Effect of 8-week Incremental Elastic-Resistance Kick Training in Taekwondo Athlete's

subjects executed three maximal RHKs with each leg, taking a 20-second rest between kicks. The best performance time was recorded.

For E-H reaction measurements, participants sit about 50 cm from the computer screen, with the screen placed 15 cm in front of and at the same height as the response panel. The response involves using the index finger of one hand, with the other hand resting beside the panel.

Simple Eye-foot (E-F) reactions were measured similarly, with the participant seated the same distance from the screen. The response panel is placed on the floor, positioned under the seated subject's foot. The response is made using the toe, while both hands rest on the desk and the other leg is positioned next to the panel.

Participants, free from lifting restrictions, underwent Isometric Muscle Strength (IMS) testing using a back-leg-chest dynamometer (Saehan, SH5007, Masan 630-728, Korea). This device, correlated (r = 0.77, p <.001) with manual muscle tests 29, measures force applied to a spring, moving a pointer to indicate the exerted force. The dynamometer records up to 300 kg with 1 kg resolution, accurate to + 0.5 kg at 100kg. Subjects were instructed to stand with a 30-degree knee flexion and hip flexion, maintaining a proper lordotic curve, and then exert force using their legs and arms. The average of two strength measurements at each testing phase distinguished between learning and training effects. Participants controlled the exertion level, with to avoid discomfort.

The Margaria-Kalamen stair climb test measures an athlete's lower body peak power 30. Participants start 5 meters away from the first stair, quickly ascending on the researcher's signal, taking three steps at a time. Timers on the 3rd and 9th steps record the duration of the climb, starting and stopping as the participant hits these steps. The best performance time from three trials, each followed by a 20-second rest, is used. Anaerobic power, calculated in watts, is derived by multiplying the participant's weight by the stair height (16 steps) and gravitational acceleration (9.81 m·sec-1), and dividing by the time taken. This formula for computing anaerobic-alactic power follows 31:

Equation: Anaerobic Alactic Power (watts) = (body mass (kg) × distance (0.96 m) × 9.81m·sec-1) / time (sec-1).

In the 10 m sprint test (S-10m), participants completed three maximum-effort 10-meter sprints, timed using a Brower equipment (Wireless Sprint System, Draper, UT, USA). Photocells were placed at the start line (0 m) and at the 10 m mark, positioned 1 meter above the floor, aligning with the manufacturer's standard tripod height. Sprints were interspersed with 3-minute rest periods, and the fast sprint was recorded. This system validity and reliability have been confirmed, demonstrating an intraclass correlation coefficient between 0.92 and 0.98 and a coefficient of variation of 1.6% 32.

Lower limb power was evaluated using the counter movement jump (CMJ) test. Participants began each CMJ from a static standing position, executing a countermovement and then a rapid extension of the lower limb. They perform three maximal effort CMJ's, with 90-second rest intervals between jumps. The countermovement phase was self-selected, allowing athletes to use their preferred jumping technique. Participants were instructed to keep their trunk vertical and hands on their hips during jumps. Data was captured using an iPhone 11 Pro with My Jump app 27, recording at 240 frames per second.