Female participation in high-contact sports has increased dramatically in the past two decades, raising concern regarding injury to the female breast and the need for protective equipment. While the use of chest/breast protectors by women is advocated, little is known of their efficacy and effect on athletic performance. The purpose of this study was to determine the effects of chest/breast protector use on measures of performance and comfort, and to determine the mechanical response of the protectors to applied impacts. The four chest/breast protectors selected for study included rigid polyethylene and flexible closed-cell foam styles. To evaluate physiological and comfort differences among the control (no protector) condition and the protectors, female subjects completed a submaximal treadmill running protocol, during which metabolic, skin temperature and perceived comfort data were collected. To evaluate effects on general agility, subjects completed a timed agility test. To assess cushioning properties, the vertical acceleration-time and force-displacement histories of a projectile during surface contact with each protector were analyzed using a drop test method. Analysis of variance methods were used to compare metabolic, temperature, comfort, agility, and energy absorption variables. Graphic presentations accompanied by qualitative interpretation of data across the time history of the impacts were used to describe cushioning properties of the protectors. The chest/breast protectors in this study did not significantly increase oxygen consumption for submaximal treadmill running. Some but not all protectors produced significantly higher skin temperatures than the no-protector condition. Greater temperatures and temperature differentials between the skin and exterior equipment surface were associated with multiple plastic/fabric layers and closed-cell foam construction. No protectors produced significantly higher ratings of thermal sensation or perceived skin wettedness than the control condition. Two protectors were assessed as similar to the control condition on general comfort sensation while two were deemed to be significantly less comfortable. There was no decrease in general agility associated with protector wear. The closed cell foam protector generally showed better shock attenuation characteristics, while the rigid protectors generally demonstrated superior shock absorption. Relationships with regard to cushioning properties changed in response to systematic variation of missile mass and drop height. / Graduation date: 1992