Cardio & Fat Loss - Part Two

So in the first article here, we looked at the questions I want you to have asked and answered before addressing whether or not you need cardio for weight loss.

I'm now going to assume you have that in place. If not, I will say it once more. It matters more than the rest of this for weight loss. Go do it first. Unless you're about to ride at dawn which is obviously superior in every way to everything.

When it comes to Cardio, the options are huge there are almost infinite variations available with every conceivable piece of kit.

After all Cardio is anything that creates a demand for blood and oxygen, and we can do that by moving anything and everything.

That said, we are going to classify all of those options into three distinct types of training.

HIIT - High Intensity Interval Training
MISS - Moderate Intensity Steady State
LISS - Low Intensity Steady State

We'll look at each one, what it is, how to apply it and who would benefit the most from it. There is then a summary at the bottom of the page for all of these.

HIIT - High Intensity Interval Training

Repeated short bursts of exercise above Anaerobic Threshold interspersed with periods of recovery at much lower intensities.

During exercise, the oxygen consumption above which aerobic energy production is supplemented by anaerobic mechanisms, causing a sustained increase in lactate and metabolic acidosis, is termed the anaerobic threshold.

These typically require efforts of 80-95% of MHR (Maximum Heart Rate) for short work periods paired with a longer period of rest or recovery at an effort of around 40-50% MHR. They may also use V02 max calculations rather than MHR for this. Traditionally HIIT uses around a 1:2 - 1:3 work to recovery ratio.

It has been shown that when comparing calorically matched LISS, Intervals and Weight Training sessions, Resting Metabolic Rate is higher at 12 and 21 hours post session when performing Intervals and Weight Training than Low Intensity Steady State sessions.

This suggests that Intervals and Weight Training may be more effective at increasing Total Daily Energy Expenditure than LISS. But we must counter this with the knowledge that HIIT can only be done for short periods of time compared to LISS, which may mean that we end up burning more total calories during the LISS session simply because we can do it for longer. 

What this may ultimately mean is that HIIT is a more effective way of burning calories if you are hard pressed for time. Now if we are to talk about the other health benefits of Cardio, we also find that HIIT allows us to create generally the same adaptations as LISS but in a much shorter period of time. Again this suggests that HIIT is more time efficient. 

Finally the adaptations to HIIT may not interfere with the adaptations to Weight Training (which are going to be more favourable to our long term ability to maintain weight loss and certainly the muscle tissue that gives our body a great aesthetically pleasing physique) that more moderate intensity approaches may.

This Interference will be explained further below. 

The main difficulty with HIIT is that it is pretty damn hard to do and requires much more motivation than LISS. You have to really push yourself to high levels of discomfort during those brief working periods. I know I, for one, struggle to do this when dieting hard and getting in my weight training as well. There is a finite pool of recovery and resource that we must pull from when training and at some point we will start to overtrain and/or under recover. At this point we are going backwards and this is more likely to happen if doing lots of HIIT on top of dieting and Weight Training.

To pull a quote from a study that sums it up nicely: 

"...this protocol is extremely hard, subjects have to be highly motivated to tolerate the accompanying discomfiture."

It is genuinely hard and many beginners will not be able to tolerate the discomfort necessary to do HIIT. But if you can tolerate, or even enjoy, that level of work, then HIIT is the most time efficient training methodology we have for Fat Loss.

Note - HIIT is not TABATA or Insanity Classes. High Intensity Physiology can't be sustained for that prolonged a length of time. No matter how sweaty or hard the class is, it isn't HIIT.

Use HIIT if you meet the following criteria:

  • Highly motivated with an ability to tolerate some physical and mental pain
  • Want to minimise the amount of training time required
  • Have lower levels of life stress
  • Have an appreciation of recovery methods including nutrition, sleep and relaxation
  • You personally enjoy short hard bursts compared to longer & slower workouts
  • Have a base of training in place already

I have a small caveat on top of that if you are in Prep, avoid doing HIIT (or MISS workouts) in the same workout as you Weight Train.

A study found that exercises that produce large amounts of local fatigue (say in the legs when running) may limit performance when both are taken to significantly fatiguing level, which may then limit your ability to adapt to the training itself (which is the whole point of training).

Where possible I would recommend performing these on separate days, or if you must, using a HIIT workout for the legs when Weight Training the upper body and vice versa. For the record performing Resistance & Cardio work in the same program is known as Concurrent Training, this will become more relevant in a moment.

Putting It Together

If you are already performing around 5 Resistance Training sessions a week, I would suggest lower intensity training modalities first. After all, Resistance Training is quite similar to HIIT. Around 10-30 seconds of work per set with around 60-90 seconds recovery sure sounds quite similar to a standard weights session to me.

If you have lower life stress and good recovery capacity then I would usually suggest short HIIT workouts on either rest days or non competing workout days.

MISS - Moderate Intensity Steady State

 We will define this as exercising just below your Anaerobic Threshold

This is the level I find most people go to when self selecting cardio. It's that level that is really challenging but just about sustainable for an extended period of time. When most of us first start exercising we go here, probably because it allows us to work for longer periods of time at a level that is physically demanding to maintain. And so we find ourselves at the Interference Effect:

What Is The Interference Effect?

It is the conflicting adaptations of training for strength and endurance at the same time. The two effects are at opposite ends of muscular adaptation, meaning the change seen to be better at the one is specific and entirely different than the change required for the other. This is summed up below:

Endurance Training Effect

The major metabolic adaptations of a muscle to endurance exercise are seen below, as you would expect these adaptations help increase the ability to perform prolonged strenuous exercise however they do nothing to change the size and shape of the muscle itself.

I also have to point out that muscles don't change shape as such, they can only get bigger or smaller. In other words they don't become quadrangular because you discovered a new move! When talking about Tone or Shape, what we're really saying is that we want to make the muscle a little bigger and reduce the body fat around it.

  • Slower utilization of muscle glycogen and blood glucose
  • Greater reliance on fat oxidation
  • Less lactate production when exercising at that intensity

Strength Training Effect

Strength Training requires an entirely different set of adaptations that are designed to help you produce more force to overcome an object (the purpose of strength). Some of those are Neural (your nervous system improving co-ordination like riding a bike or writing your name) and some of them are Muscular (which are within the tissue of the muscle itself). 

When you first learn a movement the main ways in which you improve are actually because of Neural changes. The more complex a movement, the longer it takes you to get good at doing it. And, annoyingly, until you are good at performing it, it won't be challenging the Muscle itself very well. This is because your ability to produce the amount of force needed to overcome the object is limited by technique, not pure muscular force.

  •  An increase in the ability to contract the muscle
  • An increase in the size of muscle fibres
  • An increase in the activity of satellite cells (read more here)

I will contend that over the long term the changes seen with Weight Training and HIIT are more beneficial to the maintenance of a lower body weight, better body shape and the increased self confidence that comes with that.

In other words, over the long term you will find it easier to stay in shape with Weight Training or HIIT than with MISS or LISS. This is because the greater the amount of Fat Free Mass (FFM) you carry the higher your Resting Metabolic Rate will be. And FFM is likely to be increased and/or maintained better with Resistance Training than any other training modality. Note, I am not saying that this is a huge difference, just because you Weight Train 100% does not mean you can live of cake and doughnuts!

For example

  • Person A has a RMR of 1800 calories
  • Person B has a RMR of 1900 calories

Both of them eat 200 calories. Person A has overeaten by 200 calories while person B has only overeaten by 100. This may not sound like much, but if they did this every single day for a year (obviously it will be different in reality) and their body stored all of this as fat (it won't):

  • Person A would gain 20.9 pounds of Fat
  • Person B would only gain 10.5 pounds of Fat

This is how people seem to gain weight by the way, gradually. No-one ever woke up 4 stone heavier overnight, it happened brick by brick, meal by meal, 100 calories more by 100 calories more. This is the real creep of age. It has much less to do with the inevitable slowing down of your body and much more to do with the gradual overeating and under-moving we do with age. This compounds the loss of Lean Body Mass (including organs) which in turn slows down our caloric requirements and makes it even easier to over eat. Some slowing is inevitable, but the best defence you have against it is to hold on to your precious LBM. And the best defence we have is Weight Training and Protein.

So we can conclude that having a higher RMR is beneficial to weight maintenance. Again it's not all that matters. We have already spoken about variations in NEAT without even mentioning exercise itself. But, all things being equal a higher RMR is better than a lower RMR.

Weight training for 9 months has been shown to increase RMR by 5%. As always, some people respond better than others. For overweight or obese people the maintenance of LBM during weight loss appears to be easier than for leaner people. It has been shown that both Endurance and HIIT Training help to control the loss, or even increase the amount, of LBM when dieting for these groups. But it has also been shown that, even for the obese, Weight Training can increase LBM during dieting periods. Hopefully by now, I've convinced you of the importance of this. 

The final thing I may offer you for this is something I think you may have seen and noticed too. I know lots and lots of great looking early 20's Cardio Bunnies. I don't know many great looking early 40's Cardio Bunnies. This is likely to do with the cumulative effect of everything described above over 20 years. 

Because of this I think it's hugely important to emphasise the maintenance of FFM when dieting if pursuing successful long term weight loss. 

Back To The Interference Effect 

In an analysis of 21 studies investigating the effects of Concurrent Training (Weight Training and Endurance Training together) versus Weight Training alone, Concurrent Training was found to reduce the strength and hypertrophy effect of Resistance Training quite significantly. And in particular that running was more associated with this effect than cycling. This interference effect will be more or less pronounced depending on how much you do, how hard you do it and the type of endurance training you perform.

However if you are not tracking your food intake, there may be some benefit to performing Concurrent Training for body composition. One study found that, in non-dieting conditions, Concurrent Training led to a 3.5% loss in body fat in 10 weeks, compared to 1.4% with Weight Training and 2.3% with Endurance Training alone. Of note, they also found that Concurrent Training and Weight Training increased metabolic rate by around 100 calories, whereas Endurance Training only reduced it by 50.

It should be noted that study this was performed on physically active young men, who had been training at least 3 times per week for at least a year, and had a body fat of between 9-20%. In other words they were in reasonable shape already and as a result I think it can be assumed that they weren't really overeating before the study. As a result the simple act of adding exercise into their lifestyle will likely have put them into a calorie deficit. This cannot be assumed for other demographics.

Remember, we are asking - what is the best cardio for body composition?

Simply put there are more effective and intelligent ways than MISS. I think it's reasonable to conclude that MISS (in particular running based MISS) may lead to a greater Interference Effect than HIIT or LISS, which could negatively affect our ability to maintain Fat Free Mass during a diet.

The other concern I have with MISS is that it is more fatiguing than LISS without the positive LBM effects of HIIT or Resistance Training. The more taxing a workout is, the more fatiguing it is. So we have a cost-benefit analysis to consider:

  • HIIT - Large Training Effect + Large Fatigue Effect
  • MISS - Moderate Training Effect + Moderate Fatigue Effect
  • LISS - Small Training Effect + Small Fatigue Effect

I'm not saying there is no place for MISS in training for weight loss and body composition, but I do think it's a poorer choice than the alternatives, unless an individual really happens to enjoy it. And I will also say that if you have everything else in the right place, one 10km jog a week is unlikely to have a detrimental effect on your results.

Putting It Together

If you are not controlling calorie intake directly, and are naturally maintaining your bodyweight, then combining MISS and Resistance Training may be an effective way to go.  If you're in Prep or are interested in being a Fitness Model, there are better strategies

LISS - Low Intensity Steady State

working at a very low sub-maximal level of exertion

Walking is probably the best example of this. For an active individual it's a movement that you almost certainly don't consider to be exercise. And for that reason, it is a really useful, non-stressful way of increasing your energy expenditure. Bear in mind that for some people walking may be HIIT or MISS depending upon their circumstance and fitness levels.

The Main Cons

Time consuming
Minimal training effect created
Can be a little boring

The Main Pros

Minimally fatiguing
Minimal stress and recovery cost
Can be done when energy is low

You'll notice that the pro's and con's are two sides of the same coin here. And that is both the upside and downside of LISS in a nutshell. It's easy, which is a great way of increasing expenditure in a depleted, dieted and low energy state. But it's not that effective if those things aren't in place yet, at least for fat loss, for the exact same reasons. It has a minimal caloric burn with no positive effect on Resting Metabolic Rate or Fat Free Mass.

Putting It Together

It is useful for recovery from a trauma or injury (though this can easily be HIIT for these people). It is a very low commitment, low stress, low cost way of starting to incorporate more movement into someone's lifestyle. It can be useful for everyone from a complete beginner to a prep competitor. It can be used to increase movement expenditure without increasing stress and eating into recovery.