(I recall the Rollins College soccer team had set of practice uniforms
with this type of shirt. I don't think they played actual games in
them.)
The term 'shimmel shirt' is a non-slang term used in the clothing
industry for garments of tis type for either sex.
Slang terms include belly shirt, (USA) belly top, (UK) etc.
Russell Athletic Shimmel T-Shirt - medium weight, 50/50 blend, shimmel
t-shirt. $6.99 Call for team discounts.
The North Face: Women's Espial Shimmel - Soft, comfortable and
lightweight, the Espial Shimmel features a built-in shelf bra and
seamless construction on side panels for increased comfort and reduced
chafing. $34.95