In the industry, ergonomics evaluation is a major means of preventing work related injuries such as musculoskeletal disorders. However, ergonomics evaluation is usually a tedious process. This is especially true when accurate information about the internal efforts of the human operator is needed. In this paper, we present an intuitive tool combining virtual reality and physics-based virtual humans for ergonomics studies. Immersed in a real-time physics simulation, the user can puppeteer the virtual human to explore various postures. In addition, the user can make the virtual human apply forces on the environment, while being able to monitor its joint torques. The virtual human is torque controlled using a quadratic programming based controller which guarantees dynamically consistent postures and joint torques. The features of the tool are illustrated in a hand pushing experiment, with different morphologies and target positions. The experiment gives quantitative results that are consistent with the expected impact of the morphology and the target position on the joint torques. This makes this approach promising in an ergonomics context when prototyping workplaces.