Your mileage may vary..
The capacity for this device is just right for longer runs 5 to 10 miles.
I'm a little large (6 ft, about 220 lbs.)and need the hydration.
I used it on a Bartram Trail race (8 miles at 3500 ft. elevation) in NC just two weeks ago.
I fumbled with side/cinch straps a little, but eventually figured out how to best use them.
It's a good size, but takes getting used to running with a lumbar pack with that much water volume.
I think this one is best for fitness walkers and day hikers.
It can work for trail runners, but you need to be a decent size (min. 5 ft. 10 in.)and have the strength to carry that much weight (roughly 4 pounds filled) at your center of gravity.
If your smaller than the min., I recommend a smaller volume lumber pack or go with a over the shoulders type hydration pack.