Vitamin D levels and bone mineral density of middle-aged premenopausal female football and volleyball players in Japan: a cross-sectional study.

BACKGROUND: The number of football teams in senior categories has increased. As outdoor sports entail players being exposed to sunlight, playing football may contribute to maintaining vitamin D stores and body mineral density while preventing osteoporosis. This study aimed to determine the bone mineral density and vitamin D levels in middle-aged premenopausal female football players. METHODS: Participants were premenopausal females in their 40s. We evaluated bone mineral density of the second to the fourth lumbar vertebrae and femoral neck, serum 25-hydroxy vitamin D (25-OHD) levels, which is an indicator of vitamin D stores, and body composition. In addition, we administered a questionnaire survey on exercise habits and lifestyle. Ninety-two participants were categorised into three groups: the football group (n = 27), volleyball group (n = 40), and non-exercise group (n = 25). RESULTS: Bone mineral density was higher in the football and volleyball groups than in the non-exercise group (P < 0.01). The volleyball group had a significantly higher bone mineral density of the lumbar spine and femoral neck than the non-exercise group (P < 0.01). The football group had a significantly higher bone mineral density of the femoral neck than the non-exercise group (P < 0.01). Although the football group had played fewer years than the volleyball group (P < 0.01), serum 25-OHD levels were the highest in the football group and were significantly higher than those in the volleyball and non-exercise groups (P < 0.01). CONCLUSIONS: Middle-aged premenopausal football players had higher body vitamin D levels and bone mineral densities than non-active females. These results suggest that playing football may contribute to the prevention of osteoporosis. TRIAL REGISTRATION: UMIN Clinical Trials Registry UMIN000054235. 2024/04/23. Retrospectively registered.

Awareness of fifth metatarsal stress fractures among soccer coaches in Japan: A cross-sectional study.

Although a fifth metatarsal stress fracture is the most frequent stress fracture in soccer players, awareness of fifth metatarsal stress fractures among soccer coaches is unclear. Therefore, we performed an online survey of soccer coaches affiliated with the Japan Football Association to assess their awareness of fifth metatarsal stress fractures. A total of 150 soccer coaches were invited for an original online survey. Data on participants' age, sex, types of coaching licence, coaching category, types of training surface, awareness of fifth metatarsal stress fractures, and measures employed to prevent fifth metatarsal stress fractures were collected using the survey. Data from 117 coaches were analysed. Eighty-seven of the 117 coaches were aware of fifth metatarsal stress fractures; however, only 30% reported awareness of preventive and treatment measures for fifth metatarsal stress fractures. Licensed coaches (i.e., licensed higher than level C) were also more likely to be aware of fifth metatarsal stress fractures than unlicensed coaches were. Furthermore, although playing on artificial turf is an established risk factor for numerous sports injuries, soccer coaches who usually trained on artificial turf were more likely to be unaware of the risks associated with fifth metatarsal stress fractures than coaches who trained on other surfaces were (e.g., clay fields). Soccer coaches in the study population were generally aware of fifth metatarsal stress fractures; however, most were unaware of specific treatment or preventive training strategies for fifth metatarsal stress fractures. Additionally, coaches who practised on artificial turf were not well educated on fifth metatarsal stress fractures. Our findings suggest the need for increased awareness of fifth metatarsal stress fractures and improved education of soccer coaches regarding injury prevention strategies.　.

Effects of high-frequency hyperthermia on the elastic modulus of the lumbar muscle in female athletes with low back pain: A randomized crossover trial.

OBJECTIVE: To investigate the effects of capacitive and resistive monopolar radiofrequency (CRMF) on the shear elastic modulus of the multifidus and erector spinae muscles in female athletes with low back pain (LBP) and a history of LBP. DESIGN: Randomized crossover trial. SETTING: Academic institution. PARTICIPANTS: Twenty female university athletes with LBP or a history of LBP were included. INTERVENTIONS: All participants received CRMF, hotpack, and sham (CRMF without power) in a random order on the right side of the lumbar region. More than 2 days were allocated between the experiments to eliminate any residual effects. MAIN OUTCOME MEASURES: The shear elastic moduli of the right multifidus and erector spinae were evaluated in the prone (rest) position while sitting with 35° trunk flexion (stretched) using shear wave ultrasound imaging equipment. The moduli were measured before, immediately after, and 30 minutes after the intervention. RESULTS: Repeated-measures 2-way analysis of variance and post hoc analysis showed that the moduli of the CRMF group were significantly lower than those of the sham group in the stretched position immediately after intervention (P = .045). This difference diminished 30 minutes after the intervention (P = .920). CONCLUSIONS: CRMF can be used to reduce the shear elastic modulus of the multifidus muscle in the short term. Further studies are warranted to determine how to provide longer effects. TRIAL REGISTRATION: None.

Differences in the elastic modulus of the lumbar muscles between female athletes with and without low back pain.

BACKGROUND: Low back pain is the most prevalent musculoskeletal disorder affecting performance and sports participation among athletes and is more prevalent among female athletes. Evaluating the stiffness of the lumbar muscles is important for understanding the pathophysiology of low back pain. Therefore, this study examined the differences in stiffness of the lumbar multifidus and erector spinae muscles between female university athletes with and without low back pain. METHODS: This was a cross-sectional study. The study was conducted at a single centre, the university research laboratory. Twenty female university athletes with low back pain or a history of low back pain and 20 without low back pain participated in this study. The shear elastic moduli of the multifidus and erector spinae muscles were evaluated in the prone (to relax the muscles) and sitting with 35° of trunk flexion (to stretch the muscles) positions using shear wave ultrasound imaging equipment. FINDINGS: The low back pain group showed significantly greater shear elastic modulus in the multifidus in both prone and sitting positions than the non-low back pain group. There were no differences in the erector spinae muscle between the two groups at either position. INTERPRETATION: These results provide new insights into the microscopic characteristics of low back pain pathophysiology in young female athletes. Stiffness assessment using shear wave elastography will help provide a specific treatment strategy for female athletes with low back pain or a history of low back pain.

Effects of a wearable device and functional wear on spinal alignment and jump performance.

BACKGROUND/OBJECTIVE: To elucidate the effects of walking exercise using a wearable device and functional wear on spinal alignment and jump performance. METHODS: In total, 27 female college soccer players were randomly divided into two groups: trunk solution (TS) and compression garments (CGs). Spinal alignment, jump performance, and electromyography activity during the jump performance of the two groups were measured after a 20-min walking exercise. The values for each group were compared t pre- and post-intervention. RESULTS: The flexibility of the lower thoracic vertebrae in spinal alignment was increased during extension in the TS group. However, the post-value of the abdominal external oblique muscle during a countermovement jump (CMJ) was significantly lower than its pre-value (p < 0.05). In addition, even though spinal alignment was not affected in the CG group, post-values of the jump height during squat jump and CMJ were significantly higher than their pre-values (p < 0.05). Furthermore, the post-value of the biceps femoris during the countermovement jump with arm was significantly lower than its pre-value (p < 0.05). CONCLUSION: Our study suggested that walking exercise using TS may increase the range of motion of the lower thoracic vertebrae in athletes and reduce the muscular activity of the vastus lateralis during CMJ. Additionally, although spinal aliment is not affected, the jump height may increase using CGs.

Reliability assessment of the functional movement screen for predicting injury risk in Japanese college soccer players.

[Purpose] This study aimed to assess the reliability of the Functional Movement Screen and explore whether this evaluation tool can predict the risks of personal injuries in Japanese soccer players. [Participants and Methods] Seventy-five Japanese college soccer players who participated in our 1 year prospective cohort study underwent a Functional Movement Screen assessment. Demographic data, athletic characteristics, and types and frequency of injuries sustained, were analyzed with the assessment results. [Results] There was no significant difference in the mean Functional Movement Screen composite scores between genders. Although the Functional Movement Screen showed excellent inter-rater reliability (0.92), low overall internal consistency (0.35) was observed. A maximum score of 3 in straight leg raise occurred in 94% of the females and was considered a ceiling effect. None of the cut-off point scores of the Functional Movement Screen were associated with the number of overall injuries, lower limb injuries, and traumatic injuries, or time to return to play. The Functional Movement Screen composite score of ≤15 represented the maximum sensitivity of 76.92% and specificity of 34.78% with 0.56 in the area under the curve. [Conclusion] Functional Movement Screen composite scores do not have sufficient sensitivity and specificity for predicting injuries in Japanese college soccer players.

Association between the ACE I/D polymorphism and muscle injuries in Italian and Japanese elite football players.

ACE I/D polymorphism has been recently associated with the susceptibility to inflammation and muscle damage after exercise. The aim of this study was to understand the association between the ACE I/D polymorphism and muscle injuries in a large cohort of elite football players from two different countries. Seven hundred and ten male elite football players from Italy (n = 341) and Japan (n = 369) were recruited for the study. Genomic DNA was extracted from either the buccal epithelium or saliva using a standard protocol. Structural-mechanical injuries and functional muscle disorders were recorded from 2009 to 2018. A meta-analysis was performed using Review Manager 5.3.5. In the Japanese cohort, the ACE I/D polymorphism was significantly associated with muscle injury using the D-dominant model (OR: 0.48, 95% CI: 0.24-0.97, P = 0.040). The meta-analysis showed that in the pooled model (Italian and Japanese populations), the frequencies of the DD+ID genotypes were significantly lower in the injured groups than in non-injured groups (OR: 0.61, 95% CI: 0.38-0.98, P = 0.04) with a low degree of heterogeneity (I2  = 0%). Our findings suggest that the ACE I/D polymorphism could influence the susceptibility to developing muscle injuries among football players.

Evaluating the Risk of a Fifth Metatarsal Stress Fracture by Measuring the Serum 25-Hydroxyvitamin D Levels.

BACKGROUND: The fifth metatarsal bone is a common site of stress fractures in soccer athletes. Although several endocrine risk factors for stress fractures have been proposed, the endocrine risks for fifth metatarsal (5-MT) stress fractures have not been evaluated. METHODS: To evaluate the endocrine risks of fifth metatarsal stress fractures, we conducted a cumulative case-control study. The present study included 37 athletes, of which 18 had a history of a zone 2 or zone 3 fifth metatarsal stress fracture and 19 controls. We analyzed serum 25-hydroxyvitamin D (25-OHD), serum parathyroid hormone (PTH), as well as biochemical markers of bone turnover by univariate or multivariate analyses. RESULTS: Logistic regression analyses adjusted for multiple confounders revealed that insufficient serum 25-OHD levels less than 30 ng/mL (odds ratio [OR], 23.3), higher serum PTH levels (OR, 1.01), or higher serum bone-specific isoform of alkaline phosphatase levels (OR, 1.10) rather than serum tartrate-resistant acid phosphatase 5b were associated with statistically significantly increased odds of 5-MT stress fractures. A postestimation calculation demonstrated that 25-OHD levels of 10 and 20 ng/mL were associated with 5.1 and 2.9 times greater odds for 5-MT stress fractures, respectively. CONCLUSION: 25-OHD insufficiency was associated with an increased incidence of 5-MT stress fractures. This insight may be useful for intervening to prevent 5-MT stress fractures. LEVEL OF EVIDENCE: Level III, case-control study.