In the drummer's universe, trained muscle is far more useful for the faculties listed above, rather than for doing what most people would assume we use our muscles for; hitting stuff hard.
Certain styles of music necessitate such techniques more so than others, but regardless of what styles you fancy, the ability to play fast, succinct strokes (whether as a fill, solo, or a more typical rhythmic orchestration) WILL come in handy. Trust me on that one. In order to be at the top of the "percussive food chain", chances are you're gonna need to bulk up if you want to be able to hit light speed with your strokes.
Now, I bet you're wondering; "I've seen Ata before, and he's scrawnier than a vegan spider monkey with a bowel infection". This (embarrassingly), is true. But you see, I'm not referring to the 'muscles' that you think I'm referring to. I'm talking about the fingers.
The fingers are arguably the most critical feature of a drummer. They allow us to control and regulate our strokes, play faster, and manage our dynamics easier. Compared to the rest of our arm, the fingers are a much more sensible choice of muscle for playing things in the upper quadrant of the metronome because of their weight, dexterousness, and low energy consumption rate.
When playing with a matched grip (students of mine: you all play matched grip), the middle, ring and pinky fingers are the virtual 'motors' that (should) propel your strokes at certain 'higher' tempos. The forefinger and thumb merely act as a 'securing point' (more rightfully The stronger those three 'motor muscles' are however, the quicker you will be able to perform certain techniques and for longer, also.
To strengthen your finger muscles, try out some of these simple exercises;
1- Squeeze a tennis ball (or firm stress ball) for five minutes, three times a day.
2- Do 'weights' with your fingers by lifting a ceramic mug (yes, you heard correctly) by it's handle, one finger at a time for five lifts a finger.
3 - 'Finger sit-ups' can be achieved by laying your hand flat on a table, getting a golf ball sized wad of blu-tak, attaching it to the end of one selected finger at a time and lifting that finger off the table to hold for ten seconds.
4 - Moving one finger at a time in a 'spiraling motion' for fifteen seconds each, and repeating for five minute sessions, three times a day.
5 - Start lifting your mama's shopping bags with your fingers, NOT your arms each time she needs help carrying them from the car (haha)
I've seen many young drummers try to play brisk sixteenth note orchestrations (for example) with their whole arm. At a certain point, this becomes completely exhausting, and the young drummer either loses time, is unable to continue playing at all, or even (in the absolute worst case) sustains a minor injury.
The forearm muscles are heavier, slower, and require more movements to actually articulate when laying the drums. It is just simply impossible to play certain techniques with your whole arm.
If you dont believe me, try playing 16th notes at 260bpm with your WHOLE arm. I'll give away a cash prize for any drummer who can pull such a feat off for even sixty seconds. It just isn't going to happen.
So why stop there? Come and see me, and we will get to talking about proper grip technique, the efficiency of using the fingers as opposed to the arm for various types of strokes and techniques, and how you can further your finger exercises to add strength and endurance to your playing.
And no - before you ask - picking your nose isn't one of them.
(No matter how strong you think your fingers are, you must practice hand safety to avoid injuries to the fingers. According to professionals at the American Society for Surgery of the Hand, you should take regular breaks from repetitive-motion activities, such as the exercises listed above).