As data were unavailable, this study quantified the forces acting on the upper extremities during water-skiing takeoff in 10 male volunteers (mean age: 28 years). Body weight ranged between 141 and 195 lbs. Low, medium, and full-power takeoffs were used to propel each skier out of the water. Although low-power takeoffs produced significantly less peak force (P < or = .0004), they yielded a trend toward greater time under load (P = .097). As the data suggest that forces assume roughly one and one-half times body weight, individuals with pre-existing shoulder morbidity may risk exacerbation of their condition.