There are certain questions people only ask when they go from theory to practice, and this is one of them. Cardio or weights? That means you’ve really started working out, and that’s fantastic. But now you’re facing the number one enemy in the fitness world –after laziness and a sweet tooth-, and it is gym myths. Now everybody will have a different answer to your questions, but most of them are not based on science. So, that’s precisely where we are going to start this time, and if the molecular jargon is not your thing, you can just skip it and go straight to the next subheading.

The science behind it all

Yes, there’s a scientific answer to this apparently simple question, but we promise we’re going to try to make it simple. There’s an enzyme in your muscles called AMP kinase, and if you ever thought you were a multitasker, you need to see this guy. The AMP-activated protein kinase is virtually everywhere and does everything in your muscles. Without it you could never have a good workout session, you would never have muscle gains or increase your endurance.

Since the AMP kinase is in charge of stimulating muscle gains and increasing your endurance at the same time, there’s no way it will do both things at the same time. In other words, you can’t expect to train for a marathon without reducing your muscle gains or pumping your muscles without slowing your endurance gains. This wonderful enzyme modulates muscle activity, and it is one of those guys having too much to do and only two hands. So, that’s why you need to choose where to keep your AMP kinase busy if you want excellent results.

So, what’s the answer?

In simple words, your muscles can focus either on increasing muscle mass or endurance, but not both at the same time. So, you need to focus on what’s most important for you. Do you want to build muscle or put down weight? Do you want to prepare for your next 5K marathon or pump your muscles for summer? 

After setting your priorities straight, you have reached the answer yourself. If you want to be an excellent runner, go ahead and start with the treadmill, make your muscles regret the day they were born… or built… well, you understand what I mean. But if you want to be the best weightlifter or bodybuilder, go straight to the iron section and make the dumbbells sweat before starting your cardio.

Of course, there’s more to it than a simple answer, and you can benefit from both worlds by alternating cardio and weights first. But keep in mind you should always start with your priority. Another thing to note is that sometimes you might want to start with 5-10 minutes cardio to warm-up before your weight training, and you can rest assured that will not affect your gains.