Four track and field athletes were subjects in a study that analyzed seven jumping exercises and flop-style high jump takeoffs for ground reaction forces, knee angular kinematics, and electromyographic activities of knee extensor musculature. The ground contact times varied between 177 ±13 (flop) and 278 ±25 ms (standing five jumps). The peak ground contact forces were from 5002±130 N (special drop jump) to 8202±901 N (ranning five hops). Average knee angular velocities were highest in the eccentric phase of the flop takeoff (ω = 7.1 ± 2.1 rad × s^-1). Electromyographic activities before the ground contact and during the eccentric phase of contact were highest in the flop-style high jump, while during the concentric phase of contact a special drop jump exercise showed the highest activity. Preactivity IEMG correlated with the eccentric IEMG, force, and knee angular velocity positively and with the contact time negatively (p<0.001), while eccentric IEMG correlated with the eccentric force and angular velocity positively and with the contact time negatively (p<0.001).