Risk Factors for Non-Contact Lower-Limb Injury: A Retrospective Survey in Pediatric-Age Athletes

Impact of Starting Knee Flexion Angle on Muscle Activity and Performance during Plyometrics without Jumping

Most of the existing research has focused on jump plyometrics, where landing reaction forces must be dissipated among lower limb articulations. In contrast, the investigation of resisted plyometrics without jumping, devoid of such landing forces, remains relatively limited. This study aimed to (i) investigate the impact of resisted plyometrics without jumping at two knee flexion angles (60 and 90 degrees) on vastus muscle activity relative to limb dominance and (ii) assess strength, power, and work during the concentric-eccentric phases of these exercises. Thirty-one healthy participants underwent quantification of lower limb muscle amplitude, strength, power, and work during resisted plyometrics without jumping from both 60° and 90° knee flexion positions. After anthropometric evaluations, participants used a dynamometer with a load equal to 80% of body weight while wireless surface electromyography electrodes recorded data. Statistical analyses utilized paired t-tests or nonparametric equivalents and set significance at p ≤ 0.05. Results showed significantly higher muscle activity in the vastus medialis (VM) (dominant: 47.4%, p = 0.0008, rs = 0.90; nondominant: 54.8%, p = 0.047, rs = 0.88) and vastus lateralis (VL) (dominant: 46.9%, p = 0.0004, rs = 0.86; nondominant: 48.1%, p = 0.021, rs = 0.67) muscles when exercises started at 90° knee flexion, regardless of limb dominance. Substantial intermuscle differences occurred at both 60° (50.4%, p = 0.003, rs = 0.56) and 90° (54.8%, p = 0.005, rs = 0.62) knee flexion, favoring VM in the nondominant leg. Concentric and eccentric strength, power, and work metrics significantly increased when initiating exercises from a 90° position. In conclusion, commencing resisted plyometrics without jumping at a 90° knee flexion position increases VM and VL muscle activity, regardless of limb dominance. Furthermore, it enhances strength, power, and work, emphasizing the importance of knee flexion position customization for optimizing muscle engagement and functional performance.

Predicting the Risk of Injuries Through Assessments of Asymmetric Lower Limb Functional Performance: A Prospective Study of 415 Youth Taekwondo Athletes

Background

The impact of interlimb asymmetries on sport injuries is unclear because of inconsistent findings, and there is a lack of research on youth athletes and the sport of taekwondo.

Purpose

To examine the effects of functional interlimb asymmetries on noncontact lower limb injuries in youth athletes.

Study Design

Cohort study; Level of evidence, 2.

Methods

A total of 415 taekwondo athletes (318 boys and 97 girls) aged 6 to 17 years underwent baseline testing to determine interlimb asymmetries through the single-leg countermovement jump (CMJ), hop, and triple hop tests as well as the Star Excursion Balance Test. The athletes were then evaluated for 12 months to observe the occurrence of noncontact lower limb injuries.

Results

During the study, 98 athletes (70 boys and 28 girls) sustained at least 1 noncontact lower limb injury. Athletes with higher interlimb asymmetries in single-leg CMJ height showed a significantly increased risk of noncontact lower limb injuries (boys: odds ratio [OR], 1.053 [95% CI, 1.027-1.080], P < .001; girls: OR, 1.070 [95% CI, 1.016-1.128], P = .011). Asymmetry in single-leg CMJ height of ≥15.28% was found to be the cutoff point for predicting noncontact lower limb injuries in boys (OR, 4.652 [95% CI, 2.577-8.398]; P < .001).

Conclusion

This study highlights the utility of interlimb asymmetries in unilateral jump performance as a tool for assessing the risk of noncontact lower limb injuries in youth taekwondo athletes of both sexes. A proper evaluation of interlimb asymmetries may improve prevention strategies for youth athletes.

AN INVESTIGATIVE ANALYSIS OF BASKETBALL INJURIES BY COLLEGE STUDENTS

ABSTRACT Introduction Basketball is a sport with strong rivalry, being, therefore, a modality with great facility to cause sports injuries along its practice. Objective Investigate the status of sports injuries in college basketball for amateur students. Methods 480 college students who were not basketball experts were selected as research volunteers. The current status of sports injuries in the 12-week optional basketball course was investigated, and the main risk factors were analyzed. Results Among amateur male college students, the average playing age of third-grade male college students is higher than that of second-grade male college students, and the weekly playing frequency is lower than that of second-grade male college students. The incidence of basketball sports injuries among male college students who do not specialize in basketball from childhood to adulthood is up to 90.7%, and 85.5% during their college years. Conclusion In basketball sports, the most vulnerable parts of amateur male college students are the wrist joint, ankle joint, knee joint, leg, head and face, shoulder, waist, and back, respectively. Level of evidence II; Therapeutic studies - investigation of treatment outcomes.

Muscle and Tendon Stiffness of the Lower Limb of Professional Adolescent Soccer Athletes Measured Using Shear Wave Elastography

BACKGROUND

While adolescents have specific risk factors for acute and chronic injury, there is a lack of preventive medicine algorithms for this vulnerable group. Shear wave elastography (SWE) is currently mainly used for assessing muscle and tendon stiffness in adult athletes and can diagnose tissue pathologies such as tendinopathy. The aim was to investigate differences in quadriceps tendon and muscle stiffness between adolescent and adult professional soccer players using SWE and identify lateral imbalances in order to improve the knowledge of preventive medicine algorithms for professional adolescent athletes.

METHODS

Standardized SWE examinations of both lower limb tendons and muscles (the quadriceps tendon (QT) and the vastus medialis (VM) muscle) in the longitudinal plane and relaxed tendon position were performed in 13 healthy adolescent soccer athletes (13-17 years), and a control group of 19 healthy adult professional soccer athletes (18-29 years).

RESULTS

Adolescent soccer players had lower stiffness values for both the quadriceps tendon (3.11 m/s vs. 3.25 m/s) and the vastus medialis muscle (1.67 m/s vs. 1.71 m/s) than adult athletes. Moreover, QT stiffness in adolescent soccer players was significantly lower on the right side (QT: adult 3.50 m/s (2.73-4.56) vs. adolescent 2.90 m/s (2.61-3.12); p = 0.031). Analysis of the lateral differences revealed softer QT and VM tissue on the right side in over two-thirds of adolescent soccer athletes. Over two-thirds of adults had stiffer QT and VM tissue on the right side.

CONCLUSION

In adolescent soccer players, the stiffness of the QT and VM muscle measured by SWE is lower in the right leg. SWE of the musculoskeletal system may thus become a relevant diagnostic tool to detect early lateral imbalances as a main risk factor for injury and may thus contribute to the prevention of acute and chronic injury prevention in adolescent athletes.

Force, Power, and Morphology Asymmetries as Injury Risk Factors in Physically Active Men and Women

This study aimed to investigate whether asymmetry of force, power, and tissue morphology are lower limbs (LL) injury risk factors in physically active adults. Fifty-eight men aged 23.8 ± 1.2 years and forty-seven women aged 23.3 ± 1.0 years were examined. Physical activity level was measured by the International Physical Activity Questionnaire, and injury data were collected with the Injury History Questionnaire. The countermovement jump was performed to evaluate force and power. LL tissue composition was evaluated by a bioimpedance analyzer. The symmetry indices were calculated. A comparison between injured and non-injured subjects in both sexes was conducted to determine indices associated with injuries. The symmetry indices cut-off points were calculated to establish values indicating a significant injury risk increase, and logistic regression was performed. The relative peak force asymmetry above 4.049% was associated with increased injury risk in men. The LL skeletal muscle mass asymmetry above 3.584% was associated with a higher injury risk in women. Increased asymmetry in indicated indices by 1% was associated with 19.8% higher injury risk in men and 82.6% in women. Asymmetry proved to be an injury risk factor. However, a more suitable index for men is relative peak force asymmetry, whereas LL skeletal muscle mass asymmetry is more suitable for women.