I already had monster glutes, but when the snow falls and I'm pushing 42x17 on spiked tires @ 25 psi through 4" of sloppy snow for 3 weeks, the Quad Djinni visits me at night and pumps me up. Seriously, I put on some newish jeans, and after fighting to pull them up over my thighs, they sagged back down a little and were held in place by my quads and hams. Even with wallet, keys and lots of coins, they wouldn't droop. I felt stoopid, but strangely energized.