Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
trainer [ˈtreɪnər] n (coach) тре́нер; (of animals) дрессиро́вщик[-щица]
trainers
npl (sports shoes) кроссо́вки fpl
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.