Three sets, each lasting 60 seconds, with a 30-second break between sets for two times for week. During each FR session, a complete sequential movement was always performed, starting from the gastrocnemius muscles and ending with the soleus. A metronome was set to play one complete repetition every 2 seconds to establish the speed of execution.

For the FR, participants were asked to place the roller behind their leg. Three sets, each lasting 60 seconds, with a 30-second break between sets, were performed, for a total of 90 rolls per set.

Initially, the athlete stands upright on a flat surface or force platform, feet shoulder-width apart, hands on hips (to eliminate arm swing). Without a pause, the athlete performs a quick downward movement (countermovement) by bending the knees and hips, then immediately jumps vertically as high as possible. The athlete lands in an upright position on the same spot, trying to absorb the impact with knees slightly bent. Jump height and flight time is recorded using an optical system, Optojump™ system(Microgate, Bolzano, Italy) connected to a personal computer with dedicated software(OptojumpTM Next software). The system consists of two optical bars, a receiver and a transmitter, positioned 1m apart. The bars identify ground contact time(with a precision of 1ms) and then convert non-contact time into cm. Based on recommendations on optimal jump height (20 to 60cm).

Each participant was fitted with an inertial sensor (Beyond Inertial, Motusech, Roma, Itay) in the center of the foot, using an elastic band supplied with the sensor. The starting position was standardized with the subjects sitting on a medical bed with the popliteal cord attached to the edge of the bed, forming a 90° angle. The position of the foot, on the other hand, was placed in a neutral position using a laser level. Subsequently, the dorsal flexion movement was performed.

Ankle stability was assessed using a functional monopodalic protocol, which involved four jumps on one foot: two per leg, both frontally and laterally. These jumps were performed by stepping over an adjustable obstacle set at 70% of the maximum height reached on a pressure platform (SensorMedica freeMed 40×40, Guidonia Montecelio, Italy). The platform has an active sensory surface of 40×40 cm with a thickness of only 8 mm and a low weight of approximately 4 kg. Inside, there are resistive sensors coated in 24K gold on conductive rubber, with a density of approximately 10,000 sensors/m².The acquisition frequency is high, up to 400 Hz, allowing for detailed dynamic analysis, and the sensors have a life cycle of over 1,000,000 cycles of use