Since it is so fitted, I would definitely size up and be aware that if you are heavy in the chest area, the built in bra will not be your friend. But the quality of it is amazing and POCKETS!!
I sized up to XL from my normal L size because I don't like super form fitting tanks. Decided I didn't love it enough to keep it though as it was a little thicker than I would like for running.
Great top that eliminates the need for a sports bra. The built in bra is perfect for all the running, jumping, and lifting I do! Super comfortable and sturdy top that I use for hiking as well. Love the pockets!!!
I usually wear a medium in Senita tops, but the medium in this is much too small on me. For reference, my measurements are Chest: 38", Waist: 34", and Hips: 43". I found that even returning for the large was still a bit tight for my liking, but more doable around my chest. If I could order again I would probably go two sizes up, but that is only because my hips are much bigger then my chest and needs the extra room to have the top not ride up on me. I don't think you could run in this without another sports bra, but it would be more comfortable for me to have it a bit looser. Other then that, I love the pockets in the shirt! Just wish it ran a bit looser. Maybe it is meant for muscular people and not those of us with a but of jiggle since I thought it was so tight at a large. Should be fine if you size up though.
I love this thing. The only draw backs are: it is not supportive enough for a run and it is straight **** getting it off once it is sweaty (like every sports bra though). I love the padding for an easy go to item. I have worn this to summer concerts and the red one is so pretty. It is wicking and handy