The present disclosure is directed to a body-worn sensor-based system for evaluating the biomechanics and the motor adaptation characteristics of postural control during a sport activity such as a golf swing. Various embodiments use sensors such as accelerometers, gyroscopes, and magnetometers to measure the three-dimensional motion of ankle and hip joints. In several embodiments, additional sensors attached to other body segments are used to improve the accuracy of the data or detect particular instants during the swing (e.g., top of back swing, instant of the maximum speed of arm, and instant of ball impact). In a golf embodiment, the system combines the measured data in conjunction with a biomechanical model of the human body to: (1) estimate the two-dimensional sway of the golfer's center of mass; (2) quantify and evaluate the golfer's balance via his/her postural compensatory strategy; and (3) provide visual feedback to the golfer for improving dynamic postural control.