Translational Sports Medicine

Background. Anterior cruciate ligament (ACL) injuries are commonly assessed using clinical examination and magnetic resonance imaging, but these methods have limitations in reproducibility and quantification. Instrumented laxity measurements using devices, like the DYNEELAX®, offer an alternative approach. However, to date, there is no human data on the DYNEELAX® and the reliability of these devices remains a subject of debate, and there is no consensus on appropriate knee tightening levels for testing. We hypothesized that the DYNEELAX®, with standardized knee tightening, would provide reliable measurements of knee laxity in adult volunteers. Methods. This prospective cohort study involved 48 pain-free adult volunteers. Laxity measurements were taken using a robotic-type motorized instrument (DYNEELAX®) on two separate occasions, at least 1 h and no more than 8 h apart, with knee tightening forces of 90 N ± 5 N. Metrics of anterior tibial translation and internal/external tibial axial rotations were recorded. Results. The device displayed excellent intrarater reliability for all the metrics, with intraclass correlation coefficients ranging from 0.91 to 0.96. Anterior translation exhibited the highest reliability (intraclass correlation coefficient = 0.96), with a minimum detectable change of 0.83 mm. Conclusions. DYNEELAX® is reliable in measuring knee laxity in adult volunteers when using standardized stabilizing knee tightening forces of 90 ± 5 N. The most sensitive measurement parameters (in terms of minimum detectable change as a proportion of the observed range) were anterior translation (in mm) at 150 N and secondary compliance.

The purpose of this study is to compare the effects of 2- and 5 min of static stretching protocols on the changes in blood circulation of tendon (as well as muscle) and heart rate. Twelve healthy males (age: 26.2 ± 9.1 yrs) volunteered for this study. Before, during stretching, during the recovery period (30 min), blood circulation (oxyhemoglobin; oxy, deoxyhemoglobin; deoxy, blood volume; THb, oxygen saturation; StO₂) of the Achilles tendon and medial gastrocnemius muscle were measured using red laser lights and near-infrared spectroscopy. In addition, heart rate was measured during the experimental period. For 2- and 5 min of static stretching, oxy, deoxy, THb, and StO₂ of the tendon did not change during or after stretching. Regarding muscle blood circulation, oxy and StO₂ decreased, and deoxy and THb increased during 2- and 5 min of static stretching but returned immediately upon completion. In addition, heart rate significantly reduced during and after stretching, whereas the changes in blood volume of tendon and muscle during stretching were not associated with those in heart rate (except for the relationship between tendon THb and heart rate in 2 min of static stretching). These results suggest that static stretching showed no change in tendon blood circulation, although muscle blood circulation during stretching was altered. In addition, significant heart rate reduction with static stretching was not associated with changes in tendon and muscle blood circulation.

Background. B-mode ultrasonography is an accessible and cost-effective method to assess muscle size and quality through muscle thickness (MT) and echo intensity (EI), respectively. Muscle thickness and EI have demonstrated relationships with maximal strength and local muscle endurance, providing a noninvasive and efficient modality to examine muscle fitness. However, these relationships have not been quantified in the individual quadriceps muscles of habitually endurance-trained populations, which may provide information to practitioners regarding rehabilitation and performance. Methods. Twenty-three participants (males: N = 10; females: N = 13) underwent B-mode ultrasonography to assess MT, EI, and adipose tissue thickness-corrected echo intensity (cEI) in the vastus intermedius (VI), vastus lateralis (VL), and rectus femoris (RF). Muscle fitness was evaluated through maximal strength (1RM) and local muscle endurance (4 sets to failure at 50% 1RM) during dynamic knee extension. Relationships between ultrasonography outcomes and muscle fitness were examined through stepwise multiple linear regression. Results. The results indicate that VI cEI is the strongest predictor of 1RM strength (r = −0.643), while no ultrasonography-derived measures significantly predicted local muscle endurance. Conclusion. The study demonstrates that ultrasonography, specifically measures of cEI in the VI, has the greatest association with maximal strength in endurance-trained individuals. These findings suggest monitoring VI muscle size and quality may benefit practitioners who aim to improve knee extension strength for performance or following injury. In addition, the findings support the use of EI examinations in trained populations.

Background. The growth in participation in collegiate athletics has been accompanied by increased sport-related injuries. The complex and multifactorial nature of sports injuries highlights the importance of monitoring athletes prospectively using a novel and integrated biopsychosocial approach, as opposed to contemporary practices that silo these facets of health. Methods. Data collected over two competitive basketball seasons were used in a principal component analysis (PCA) model with the following objectives: (i) investigate whether biomechanical PCs (i.e., on-court and countermovement jump (CMJ) metrics) were correlated with psychological state across a season and (ii) explore whether subject-specific significant fluctuations could be detected using minimum detectable change statistics. Weekly CMJ (force plates) and on-court data (inertial measurement units), as well as psychological state (questionnaire) data, were collected on the female collegiate basketball team for two seasons. Results. While some relationships (n = 2) were identified between biomechanical PCs and psychological state metrics, the magnitude of these associations was weak (r = |0.18-0.19|, ), and no other overarching associations were identified at the group level. However, post-hoc case study analysis showed subject-specific relationships that highlight the potential utility of red-flagging meaningful fluctuations from normative biomechanical and psychological patterns. Conclusion. Overall, this work demonstrates the potential of advanced analytical modeling to characterize components of and detect statistically and clinically relevant fluctuations in student-athlete performance, health, and well-being and the need for more tailored and athlete-centered monitoring practices.

Background. For professional road cyclists, most overload injuries affect the lower limbs. They are mostly represented by contractures or muscle shortening, characterised by a variation of muscular tone, stiffness, and elasticity. This real-life study aimed to assess specific mechanical parameters in top-class female cyclists who participated in 3 races a week. Hypothesis. Muscle tone, stiffness, and elasticity will be affected immediately after competition and at the end of the week due to accumulated fatigue. Methods. Six professional cyclists were evaluated. This pilot study consisted of a controlled trial and three days of competition, with rest days between them. MyotonPRO was used to measure tone, stiffness, and elasticity in six leg muscles: vastus lateralis (VL), vastus medialis (VM), rectus femoris (RF), biceps femoris (BF), lateral gastrocnemius (LG), and medial gastrocnemius (MG). Daily basal and pre- and postrace measures were carried through to the 3 races in a week. Results. The muscular tone of VL, VM, LG, and MG and the stiffness of VL, VM, RF, BF, LG, and MG decreased after races. VL and RF were mostly affected by () and (), respectively. Basal elasticity improved over time until the last day. Conclusions. Muscle tone and stiffness decreased after a very intense and exhausting cycling endurance competition. Basal elasticity improved immediately after the race and continued this trend until the end of the week. More research is needed on changes in mechanical properties in competition and risk prevention of injuries.

This study aimed to investigate how overall competitive winningness in combat sports depended on patterns of victory and loss, as well as training habits. Competitors (N = 280) from several combat sports participated in the study. The online survey included questions on self-reported patterns of victory (and loss), training habits, general demographics (e.g., age), and sport-specific information (e.g., stage of career and competitive style). Overall, it was found across four models that reflected diversity of winningness in combat sports that the most important predictors of competitive winningness were loss by points (negative), loss by submission (negative), loss (negative) or victory (positive) by throw or technical fall, and loss (negative) or victory (positive) by knockout. The findings applied to amateur and regional/state athletes, and rarely to karate or tae kwon do. Findings around demographics or training habits were largely unremarkable, outside of a relationship between higher training loads and less career winning in wrestlers. Results show that while winning via a finishing sequence (e.g., knockout or submission) is preferable to the judge’s decision or points, the matter of victory is less important than the methods by which an athlete loses. In grappling-only sports, we observed a trend that more losses via finishing sequence were worse for careers than losing by points. In fact, having most of one’s losses coming via judge’s decision or points was beneficial in wrestling and judo, perhaps due to athletes taking less risks and having better defence. These findings may aid practitioners developing effective tactics and training programs.