Kinematic factors influencing performance and injury risk in the bench press exercise.

The purpose of this research was to identify kinematic factors that could be relevant to performance and injury risk in the bench press. The methods used included: use of high-speed, 2D cinematographic procedures to record the performances of 36 subjects (19 experts and 17 novices), determination of the kinematic and kinetic differences between the groups, and identification of a rationale describing how those kinematic differences could lead to the kinetic differences. Kinematic factors so identified could influence performance and injury risk. In addition to the fact that experts were able to lift 79% more weight than the novices, the pertinent kinetic differences included the following: 1) the difference in peak force exerted while lowering the bar was only 43%; 2) the difference in peak force exerted while raising the bar was only 45%; and 3) the difference in minimum force exerted while raising the bar was 87%. There was no significant difference in torque required at the shoulder. The relevant kinematic differences were: 1) the expert group maintained a smaller bar speed while lowering the bar, 2) the expert group used a bar path closer to the shoulders; and 3) the expert group used a different sequence of bar movements. The roles of these kinematic factors in the bench press merit further investigation.