Activities of ankle muscles during gait analyzed by simulation using the human musculoskeletal model

Comparison between the effects of tibialis posterior versus fibularis longus Kinesio taping on foot posture, physical performance, and dynamic balance in young women with flexible flatfoot

Purpose

The purpose of the study is to compare the effectiveness of the tibialis posterior Kinesio taping and fibularis longus Kinesio taping on the foot posture, physical performance, and dynamic balance in young women with flexible flatfoot.

Methods

Twenty-four subjects were recruited for the study. They were randomly divided into groups (A = 12, B = 12). In group A, Kinesio taping was applied on the tibialis posterior, and in group B, Kinesio taping was applied on the fibularis longus and remained for 30 min. Outcome measures were the navicular drop test (NDT), foot posture index (FPI), timed up and go (TUG) test, and Y-balance test. The pre- and post-treatment results were compared for each group; between-group differences were determined as well.

Results

For group A, NDT, FPI, and TUG test changed significantly (P = 0.01, P = 0.001, P = 0.006, respectively). For group B, the FPI score decreased (P = 0.03), and the Y-balance test in the anterior direction improved significantly (P = 0.01). Any variables have not shown a significant difference between groups (P > 0.05).

Conclusion

Kinesio taping of the tibialis posterior and fibularis longus can improve foot posture in young women with flexible flatfoot. Also, physical performance and dynamic balance improved by Kinesio taping of the tibialis posterior and the fibularis longus, respectively. In addition to the tibialis posterior, we found that the fibularis longus muscle can be considered a therapeutic target for managing flexible flatfoot in healthy young women.

Iron Supplementation Improves Skeletal Muscle Contractile Properties in Mice with CKD

Background

Patients with chronic kidney disease (CKD) frequently have compromised physical performance, which increases their mortality; however, their skeletal muscle dysfunction has not been characterized at the single-fiber and molecular levels. Notably, interventions to mitigate CKD myopathy are scarce.

Methods

The effect of CKD in the absence and presence of iron supplementation on the contractile function of individual skeletal muscle fibers from the soleus and extensor digitorum longus muscles was evaluated in 16-week-old mice. CKD was induced by the adenine diet, and iron supplementation was by weekly iron dextran injections.

Results

Maximally activated and fatigued fiber force production was decreased 24%-52% in untreated CKD, independent of size, by reducing strongly bound myosin/actin cross-bridges and/or decreasing myofilament stiffness in myosin heavy chain (MHC) I, IIA, and IIB fibers. Additionally, myosin/actin interactions in untreated CKD were slower for MHC I and IIA fibers and unchanged or faster in MHC IIB fibers. Iron supplementation improved anemia and did not change overall muscle mass in CKD mice. Iron supplementation ameliorated CKD-induced myopathy by increasing strongly bound cross-bridges, leading to improved specific tension, and/or returning the rate of myosin/actin interactions toward or equivalent to control values in MHC IIA and IIB fibers.

Conclusions

Skeletal muscle force production was significantly reduced in untreated CKD, independent of fiber size, indicating that compromised physical function in patients is not solely due to muscle mass loss. Iron supplementation improved multiple aspects of CKD-induced myopathy, suggesting that timely correction of iron imbalance may aid in ameliorating contractile deficits in CKD patients.

Risk factors for throwing elbow injuries during pitching analyzed by simulation using human musculoskeletal model in youth baseball pitchers

BACKGROUND

Pitching mechanics are believed to be risk factors for throwing elbow injury. Thus, a prospective study of abnormal mechanics in youth baseball players is needed. This study aimed to analyze the ulnar collateral ligament during normal pitching using SIMM (Software for Interactive Musculoskeletal Modeling) for analysis and investigate the risk parameters of throwing elbow injuries in youth baseball players. We hypothesized that excessive ulnar collateral ligament force during pitching would be a risk factor for throwing elbow injuries in this population.

METHODS

In this cohort study, youth baseball pitchers (aged 9-11 years) were instructed to throw a ball into a netted target. Using a SIMM musculoskeletal model, we analyzed the force of the anterior band of the anterior oblique ligament, posterior band of the anterior oblique ligament (AOL_PB), and elbow varus moment during pitching (foot contact to ball release). We calculated the integral of each force of the anterior band of the anterior oblique ligament and AOL_PB during pitching and summarized these data to establish an impulse at the medial epicondyle. Each participant was followed up for 12 months to assess the occurrence of throwing elbow injury.

RESULTS

During the 12-month follow-up period, 18 pitchers (28.1%) reported throwing elbow injuries in the throwing arm. The results of this study showed that the maximum AOL_PB force and the impulse at the medial epicondyle were risk factors for throwing elbow injuries. The maximum AOL_PB force was significantly higher in the throwing elbow injury group than in the uninjured group (59.4 ± 17.8 N vs. 47.1 ± 17.5 N, P = .014). The impulse at the medial epicondyle was also significantly different (11.1 ± 4.0 N ･ s in the throwing elbow injury group vs. 8.3 ± 4.4 N ･ s in the uninjured group, P = .025).

CONCLUSIONS

Increasing the AOL_PB force or the impulse at the medial epicondyle may increase the risk of throwing elbow injuries in youth baseball pitchers. It may be possible to reduce injury risk by focusing on ways to decrease AOL_PB load and cumulative stress on the medial epicondyle throughout the throwing motion while still maintaining high levels of ball velocity.