Relative strength is strength in relation to your body weight. Relative strength have a determining importance in sports in which the athlete shifts his body in space without any additional external weight. (H/J and L/J) as well as in sports in which he has to restrict his own weight within the framework of weight division (e.g., boxing, wrestling, weight lifting, etc.)
e.g., if 1 RM (repetition maximum) is 50 kg and body wt. is 50 kg and if 1 RM is 70 kg and body wt. is 50 kg, in second category the relative strength is more.
