Objective: The purpose of this study was to investigate the effectiveness of aquabag training by examining the biomechanics of the landing phase during jump squats, with a focus on changes in inertia. In addition, the study aimed to provide guidelines for efficient landing mechanics in Taekwondo players. Method: For this study, 10 Taekwondo players (age 19.6 ± 0.7 yrs, height 174.5 ± 3.7 cm, weight 69 ± 8.6 kg, career 14.8 ± 0.9 yrs) with no musculoskeletal disorders and experience in national-level competitions were selected as participants. Surface electromyography (QEMG8, Laxtha Inc., Korea) was used to measure muscle activation of the left thigh muscles (rectus femoris, biceps femoris) and shank muscles (tibialis anterior, medial gastrocnemius), gluteus muscles (gluteus medius, gluteus maximus) and left core muscles (rectus abdominis, erector spinae), with two force platforms (AMTI, OR6-5) used to analyze ground reaction forces. The participants were divided into two groups using aquabag and barbell during jump squat exercises, with the exercise order randomized. Statistical differences in the electromyography and ground reaction force data between the groups were tested using SPSS 29.0, and paired t-tests were conducted to verify statistical significance (p<.05). Results: The results of this study were as follows. First, The aquabag group exhibited a significantly higher maximum integrated electromyography (iEMG) value for the rectus femoris (p=.027). There were no significant differences between the groups in terms of load rate during landing, but the barbell group showed a tendency for a relative decrease. Although there was no statistically significant difference in the joint angular velocity, the aquabag group tended to show an increase. The knee joint angle at the MF point was significantly higher in the aquabag group than in the barbell group (p=.002). Conclusion: The results suggest that using the aquabag in jump squat landing movements increases muscle activation by generating resistance through the incompressible nature of water, making it effective for landing training in environments similar to Taekwondo practice. The aquabag, with its fluctuating resistance, promotes unstable landings compared to the barbell, potentially improving athletes adaptation to real-world conditions. It may aid Taekwondo athletes in enhancing landing mechanics and preparing for instability.
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