Zijian Liu

Dr. Zijian Liu

Waseda University, Tokyo, Japan
orcid

Research Focus & Metrics

Academic Career Length

5Years (2022-Present)

(Calculated once Scilit publication data is synced: current year − year of first publication + 1)

Representative Publications

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20 October 2024 in The Physician and Sportsmedicine
Verified
Journal Article
Closed access
Zijian LiuZijian Liu
Zijian Liu
RYRyusei Yamaguchi
Ryusei Yamaguchi
SFSiyang Fu
Siyang Fu
HZHanye Zhao
Hanye Zhao
YLYanshu Li
Yanshu Li
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
Dancesport is performed in high-heeled shoes. Dancesport athletes may have a higher prevalence and incidence of ankle sprains, which can affect their performance. However, the occurrence of ankle sprains among dancesport athletes remains unclear. This study aimed to determine the prevalence and incidence of ankle sprains among elite dancesport athletes and to investigate the related information. We conducted a mixed descriptive epidemiological study (cross-sectional and longitudinal) involving 198 elite adolescent dancesport athletes, using past medical records and questionnaires administered to the participants. Data on the occurrence of ankle sprains among all participants were compiled using medical records and information on injury mechanisms, missed days, severity types, and countermeasures for ankle sprains were collected. The prevalence of chronic ankle instability (CAI) among the participants was assessed using a questionnaire. Following the initial survey, we conducted a one-year follow-up study to investigate the incidence of ankle sprains, incidence rate per 1000 exposure hours, and recurrence of ankle sprains. The cross-sectional study and longitudinal study included 198 participants and 92 elite dancesport athletes, respectively. The prevalence of ankle sprains and CAI was 49.5% and 45.1%, respectively. Of all ankle sprains, 88% were medial injuries. The most common injury mechanisms were turning (46.9%) and jumping (46.9%). The average number of missed days due to ankle sprains was 11.2 days. Most injuries were managed with rest, and only one male athlete underwent surgery due to an ankle sprain sustained during dancing. During the one-year follow-up, the incidence of ankle sprains, incidence rate per 1000 exposure hours, and recurrence rate of ankle sprains were 46.6% (male, 41.2%; female, 48.8%), 0.65 ankle sprains/1000 h, and 35.3%, respectively. No sex-related differences were observed. It is crucial to focus on the occurrence of ankle sprains and CAI in dancesport athletes with high heels. Future research should clarify the impact of ankle sprains on dancesport performance and develop preventive measures to reduce the incidence and recurrence of these associated injuries.

30 July 2024 in Journal of Foot and Ankle Research
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Journal Article
Open access
Zijian LiuZijian Liu
Zijian Liu
TOTakumi Okunuki
Takumi Okunuki
HYHiroki Yabiku
Hiroki Yabiku
SCShuo Chen
Shuo Chen
THTakuma Hoshiba
Takuma Hoshiba
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
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.

1 January 2024 in Journal of Sport Rehabilitation
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Journal Article
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Zijian LiuZijian Liu
Zijian Liu
YZYicheng Zhong
Yicheng Zhong
TMToshihiro Maemichi
Toshihiro Maemichi
QZQianhui Zhou
Qianhui Zhou
TOTakumi Okunuki
Takumi Okunuki
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
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.

29 January 2024 in Journal of Dance Medicine & Science
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Journal Article
Closed access
Zijian LiuZijian Liu
Zijian Liu
YGYining Gong
Yining Gong
HNHideaki Nagamoto
Hideaki Nagamoto
TOTakumi Okunuki
Takumi Okunuki
RYRyusei Yamaguchi
Ryusei Yamaguchi
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
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.

15 October 2024 in BMC Sports Science, Medicine and Rehabilitation
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Journal Article
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Zijian LiuZijian Liu
Zijian Liu
YZYicheng Zhong
Yicheng Zhong
SCShuo Chen
Shuo Chen
HTHirofumi Tanaka
Hirofumi Tanaka
YLYanshu Li
Yanshu Li
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
Dancers have a higher prevalence of hallux valgus (HV) than the general population. However, no reports specifically addressing treatment strategies for HV in dancers, or their effectiveness have been published. This study aimed to determine the effects of 4 weeks of foot exercises on subjective clinical outcomes, the HV angle, and change of foot plantar pressure during specific dance techniques. Thirteen female elite adolescent dancesport athletes (age: 16.4 ± 3.3 years) completed the program. The HV angle was measured based on foot photographs. Clinical assessments were performed using the visual analog scale for first metatarsophalangeal (1st MTP) joint pain, and the Foot and Ankle Outcome Score. The changes in plantar pressure during two dance techniques (demi-pointe and plié) were measured. The plantar pressure was measured in six areas of the foot. All of these parameters were compared before and after the intervention by using chi-square tests and Student’s paired t-test (statistical significance: p < 0.05). The HV angle was significantly reduced from 20.1° to 15.4° after the intervention. Participants reported an average subjective completion rate of 70.3% ± 14.6% over 3 weeks, exhibiting no significant differences despite an apparent trend toward improvement. Significant changes were noted in 1st MTP joint pain and subjective outcomes, and toe function significantly improved in the “paper” movement. The foot-exercise program changed plantar pressure distribution during the demi-pointe and plié techniques, with increased hallux pressure and decreased 2nd-5th MTP joint pressure. In elite adolescent dancesport athletes, 4 weeks of foot-exercise rehabilitation reduced the HV angle and improved in subjective outcome and function during the two dance techniques. Coaches should consider utilizing foot-exercise training programs in a dancer training program for HV.

Verified
Journal Article
Open access
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SIShota Ichikawa
Shota Ichikawa
Tsukasa KumaiTsukasa Kumai
Tsukasa Kumai
YAYui Akiyama
Yui Akiyama
TOTakumi Okunuki
Takumi Okunuki
TMToshihiro Maemichi
Toshihiro Maemichi
HNHisateru Niki
Hisateru Niki
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.