Consider that if the experiment is about work done on a body in a horizontal direction, then, the only force which contributes to the work is the force exerted by the person, just as you can notice in the following illustration:
In this situation, the weight of the person (or it mass) does not contribute to the work, because only forces acting in the direction of the motion of the object contributes to total work.
In an experiment you can ask for people with different masses to do a work on a body, and determine their forces, masses and the work. And you (most probably) are not going to find a correlation between mass and work.