Sports Medicine and Injury Prevention

Time-motion analysis has been used to quantify the external load of competition and as a strategy to prevent injuries. The objectives of this study were to determine the external load of competition in breaking, using time-motion analysis, and to establish a battle model to help determine training load and prevent injuries. Using observational methodology, we analysed all the battles of 56 b-boys and 56 b-girls who participated in the Red Bull BC One from 2018 to 2021 (n = 112). To obtain the results we used different analysis techniques. The significance level established was ρ ≤ 0.05. The results show that the time and sequence values have increased in recent years. The total battle time reaches 195 s for bboys and 170 s for bgirls. Men show greater strength and explosiveness, with higher values in total time and sequentiality, using more powermove. Women have higher split time values, showing greater endurance in the movements and using more footwork. The first two rounds have the longest duration for both sexes and the most used categories are also the most injurious in this discipline. Women use less powermove than men and have a lower injury rate. With these results, breaking professionals will be able to elaborate adequate training for their athletes. We conclude that there are significant differences between sexes when it comes to dancing, diminishing as the tournament progresses. We propose a model of temporal and sequential structure individualised by sex. The most damaging elements of breaking (powermove and footwork) should be taken into account when analysing the results and preparing the athletes. Full article

Maintaining the health of the musculoskeletal system in movement-associated professions, such as dance teachers, is of great importance for a long-lasting professional practice. The aim of this study was to record work-related musculoskeletal disorders and the causes of these disorders for dance teachers in Germany. Using a retrospective cross-sectional survey, data on the occurrence of work-related musculoskeletal disorders were collected from n = 229 dance teachers (n = 181 women) aged 22 to 77 years using an online questionnaire. In addition, differences between sexes and among dance styles were also analysed. The 12-month prevalence was 60.7% (95% CI: 54.0–67.1%), and on average, there were 2.58 disorders per dance teacher per year (95% CI: 2.17–2.99). Work-related musculoskeletal disorders affected male and female dance teachers equally (φ = 0.11, p = 0.088 resp. r = 0.080, p = 0.228). Disorders were mainly registered in the lumbar spine (14.9%) and ankle (12.5%). The joint structures (29.9%) and the musculature (20.9%) were most frequently affected. Specific movements (18.7%) as well as fatigue and overload (15.2%) were mentioned as the most frequent causes irrespective of dance style. Dance teachers were not significantly differently affected for musculoskeletal disorders than the general working German population. Future studies should consider a prospective evaluation of such disorders and develop prevention strategies with consideration of sex- and dance style-specific circumstances. Full article

Introduction: The aim of the present study was to analyze the influence of different music genres, three modulated noises and a pink noise on the heart rate (HR) and to compare between young healthy adults (YA), elderly healthy adults was (EA) and patients with Parkinson’s disease (PD). Furthermore, a sound condition comparison for each group was conducted. Methods: A total of 77 subjects (41m/36w) were divided into healthy adults aged 20–35 years (YA) and 55–76 years (EA) as well as adults diagnosed with Parkinson’s disease (42–76 years) (PD). The “Polar OH1”, an optical pulse sensor, determined the heart rate. All test persons used identical wireless headphones (Bose QC35). The music genres were classical, relaxation and heavy metal with different speeds (bpm) while the three modulated noises were equivalent to these three music styles. To exclude visual information, everyone wore a blindfold. Significance was set at 5%. Results: When comparing experimental conditions within a subject group, there was a significant difference (p ≤ 0.001). between the different measurement mostly in group YA but barely noticeable in group EA. Subject group PD had no significant condition differences. For each sound condition the median HR was higher in YA than in EA (p ≤ 0.001–0.05). Conclusion: The heart rate was not affected by wearing headphones with or without the noise canceling mode. While listening to the music or the tones, younger people have a higher HR variability than older people which may, thus, make them more sensitive to the conditions studied. It can be assumed that the listening to music has no systematic influence on decreasing or increasing the HR. Full article

The high work-related loads on the skin of dancers is the result of numerous factors. While initial studies have looked at the consequences of exposure, information on skin condition is still completely lacking. This study includes for the first time an analysis of the skin as well as the relevant skin care behaviour. Methods: A total of n = 35 professional dancers (PT) underwent skin analysis (transepidermal water loss, TEWL; moisture content and oil level) as part of a dermatological examination. This was done at different work load periods (phase of increased demands and resting phases, T1 and T0, respectively). Results: Acne (17.1%), herpes labialis (8.6%), and allergic rhinitis (14.3%) were among the most common pre-existing conditions. Low moisture contents and oil levels of the skin were found in selected localizations. TEWL index values were normal. There were no significant differences in measured values between T0 and T1. Subjects with skin lesions at rest showered significantly more often than their unaffected counterparts. Inflammation was particularly frequent after hair removal, especially in the intimate area (40.6%). Conclusions: Occupational exposures appear to be reflected in the results. However, studies with larger groups are needed to verify these results. Full article

Introduction: Studies of vocational ballet students are sparce. In particular, there is a lack of gender comparisons. The aim of the present study, therefore, was to give a musculoskeletal and sociodemographic description of the typical vocational ballet student in gender comparison. Methods: In this study, n = 414 female and n = 192 male students of the John Cranko School (JCS), aged between 5 and 22 years (Mean ± SD: 13.9 ± 3.5), were examined by an experienced orthopedist and dance physician. Results: Males started ballet (5.8/8.2 years, p < 0.001) and training at later age than females (13.5/14.6 years, p < 0.05). There was a high prevalence of low body weight among both sexes; however, particularly among female participants (58.4/16.2%, p < 0.001). Both sexes showed a large external rotation of the hip (f/m: 59/62°, p < 0.001), a large turnout (f/m: 82/86°, p < 0.01), high values for plantarflexion of the ankle joint (f/m: 72/68°, p < 0.001) and dorsiflexion of the metatarsophalangeal joint of the big toe (f/m: 90/87°, p < 0.001). Discussion: Differences in ballet-specific characteristics between genders (f/m) are converging and are smaller than described in the past. The particularly high prevalence of low body weight among students in the vocational training sector, particularly among females, highlights the need for deeper diagnostic investigation. Full article

Introduction: An altered dental occlusion can also affect balance stability or mobility. Thus, the aim of this study was to examine whether wearing a mandibular splint, which retains the occlusion close to the centric occlusion, can increase or decrease balance stability and the range of motion (ROM) of the cervical spine as opposed to the habitual occlusion, and if there is a difference between men and women. Material and methods: In this study, 41 male (34.7 ± 11.4 years) and 50 female subjects (29.3 ± 12.7 years) participated. Cervical spine ROM was recorded using the Zebris CMS 70P system. For balance stability, a pressure measuring platform integrated into the treadmill system (FDM-T) of the company Zebris^® Medical GmbH was used. Here, the area of the ellipse and the length of the Center of Pressure (CoP) was recorded whilst in the bipedal and unipedal stance. Results: The sex comparison showed significant differences for the area of the ellipse of the right leg and ROM extension in the habitual occlusion: females showed a better balance stability and a larger ROM extension. When wearing the splint, only the CoP of the left leg was significant with a better balance stability in female subjects. Within the male subjects, the ellipse area in the bipedal and unipedal (left/right) stance showed mostly significant reductions, while the rotation left and right as well as the lateral flexion (left/right) improved when wearing the splint. Female subjects, when wearing the splint, showed a significant decrease of the ellipse area and the CoP length when standing on either leg. Flexion, rotation to the right and lateral flexion to the left/right, all increased significantly. Conclusion: Wearing a splint that keeps the jaw close to the centric relation improved balance stability and increased the ROM of the cervical spine for both male and female subjects. Women may have marginally different basic balance stability strategies than men, with regard to bipedal and unipedal standing. Nevertheless, there are scarcely any differences between the two sexes in the adaptation when wearing a splint. Changing the jaw relation in healthy adults can possibly support the release of movement potentials that simplify the performance of everyday activities or sports movements. Full article

Up to the present, there has been a lack of studies on the skin health of professional and recreational dancers. Dancers are at risk of skin diseases due to contact with allergenic or irritating substances and working in humid environments. The aim of the present study was, therefore, to examine skin health in two different dance styles and training periods. Methods: Physical dermatological examination of professional dancers (PD; n = 35) and Latin American formation dancers (LD; n = 79) after a 4-week period of recovery (T0) and a period of high training or work load (T1). Results: PD are significantly more frequently affected by skin dermatoses than LD (T0, p = 0.004) (frontal traction alopecia, hair loss, facial seborrhoea, xerosis cutis of the trunk and extremities, and facial folliculitis). The following significant differences between the sexes were observed in the LD: more folliculitis of the trunk in male subjects (T0 and T1, p = 0.009), more frequent xerosis cutis of the extremities (p < 0.001) and perioral dermatitis in female subjects (T1, p = 0.043). Subjects with skin lesions trained more frequently, performed more times per year, and had longer dance experience. Discussion: Based on the findings, preventive measures for skin protection (especially informing dancers about skin health) are necessary. At the same time, further studies on this topic are important. Full article

The aim of this study was to analyse the effect of an individual training programme based on the tensiomyography results in the contractile properties of the knee flexor muscle with football players. Thirty-four subjects were recruited and assigned to an experimental (EG) or control group (CG). The contraction time and the muscle displacement measured by tensiomyography were assessed on two occasions: pre-time (middle of the competitive season, January) and post-time 8 weeks later. The training programme aimed to improve muscle tone and explosiveness according to the individual needs of each player. There was a significant interaction between time (assessment points) × group (EG vs. CG) × muscle in multivariate analysis. The findings confirmed that mechanical and neuromuscular characteristics changed over time and varied with the individual training programme (EG vs. CG) and the muscle being analysed. The 90° change of direction worsens the execution time in the control group and is maintained in the experimental group. The individual training programme, based on the tensiomyography results, showed improvements in the contractile properties in the muscles. Football coaches could use the programme to improve neuromuscular characteristics that improve performance and reduce the risk of muscle injury. Full article

Background: In order to determine possible pathological deviations in body weight distribution and body sway, it is helpful to have reference values for comparison: gender and age are two main influencing factors. For this reason, it was the aim of the present study to present reference values for women between 51 and 60 years of age. Methods: For this study, 101 subjectively healthy female Germans aged between 51 and 60 years (55.16 ± 2.89 years) volunteered and were required to stand in a habitual posture on a pressure measuring platform. Results: The average BMI of this age group was 25.02 ± 4.55 kg/m². The left and right foot showed an almost evenly balanced load distribution with a median load of 52.33% on the left foot [tolerance interval (TR) 38.00%/68.03%; confidence interval (CI) 51.00%/53.33%] and 47.67% on the right foot [TR 31.97%/62.00%; CI 46.67%/49.00%]. The measured median load of the forefoot was 33.33% [TR 21.37%/54.60%; CI 30.67%/36.00%] and that of the rear foot was 66.67% [TR 45.50%/78.63%; CI 64.00%/69.33%]. The median body sway in the frontal plane was 11 mm [TR 5.70 mm/26.30 mm; CI 10.00 mm/11.67 mm] and that of the sagittal plane was 16 mm [TR 7.37 mm/34.32 mm; CI 14.67 mm/18.67 mm]. The median ellipse area was 1.17 cm² [TR 0.29 cm²/4.96 cm²; CI 0.98 cm²/1.35 cm²], the median ellipse width was 0.91 cm [TR 0.42 cm/1.9 cm; CI 0.84 cm/1.02 cm] and its height was 0.40 cm [TR 0.22 cm/0.89 cm; CI 0.38 cm/0.43 cm]. Conclusions: The left-to-right ratio is almost balanced. The load distribution of the forefoot to the rear foot is approximately 1:2. The median body sway values for the frontal and sagittal planes (11 and 16 mm, respectively) agree with other values. The values for the height, body weight and the BMI are comparable to the values of average German women at this age; therefore, the measured values show a presentable cross section of women in the 51–60 age group in Germany. The present data can be used as a basis for women aged 51–60 years and can support the detection of possible dysfunctions as well as injury prevention in the parameters of postural control. Full article

Since the flat serve (FS) minimizes the ball spin and kick serve (KS) combined topspin and sidespin, this systematic review aimed to explore the ball impact location (BI) within the FS and KS at the professional men, junior men, and women tennis players. The PRISMA guideline was used, and the original articles were searched in Scopus, Web of Science, and PubMed. The means and standard deviations computed from the distance of BI from the origin within the FS and KS on the x, y, and z axes (global coordinate system) were normalized by the participants’ height and weighted by the number of participants in one-way ANOVA. Ten articles with a pooled sample of 133 males and 51 females aged 11–25 were included. The professional men had more stable BI on the x-axis within the FS by 56% (p < 0.001), within the KS by 58% (p < 0.001), and on the y-axis within the KS by 90% (p < 0.001) than junior men. The professional and junior men had the BI more leftwards from the origin on the x-axis within the KS by 188% (p < 0.001) and 88% (p < 0.001), respectively than within the FS. Full article