Eric Helms is a pro natural bodybuilder, raw powerlifter and a coach at 3D Muscle Journey. He is based in Auckland, New Zealand.
There are plenty of reasons to do high-intensity interval training. It’s quick. You can get the same cardiovascular adaptations as moderate-intensity cardio or endurance training in a fraction of the time. So it’s time-efficient.
You also burn a few extra calories doing HIIT than during other forms of cardio, although not as many as was first thought. It’s like driving a car. Driving for a long distance at a constant speed is the most efficient way. You use less gas. Stopping and starting is far less efficient because you have to use a lot more gas to move up through the gears. Going from 0 to 60 requires more energy than cruising at 30. It’s the same with your body. Going from a static to dynamic state requires energy and you need to pay off that metabolic cost. In technical terms this is what’s called excess post-exercise oxygen consumption or EPOC.
Remember that your body has different energy systems – aerobic, anaerobic, ATP-CP, beta-oxidation, glycolysis – and they all feed off each other. There isn’t an on or off switch when you’re using one and not another. If you’re using one system another one is replenishing. So if you go straight into your anaerobic system, you use your aerobic to pay it off. That’s basically how EPOC works. And HIIT does create a greater (although relatively modest) EPOC.
The other main benefit is intensity. Have you ever watched a sprinter in mid-stride? Everything is firing. If you’re propelling yourself at a faster rate you’re using more muscle power. That’s one of the reasons why sprinters look different to marathon runners. Another is that they also lift weights, of course.
HIIT is therefore closer to resistance training and therefore doesn’t ‘compete’ against resistance training adaptation like endurance training does[3,4].
In summary, HIIT is a time-efficient way to do cardio that burns a few extra calories after the fact that also doesn’t have the potential to interfere with muscular adaptations. Based on these factors it’s tempting to jump on the HIIT bandwagon and do as much as you can.
However, what are the downsides of HIIT? There was study conducted in the late 1980s comparing trained marathon runners to trained sprinters. It wasn’t just about HIIT, but specifically about sprinting and long distance running. They found that there’s twice the injury rate in sprinters, specifically hamstring strains, than in marathon runners. But it’s even worse than it looks because think about how far and for how long marathon runners run. If we talk about the rate of injury per unit of time running or unit of distance covered, then that’s when you really appreciate how crazy that rate of injury is in comparison. It’s actually nuts. Sprinters get a lot of hamstring injuries compared to distance runners.
And that’s a study of properly-trained sprinters, not bodybuilders pretending they know how to sprint! You can imagine what happens when big bodybuilders start sprinting as their primary form of cardio. I don’t need to imagine: I’ve strained my hamstrings doing sprints and I’ve watched others do so the same. In summary the higher the intensity, the higher the risk of injury, at least when it comes to running.
Cardio isn’t magic
One of the most common HIIT protocols follows the model of 10 to 30 seconds all-out, then 30 to 90 seconds of rest. Do you recognise a similarity between this and another type of training? I do, and it’s called lifting weights. It’s called hypertrophy training. If you lift weights, and you train three times per week, you are already doing three HIIT sessions per week. Your body does not know the difference based on the activity you’re doing. Have you ever tracked your heart rate when lifting weights? If you’re doing a five-rep max for three sets your heart is going to be beating pretty fast. It’s going to be up there near its max.
I am thoroughly unconvinced that someone doing six weights session per week, who then adds in a session of HIIT cardio, is getting some new adaptation that was not occurring already. So HIIT cardio isn’t magic. It’s not a novel metabolic stress to your body if you are already doing vigorous resistance training on a regular basis. If you lift weights then you’re already doing it. I think that should change the way you think about HIIT, in my opinion.
Higher impact costs
HIIT can be high impact and some studies have shown that higher-impact movements with greater eccentric components – so more muscle damage and joint stress – can negatively impact the efficiency of weight training. It also appears that running causes more interference with strength and hypertrophy than cycling, which is zero impact and primarily concentric[3,6].
I’m not saying don’t do HIIT, but when you choose a HIIT protocol it’s very important to choose the best one for you, specifically one that minimises muscle damage, risk of injury, and does not impede recovery. In terms of muscle damage, you’re already causing plenty lifting weights, no need to let cardio get in the way further. So what is the best way to add in some HIIT to reduce impact, the eccentric component and all the other factors that will negatively interfere with weight training?
Get back to basics
I think the best form of HIIT cardio is additional weight-training. This is a new theory for me, but I got to a point where I thought ‘why I am trying to be a sprinter when I want to be a better bodybuilder? Besides, everyone hates cardio anyway!’ This was a conclusion I came to after getting involved with Olympic weightlifting. Have you ever seen Dmitry Klokov, or any of those guys doing barbell complexes? What’s not to like?
In fact, in the recent review article I wrote with my colleagues Peter Fitschen, Alan Aragon and Brad Schoenfeld we suggested full body modalities of cardio such as cleans or kettlebell work to reduce interference. These days I only encourage my athletes to get on the ‘hamster wheel’ if they actually enjoy it, if not they get to lift weights! Now this doesn’t mean just go hog wild and add volume, it needs to be something that won’t interfere with your actual training.
Here is a common protocol I recommend that can be done for even those not proficient in Olympic movements. For males, get a 20kg bar with 2.5-5kg per side, for females get just the bar. Then do five RDLs, five bent-over rows, five hang cleans, five presses, and finish with five front squats. By the end your heart rate will be through the roof. Drop the bar, catch your breath, then go again; repeating until you’ve burned your target number of calories or completed the length of time you want. The beauty of it, is you will actually enjoy it, because it’s lifting weights, not traditional cardio.
You’ll be using movement patterns you are likely already accustomed to, so delayed onset muscle soreness, muscle damage, and injury risk will be minimal. You won’t risk messing yourself up ahead of a heavier session the next day. In fact, it might even have flushed a lot of blood through the muscle groups you usually work, so it could potentially act as active recovery. How cool is that? That’s the type of cardio I get on board with.
The case for creativity
You are only limited by your creativity when it comes to cardio. Also remember that you are a strength athlete first. We grow muscle from weight training, cardio’s place is extra calories burned. It’s not about squeezing your glutes on the elliptical training: that’s what squats and deadlifts are for. And a specific form of cardio does not do magic things like bringing out separation or striations.
Cardio in the simplest form is just your heart rate being elevated and your energy expenditure increasing. In essence, we are all doing cardio at some intensity all the time, your heart beats and you burn calories 24/7. If you are reading this and your heart’s not beating then you have bigger problems than working out the right HIIT protocol for you. So the right HIIT modality for you is the one that burns calories but doesn’t negatively impact your weight training. I dare say this is the one time that Cross Fit-style activities appeal to me.
I don’t mind swinging a kettlebell or flipping a tire or hitting something with something else if you find it more enjoyable than hours on a stationary piece of cardio equipment. Find what works for you without affecting your primary goal of adding muscle and burning fat. Just get creative.
Lastly, I’d like to say that endurance training and low-intensity calorie burning are not the same thing. Sure, training for a marathon might interfere with your weight training, but walking your dog, or taking a stroll is not going to elicit endurance adaptations, so therefore it cannot interfere with strength or hypertrophy adaptations. So you don’t always have to do HIIT, if you’re tired and need to burn a few more calories and time isn’t a concern, take a slow stroll or a casual bike ride.
1. Burgomaster, K.A., et al., Similar metabolic adaptations during exercise after low volume sprint interval and traditional endurance training in humans. Journal of Physiology, 2008. 586(1): p. 151-60.
2. Borsheim, E. and R. Bahr, Effect of exercise intensity, duration and mode on post-exercise oxygen consumption. Sports Medicine, 2003. 33(14): p. 1037-60.
3. Wilson, J.M., et al., Concurrent training: a meta analysis examining interference of aerobic and resistance exercise. J Strength Cond Res, 2011.
4. Hawley, J.A., Molecular responses to strength and endurance training: are they incompatible? Applied Physiology, Nutrition, and Metabolism, 2009. 34(3): p. 355-61.
5. Lysholm, J. and J. Wiklander, Injuries in runners. The American Journal of Sports Medicine, 1987. 15(2): p. 168-171.
6. Gergley, J.C., Comparison of two lower-body modes of endurance training on lower-body strength development while concurrently training. Journal of Strength and Conditioning Research, 2009. 23(3): p. 979-87.
7. Helms, E.R., et al., Recommendations for natural bodybuilding contest preparation: resistance and cardiovascular training. Journal of Sports Medicine and Physical Fitness, 2014.