Participants in the experimental group performed French Contrast Training twice per week for 8 weeks, including heavy resistance, plyometric, loaded power, and assisted exercises.

Standard football training

Participants in the experimental group performed French Contrast Training twice per week for 8 weeks, including heavy resistance, plyometric, loaded power, and assisted exercises.

The pre-test and post-test Relative Strength Index (RSI) values of the sample group were obtained using the countermovement jump (CMJ) test. Participants started from an upright standing position on the platform with their feet shoulder-width apart and hands placed on their hips to eliminate arm swing. From this position, they were instructed to perform a rapid downward movement by flexing the hips and knees, immediately followed by a maximal vertical jump without any pause between the eccentric and concentric phases. Participants were required to keep their hands on their hips throughout the movement and to take off and land with both feet while attempting to jump as high as possible.

Anaerobic profile (anaerobic capacity and fatigue index values) of the football players were assessed using a mechanically braked cycle ergometer connected to a computer and compatible software Wingate 894E test system. Prior to testing, the saddle height and pedal position were individually adjusted for each athlete to ensure an approximately 10% knee flexion angle at the lowest pedal position. After entering the athletes' descriptive information into the computer, the resistance load was automatically calculated by the system as 75 g per kg of body mass and subsequently applied to the ergometer's braking mechanism

The 10-meter sprint performance of the football players was assessed using a photocell timing system (Optojump, Microgate, Italy). Two pairs of photocells connected to an electronic timing system with dual-beam functionality and a measurement accuracy of ±0.001 s were positioned at the start and finish lines along a straight 10-meter track, with the sensors mounted 90 cm above the ground to ensure precise detection of the participants' movements. Participants began each trial from a standing start position, with one foot placed slightly forward, positioned 50 cm behind the starting photocell gate to standardize the initial stance.