Author(s): MASASHI, I., KANNO, K., KINASHI, Y., FURUHASHI, Y., YOSHIDA, T., TANIGAWA, S., MAEMURA, H., Institution: UNIVERSITY OF TSUKUBA, Country: JAPAN, Abstract-ID: 1254

INTRODUCTION:
Video feedback provides visual information by visual electronic devices to athletes. Previous research reported that video feedback improves sports performance in many sports events¹. Drop jump (DJ) is one of plyometrics that enhances the stretch-shortening cycle. Yoshida et al. reported that watching a model video in male athletes improved DJ performances². However, no studies have investigated the effects of different types of video feedback on DJ performance. Clarifying the effect of different types of video feedback, such as self-video (SV), model video (MV), self and model videos (SVMV) on DJ performance may provide practical insights into effective video feedback strategies for DJ training.
METHODS:
Thirty-one healthy male university students participated in this study and performed two DJ trials under four conditions (SV, MV, SVMV, CON). The feedback for each condition was as follows: SV: self-video was shown after DJ trial, MV: model video was shown before DJ trial, SVMV: self-video was shown after DJ trial, and model video was shown before DJ trial, CON: no feedback was given. Three-dimensional coordinates of the 12 retroreflective markers fixed on each subject’s body were obtained using a Vicon T20 system with 10 cameras operating (250 Hz). Ground reaction force was measured by two force platforms (1000 Hz). From the data measured, reactive strength index (RSI), contact time (CT), jump height (JH), joint torque, joint power, angular flexion displacements of the lower limb joints were calculated. In addition, participants were asked about perception on video observations by the questionnaire.
RESULTS:
For RSI, it tends to be significantly higher under the SVMV than CON (p < 0.10). For CT, it was significantly lower under the SVMV than CON (p < 0.05). For ankle torque, it was significantly larger under the SVMV than CON (p < 0.05). For positive ankle power, it was significantly larger under the SV and the SVMV than CON (p < 0.05). For positive hip power, it was significantly smaller under the SVMV than CON (p < 0.05). For hip flexion displacement, it was significantly smaller under the SVMV than CON (p < 0.05). For knee flexion displacement, it was significantly smaller under the SVMV than CON (p < 0.05). For perception in video observation, participants focused more on entire DJ movement under the SVMV than SV (p < 0.05).
CONCLUSION:
These results suggest that watching self-video after DJ trial and model video before DJ trial improves DJ performance. Therefore, when coaches provide video feedback to athletes, coaches should instruct athletes to focus on entire movement rather than part of movement.
REFFERENCES:
1) Schenk, M., & Miltenberger, R. (2019) A review of behavioral interventions to enhance sports performance. Behavioral Interventions, 34 (2): 248-279.
2) Yoshida et al. (2024) Acute effects of an instructional movie on drop jump performance and lower limb kinematic variables. Frontiers in Virtual Reality, 4: 1198511.