Slow and steady may have helped the tortoise beat the hare, but if you’re serious about losing body fat and getting back into shape you need to be clever with your cardio for the fastest-possible results, says New Body Plan editorial director Joe Warner
If you’ve tried and failed to lose weight through exercise in the past, the chances are you started going jogging. But while steady-state cardio – which is the term for when you run, cycle or swim at a consistent and comfortable intensity for a significant amount of time – has many health benefits, turning your body into a fat-burning machine isn’t one of them.
That’s because endurance-based cardio exercise doesn’t push your heart, lungs and muscles hard enough to initiate the process in which your body is forced to start tapping into fat cells to release fuel for energy.
Don’t get us wrong: cardio can be great for your physical and mental health, but to turn running, cycling, swimming or any other type of cardio sessions into a legitimate fat-torching activity you need to get more intense.
The power of HIIT
That means your cardio sessions, whether in the gym or in the great outdoors, need to be short in time and intense in effort. Why? To elevate your heart rate, increase oxygen consumption, and push you out of your comfort zone to increase the rate at which your body burns fat, not just during training but for hour and hours afterwards. And the smartest way to use cardio to get leaner is by doing high-intensity interval training (HIIT).
There’s plenty of solid scientific research to back up the efficacy of HIIT for fat loss. One study, published in the Journal Of Sports Medicine And Physical Fitness, compared HIIT to conventional training and found that HIIT resulted in a significantly greater reduction in both adipose fat (the fat stored just underneath the skin), and visceral fat (which is stored around the organs). Too much of either is incredibly bad for your health.
The same study also found that HIIT had a positive impact on total body-fat levels and improved hand grip strength, which is a surprising but solid indicator of longevity, as well as sprint endurance, jumping ability and flexibility. So if you want to strip away belly fat quickly, look and feel fitter, and improve the health of your heart, keep reading to find out everything you need to know about HIIT.
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What is HIIT?
HIIT is a form of cardio exercise that is based around short and intense bouts of all-out effort interspersed with brief periods of rest. The aim is to push your heart, lungs and muscles hard, back off, then push on again to send your heart rate soaring, increase oxygen expenditure and get a sweat on.
HIIT is on the opposite end of the cardio spectrum to LISS, or low-intensity steady state exercise, such as a long endurance-style run where your pace remains consistent throughout and your heart rate never gets close to its maximum.
Why does HIIT burn fat?
HIIT is the most intense form of cardiovascular training and studies prove it’s far more effective at burning body fat than LISS and other types of cardio. That’s because HIIT has a similar effect on your body as weight training, in that it boosts levels of hormones associated with increased muscle mass and reduced body fat, specifically in that it raises growth hormone levels and improves insulin sensitivity.
HIIT also accelerates fat loss because of excess post-exercise oxygen consumption (EPOC), because intense training creates an oxygen debt and a build-up of lactic acid in your muscles. This oxygen debt and lactic acid must be repaid and removed, respectively, once you’ve finished exercise. Both these processes stoke up your metabolism, which is the rate at which your body burns calories at rest. That’s great news for your leaner-body aspirations because it means you’ll continue to burn fat for fuel long after your workout has ended.
What else is HIIT good for?
The benefits of HIIT over LISS and other forms of steady-state cardio are numerous. It works your cardiovascular system close to its maximum output so it will increase your fitness levels, and so has huge crossover benefits to many sports, as well as improving the health of your heart, lungs and entire circulatory system. It also doesn’t take very long to do, which has an obvious time-benefit over LISS, and can be done in many different ways, such as sprints, kettlebell swings, prowler pushes or farmer’s walks, so it never gets boring or repetitive, which can be the case with running.
How do I do a HIIT workout?
When lifting weights there is a right way and a wrong way to train for fat loss, but for HIIT you are only limited by your imagination. Just follow these guidelines to make your HIIT sessions fun, challenging and rewarding so that every sessions moves you ever-closer to your better-body goal.
Enjoy the exercise
You’re far more likely to start, and then complete, a HIIT session if it’s based on an exercise or equipment that you like. Hate running but love rowing? Then do your HIIT workout on a rowing machine. If you despise all cardio machines then use a kettlebell for swings, or heavy dumbbells for farmer’s walks.
Warm up slowly
If you’re doing a standalone HIIT session then you’ll need to thoroughly warm-up your central nervous system, cardiovascular system and your major muscles to prepare for the intense work ahead to push yourself as hard as possible without the risk of injury.
Start by doing slower, lighter or easier efforts of the main exercise or activity you’ll do in the main session, interspersed with some dynamic stretches, gradually increasing the intensity over ten minutes until you feel warm and slightly sweaty and start to get a little out of breath. If your HIIT work is at the end of a weights session your body will already be warmed up, so just spend five or so minutes gradually increasing the intensity of your HIIT activity to get your mind and muscles fully primed and then you’re ready to go.
For decades it was assumed that static holds, when you stretch a muscle to its limit then hold the position for 30 seconds or longer, were the best way to prepare muscles for exercise. But forcing them into held stretches when they are still cold, tight and inflexible makes the muscles weaker, so you can’t perform to your potential, and increases the risk of pulls and other injuries. Instead do some dynamic stretching, such as high-knee raises and heel-to-bum kicks, and plyometric moves, such as squat jumps or box jumps, as part of your warm-up.
Quality beats quantity
There is no perfect time length for a HIIT workout; the duration of the session will be dictated by the activity. For instance, a 1km all-effort on the rowing machine won’t take very long, but leave you in a sweaty, breathless heap at the end of it, whereas a 5km run where you alternate between 400m sprints and 600m of slower recovery running will take far longer. The key is to make the bouts of all-out effort as intense as possible to raise your heart rate and create that oxygen debt.
Mix it up
As with any form of exercise if you do the same thing session after session your body will quickly adapt to the demands you’re placing on it and you’ll get diminishing returns. So while it’s important to base your HIIT work around exercises and equipment you prefer, you still need to shake things up regularly to keep your body guessing as to what’s coming next so it never has the chance to get into its comfort zone. For example, instead of only ever doing 400m sprints and 600m recovery running on the treadmill, play around with the distance splits, so some sessions are 100m work and 200m rest, while some are 800m work and 800m rest. Changing it up not only keeps HIIT more effective for fat loss, it also makes each session fresh and challenging.
When do I do a HIIT session?
When training to burn fat, lifting weights should take precedent in your exercise schedule because weight training has the biggest impact on your body composition by building muscle and burning fat. In an ideal world you’ll lift weights four times per week, but that doesn’t mean that HIIT training can’t also have a part to play each week, although there are a couple of caveats.
If you’re new to weight training then focus first only on lifting weights, because if you do it right it’s going to take a lot out of you, and you don’t want to burn out too soon on your better-body journey by overdoing it. What’s more, at this stage lifting weights is enough on its own to start making major improvements to your physique, so holding back on HIIT is a good idea because you can then deploy it down the road when your fat-loss results start to slow and you want to re-accelerate your progress.
When you introduce HIIT into your weekly training schedule you have two choices: you can either include some HIIT work at the end of a weights workout; or you can do it as a standalone session on one of your “rest” days.
However, if you feel tired on a rest day then you must prioritise getting proper rest so you’re fresh and ready for your next weights session; forcing out a HIIT session that makes you even more tired is counter-productive, because lifting weights as well as you can always comes first in any fat-loss plan.
Another thing to bear in mind if you’re doing standalone sessions is that you don’t want to have too many carbs in your system when you start it, because your body will prioritise using them for fuel. If it’s been a while since you last ate carbs then your body will have no choice but to start tapping into body fat stores for the energy it needs.
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If you want to include HIIT in your weights workout then you must do it after the session, never before, like how the “Fat-Loss Finishers” are structured in the New Body Plan training plans. The reason is simple: HIIT training fatigues your muscles and your central nervous system so makes you weaker, and you don’t want to then go and lift heavy weights when in a fatigued state. You’ll have to select lighter weights, won’t be able to push as hard to complete those tough sets, and will open yourself up to injury.
Doing HIIT after weights also ensures that any carbs in your system have already been burned fuelling the weight lifting, so fat cells will be tapped to release extra energy. Always do your weights first when you’re fresh and raring to go, and finish with HIIT to burn even more calories in the safest and most effective way possible.