Hot Topic: Function

John Katsavos
3 min readApr 30, 2021

All week this week we have been going into in depth about the term function. As you probably know by now I don’t like how it is being used currently by the mainstream. Especially with the two terms that I have associated with function which are isolation and muscle confusion.

When it comes to isolation, the term is just used because it is a simple term that we can impart as it “looks” like you are “isolating” the muscle…by now you probably know better that this is just not true. Just because it “looks” like you are isolating the area, doesn’t mean that you are truly isolating that joint. All muscles, save for a very few, cross two joints. Therefore, isolation in your shoulder is an impossibility. PERIOD.

I’ll give you an example of a seated preacher curl and THIS time I WILL discuss ALL of the muscles that are included, to finally put an end to this nonesense.

First, you need to grip the dumbbell, therefore you need all of the forearm muscles engaged. Flexor Carpi Ulnaris, Palmaris Longus, Flexor Carpi Radialus, Pronator teres, flexor digitorum superficialis, flexor digitourm profundis, flexor policias lungus, pronator quadratus. All of these muscles in some capacity flex the elbow, wrist and fingers/thumb (yes these two are different).

Then you have the brachioradialus, Extensor Carpi Radialis Longus and Brevis, Extensor Digitorum Communis, Extensor Digiti Minimi, Extensor Carpi Ulnaris, Anconeus, Supinator, Abductor Pollicis Longus, Extensor Pollicis Brevis, Extensor Pollicis Longus, Extensor Indicis Proprius. All of these muscles extend and extend the elbow, wrist and hand.

Getting lost yet?

And that’s just the forearm distal (farther from) of the elbow to the hand, you still have muscles proximal (closer to) the shoulder area, the shoulder area to spine, the spine to both the head and to the hips, AND you have to take into consideration the anchoring efficiency of the other side of the body that is not holding a dumbbell (remember Newton's third law of motion?).

And this is in a seated position in a preacher bench.

So, how exactly am I “isolating” the biceps????

The other topic that I was talking about here was muscle confusion…

I shutter every time I heard this term!

The term implies that you “trick” the muscle into staying OFF when you need to have it ON.

Can you imagine what will happen if you are doing a squat with 100 pounds on your back and quads don’t fire when they’re supposed to!!!! Your femur (thigh bone) is going to shoot right out of it’s socket!!

Or your lats? Yes your lats fire when you are squatting as it is support muscle for the mass (another term that I am going to rip apart) that is on your back so it doesn’t come crashing down on and destroy your spine into bits.

It’s like I always say:

“There is no such thing as muscle confusion, only brain confusion”

So, the next time you hear a trainer say that “…this is an isolation exercise.” or “Today were going to switch it up and have some muscle confusion” you can have an educated conversation as to why it is not. Or better yet find a trainer that is smart enough that won’t use those terms at all.

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