No, your regular bra is not good enough. You need a sports bra. Not all sports bras are created equal. We want one that is moisture wicking, is comfortable and will supports “the girls”. To make it even more interesting over 80% of women are wearing the wrong bra size.
There are two key types of sports bras – compression vs. encapsulation. Compression sport bras compress the breast tissue. They tend to come in sizes S,M,L,XL. They are not usually the best match for more endowed ladies. Encapsulation sport bras usually have wires, giving them more support than standard compression bras. They tend to come in sizes like 36D, 34F, 32H. Panache, Shock Absorber, & Enell are good bra brands for more endowed ladies. Encapsulation bra sizes usually match your regular bra size (remember that 80% of you are wearing the wrong size)
Regardless of what sports bra type you choose, you want to make sure to use body glide or a similar anti chafing product (vaseline will also work but might stain). A 3 hour run can cause a bunch of friction & when it combines with your sweat we are talking about some very sore places or worse blisters on body parts you don’t want hurting.
If you aren’t getting enough support, you usually don’t want to wear double bras at the same time. This will trap in more moisture on your skin which is a big contributor to raw, sore skin. It is more likely time to replace your sports bra. A sport bra is usually only good for about 3 months. After that it can be stretched out and less supportive just like a pair of sneakers can be worn out. Or it could be that you have lost weight and need a new and better fitting bra.