A sports watch tracks your effort during training and shows you what your heart rate is doing which helps you work at the right intensity. Heart rate data tells you whether you are in the aerobic zone for endurance or pushing hard enough for strength work. Water resistance matters so you can wear this during any sport without worrying about damage. Battery life should be long enough that you are not charging constantly. GPS features let you track distance and route if you are running or cycling. These training watches provide the data that transforms random effort into structured training with actual progression.