Calorie count when performing activity way off.

  1. So over the past couple of days the active calorie count seems be way off. Example, did a 3hr + bike ride on Sunday and only registered 321 active calories(clearly not right). Went for a 17.5km run tonight and only registered 31 active calories. Worked fine on Saturday for a 26km run(1938 calories). What has happened here? Any help would be appreciated. Thanks