Author(s): GREEN, A., SZELES, K.T., Institution: UNIVERSITY OF JOHANNESBURG, Country: SOUTH AFRICA, Abstract-ID: 930

INTRODUCTION:
Landing requires athletes to attenuate ground reaction forces in three planes while establishing postural stability. Various jump or landing tasks are employed to monitor performance and injury risks. These include the Drop Landings (DL); Drop Jumps (DJ) and Countermovement Jumps (CMJ). Moreover, landing stability can be quantified using Dynamic Postural Stability Indices (DPSI) and Time to Stabilisation (TTS). The study purpose was to evaluate the stability indices of landing phases across the various landing conditions.
METHODS:
20 female recreational athletes (age: 23.4 ± 2.87 years; mass: 62.85 ± 10.28 kg; height: 1.69 ±0.08 m) volunteered to complete 40cm DL, 40cm DJ and CMJ in a randomised order. All kinetics were recorded using two Bertec force plates at 1000Hz. Force tracings were analysed in MatLab, where stability metrics (APSI, MLSI, VSI, DPSI and TTS) were calculated. One-way ANOVA with appropriate post-hoc tests were conducted with significance at p<0.05.
RESULTS:
Stability indices showed differences across all three landings and directional components (p<0.001). Higher APSI were recorded for DL (0.059 ± 0.013) compared to DJ (0.027 ± 0.025) and CMJ (0.019 ± 0.013) and a lower MLSI in DL (0.023 ± 0.01) compared to CMJ (0.032 ± 0.015). VSI and DPSI were the lowest in DL (0.265 ± 0.068; 0.273 ± 0.07) compared to DJ (0.578 ± 0.175; 0.564 ± 0.148) and CMJ (0.514 ± 0.136; 0.516 ± 0.136). Finally, no TTS differences were observed across the landings (DL: 1.50 ± 0.27s; DJ: 1.52 ± 0.35s; CMJ: 1.40 ± 0.28s).
CONCLUSION:
Stability differences were noted across the various conditions, with the DL reporting the most differences with DJ and CMJ. It’s apparent that DJ and CMJ are more dynamic movements and more variable in terms of joint movements (1). Furthermore, studies have shown that cognitive load can negatively impact knee joint stability during landing tasks (2), showing that dual-task conditions can significantly increase peak GRF. This may translate into the findings of the current study, where VSI and DPSI are significantly larger in DJ and CMJ compared to DL. Additionally, DJ and CMJ require more reactive landings compared to DL. APSI in DL may indicate a greater joint excursion as most of the force attenuation occurs in the AP and vertical planes. Specific to the vertical stability (VSI & DPSI) differences might be attributed to the landing heights, leading to greater joint flexion angles and higher GRF (3).
In conclusion, Landing stability may be determined by the dynamics of the jump or preceding events. Additionally, postural stability might be affected by the landing height and kinematic strategies used to attenuate force.
References:
1 González-García et al. Appl Sci. 2024;14(6):2662.
2 McCarren et al. Mil Med. 2023;188(7-8): e2102–e2108.
3 Verniba et al. Sports Med Open. 2017;3: 6.