Nathan Women's VaporAiress Hydration Pack - 2L Water Bladder Running Vest for Marathon, Hiking & Cycling | Lightweight Hydration Backpack for Outdoor Sports & Fitness Activities

The Nathan Vaporairess is a decent hydration pack. I have been in search of a good pack for my longer runs and for my upcoming Spartan Races. However, the first time I used this hydration pack for a quick 6 mile run, my lower back was in pain! I have never had any issues with my lower back before. Even with other hydration packs, weighted vests etc but after I took off the pack my lower back was killing me for hours. I tried it again for a 5 mile run once my back was better, just to see if it would happen again, and my lower back hurt again.I am a 34B, 29 years old in very good health and in very good athletic shape. I ordered the small/medium however it feels like it is just slightly too small due to my muscle around my shoulders. If I had no muscle, then it would fit probably perfectly. I am athletically built and have broader shoulders.Pros - I like the straps in the front across the chest and how easily adjustable they are. I like the magnetic piece for the water hose. That stayed in place the whole run and was very easy to use and put back after a quick drink. I liked the pockets on the side and in the back. My big phone was able to fit nicely in the front pocket that is meant for a water bottle. The bladder was nice and easy to fill.Cons - the water bounced around a lot and I kept having to readjust the pack and pull it back down in the front as it kept sliding up. I think this is why it hurt my lower back, having to readjust the pack. The pocket for the bladder is open, no button or zipper or anything to close the pocket which I thought was odd. I, personally, would like to make sure that I have some sort of pocket that closes for the bladder so it does not slide out if anything were to happen. I would like the pack to sit slightly lower. It seemed very high on my chest and my back which did squeeze my underarms slightly near my armpits. I like to wear tank tops while running but it chaffed slightly near my armpits while running so I had to wear a tshirt the second time and the chaffing did not happen. This may have happened because it felt as though it was slightly too small.Overall, I could see this being a decent hydration pack for a walk but for running and for endurance races, I do not believe this is the right pack, especially for a woman. Design and fit is almost there. Price seemed slightly high for this type of hydration pack.