Higher Vertical Jumping Asymmetries and Lower Physical Performance are Indicators of Increased Injury Incidence in Youth Team-Sport Athletes.

ABSTRACT: Fort-Vanmeerhaeghe, A, Milà-Villarroel, R, Pujol-Marzo, M, Arboix-Alió, J, and Bishop, C. Higher vertical jumping asymmetries and lower physical performance are indicators of increased injury incidence in youth team-sport athletes. J Strength Cond Res 36(8): 2204-2211, 2022-To date, the literature about the association between injury-risk factors and actual injury incidence in young elite team-sports athletes is scarce. The main objective of this study was to examine how modifiable factors may affect injury incidence. Eighty-one young elite team-sports athletes (age: under-14 to under-18) performed the countermovement jump (CMJ), a single leg CMJ (SLCMJ), the one-legged hop test (OLHT), a 30-m sprint test, the V-cut test, a repeated sprint ability, and the 30-15 intermittent fitness test (IFT) during the pre-season period. Interlimb asymmetries were calculated for SLCMJ and OLHT. Injuries were recorded prospectively for the entirety of the 2017-2018 season. Comparison of injury and noninjury data was performed using a two-way analysis of variance (ANOVA). Results of the ANOVA according to injury showed significant differences in CMJ ( p = 0.01), SLCMJ on the lowest performing limb ( p = 0.03), and SLCMJ asymmetry (<0.001). Sex × injury interaction was significant from CMJ ( p = 0.018) and 30-15 IFT ( p = <0.001). In conclusion, this study indicated that athletes with greater interlimb asymmetries, less vertical jump capacity, and lower intermittent aerobic fitness had a greater predisposition to injury. Therefore, monitoring CMJ, aerobic performance, and interlimb asymmetries is recommended given their sensitivity to detect significant differences between injured and healthy youth athletes.

Neuromuscular fatigue effects on Hamstring to Quadriceps Ratio in young female players

INTRODUCTION: Two of the main modifiable risk factors for suffering an injury in the anterior cruciate ligament are known to be the Hamstring-to-Quadriceps (H/Q) Ratio and neuromuscular fatigue. The main purpose of this research was to study the effect of neuromuscular fatigue on the H/Q Ratio and the maximum isometric strength of the quadriceps and hamstrings in teenage female basketball and handball players. MATERIAL AND METHODS: This is an experimental, pre-post intervention study with a sample of 19 female basketball players and 11 female handball players (17.02±1.19 yo, 177.8±7.2cm and 68.6±9.3kg). To assess muscle strength, a maximum isometric strength test was performed in a 90° hip and 60° knee position. The H/Q Ratio was then calculated. The 30-15 Intermittent Fatigue Test (30-15 IFT) was used to induce fatigue, measured using the Rating of Perceived Exertion (RPE) scale. A descriptive analysis and a Student's t-test were performed to study the differences in the H/Q Ratio, muscle strength and pre-post intervention fatigue. RESULTS: Although the H/Q Ratio decreased after the 30-15 IFT, the differences were not statistically significant. Regarding strength values, the right and left quadriceps presented strength reductions of 4.52% and 5.55%, respectively. The reduction in strength was statistically significant (p≤0.05), especially in the right hamstring (7.3%) and in the left hamstring (7.5%). The study conclusions suggest that leg muscular strength decreases after a fatigue test and that there is a tendency for the H/Q Ratio to decrease also

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