The picture below (Fig.4) shows a gymnast performing the "iron cross" routine, in which he is suspended as shown by the ropes in each hand. Assuming that only one muscle group is dominant, and using a vector force triangle approach, estimate the magnitude of the joint contact force at the shoulder for this routine in terms of the body-weight of the gymnast. State any additional assumptions.

Figure 4: Body geometry of a person performing the "iron cross" routine