T-shirts and tank tops

Pay attention to the width of the straps, though: narrow ones cut in and chafe under the straps of a running vest, while wider ones or a racerback design are more comfortable. A T-shirt with sleeves protects your shoulders from the sun, which you will appreciate on long summer runs. Look for a slightly dropped hem at the back so the fabric doesn't ride up above your waist. A quick-drying knit will handle a workout every other day.