Author(s): ANDO, R., HOMMA, H., YAMASHITA, D., Institution: JAPAN INSTITUTE OF SPORTS SCIENCES, Country: JAPAN, Abstract-ID: 1243

INTRODUCTION:
Several studies have examined countermovement jump (CMJ) force–time metrics over the course of a basketball match from the perspective of fatigue monitoring; however, no clear declines in these metrics have been demonstrated (e.g., Cabarkapa et al., 2024). This lack of decline may be attributed to inter-individual variability, because players in team sports assume different roles depending on positions. Therefore, it is necessary to clarify whether CMJ force–time metrics change over the course of a match and in relation to external loads in one-on-one sports, such as racket sports. The purpose of this study was to examine the relationships between external loads during a badminton match and CMJ force–time metrics.
METHODS:
Twenty-two collegiate badminton players participated in the study (age: 20 ± 1 years; height: 172.3 ± 5.5 cm, body mass: 64.4 ± 4.5 kg, Tier 3 [McKay et al., 2022]). They performed a badminton match while wearing an inertial measurement unit (IMU) on the lower back and all participants completed three games regardless of the outcomes of the first two games. Accumulated acceleration load (AAL) was calculated based on three-axis acceleration and further categorized by intensity into AALlow, AALmedium, AALhigh, and AALvery high. Three countermovement jumps without arm swing were assessed using a uniaxial force plate system at baseline (before the first game) and after the first, second, and third games. Relationships between each level of AAL intensity and relative changes in jump height, peak concentric force, and peak eccentric force during countermovement jumps were examined using Pearson’s correlation coefficient.
RESULTS:
CMJ height was higher after each game (means: 41.2–41.9 cm) than at baseline (37.5 ± 3.4 cm) (p < 0.05). Peak concentric and eccentric forces were also higher after each game (concentric means: 1411–1463 N; eccentric means: 1618–1653 N) than at baseline (concentric: 1389 ± 168 N; eccentric: 1539 ± 155 N) (p < 0.05). Relative changes in CMJ height from baseline to the third game were negatively correlated with AALvery high from the first to the third games (rs = −0.486, p < 0.05). Similarly, relative changes in peak concentric force were negatively correlated with AALhigh (rs = −0.496, p < 0.05) and AALvery high (rs = −0.599, p < 0.05), and relative changes in peak eccentric force was negatively correlated with AALvery high (rs = −0.473, p < 0.05).
CONCLUSION:
Although all participants performed a warm-up before the matches, badminton match play itself likely acted as an additional warm-up, as indicated by the increases in CMJ height and concentric and eccentric forces. However, the negative relationships between relative changes in external load and CMJ height suggest that players with a lower volume of high-intensity external load may gain greater benefit from this additional warm-up effect, whereas those with a higher volume may offset it.