Isokinetic Knee Muscle Strength Parameters and Anthropometric Indices in Athletes with and without Hyperextended Knees.

Background and Objectives: Hypermobility has been linked to decreased knee performance, including isokinetic and isometric knee strength. This study aimed to determine whether athletes with and without knee hyperextension have different hamstring-to-quadriceps strength (H/Q) ratios and to investigate the associations between knee hyperextension indices and H/Q ratios and anthropometric characteristics. Materials and Methods: The sample consisted of 47 healthy male athletes without knee injuries aged 23.48 ± 3.54 years. The variables included the degree of knee hypermobility, isokinetic parameters of the leg musculature, and anthropometric indices. Differences between athletes with and without hyperextension were calculated using an independent sample t-test, effect sizes, and discriminant analysis, while associations between the variables were checked by Pearson's correlation coefficient and multiple regression analysis. Results: Athletes with hyperextended knees had shorter legs (t value = -2.23, p = 0.03, moderate ES) and shins (t = -2.64, p = 0.01, moderate ES) and a lower H/Q ratio at an angular velocity of 60°/s (t = -2.11, p = 0.04, moderate ES) than those in the nonhyperextended group did; these differences were supported by discriminant analysis (Wilks' L = 0.60, p = 0.01). An increase in the H/Q ratio at an angular velocity of 60°/s was associated with the degree of knee hypermobility (R = -0.29, p = 0.04). Conclusions: This research showed that athletes with knee hypermobility have weaker hamstring strength and thus a lower H/Q strength ratio at lower angular velocities. These findings suggest that targeted strength training programs for leg (i.e., hamstrings) muscles should help individuals with knee hypermobility.

(Low) Energy Availability and Its Association with Injury Occurrence in Competitive Dance: Cross-Sectional Analysis in Female Dancers.

Background and objectives: The risk of low energy availability is related to various health problems in sports. This cross-sectional study aimed to identify a possible association between various dance factors, anthropometrics/body build, and energy availability with injury occurrence in contemporary dancers. Materials and Methods: The participants were 50 female competitive dancers (19.8 ± 4.1 years of age). The independent variables included age, dance factors (amount of training and competitions per week-exposure time, experience in dance), anthropometrics/body composition (body height, mass, BMI, body fat percentage (BF%), and fat-free mass (FFM)), and energy availability score (EAS; evaluated by accelerometer-based measurement of energy expenditure and Dance Energy Availability Questionnaires). The dependent variables were the occurrence of (i) soft-tissue injuries and (ii) bone injuries. The measurements were obtained by experienced technicians during the pre-competition period for each specific dance discipline. Univariate and multivariate logistic regressions were calculated to identify the associations between independent variables and injury prevalence. Results: The results showed that EAS (OR = 0.81, 95% CI:0.65-0.91), age (OR = 1.65, 95% CI: 1.1-2.46), higher BF% (OR = 1.23, 95% CI: 1.04-1.46) and BMI (OR = 1.61, 95% CI: 1.05-2.47) were correlated with soft-tissue injuries. Dancers who suffered from bone injuries reported higher exposure time (OR = 1.21, 95% CI: 1.05-1.37) and had lower values of FFM (OR = 0.73, 95% CI: 0.56-0.98). Multivariate regression analyses evidenced a higher likelihood of soft-tissue injuries in older dancers (OR = 1.75, 95% CI: 1.21-2.95) and the ones who had lower EAS (OR = 0.84, 95% CI: 0.71-0.95) while the exposure time was associated with a higher likelihood of bone injuries (OR = 1.21, 95% CI: 1.05-1.39). Conclusions: In order to decrease the injury prevalence among dancers, special attention should be paid to maintaining adequate nutrition that will provide optimal available energy for the demands of training and performing. Additionally, the control of training volume should be considered in order to reduce traumatic bone injuries.

Disordered eating, amenorrhea, and substance use and misuse among professional ballet dancers: Preliminary analysis.

BACKGROUND: Substance use and misuse (SUM), eating disorders (ED) and consequent amenorrhea (AM) occur frequently in professional ballet dancing. The objective of this study has been to explore the prevalence and association between ED, AM and SUM in ballet. MATERIAL AND METHODS: The sample comprised 21 ballet dancers, 23.1±4.5 years old, members of the professional National Ballet Ensemble from Croatia. Variables were collected by questionnaires examining SUM, occurrence of amenorrhea, and corresponding ballet-specific and socio-demographic factors (Questionnaire on Substance Use - QSU) and the level of ED (Brief Eating Disorder in Athletes Questionnaire - BEDA-Q). RESULTS: Smoking is prevalent in 40% of dancers (25% smoke on a daily basis), 36% often use analgesics, and 25% engage in binge drinking at least once a month. Smoking and binge drinking are less frequent in ballerinas with a higher academic level (r = 0.60 and r = 0.54 for binge drinking and smoking, respectively; p < 0.05). Alcohol drinking is higher among dancers who consume analgesics more often and those with a higher BEDA-Q score (r = 0.53 and r = 0.54 for analgesics and BEDA-Q, respectively; p < 0.05). Amenorrhea is more prevalent among those dancers with a higher BEDA-Q score. Women who consume nutritional supplements are less likely to use analgesics (Mann Whitney U test = 2.11; p < 0.05). CONCLUSIONS: Efforts seeking to prevent ED in ballet should target dancers who consume alcohol to a greater extent. Future studies should specifically explore the less frequent consumption of analgesics among dancers who consume nutritional supplements.

The training effects of dance aerobics: A review with an emphasis on the perspectives of investigations.

The training effects of contemporary aerobics programmes (hi lo, dance aerobics, step aerobics, aqua aerobics etc.) have been frequently investigated. However, we found no recent paper which reviewed aerobic programmes with regard to their training effectiveness, characteristics of the subjects involved, variables of interest and experimental design. In this paper we summarise the findings of more than 40 studies published in the 2000-2011 period that investigated the training effects of different forms of contemporary aerobics. In this review, the studies are grouped according to their characteristics (sample of subjects, variables of interest, study design, effects, etc.). Around 80% of the investigations dealt with females, with adults being most commonly observed. In the majority of investigations, the authors studied different variables at the same time (morphological anthropometric, motor, cardiovascular, biochemical indices, etc.). In recent studies a trend toward a psychological status examination is evident. In most instances positive training effects on motor-endurance and varsity of physiological variables are declared throughout a training period of 8 to 12 weeks. However, the positive changes in anaerobic endurance are not evidenced. Knowing the tendency of the overall increase of certain psychological disorders in population (including depression) there are indications that future, potentially highly interesting studies will deal with the psychological status of adults and older subjects.

Injury Occurrence in Modern and Hip-Hop Dancers: A Systematic Literature Review.

INTRODUCTION: Dance-related injuries have become a field of great interest to researchers, with the most commonly reported injuries being those sustained by ballet dancers. However, there is a lack of research into injuries sustained by those who perform modern and hip-hop dance. METHODS: A systematic literature review using the MEDLINE research database was performed and a search carried out for full-text studies that investigate injuries in modern and hip-hop dance. RESULTS: While a total of 74 hits were obtained from various searches, only nine studies were included in the systematic literature review. Six of them examined modern dancers, two examined break dancers and one examined hip-hop dancers. The results show that hip-hop dancers (and especially break dancers) sustain more injuries in comparison to modern dancers. The most common injuries are in the lower extremities, with studies revealing that overuse injuries occur in up to 71% of cases. CONCLUSIONS: The injury incidence rate in hip-hop dance seems to be higher compared to modern dance, chiefly because of the more demanding biomechanics involved and the dance techniques employed. Prevention management can have a positive effect on the number of injuries.

Predicting Injury Status in Adolescent Dancers Involved in Different Dance Styles: A Prospective Study.

The positive effects of dance on health indices in youth are widely recognized, but participation in dance is accompanied with a certain risk of injury. This prospective study aimed to investigate injury occurrence and to evaluate the possible influences of specific predictors on the occurrence of musculoskeletal problems and injuries in adolescent dancers. Participants were 126 dancers (21 males; 11-18 years), who were competitors in the urban dance, rock and roll, and standard/Latin dance genres. Predictors included sociodemographic factors, anthropometric/body build indices, sport (dance) factors, and dynamic balance. The outcome variable was injury status, and this was evaluated by the Oslo Sports Trauma Research Centre Overuse Injury Questionnaire (OSTRC). Predictors were evaluated at baseline, and outcomes were continuously monitored during the study period of 3 months. During the study course, 53% of dancers reported the occurrence of a musculoskeletal problem/injury, and dancers suffered from an average of 0.72 injuries over the study period (95% CI: 0.28-1.41), giving a yearly injury rate of 280%. Gender and dance styles were not significantly related to the occurrence of injury. Higher risk for injury was evidenced in older and more experienced dancers. Dynamic balance, as measured by the Star Excursion Balance Test (SEBT), was a significant protective factor of injury occurrence, irrespective of age/experience in dance. Knowing the simplicity and applicability of the SEBT, continuous monitoring of dynamic balance in adolescent dancers is encouraged. In order to prevent the occurrence of musculoskeletal problems/injuries in youth dancers, we suggest the incorporation of specific interventions aimed at improving dynamic balance.

Injury Occurrence and Return to Dance in Professional Ballet: Prospective Analysis of Specific Correlates.

Professional ballet is a highly challenging art, but studies have rarely examined factors associated with injury status in ballet professionals. This study aimed to prospectively examine gender-specific correlates of injury occurrence and time-off from injury in professional ballet dancers over a one-year period. The participants were 99 professional ballet dancers (41 males and 58 females). Variables included: (i) predictors: sociodemographic data (age, educational status), ballet-related factors (i.e., experience in ballet, ballet status), cigarette smoking, alcohol drinking, and consumption of illicit drugs; and (ii) outcomes: injury occurrence and time-off from injury. Participants were questioned on predictors at the beginning of the season, while data on outcomes were collected continuously once per month over the study period. Dancers reported total of 196 injuries (1.9 injuries (95% CI: 1.6⁻2.3) per dancer in average), corresponding to 1.4 injuries per 1000 dance-hours (95% CI: 1.1⁻1.7). In females, cigarette smoking was a predictor of injury occurrence in females (OR: 4.33, 95% CI: 1.05⁻17.85). Alcohol drinking was a risk factor for absence from dance in females (OR: 1.29, 95% CI: 1.01⁻4.21) and males (OR: 1.21, 95% CI: 1.05⁻3.41). Less experienced dancers were more absent from dance as a result of injury than their more experienced peers (Mann-Whitney Z: 2.02, p < 0.04). Ballet dancers and their managers should be aware of the findings of this study to make informed decisions on their behavior (dancers) or to initiate specific programs aimed at the prevention of substance use and misuse in this profession (managers).

Investigating the Prevalence and Predictors of Injury Occurrence in Competitive Hip Hop Dancers: Prospective Analysis.

Hip hop is a popular form of competitive and recreational sport worldwide, but studies rarely investigate injury prevalence and factors associated with injury occurrence in this sport. This study aimed to prospectively examine injury occurrence in hip hop dancers in a three-month period and to evaluate potential predictors of injury occurrence in hip hop dancers. The participants were 129 competitive hip hop dancers (114 females, 17.95 ± 4.15 years of age). Study predictors were obtained at study baseline and included sociodemographic factors, sport-related factors, previous injury status, anthropometric and body build indices (body height, mass, body mass index, and body composition variables), and dynamic balance performance (obtained by the Star Excursion Balance Test-SEBT). The outcome was injury occurrence, which was prospectively observed once a week by the Oslo Sports Trauma Research Center Overuse Injury Questionnaire (OSTRC). During the course of the study, 101 injuries occurred, equating to an annual injury incidence of 312%. On average, each dancer suffered 0.78 injuries (95% Confidence Interval (95% CI): 0.61-0.97) across a study period of three months (0.76 (95% CI: 0.60-0.95) and 0.93 (95% CI: 0.75-1.13), in females and males, respectively; Mann Whitney Z-value: 0.68, p = 0.52). Seventeen percent of dancers suffered multiple injuries, and 49% of all injuries were time-loss injuries. The knee was the most frequently injured body location (42% of all reported injuries), followed by the back region (32%) and the ankle (15%). Previous injury was a strong predictor of injury occurrence (Odds Ratio: 3.76, 95% CI: 1.87-4.59). Lower injury risk was evidenced among those participants who achieved better scores on several SEBT variables, irrespective of gender and previous injury status; with no significant influence of anthropometric and body build variables on injury occurrence. This study highlighted a high injury rate in hip hop dancers. Dancers and coaches should be informed about the certain protective effects of dynamic balance on the prevention of musculoskeletal injury in hip hop in order to assure safe and effective practices. The usage of SEBT as a convenient and cheap testing procedure is encouraged in other dance disciplines.

What drives athletes toward dietary supplement use: objective knowledge or self-perceived competence? Cross-sectional analysis of professional team-sport players from Southeastern Europe during the competitive season.

BACKGROUND: Issues related to knowledge of nutrition and dietary supplementation (DS) are understudied in professional athletes. This study aimed to examine the possible association between knowledge of nutrition and DS (KN&DS) and dietary supplement use (DSU) among professional athletes involved in team sports. METHODS: The sample comprised professional team-sport athletes (N = 912, age: 22.11 ± 3.37 years, 356 females) involved in four Olympic sports: basketball (N = 228), soccer (N = 324), volleyball (N = 154), and handball (N = 206). The participants were tested by previously validated questionnaires to examine their self-perceived competence on nutrition and DS (S/KN&DS), their objectively evaluated (tested) KN&DS (O/KN&DS), sociodemographic and sport-specific variables (predictors), and DSU (criterion). Associations between the predictors and the criterion (No-DSU - Irregular-DSU - Regular-DSU) were determined by multinomial regression analysis for the total sample and separately for the studied sports. RESULTS: DSU was found to be less prevalent in older and more successful players. The O/KN&DS and S/KN&DS were positively correlated with DSU, but S/KN&DS was a stronger predictor of DSU than O/KN&DS. Sport-specific associations between predictors and criterion were identified, with stronger correlations in sports with a higher prevalence of DSU. CONCLUSIONS: Due to the low correlations between O/KN&DS and S/KN&DS in the studied players, this study highlights the necessity for more frequent monitoring of biomarkers of nutritional status and its usage by coaches and practitioners to provide quantitative instruction.

Body asymmetries in dancers of different dance disciplines / Asimetrías corporales en bailarines de diferentes disciplinas de baile

SUMMARY: Dance is an attractive sport discipline in which participation is increasing every year, unfortunately, the prevalence of injuries is also increasing. Various dance disciplines and dance techniques require body control, often in extreme anatomical positions that place a heavy strain on the musculoskeletal system. The aim of this research was to analyze body asymmetries of four different dance disciplines (standard and Latin American dance - STLA, acrobatic rock and roll - RNR, breakdance - BD and hip hop - HH), by using anthropometric (InBody 720; Biospace Co., Ltd) and 3D body measurements (NX-16; TC2) to establish possible later discomforts and injuries. T-test was performed to find differences between left and right extremities in all four dance disciplines. Results of the study showed that asymmetries are present in all of the studied dance disciplines. When comparing dance disciplines, we found out that STLA dancers are the most prone to develop body asymmetries (six out of nine paired variables), mainly because of the closed position. The position itself is the asymmetry and in which dancers remain for a very long time while training the technique of each dance. As dance is known for its asymmetrical movement of the body and it is expected that some of the asymmetries will appear after a few years of training. For a better understanding of possible consequences of asymmetries in dancers' bodies, further and more detailed analysis within each dance discipline is required.

RESUMEN: El baile es una disciplina deportiva atractiva cuya participación aumenta cada año, sin embargo también aumenta la prevalencia de lesiones. Varias disciplinas de baile y las técnicas de baile requieren el control del cuerpo en posiciones anatómicas extremas las cuales ejercen una gran presión sobre el sistema musculoesquelético. El objetivo de esta investigación fue analizar las asimetrías corporales de cuatro disciplinas de baile diferentes (baile estándar y latinoamericano - STLA, rock and roll acrobático - RNR, breakdance - BD y hip hop - HH), utilizando técnicas antropométricas (InBody 720; Biospace Co., Ltd) y mediciones corporales en 3D (NX-16; TC2) para establecer posibles molestias y lesiones posteriores. Se realizó la prueba T para determinar diferencias entre los miembros izquierdo y derecho en las cuatro disciplinas de baile. Los resultados de este estudio mostraron que las asimetrías se encontraron en todas las disciplinas de baile. Al comparar las disciplinas de baile, descubrimos que los bailarines de STLA son los más propensos a desarrollar asimetrías corporales (seis de nueve variables pareadas), principalmente debido a la posición cerrada. La posición en sí es asimétrica y en la que los bailarines permanecen durante mucho tiempo mientras entrenan la técnica de cada baile. Como el baile es conocido por el movimiento asimétrico del cuerpo, es posible que algunas de las asimetrías aparezcan después de algunos años de entrenamiento. Se requiere un análisis más profundo y detallado dentro de cada disciplina de danza para una mejor comprensión de las posibles consecuencias de las asimetrías en los cuerpos de los bailarines.

The association between body-built and injury occurrence in pre-professional ballet dancers - Separated analysis for the injured body-locations.

OBJECTIVES: This study has aimed at identifying prevalence of injury-occurrence in 24 pre-professional-ballet-dancers (females, 16-18 years of age), and identifying the associations between the body-built and prevalence of injuries. MATERIAL AND METHODS: The sample of variables included: body mass, body height, and 3 somatotype characteristics (mesomorph, ectomorph and endomorph) and data on injuries over the preceding year. RESULTS: Dancers were mostly ectomorphic-mesomorph (endomorphy: 2.6±0.54, mesomorphy: 3.99±0.77, ectomorphy: 3.23±0.54). The most commonly injured locations were the foot (17% of all injuries) and ankle (17%). Majority of the injuries occurred while practising but 37% of hip-injuries occurred while performing. Ankle-injuries resulted in longest absence from ballet. Endomorphy was related to ankle-injury (odds ratio (OR) = 1.9, 95% confidence interval (CI): 1.4-2.3), ectomorphy to foot injury (OR = 1.7, 95% CI: 1.1-2.9), and body-mass to injury to the toes (OR = 1.7, 95% CI: 1.4-3.1). CONCLUSIONS: The results of this study allow for recognizing those dancers who are particularly vulnerable to injuries of certain body location. A more profound analysis of the possible mechanisms that lead to hip-injury during performance is needed. Int J Occup Med Environ Health 2017;30(1):151-159.