The research aims to evaluate the biomechanical and electromyographyfor lower lemb in specific exercises for decathlon event methods: The researcher used the descriptive analytical, using tools and devices for biomechanical and electromyography analysis (EMG), due to its suitability to the nature of the research. The research sample consists of a decathlon competitor who was chosen intentionally and obtained second place. In the Republic Championship for Athletics under 18 years 2022/2023, registered with the Sporting Sports Club (age 17.8±0.69 years, weight 70.34±0.15 kg, height 172.54±0.85 cm), the competitor made 3 attempts for each exercise, with a total of 15. The best attempt for each exercise was chosen and analyzed. Data were collected using a Swedish-made muscle electrical activity analysis system (Myon Simply Wireless) to measure the electrical activity of the muscles, and a force measuring device (Bertec 4060-10) to measure the lifting force of the lifting leg, the maximum momentum, the time of reaching maximum force, and the speed of force development, and three-dimensional imaging using Eight cameras with a frequency of 100 cadres per second. The biomechanical measurement and evaluation process was carried out using the motion analysis program (9.02 SIMI 3D motion analyses) to extract the biomechanical variables of the body’s center of gravity and the force measurement platform (FORCE PLATE FORME Bertec4060-10). Results: Specific exercises in their various forms depend on the direction of muscular action, lengthening and shortening. This type of exercise increases strength and therefore ability, and reduces energy consumption if performed with correct technique and high consistency. Recommendations: The use of different movement patterns in reverse movement jumps and the combination of landing and rising enhances From the competitor's ability to coordinate movement, and this appears in muscle activity, strength and speed values, as well as performance time