The ornamental design for a pair of leggings with a resistance band, as shown and described.
FIG. 1 is a front-top-left perspective view of a pair of leggings with a resistance band showing my new design;
FIG. 2 is a rear-bottom-right perspective view thereof;
FIG. 3 is a front elevational view thereof;
FIG. 4 is a rear elevational view thereof;
FIG. 5 is a left elevational view thereof;
FIG. 6 is a right elevational view thereof;
FIG. 7 is a top plan view thereof;
FIG. 8 is a bottom plan view thereof;
FIG. 9 is a reduced front elevational view thereof being worn by a user; and,
FIG. 10 is a reduced rear elevational view thereof being worn by the user.
The broken lines showing a user in FIGS. 9 and 10 are included for the purpose of showing environmental structure and form no part of the claimed design.