This research aims to identify the effect of Contrast training on the dimensions of the heart, muscular ability, and complex skills of handball players. One of the most important results was the effect of the differentiated training program positively on the variables of the dimensions of the heart, muscular ability and the complex skills under research for handball players, and one of the most important recommendations was the use of Contrast training for handball players because of its importance in improving the dimensions of the heart and developing the muscular ability and skill level of handball players .