Though I have access to a long handled sledge hammer, today I used my one handed sledge. Made the workout up as I went along, and realized these things could be used as light clubbells.
First I warmed up by doing wood choppers as one would with a dumbell. The hammer is about 8 lbs. but so topheavy it felt twice as heavy, not to my obliques though so I quit. Then I did the most importannt warmup, l-flyes gripping the hammer behind the head. 2x20 each arm, simple and easy but worth it.
I had planned to use my clawhammer to warm up on the tires preparing for the sledge. But After a compound set each of one arm front, side, and rear laterals with the sledge, held in clubbell fasion, I felt pumped and ready to go.
Let me just say, swinging short gripped sledges is sorta like throwing shotput like a baseball. In the end I only felt comfortable doing this: OH swing, with non-striking hand held above head. Strike, bring back up following momentum from the bounce, switch hands, repeat.
Did this for about 20 minutes, with several breaks, under 30 seconds.
All in all, it was fun to try but, I felt really uncomfortable with my focus interupted by worries of torn rotators and ball joints poppinging out of sockets. All I really got outta this than normal sledge hammering, is hands that can't open or close.
I ended things by trying to do some Thor's Hammers, and couldn't hold the thing anymore. Wrists and the lower forearm muscle are devastated as well. I do feel more lat burn than normal, but everything else is typical sledgehammer soreness.