Sports shirts with zippers that come to the mid-chest are great for days when it's chilly when you start your workout but you know you'll warm up once you get moving. Most sports apparel manufacturers offer workout shirts in half-zip styles. The half-zip fitness shirts also have stand-up collars that form a mock turtleneck when zipped up for extra warmth. Some half-zips have zippered pocket on the sleeves for gel packs, or side pockets that hold keys and gloves. Most half-zip workout shirts are long-sleeved, you can find short-sleeved half-zips if you look where cycling clothes are sold; many cyclists favor fitted short-sleeved tops with a half-zip.