2.6.2. Single Leg Countermovement Jump (SLCMJ) Test
The participants performed SLCMJ from a standing position with one bare foot on the board and the free lower limb bent and not touching the force plate. The gymnasts were instructed to place their hands on their hips and jump as fast and high as possible. The first movement consisted of a single-leg half squat, i.e., knee at ~90° and, then, without a pause, a single-leg jump pushing vertically off the ground. Each participant completed six jumps (three with the right leg and three with the left as support) with 1 min rest periods between them. The jumps with the highest power value for the right and the left lower limbs were used for further analysis (Data for the CMJ and SLCMJ tests were collected using a force plate (Kistler 9260AA, Winterthur, Switzerland) connected to a data acquisition system (Kistler 5695b, Winterthur, Switzerland). We employed the MARS software (Kistler, Winterthur, Switzerland) to acquire and store the raw data (sampling rate 1000 Hz) and to calculate all dependent variables. Calibration of the system was performed according to the MARS software recommendations. The CMJ and SLCMJ variables measured were: jump height of flight (Height), which was the height of the jump calculated from the deformation of the platform’s force sensors, measured in meters; this parameter was calculated from the take-off speed. Vertical take-off velocity (Take-off) was the velocity of the vertical movement at the time of take-off, calculated from flight time, measured in m/s. The average power (AVE P) is measured in watts (W). Moreover, the maximum concentric rate of force development (RFD)—P3 was also calculated. P3 is the software designation for the portion of the force curve used to calculate the RFD. The force platform software (MARS) calculates the RFD from the maximum slope of the force curve from the start of the concentric movement to the force peak.The RFD parameter indicates maximal force development in a unit of time and is an index of explosive strength [