Background: This study aimed to determine the risk factors of hallux valgus angle among preprofessional adolescent dancesport athletes.Methods: A total of 275 athletes, (73 males and 202 females) aged between the ages of 11 and 18 years, participated in this study. A cross‐sectional questionnaire was used to survey their demographic characteristics (sex and age), training information (starting age, weekly training time, and athletic career [number of years of training at this specific dancesport school]), and measured their height and weight. The hallux valgus angle was measured based on foot photographs. The chi‐square test was used to compare the difference with prevalence of hallux valgus between male and female athletes. A normal distribution test was performed, and based on the test results, unpaired t‐test and multiple logistic regression were conducted to identify training factors for the hallux valgus in this cohort.Results: Chi‐square test showed higher prevalence of hallux valgus in female elite adolescent dancesport athletes than males. The t‐test results did not show any significant differences between the hallux valgus group and non‐hallux valgus groups with start age, athletic career, and weekly training time. Multiple logistic regression analysis with hallux valgus as the dependent variable revealed that the female sex was a strong predictor of a higher prevalence of hallux valgus (odds ratio [OR]: 3.954, 95% confidence interval 95% CI: 2.193–7.131, and p < 0.001). Weekly training time was also entered into the multiple logistic regression model (OR: 1.033, 95% CI: 1.001–1.067, and p = 0.041).Conclusions: Our findings revealed that the prevalence of hallux valgus in adolescent dancesport athletes was higher in females than in males. Longer weekly training time was also a risk factor for hallux valgus. Training factors should be considered in preventive programs for elite adolescent dancesport athletes, and special attention should be paid to female athletes.

We aimed to investigate the changes caused by focused extracorporeal shock wave pain therapy (f-ESWT) in patients with patellar tendinopathy by means of ultrasound imaging. We included 18 knees from 11 college athletes with patellar tendinopathy. We assessed the tendon thickness and blood flow of the patellar tendon using ultrasound imaging, rest pain using NRS and tenderness using a pressure pain gauge. We recorded four measurements: immediately before f-ESWT (PRE①) and after f-ESWT (POST①) and two weeks after the first irradiation before f-ESWT (PRE②) and after f-ESWT (POST②). Only the resting pain in both the first and second irradiations showed a significant difference immediately before and after the treatment. In terms of pain changes after two weeks later, we observed significant differences in the resting pain between PRE① and PRE② and also in the resting pain, tenderness and blood flow area between PRE① and POST②. No significant difference was seen in the tendon thickness. We concluded that pain in the patellar tendon at rest decreased before and after irradiation, suggesting that f-ESWT may have influenced the nociceptive structures and had an analgesic effect.

Introduction: The menstrual cycle is an important indicator of health in female athletes. Female elite adolescent dancers are expected to control their weight while also training intensely, which can lead to menstrual disorders. This study aimed to investigate the relationship between body composition and menstrual status in female elite adolescent dancers. Methods: In total, 131 female elite adolescent dancers (age: 15.9 ± 1.5 years) were enrolled in this study. We measured the height, weight, and body fat percentage (BFP) for each participant and calculated their body mass index (BMI). We gathered information on individual menstruation patterns and the participants’ menstrual cycles over the previous year using recall methods. We then compared the differences between dancers with menstrual cycle disorders and those without. Primary amenorrhea was defined as menarche occurring after the age of 15, while secondary amenorrhe was defined as experiencing fewer than 5 or no menstrual periods for at least 3 of the previous 12 months. We conducted a reliability test using the same questionnaire 2 weeks later. Statistical significance was defined as P < .05, and we calculated the effect sizes (d) and 95% confidence intervals (95% CI). Results: The average BMI and BFP were 22.6 ± 3.0% and 19.4 ± 2.2 kg/m², respectively. Low BFP and low BMI were observed in 51 (38.6%) and 47 (35.6%) participants, respectively. Primary amenorrhea in 3 participants (2.3%) and 29 (22.1%) reported experiencing secondary amenorrhea; they had lower BFP than the dancers who did not experience amenorrhea ( P = .041, 95% CI, −2.51 to −0.05). Conclusion: Female elite adolescent dancers in China may have lower BFP and menstrual problems. Given that lower BFP may contribute to the occurrence of menstruation disorders, it is essential to pay an attention to both BFP and the menstruation status in female elite adolescent dancers.

Background: Local high-frequency percussive (HFP) massage has recently found widespread application in physical therapy. Although HFP massage reportedly improves range of motion (ROM), the mechanism underlying its action has not yet been proven. This study aimed to clarify whether a 5-minute percussive massage regimen affects muscular or connective tissues, such as the deep fascia and deep intermuscular fascia and the change in joint ROM. Method: The study sample was calculated using G*Power analysis program, and this study enrolled 15 healthy men who underwent 5-minute HFP massage to the medial gastrocnemius muscle. Shear-wave elastography was used to measure tissue stiffness in the deep fascia, muscle, and deep intermuscular fascia through shear-wave velocity as well as the ROM of the volunteers’ ankle joint dorsiflexion before and after the HFP massage. A value of P < .05 was used to declare statistical significance, and post hoc was used to calculate the effect size using G*Power. Results: Shear-wave velocity revealed a significant change in the deep fascia (P = .003; shear-wave velocity: −0.7 m/s) and significant increase in ROM of ankle dorsiflexion (P = .002; increase in ROM: 3.0°) after 5 minutes of HFP massage. However, the muscle and deep intermuscular fascia did not exhibit any significant changes. Conclusions: HFP massage for 5 minutes modified the stiffness of the deep fascia and concurrently improved the ankle joint-dorsiflexion ROM. This method can be used as an intervention to decrease stiffness of the deep fascia and increase the ROM efficiently.

Balance is important in lifesaving competitions. We aimed to investigate the relationship between dynamic balance and physical characteristics and functions in elite lifesavers by measuring the foot muscle cross-sectional area, ankle joint muscle strength, toe grasp strength, plantar superficial sensation, and dynamic balance (Y-balance test). In this observational study, we measured the foot muscle cross-sectional area, ankle dorsiflexion, plantar flexion, external flexion, isometric muscle strength, toe grasp strength, and superficial foot sensation of 15 adult lifesavers (12 males). The results show that toe grasp strength and ankle plantar flexion isometric muscle strength are particularly important for the dynamic balance of elite lifesavers working on sandy surfaces. Sand training improves intrinsic muscle strength and dynamic balance function. However, high training intensity may reduce plantar surface sensation; this needs to be verified through sand training interventions in the future.

Objective: With the remarkable advances in diagnostic ultrasound equipment, there is a growing need for ultrasound diagnosis of muscle and soft tissue injuries in sports injuries. Among these, hamstring strains are often difficult to treat and require early and accurate diagnosis. Injuries to the proximal part of the hamstring often take a long time to heal. For this reason, the diagnosis of proximal hamstring injuries is extremely important. The structure of the origin tendon is characteristic, and it is a complex in which the semitendinosus muscle (ST) of the medial hamstring and the long head of the biceps femoris muscle (BFLH) of the lateral hamstring share a conjoint tendon (CT). On the other hand, the semimembranosus muscle (SM) attaches to the ischial tuberosity independently. In this study, we created a classification of injury sites focusing on the origin tendon, and investigated the distribution of injury location, relationship to the player’s position, and the detection rate of ultrasound diagnosis. Material and Methods: We used ultrasound and MRI to diagnose 52 university men’s rugby players who had suffered a hamstring strain for the first time and investigated the distribution of the injured areas. We performed an ultrasound scan as the initial diagnosis and used MRI as a final diagnostic tool. A classification focusing on the origin of the muscle was created. First of all, it was divided into two types: the BFLH-ST complex type, which originates in the CT, and the SM type, which originates in the SM tendon. We also classified BFLH-ST complex damage, including CT damage, as Type I, a BFLH injury without CT injury as Type II, and a ST injury without CT injury as Type III. We then investigated the distribution of the injury location. The degree of ultrasound detection in each injury type was evaluated in three grades. The frequency of BFLH complex and SM injuries was investigated in players who played the forward (FW) and back (BK) positions. Results: The distribution was 40 limbs (77%) for BFLH-ST complex injury type and 12 limbs (23%) for SM injury type. In the BFLH complex type,19 limbs which met the Type I classification criteria for CT tear, 19 limbs met the Type II, and 2 limbs met the Type III. FWs had a higher incidence of SM injuries and BKs had a higher incidence of BFLH-ST complex injuries. With regard to the detection of muscle injuries via ultrasound, a high rate of detection was possible, except for a slight injury to the myofascial junction of the BFLH. Discussion: In terms of the distribution, the BFLH-ST complex, which shares the same origin tendon (i.e. CT), had a higher frequency of muscle tears than the SM. In addition, CT junction injuries occurred frequently in Type II as well as Type I (=CT injury). One possible cause is that the CT is subject to concentrated traction stress from both the medial and lateral hamstrings. With ultrasound, the detection rate of muscle damage around the BFLH-ST complex and SM originating tendon was high, suggesting that it is useful as an initial diagnosis. From this, it can be said that ultrasound is also useful for primary evaluation of “proximal hamstring injury”, which is prone to severe and should be given a final diagnosis using MRI. Conclusions: We created a classification system focusing on the originating tendons and clarified their incidence rates. In this study, ultrasound was found to be useful in the detection of originating tendon injuries. We also identified the characteristic sonographic findings of each type.