Removing bad smell of constant use cotton clothes

Have here several cotton clothes that due to constant use, keeps with bad smell, even after washing.

After been washed, when it's used, after a few minutes it begans to smell bad again.

Already discovered that keeping it about 6 months at wardrobe without use neither washing makes it return to normal.

Any idea on how to remove this? Preferably chemical ways.

Cotton is notorious for retaining bad smells.

I do a lot of landscaping and noticed that sweating all day makes the armpits stain and go discoloured. Rain is no better. Wearing rain gear gets very smelly and you notice it once the rain gear comes off.

My recommendations:

• If you use rain gear, wash them at least once a week and let them drip dry. Use an antibacterial laundry soup. If you do this try not to wear when they are damp. (I have three pairs in use at all times.)
• Cottons should be washed in the hottest possible temperature possible and with an antibacterial laundry soap.
• I would recommend putting in a small amount of bleach into the the washing cycle only if this will not damage the clothes. (Please read and follow the directions on the label for washing always.)
• Pretreating your clothes may be helpful too. I use shout on nasty stains.
• Use the longest cycle possible that you washer provides.
• Dry your clothes as fast as possible as bacteria loves a damp atmosphere.