I claim the ornamental design for a lighted dumbbell, as shown and described.
FIG. 1 is a perspective view of a lighted dumbbell showing my new design in an on position;
FIG. 2 is a perspective, exploded view thereof showing the interior weighted elements of my new design.
FIG. 3 is a right side elevational view thereof, a left side elevational view being a mirror image thereof;
FIG. 4 is a front elevational view thereof, a rear elevational view being a mirror image thereof;
FIG. 5 is a top plan view thereof;
FIG. 6 is a bottom plan view thereof;
FIG. 7 is a front elevational view of the first weighted element of my new design; and,
FIG. 8 is a front elevational view of the second weighted element of my new design.
The broken-line disclosure in the views represents portions of the article in which the claimed design is embodied, but which form no part of the claimed design.