Systems and methods for formulating a performance metric of a motion of a swimmer

A system for formulating a performance metric of a motion of a user, the system comprising:

• a wearable sensor device including at least one pressure sensor, an inertial measurement unit (IMU), a microprocessor in communication with the at least one pressure sensor and the IMU, and at least one housing to house the microprocessor, the at least one pressure sensor and the IMU;
• and
• a processing unit configured to combine pressure sensor data from the pressure sensor and inertial data from the IMU, wherein the combined pressure sensor and inertial data is used to infer force data including at least one force magnitude, at least one force direction, and any one or a combination of:
• (i) a proportion of force magnitude that is in a forward direction, (ii) an angle of the motion, and (iii) force segmentation, wherein the at least one force magnitude or the at least one force direction are calculated from either (i) a drag force and a first lift force or (ii) a drag force, a first lift force, and a second lift force.