"bulk up muscle" is correct and usable in written English.
You can use it when referring to increasing the size and strength of one's muscles. For example, "I've been hitting the gym hard lately to bulk up muscle."
Also, their wing bones are thicker than normal, with knobs to support bulked up muscles connected to the feathers.
He begins a careful and ritualized effort to bulk up, reading Muscle Builder magazine and arranging a bench and weights in the basement.
As the moment for migration approaches, birds bulk up, adding muscle and fat.
If I'm getting too bulky — playing football, you tend to bulk up with muscles, and my shoulders get too big and my neck gets too thick — I do lots of cardio and endurance training.
Be aware that how you exercise will differ depending on whether you want to bulk up with added muscle or simply tone your arms without adding too much muscle mass.
The powdered ingredients were sold in large plastic tubs from backstreet gyms, promising to help bulk up muscles after a workout.
Be careful though - many traditional core exercises - including those often practiced as part of pilates workouts - can actually bulk up the core muscles causing the waist to flatten out and become wider.
Before my first time on Survivor, I spent a lot of hours in the gym - bulking up with muscle strength.
Spring Training isn't the debaucherous Bacchanalia of the old days: Players make a lot more now, and "Fuck you money" contracts are at stake, so most of the conditioning work is done in the winter: bulking up, building muscle, dropping fat before the 162 game season beats them into tiny lumps.
In my 20s, I was slender and had washboard abs, yet drank protein powder and worked out so I could bulk up and be a "muscle man".
