Muscle Strength and Hamstrings to Quadriceps Ratio in Young Soccer Players: A Cross-Sectional Study

Comparative analysis of isokinetic parameters in individuals with and without chondromalacia patellae

INTRODUCTION

Chondromalacia patella (CMP) is characterizsed by cartilage degeneration, affects young adults, more women (2:1) and is responsible for 75% of knee pain complaints in the active population. The etiology is multifactorial and may be related to extrinsic factors (trauma and burden) and intrinsic factors (patellar malalignment and quadriceps weakness). Isokinetic dynamometry (ID) can aid in the detection of the causal factors of knee pain related to CMP.

OBJECTIVES

To evaluate and compare the parameters of the ID of individuals with and without CMP and correlate them with the clinical aspects of individuals with CMP.

METHODS

This is a retrospective study that analyzed ID of the knee flexors and extensors, performed between 2013 and 2019 in the isokinetic dynamometry sector of the hospital. Six hundred ninety dynamometers tests were included, both sexes, aged between 14 and 59 years, divided into chondromalacia group (342) tests and control group (348) tests. All performed ID in concentric mode for knee extension and flexion, with five maximum repetitions at an angular speed of 60°/s and 180°/s and 20 repetitions at an angular speed of 300°/s, with 30-s intervals between each. After completing the test, the patient points out a number from 0 to 10 on the visual analog scale, regarding the presence and intensity of pain during and after the isokinetic assessment.

RESULTS

The groups had similar distribution from sex (P ​= ​0.071); age (P ​= ​0.99) but were different about pain (P ​< ​0.001). CMP had greater levels of pain. In most of the muscle parameters of the extensors and flexors at 60°/s were lower in the CMP group (P ​< ​0.001).

CONCLUSION

The main predictor of chondromalacia is pain. The greater coefficient of variability and time to reach peak torque on the involved side, the average power and morphology of the extensor curve can also be predictors of chondromalacia.

LEVEL OF EVIDENCE

III.

Analysis of Genu Varum in Young Male Professional Soccer Players

Background

Bowlegs (Genu varum) are well-known leg axis deformities in adult soccer players and are associated with an increased risk of knee osteoarthritis. The time of onset of genu varum is unknown.

Purpose

To analyze the static and dynamic leg axis in young professional soccer players from childhood to adolescence.

Study Design

Cross-sectional study; Level of evidence, 3.

Methods

Leg axes of 168 male professional soccer players (336 legs) from 8 age groups (U12-U21) were analyzed. Static and dynamic mechanical femorotibial axis angles (MAAs) were determined using a noninvasive motion analysis system allowing both legs to be evaluated individually. Additionally, the intercondylar and intermalleolar distances were measured. Statistical analyses were performed using a linear mixed model including the variables of age, playing position, shooting leg, and body mass index (BMI).

Results

A significant increase in varus alignment for static and dynamic MAA was found with age. Players of the teams U17, U19, and U21 had significantly higher static MAAs (greater varus) compared with the youngest players (U12). The deviation in the dynamic MAA could be observed starting from the U15 onward. In all age groups, the dynamic MAA was significantly lower than the static MAA. No significant association was found for static or dynamic MAA with BMI, playing position, or shooting leg.

Conclusion

In this study, the degree of static and dynamic varus alignment was significantly associated with increasing age. On the basis of the study's findings, it is believed that preventive training methods particularly focusing on vulnerable age groups should be tested for efficacy.

Special Issue "Role of Exercises in Musculoskeletal Disorders-6th Edition"

The sixth edition of the Special Issue entitled "Role of Exercise in Musculoskeletal Disorders" has been collated, substantially advancing the conversation on the effectiveness and practicality of exercise-based interventions for individuals with musculoskeletal conditions [...].

Plyometric training with additional load improves jumping performance and isokinetic strength parameters of knee extensors and flexors in young male soccer players

This study investigated the effect of plyometric training with and without additional load on young male soccer players' jumping ability and isokinetic strength. Methods: In this randomized controlled trial, 39 U-17 male trained soccer players were randomly divided into plyometric training with additional load (PT+AL), plyometric training with just bodyweight (PTBW) and control (CON) groups. PT+AL and PTBW were performed for six weeks (2 days/week). Absolute peak torque (APT), relative peak torque (RPT), average peak torque (AvPT), time-to-peak torque (TPT), average rate of force development (AvRFD), vertical jump height (VJH), standing long jump (SLJ) and 15-second repeated jump tests (RJ15s) were assessed before and after the interventions. The findings showed that the performance of knee extensors in TPT-60°/s and AvRFD-60°/s, and knee flexors in APT-60°/s, RPT-60°/s, AvPT-60°/s, AvPT-120°/s, AvRFD-60°/s and AvRFD-120°/s significantly increased after PT+AL, compared to the CON (p < 0.05). Also, a significant improvement in jumping ability was observed in PT+AL compared to CON (p < 0.05). Additionally, PTBW also improved the performance of knee flexors in TPT-120°/s and AvRFD-120°/s, as well as RJ15s performance compared to the CON (p < 0.05). Furthermore, knee flexors AvRFD-60°/s increased significantly after PT+AL, compared to PTBW (p < 0.05). SO, plyometric training, with or without additional load, improved young male soccer players' strength and jumping ability. However, strength parameters - especially the rate of force development - showed a greater increase following PT + AL compared to PTBW.

Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls

(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (<0.6 H/Q ratio) and the BT (leg difference ≥4 s) as binary results according to the literature. We calculated the sensitivity and specificity, which we compared with the Chi-Square test, and the 95% confidence intervals (CI). A p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.

Follow-Up Weekly Training Distribution and Accumulated Internal Load Effects on Young Football Players' Well-Being, Physical Fitness, and Technical Performance

This study aimed to quantify the relationships among internal training load, wellness, physiological, isokinetic profile, and technical performance and assessed changes before and after a six-week pre-season structured combining physical fitness, small-sided-game and skill-based training program in young soccer players. Forty-five national-level young male soccer players (16.8 ± 0.9 years) were evaluated. There were no significant correlations between the wellness index and the physiological, isokinetic, or specific soccer skill parameters. Moderate correlations were observed between fatigue and stress (r = 0.47, moderate, p < 0.01), fatigue and average muscle soreness (r = 0.38, moderate, p = 0.01), and a large correlation between average stress and muscle soreness (r = 0.53, large, p < 0.01) were presented. All physiological, isokinetic, and technical parameters improved after a six-week pre-season training program (0.1 to -61.0%). Significant alterations in the physiological domain were observed after a six-week period, particularly in the fatigue index of the Bangsbo sprint test, YO-YO IR1 performance, and YO-YO peak La- (p < 0.01; -61.0%, 25.3%, and -19.8%, respectively). As such, the implementation of structured training and the monitoring of stress responses can lead to appropriate adaptation and balancing in the psychological and physical well-being of young national-level soccer players, particularly in the pre-season period.