RESUMEN
INTRODUCTION: The importance and potential benefits of muscular strength in the adolescent's development for health and fitness has been demonstrated in the literature. Maximal muscular strength and its assessment, however, is not a primary assessment criterium in the selection of young talented dancers. METHODS: The present study evaluated the within- and between session reliability, variability, and minimal detectable change (MDC) of the isometric mid-thigh pull (IMTP). Thirty-five participants (female n = 17) participated in 2 identical assessments on the same day with 4-hour break in between. Three 3-second IMTP were performed, and the mean peak force value was used for the analyses. RESULTS: Within-session the ICC indicated excellent reliability (ICC = .99, 95% CI: 0.98-0.99). Between-session reliability was excellent (ICC = .98, 95% CI: 0.95-0.99). The standard error of measurement was 4% (48 N), the minimum detectable change was 12% (134 N) and the CV was 3%. There were no within-session statistically significant differences, but statistically significant differences between-session were observed (P < .001). Limits of agreement ranged from -121 N (95% CI -186 to -56 N) to 307 N (95% CI 243-372 N). CONCLUSION: The observed results demonstrated excellent within- and between sessions reliability, low variability, and an MDC of 12%. The consistency of the within-session scores suggest that peak force data may be obtained with single try efforts. The statistically significant difference in the means of the retest session, however, suggests that the time of the day or the time since entrained awakening may be affecting performance in adolescent dancers. The results of the current study indicate that the IMTP is a reliable assessment tool for maximal muscular strength in adolescent dancers.
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Baile , Muslo , Humanos , Femenino , Adolescente , Masculino , Reproducibilidad de los Resultados , Prueba de Esfuerzo/métodos , Contracción Isométrica , Fuerza MuscularRESUMEN
INTRODUCTION: Neuromuscular warm-up programs, such as FIFA 11+ were developed as early as 2006. These programs have been effective in reducing the risk of injury in female athletes by decreasing the moments surrounding the knee and improving neuromuscular control during static and dynamic movements such as jumping and landing. In addition, they have been effective for improving jump height in soccer, volleyball, and basketball. METHODS: The effects of the 11+ Dance, a dance-specific neuromuscular warm-up program, was examined on jump height and lower extremity biomechanics during bilateral and single leg countermovement jumps in recreational dancers. Twenty female adolescents from 2 dance schools participated in this 2-centered 8-week controlled non-randomized trial. The intervention group (IG) performed the 11+ Dance program 3×/week for 8-weeks during the first 30-minute of their regularly scheduled dance classes. The control group (CG) continued with their regular dance classes routine. Ground reaction force and motion capture data were used to assess jump height and lower extremity biomechanics pre and post intervention. RESULTS: Both groups statistically increased their jump height (CG: Z = 1.89-2.45, P ≤ .0167; IG: Z = 2.18-2.76, P ≤ .0167). However, no statistical between group differences were observed (Z = 0.38-1.22, P > .05). During takeoff, the IG statistically reduced peak knee extension moments (t(18) = -3.04 to -3.77, P ≤ .0167) while increasing peak hip extension moments (t(18) = 2.16-2.79, P ≤ .05) and peak hip flexion angles (t(18) = 2.68-3.72, P ≤ .0167) compared to the CG. The IG also increased the hip flexion angles compared to the CG during landing (t(18) = 2.78-5.13, P ≤ .0167) while no systematic differences were observed in all other variables of lower extremity biomechanics. CONCLUSION: The reduced joint load at the knee observed during takeoff needs further investigation. Neuromuscular training, such as the 11+ Dance, is supported by numerous quality research. Due to its simplicity, the 11+ Dance may be feasible and beneficial to complement regular warm-ups in recreational dance practice.
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Baile , Humanos , Femenino , Adolescente , Fenómenos Biomecánicos , Proyectos Piloto , Extremidad Inferior , Articulación de la Rodilla , MovimientoRESUMEN
INTRODUCTION: Pre-professional ballet training involves long training hours from an early age that could influence young dancers' physical performance and injury incidence. This cross-sectional analysis investigated the relationship of year group and sex with countermovement jump and injury incidence (primary outcome) in adolescent ballet dancers at a pre-professional dance school.
Method: Countermovement jump (CMJ) height was recorded at the start of the academic year for 179 participants (M = 68, F = 111) spread across eight year-groups. Injury etiology and incidence was prospectively recorded over a 6-month period (September through February) by the medical team using a time-loss definition.
Results: Between-subject statistically significant differences were reported for sex [F(1, 153) = 101.46; p < 0.001], year group [F(7, 153) = 12.57; p < 0.001], and sex*year group [F(7, 153) = 9.22; p < 0.001]. Mean CMJ across the year groups ranged between 24.7 to 41.3 cm for males and 23.5 to 25.1 cm for females. Injury incidence per dancer was 0.84 (CI: 0.13, 1.56) and injury incidence per 1,000 hours of dance was 1.94 (CI: 1.63, 2.25). No statistically significant differences between sexes or year groups were reported for injury incidence per 1,000 dance hours and time-loss. Hours dancing was statistically significantly positively associated with CMJ (r = .481, p < 0.05) and negatively associated with injury incidence (r = -.253, p < 0.05) for males; for females it was positively associated with time-loss (r = .254, p < 0.05).
Conclusion: Even though CMJ was cross-sectionally monitored, the expected increased physical abilities in males as they grew older and progressed through their training was observed. Females did not indicate a similar increase in their physical ability, but they seemed to become more susceptible to injuries as they grow older. The lack of this speculative physiological development for the females may be associated with the ballet-only approach in their training. The use of CMJ as an injury screening tool may be limited, however, it could still be used as a tool to monitor physiological and fundamental motor skill development of adolescent dancers, as jumping is an integral part of ballet.
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Traumatismos en Atletas , Baile , Adolescente , Traumatismos en Atletas/epidemiología , Estudios Transversales , Baile/fisiología , Femenino , Humanos , Incidencia , Masculino , Destreza MotoraRESUMEN
INTRODUCTION: It is well documented that there is high prevalence of injuries in pre-professional and professional ballet dancers. Current evidence from high in quality and quantity research on in- jury prevention in sport indicates that interventions can reduce injury risks by 30% to 50%. Injury prevention research in dance is limited. The aim of this study was to assess the feasibility (adherence, fidelity, and practicality) of a randomized controlled trial for the utilization of neuromuscular training in pre-professional ballet dancers.
Methods: A convenience sample of 22 pre-professional ballet dancers were randomized into an intervention and control group. The intervention group took part in a neuromuscular-based training workout, five times per week before the ballet class, for 10 weeks. The intervention was an adaptation of the FIFA 11+, an injury prevention intervention and is called 11+ Dance. The intervention consisted of low intensity bodyweight exercises that lasted 20 to 30 minutes performed daily.
Results: Intervention adherence was 38% ± 8%, with higher participation at the beginning of the study. Attendance for post-testing was low 45% and 36% for the intervention and control group, respectively, mainly due to injury. There were no adverse effects reported, however, the participants reported delayed onset muscle soreness at the beginning of the intervention, indicating that there may be a potential training effect. Fear of muscle hypertrophy and fatigue were also reported as reasons for attrition. The repeated measures ANOVA revealed statistically non-significant differences for the countermovement jump F(1, 9) = 0.36, p = 0.564, η² p= 0.04; reactive strength index F(1, 7) = 0.02, p = 0.885, η² p= 0.003; and the isometric mid-thigh pull F(1, 12) = 0.002, p = 0.967, η² p= 0.000.
Conclusion: The results of the study, together with the feedback from the participants, suggest that some protocol modifications are necessary for the feasibility of a randomized controlled trial in a pre-professional setting. The current trial has produced valuable information for the intervention frequency and load prescription.