Not perfect, but the best I've found
I've run with several lumbar packs but have found this one to be the most user-friendly (I don't hate it). I am kind of pear-shaped (or "hippy"; I'm a women's 8 up top, and a 10 below.) but this pack stays put better than others. It still rides up a bit, but I can tighten the straps easily while running. The fluid capacity is a little small for runs longer than 16 miles--I had to refill halfway for my 20 miler. Ample storage for snack, keys, cash/ID, cell phone. It is difficult to retrieve snacks from the zippered pockets without stopping. Clips on each hip hold the water line in place, and there is a stay to tuck straps into so they don't flap in the breeze. I can sip and stow easily without breaking stride. If you expel ALL the air from the CamelBAK bladder and avoid allowing airleak into the bladder while you run, then it is SLOSH-FREE.