Cardio: will I lose my muscles?

It's a fact. Looking sexy when you're in an Adam costume needs to be dry. The abs are in a way the aphrodisiacs of man. Unfortunately no one likes cellulite. It's like that. So, how do you lose your belly fat? One of the answers that immediately comes to mind for many people is: doing "cardio". That's good, that's precisely what we are going to talk about in this article: the most effective cardio program to operate a good body recomposition, that is to say, for the uninitiated, to gain muscle and lose finally your love handles.

Most of the articles on this topic focus on the pros and cons of traditional cardio, such as as part of aerobic or low-intensity cardiovascular exercise (LISS), compared to high-intensity interval training (HIIT). . So today I am going to avoid repeating what you probably already know. What I'm going to do, however, is take a more basic approach to the subject and explain to you why maybe you just shouldn't be doing cardio, for starters ...

Cardio to burn fat

You probably do cardio because it burns fat. Many studies come up with some pretty exciting numbers regarding fat oxidation and other metabolic changes, but these are usually short-term measures, and especially relative numbers. In absolute terms, the actual amount of fat that is oxidized during a workout is minimal. We're only talking about a few grams of fat altogether here, and the total amount of fat in grams is usually closer to a single-digit number than a three-digit number .

In addition, as Alan Aragon showed in his Microscope Myths series, doing your cardio on an empty stomach or in the famous “fat burning zone” does not help either. In fact, it is often counterproductive. Indeed, at the end of the day, weight loss is always determined by the energy balance. Cardio cannot change the laws of thermodynamics. No matter how much cardio you do, if you use more energy than you burn, you won't lose weight. Cardio burns calories and its fat loss effects only exist to the extent that they contribute to an energy deficit in your diet. Consistent with this reasoning, studies have shown that burning extra calories with aerobic exercise is no more effective than simply consuming less:weight loss and fat loss are the same [ 2 ].

But wait a minute, doesn't cardio, especially HIIT, boost metabolism? Yes, but contrary to what some older research seemed to show, the increase in metabolism after a session (called EPOC, for excess post-exercise oxygen consumption, or excessive consumption of post-exercise oxygen in French) even for the sessions of the most badass cardio, lasts only 3 to 24 hours, and accounts for only 6 to 15% of the total net oxygen cost of your workout .

Ok, so cardio, whatever the modality and intensity, is not a miraculous fat burner, but it still contributes to the energy deficit and in the long term it will necessarily lead to more fat loss. , even if it's not a quick fix? We totally agree ? So what is the problem?

The disadvantages of cardio

The problem is, the calories you burn from your cardio come at a cost, and I'm not just talking about time and energy here. The late Charles Poliquin talked about the downsides of excessive LISS in his article The (Many) Cons of Aerobic Training , but even shorter cardio sessions can still take a toll on your physique and strength. Doing cardio alongside strength training lessens the positive effects of both. Simultaneous strength and endurance training decreases the progress of the cardiorespiratory system, explosiveness, strength and muscle mass [ 2 , 3 , 4 ].

This harsh reality is called the simultaneous training effect or interference effect, because the negative interaction between cardio and strength training is what happens when you try to make the body adapt in two opposite directions. When you put stress on your body, it adapts, and that adaptation is specific to the demands placed on it. The demands you place on your body with cardio and weight training are mutually exclusive. These adaptations include local changes in the composition of the muscle fiber type and the rate of muscle activation, but also central changes in the signaling of cellular pathways, the activation of genes and their concentration [ 2 , 3 ].

For example, protein kinase B / Akt (PKB) decreases protein degradation and activates protein synthesis, making its presence highly desirable for muscle gains. AMP-activated protein kinase (AMPK) increases mitochondrial proteins, glucose transport, and a number of other factors that improve endurance and cardiorespiratory fitness. The problem is that AMPK and PKB block each other's signaling downstream . This is why cardio limits hypertrophy and strength gains not only in the legs or in the parts of the body that you use for your cardio, but also in the whole body.

The intuition behind the interference effect is simple. You can't be the best sprinter and marathon runner in the world at the same time. If you want your body to be exceptional at something, you will need to specialize.

It should be noted that some studies of relatively short duration using sedentary untrained individuals found no interference effect, as the strength of the interference effect depends on the gap between the adaptations required by training. that you perform [ 2 ].

Beginners can get away with doing a lot of different things, as their level of muscle mass and strength doesn't require a lot of specialized adaptation anyway. However, the more your body adapts in any direction, the more the interference effect becomes. It may take 2-3 months of steady progress for endurance training to start interfering with your strength training .

Can the interference effect be avoided? Not completely. As I told you, the magnitude of the interference effect depends on the difference between the adaptations required to the different training constraints. The longer or more frequently you do cardio, the more severe the interference . You could make cardio undemanding, so the body wouldn't have to adapt to it, but it would burn even fewer calories, and the result is far from guaranteed.

HIIT is much less affected by interference than LISS because the adaptations required for HIIT and strength training are more similar, but based on the principle of specificity this would only partially mitigate the interference. Also, if you keep increasing the intensity and rest periods during your cardio, at some point it will simply amount to weight training with suboptimal exercises.

Conclusion

Your body cannot run two hares at the same time. In any case, not optimally. Strength and endurance training simultaneously decreases your body's adaptations to both and results in suboptimal strength and muscle gains. The only way to completely avoid the interference effect is to avoid cardio. Lots of people, including, Menno, Antoine, me, and many of our respective clients, have been able to achieve single-digit body fat percentages without doing any cardio, but following a meticulous diet. Dieting isn't necessarily cool, it doesn't make you look as badass as Bane and his Altitude Mask, and it doesn't give you any adrenaline rush or endorphins, but it does give you something far more valuable: real results, and a physique that is worth the effort.