rate. After that, perform some static stretches by holding the stretch for at least 20 seconds.

Eat healthy

Try to eat healthy (cut out the fried stuff) and load up on fruits and veggies, but don’t skip your favourite desserts, no matter how sinful they are. Instead, have a mini serving to satiate your taste buds.

Research reveals that skipping dessert can backfire and leave you wanting more. In a 2010 study published in the journal Obesity, dieters who were restricted from eating a small dessert were more likely to be left “wanting” than those who had a bite of sweets. Eliminating your favourite foods can be a recipe for disaster and may create an obsession.

Personally, I can’t keep to resolutions. As I get older (translation: injuries that take longer to heal), I occasionally cut myself some slack and allow my body a break to recharge for a week. But, that doesn’t mean I do nothing. I still stretch in bed, do breathing exercises, or take long strolls and get to know the neighbourhood dogs.

After all, you’re not participating in a sprint to get fit. Rather, we’re all runners in this slow, steady marathon for better health. There are no winners or losers, just healthier, trimmer individuals and less medical expenses.

On that note, here’s wishing readers a happy new and fit year ahead!

Contributed yy Revathi Murugappan

The writer is a certified fitness trainer who tries to battle gravity and continues to dance, but longs for some bulk and flesh in the right places. She hopes to do one final dance in 2014 before gracefully bowing out from stage to make way for the next generation.