Optimal Drop Height for Maximum Performance in Drop Jumps: Impact on Leg and Joint Stiffness

Students: Rachel Nykamp, Hailey Babcock, Jade Winter-Hare, Christopher Hernandez

Faculty Mentor: Young Min Chun

Kinesiology

College of Science, Technology, and Business

The purpose of this research was to identify the optimal drop height for peak performance and analyze the changes in leg and joint stiffness as the drop height increases. We recruited 12 healthy and physically active adults between the ages of 18 and 45 who were free from musculoskeletal injuries that could prevent physical activities. Each participant performed seven different drop jumps at heights of 0, 4, 8, 12, 16, 20, and 24 inches in a randomized order. The 0-inch condition involved a countermovement jump (CMJ) on a force platform. Three jumps were completed at each height, with approximately two minutes of rest between attempts to ensure maximum performance. The jumps were captured using eight optical cameras for 5 to 10 seconds and two force platforms for comprehensive 3D motion analysis. The independent variables include sex and condition, which comprise landing height and CMJ. The dependent variables include jump height, leg stiffness, and lower extremity joint stiffness. Males jumped significantly higher than females, regardless of the landing height. In addition, the CMJ resulted in higher jump heights compared to all other drop heights. Interestingly, while the CMJ showed a trend of increased leg stiffness with landing heights above 16 inches—and decreased stiffness below 16 inches—a significant difference in stiffness was observed only in the pairwise comparison at the 24-inch height.