HIP BUT NOT KNEE AND ANKLE STRATEGIES IMPROVE JUMP HEIGHT DURING INCREASINGLY CHALLENGING JUMP CONDITIONS
Phuong T.M. Quach, Richard Preus, Bethany A. Moore, Gary Hunter, FACSM, Patricia Perez, Harshvardhan Singh. University of Alabama at Birmingham, Birmingham, AL.
BACKGROUND: Stretch shortening cycle (SSC) potentiation is critical for greater sports performance. During jump test, a quick countermovement-initiated jump (CMJ) or drop jump (DJ) (jump preceded by a drop off from a height) is compared with a jump where a static squat of 2-3 seconds is maintained before the jump occurs (SJ). It is unknown if scaling of jump height (JHt) with increasing level of SSC potentiation is achieved by differential lower extremity joint-specific strategy. Thus, we examined the relationships of JHt potentiation with lower extremity joint-specific potentiation of a) extensor moment and b) propulsive power. METHODS: We used a rigid body model, using 36 reflective markers, and floor-embedded force plates to collect jump data in typically developing children (n = 20; age = 8 - 14 years). After familiarization, participants performed 3 trials of 3 jump types: CMJ, SJ, and DJ. JHt was calculated from the greater trochanter marker data. JHt, and joint-specific extensor moment and propulsive power potentiation were calculated as the ratio of a) DJ/CMJ, b) CMJ/SJ, and c) DJ/SJ at the hip, knee, and ankle. Scaling relationship was examined via spearman correlation coefficients between increasing level of SSC potentiation conditions and a) JHt and b) joint-specific potentiation of extensor moment and propulsive power. RESULTS: Positive scaling of potentiation of JHt (r= 0.629; p < 0.001), hip moment (r = 0.437; p = 0.001) and hip power (r = 0.495; p < 0.001) and a negative scaling of potentiation of knee power (r = -0.276; p = 0.041) occurred. Scaled potentiated JHt was positively correlated with scaled hip moment (r = 0.502; p < 0.001) and hip power (r = 0.696; p < 0.001), and negatively correlated with scaled ankle moment (r = -0.293; p = 0.03), knee moment (r = -0.348; p = 0.009), and knee power (r = -0.340; p = 0.011). Negative correlation existed between CMJ/SJ knee power and hip power (r = -0.456; p = 0.05) while positive correlation was found between CMJ/SJ ankle power and knee power (r = 0.668; p = 0.002). Separate linear regression analysis showed that scaled hip moment and power were the only predictors of scaled potentiated JHt (r = 0.533-0.661; p < 0.001). CONCLUSIONS: Scaling of extensor moment and propulsive power of only the hip potentiation predicted scaled JHt enhancement.
Quach, PTM; Preus, R; Moore, BA; Hunter, FACSM, G; Perez, P; and Singh, H
"HIP BUT NOT KNEE AND ANKLE STRATEGIES IMPROVE JUMP HEIGHT DURING INCREASINGLY CHALLENGING JUMP CONDITIONS,"
International Journal of Exercise Science: Conference Proceedings: Vol. 16:
2, Article 209.
Available at: https://digitalcommons.wku.edu/ijesab/vol16/iss2/209