An insert configured for use in an article of footwear, comprising: an insert member (237, 337) adapted to be placed in contact with the sole structure of the article of footwear, the insert member being formed of a flexible polymer material, wherein the insert member has an opening defined through the insert member, and a strip of the polymer material of the insert member extends into the opening; a sensor system (12, 212, 312) comprising a plurality of force sensors (16, 216, 316) connected to the insert member and a plurality of sensor leads (18, 218, 318) extending away from the force sensors and extending on the strip of the polymer material, the force sensors being adapted to sense a force exerted on the sole structure by the foot; and a port (14, 214, 314, 414, 514, 614, 714) connected to the insert member and the sensor system, the port comprising: a housing (24, 324, 424, 524, 624, 724) received within the opening in the insert member, the housing comprising a bottom wall (143, 343, 443, 543, 643, 743) and a plurality of side walls (139, 339, 439, 539, 639, 739) extending upward from the bottom wall, the bottom wall and the side walls defining a chamber (348, 448, 548, 648, 748) adapted to receive an electronic module (22, 322, 422, 522, 622, 722) therein; and an interface (20, 220, 320, 420, 520, 620, 720) comprising abase (358, 458, 558, 658, 758) engaged with the housing and positioned at least partially within the chamber, the base supporting a plurality of electrical contacts (356, 456, 556, 656, 756) that are exposed to the chamber and adapted to be engaged by the module to form an electrical connection, wherein the strip of the polymer material extends into the chamber, and the electrical contacts are connected to the strip of the polymer material within the chamber to connect the electrical contacts to the sensor leads and thereby place the electrical contacts in electronic communication with the force sensors. an insert member (237, 337) adapted to be placed in contact with the sole structure of the article of footwear, the insert member being formed of a flexible polymer material, wherein the insert member has an opening defined through the insert member, and a strip of the polymer material of the insert member extends into the opening; a sensor system (12, 212, 312) comprising a plurality of force sensors (16, 216, 316) connected to the insert member and a plurality of sensor leads (18, 218, 318) extending away from the force sensors and extending on the strip of the polymer material, the force sensors being adapted to sense a force exerted on the sole structure by the foot; and a port (14, 214, 314, 414, 514, 614, 714) connected to the insert member and the sensor system, the port comprising: a housing (24, 324, 424, 524, 624, 724) received within the opening in the insert member, the housing comprising a bottom wall (143, 343, 443, 543, 643, 743) and a plurality of side walls (139, 339, 439, 539, 639, 739) extending upward from the bottom wall, the bottom wall and the side walls defining a chamber (348, 448, 548, 648, 748) adapted to receive an electronic module (22, 322, 422, 522, 622, 722) therein; and an interface (20, 220, 320, 420, 520, 620, 720) comprising abase (358, 458, 558, 658, 758) engaged with the housing and positioned at least partially within the chamber, the base supporting a plurality of electrical contacts (356, 456, 556, 656, 756) that are exposed to the chamber and adapted to be engaged by the module to form an electrical connection, a housing (24, 324, 424, 524, 624, 724) received within the opening in the insert member, the housing comprising a bottom wall (143, 343, 443, 543, 643, 743) and a plurality of side walls (139, 339, 439, 539, 639, 739) extending upward from the bottom wall, the bottom wall and the side walls defining a chamber (348, 448, 548, 648, 748) adapted to receive an electronic module (22, 322, 422, 522, 622, 722) therein; and an interface (20, 220, 320, 420, 520, 620, 720) comprising abase (358, 458, 558, 658, 758) engaged with the housing and positioned at least partially within the chamber, the base supporting a plurality of electrical contacts (356, 456, 556, 656, 756) that are exposed to the chamber and adapted to be engaged by the module to form an electrical connection, wherein the strip of the polymer material extends into the chamber, and the electrical contacts are connected to the strip of the polymer material within the chamber to connect the electrical contacts to the sensor leads and thereby place the electrical contacts in electronic communication with the force sensors.