A user in locomotion on foot during an outing may identify a grade of a surface with at least one device supported by the user. A performance parameter of the user may be determined with the device based upon the grade of the surface, which may be based upon a measured physiological parameter of the user. An average foot contact time and an average pace of a user during a first outing may be identified and a relationship between them may be determined. No other average foot contact times or average paces identified during a different outing may be used to define the relationship. A single user-specific calibration contestant may define a relationship between foot contact times of a user and corresponding paces of the user, wherein no other user-specific calibration constants are used to define the relationship.