Clovishound said:
Check out Alien Gear holsters. Their premium holster uses a stainless steel insert with ballistic nylon and thermo elastic covering and a soft neoprene layer on the skin side. I can't imagine sweat being able to penetrate through to the gun. I have two of them and they are excellent holsters IMO. Very comfortable and stable. They also have adjustable cant, adjustable depth, and adjustable retention.
You will need to wear a good belt to wear the Alien Gear Holsters and some of them are very hard plastic and not comfortable to wear. I know I have about 4 different alien gear holsters and magazine holders.
An alternative might be a breathable 5.11 holster vest with padded pockets where the gun sits in a pocket and reinforced shoulders to hold up the pockets and gun. One slit pocket on each side of the chest. V neck or Crew neck styles.
http://www.511tactical.com/holster-shirt-v-neck.html?utm_medium=cpc&utm_source=google&utm_term=5.11+tactical+men%27s+v-neck+holster+shirt+%28white%29&utm_content=apparel&utm_campaign=plas
http://tacticalgear.com/511-sleeveless-holster-shirts-white~2#/17184/0,407/1
Still when I think of running I think of gym type shorts and a T shirt, socks and sneakers. Not much else will be worn while running in hot weather. Now if you are running in cold weather that's another story. Still running with a gun on my hip on inside the pants would not seem very comfortable to me.