The Effect of Strength and Plyometric Training on Functional Dance Performance in Elite Ballet and Modern Dancers

Background: Ballet and modern dance are both art forms that require technique, artistry, grace and precision. Both dance forms require a degree of strength and muscular endurance for optimal performance. It is not known what value strength or plyometric training may have on functional dance performance. Objective: To systematically review the effects of strength and/or plyometric training on functional dance performance in elite ballet and modern dancers. Methods: A systematic review of literature indexed in the following databases: Medline, CINAHL, SportsDiscus, Physiotherapy Evidence Database (PEDro) and PubMed was conducted. The quality of the studies was graded using the PEDro Scale. Results: Eight studies satisfied the eligibility criteria and were included in this review. The studies\u27 population age range was 19?27?years. Methodological scores based on the PEDro scale were 4 to 6 out of 10. All of the included studies (100%) scored 4 out of 10 or higher on the PEDro scale. Strength training resulted in significant improvements in jump height (P? Conclusion: Moderate evidence indicates that supplementary strength training interventions via traditional resistance training or whole-body vibration methods and plyometric training interventions may increase certain dance-performance measures such as jump height and general aesthetic facility without changing certain anthropometric measures in elite ballet and modern dancers

Body-size phenotypes and cardiometabolic risk in Rheumatoid Arthritis

Objectives: Obesity is a significant contributor to metabolic complications. However, such complications are not uniform in people with similar body-size. The existence of normal-weight individuals with and obese individuals without metabolic complications has been described in the general population and is important in the context of cardiovascular disease (CVD). This has not been investigated in rheumatoid arthritis (RA), a condition associated with increased cardiometabolic risk. This study aims to identify the prevalence and predictors of body-size phenotypes in RA and investigate their associations with CVD risk. Methods: Body mass index (BMI: kg/m2), body fat (BF) and fat free mass (FFM), RA characteristics and CVD risk factors were assessed in 363 (262 females) volunteers with RA. Abnormal cardiometabolic status was defined as the presence of >1 of the following: hypertension, increased triglycerides or increased Low or reduced High Density Lipoprotein, high glucose, insulin resistance. Results: Among normal-weight, overweight, and obese participants 25%, 45.8%, 57.1% respectively were metabolically abnormal. Old age (B= 1.032, err=0.011; p= 0.005), waist circumference (B= 1.057, err= 0.011; p= 0.000), and smoking cessation (B= 1.425, err= 0.169; p=0.036) were significant predictors for metabolic abnormality. Conclusions: A significant number of RA patients present with different body-size and metabolic phenotypes. BMI alone is not a sufficient indicator of cardiometabolic risk in RA; this may have significant implications in their CVD risk evaluation. Body fat distribution seems to be a significant contributor to such abnormalities. Further research is needed, focusing on the metabolic properties of specific adipose depots of RA patient

Chronic eccentric exercise and antioxidant supplementation: effects on lipid profile and insulin sensitivity

Eccentric exercise has been shown to exert beneficial effects in both lipid profile and insulin sensitivity. Antioxidant supplementation during chronic exercise is controversial as it may prevent the physiological training-induced adaptations. The aim of this study was to investigate: 1) the minimum duration of the eccentric exercise training required before changes on metabolic parameters are observed and 2) whether antioxidant supplementation during training would interfere with these adaptations. Sixteen young healthy men were randomized into the Vit group (1 g of vitamin C and 400 IU vitamin E daily) and the placebo (PL) group. Subjects received the supplementation for 9 weeks. During weeks 5-9 all participants went through an eccentric exercise training protocol consisting of two exercise sessions (5 sets of 15 eccentric maximal voluntary contractions) per week. Plasma triglycerides (TG), total cholesterol (TC), high density lipoprotein (HDL), low density lipoprotein (LDL), apolipoproteins (Apo A1, Apo B and Lpa) and insulin sensitivity (HOMA) were assessed before the supplementation (week 0), at weeks 5, 6, 7, 8 and 9. TG, TC and LDL were significantly lower compared to pre supplementation at both weeks 8 and 9 (P<0.05) in both groups. HDL was significantly elevated after 4 weeks of training (p < 0.005) in both groups. There was no effect of the antioxidant supplementation in any of the variables. There was no effect of either the training or the supplementation protocol in apolipoproteins levels and insulin sensitivity. A minimum duration of 3 weeks of eccentric exercise training is required before beneficial effects in lipid profile can be observed in healthy young men. Concomitant antioxidant supplementation does not interfere with the training-induced adaptations

Leg-length in relation to selected ballet performance indicators

It is unclear whether the modern ballet body stereotype of long limbs is advantageous in dance performance. Therefore, we investigated the relationship between leg-length and selected dance movements representative of power, dexterity, and range of motion in ballet dancers at different competence levels. METHODS: The total of 10 recreational, 24 vocational, and 10 professional ballerinas volunteered. They were subjected to: a) lower limb-length measurements, b) power tests (vertical jump-sautés and unilateral countermovement jump-temps levé), c) dexterity tests (tendus and double battement frappes), and d) flexibility tests (lateral active and passive-développé à la seconde). RESULTS: For power, regression analyses revealed negative leg-length relationships in recreational dancers (p<0.05) and positive leg-length relationships in vocational dancers (p<0.05). We also found negative relationships between leg-length and dexterity in the vocational group (p=0.01). No significant predictions of leg-length on power, dexterity, and range of motion were found in professional dancers. Multiple comparisons revealed significant differences between groups only for dexterity (p<0.01) and range of motion (p<0.01). CONCLUSION: Based on selected movements representative of power, dexterity, and range of motion, the present exploratory data indicate that lower limb length is not a determinative criterion for ballet success. Further studies should investigate whether body stereotypes, such as long limbs, are linked to dance injurie

Effects of acute exercise on liver function and blood redox status in heavy drinkers

Excessive alcohol consumption can induce oxidative stress, resulting in the development of several diseases. Exercise has been reported to prevent and/or improve a number of health issues through several mechanisms, including an improvement in redox status. It has also been previously suggested that exercise can help individuals with alcohol use disorders reduce their alcohol intake; however, research in this field is limited. The aim of the present study was to investigage the effects of acute exercise of moderate intensity on the liver function and blood redox status in heavy drinkers. For this purpose, a total of 17 heavy drinkers [age, 31.6±3.2 years; body mass index (BMI), 27.4±0.8 kg/m2; experimental group (EG)] and 17 controls [age, 33.5±1.3 years; BMI, 26.1±1.4 kg/m2; control group (CG), who did not exceed moderate alcohol consumption], underwent one trial of acute exercise of moderate intensity (50-60% of the heart rate reserve) for 30 min on a cycle ergometer, following an overnight fast, and abstaining from smoking and alcohol consumption. Blood samples were obtained before and immediately after exercise for later determination of the indices of liver function and blood redox status. The subjects in the EG had significantly higher (p<0.05) baseline γ-glutamyl transferase (γ-GT) levels compared to the subjects in the CG. Exercise thus resulted in significantly higher γ-GT levels (p<0.005) only in the EG. No significant differences in aspartate aminotransferase (AST) and alanine aminotransferase (ALT) baseline levels were observed between the 2 groups. Following exercise, the AST levels increased significantly (p<0.001) in both groups, whereas the ALT levels increased significantly (p<0.01) only in the EG. The baseline glutathione (GSH) levels were significantly lower (p<0.05) and remained low following exercise in the EG. In addition, we observed a trend for higher (p=0.07) baseline levels of thiobarbituric acid-reactive substances (TBARS), which remained elevated post-exercise in the EG compared to the CG. Significantly increased post-exercise total antioxidant capacity (TAC; p<0.01) and uric acid (UA; p<0.05) levels were noted in the CG, whereas the TAC (p=0.06) and UA (p=0.08) levels increased and approached significance post-exercise in the EG. No significant differences in the baseline levels of total bilirubin and protein carbonyl were observed between the 2 groups, even post-exercise. Thus, the findings of the present study indicate that even though heavy drinkers may be prone to oxidative stress, their exercise-induced antioxidant response is similar to that of individuals who do not drink heavily.Interna

Functional responses of uremic single skeletal muscle fibers to redox imbalances

BACKGROUND: The exact causes of skeletal muscle weakness in chronic kidney disease (CKD) remain unknown with uremic toxicity and redox imbalances being implicated. To understand whether uremic muscle has acquired any sensitivity to acute redox changes we examined the effects of redox disturbances on force generation capacity. METHODS: Permeabilized single psoas fibers (N =37) from surgically induced CKD (UREM) and sham-operated (CON) rabbits were exposed to an oxidizing (10 mM Hydrogen Peroxide, H2O2) and/or a reducing [10 mM Dithiothreitol (DTT)] agent, in a blind design, in two sets of experiments examining: A) the acute effect of the addition of H2O2 on maximal (pCa 4.4) isometric force of actively contracting fibers and the effect of incubation in DTT on subsequent re-activation and force recovery (N =9 CON; N =9 UREM fibers); B) the effect of incubation in H2O2 on both submaximal (pCa 6.2) and maximal (pCa 4.4) calcium activated isometric force generation (N =9 CON; N =10 UREM fibers). RESULTS: Based on cross-sectional area (CSA) calculations, a 14 % atrophy in UREM fibers was revealed; thus forces were evaluated in absolute values and corrected for CSA (specific force) values. A) Addition of H2O2 during activation did not significantly affect force generation in any group or the pool of fibers. Incubation in DTT did not affect the CON fibers but caused a 12 % maximal isometric force decrease in UREM fibers (both in absolute force p =0.024, and specific force, p =0.027). B) Incubation in H2O2 during relaxation lowered subsequent maximal (but not submaximal) isometric forces in the Pool of fibers by 3.5 % (for absolute force p =0.033, for specific force p =0.019) but not in the fiber groups separately. CONCLUSIONS: Force generation capacity of CON and UREM fibers is affected by oxidation similarly. However, DTT significantly lowered force in UREM muscle fibers. This may indicate that at baseline UREM muscle could have already been at a more reduced redox state than physiological. This observation warrants further investigation as it could be linked to disease-induced effects

Cardiorespiratory fitness levels and their association with cardiovascular profile in patients with rheumatoid arthritis: a cross-sectional study.

OBJECTIVE: The aim of this study was to investigate the association of different physical fitness levels [assessed by the maximal oxygen uptake (VO2max) test] with cardiovascular disease (CVD) risk factors in patients with RA. METHODS: A total of 150 RA patients were assessed for cardiorespiratory fitness with a VO2max test and, based on this, were split in three groups using the 33rd (18.1 ml/kg/min) and 66th (22.4 ml/kg/min) centiles. Classical and novel CVD risk factors [blood pressure, body fat, insulin resistance, cholesterol, triglycerides, high-density lipoprotein (HDL), physical activity, CRP, fibrinogen and white cell count], 10-year CVD risk, disease activity (DAS28) and severity (HAQ) were assessed in all cases. RESULTS: Mean VO2max for all RA patients was 20.9 (s.d. 5.7) ml/kg/min. The 10-year CVD risk (P = 0.003), systolic blood pressure (P = 0.039), HDL (P = 0.017), insulin resistance and body fat (both at P < 0.001), CRP (P = 0.005), white blood cell count (P = 0.015) and fibrinogen (P < 0.001) were significantly different between the VO2max tertiles favouring the group with the higher VO2max levels. In multivariate analyses of variance, VO2max was significantly associated with body fat (P < 0.001), HDL (P = 0.007), insulin resistance (P < 0.003) and 10-year CVD risk (P < 0.001), even after adjustment for DAS28, HAQ and physical activity. CONCLUSION: VO2max levels are alarmingly low in RA patients. Higher levels of VO2max are associated with a better cardiovascular profile in this population. Future studies need to focus on developing effective behavioural interventions to improve cardiorespiratory fitness in RA

Bone mass of female dance students prior to professional dance training: A cross-sectional study

Article Authors Metrics Comments Related Content Abstract Introduction Methods Results Discussion Conclusions Acknowledgments References Reader Comments (0) Media Coverage (0) Figures Abstract Background Professional dancers are at risk of developing low bone mineral density (BMD). However, whether low BMD phenotypes already exist in pre-vocational dance students is relatively unknown. Aim To cross-sectionally assess bone mass parameters in female dance students selected for professional dance training (first year vocational dance students) in relation to aged- and sex-matched controls. Methods 34 female selected for professional dance training (10.9yrs ±0.7) and 30 controls (11.1yrs ±0.5) were examined. Anthropometry, pubertal development (Tanner) and dietary data (3-day food diary) were recorded. BMD and bone mineral content (BMC) at forearm, femur neck (FN) and lumbar spine (LS) were assessed using Dual-Energy X-Ray Absorptiometry. Volumetric densities were estimated by calculating bone mineral apparent density (BMAD). Results Dancers were mainly at Tanner pubertal stage I (vs. stage IV in controls, p<0.001), and demonstrated significantly lower body weight (p<0.001) and height (p<0.01) than controls. Calorie intake was not different between groups, but calcium intake was significantly greater in dancers (p<0.05). Dancers revealed a significantly lower BMC and BMD values at all anatomical sites (p<0.001), and significantly lower BMAD values at the LS and FN (p<0.001). When adjusted for covariates (body weight, height, pubertal development and calcium intake), dance students continued to display a significantly lower BMD and BMAD at the FN (p<0.05; p<0.001) at the forearm (p<0.01). Conclusion Before undergoing professional dance training, first year vocational dance students demonstrated inferior bone mass compared to controls. Longitudinal models are required to assess how bone health-status changes with time throughout professional training

Altered Drop Jump Landing Biomechanics Following Eccentric Exercise-Induced Muscle Damage

Limited research exists in the literature regarding the biomechanics of the jump-landing sequence in individuals that experience symptoms of muscle damage. The present study investigated the effects of knee localized muscle damage on sagittal plane landing biomechanics during drop vertical jump (DVJ). Thirteen regional level athletes performed five sets of 15 maximal eccentric voluntary contractions of the knee extensors of both legs at 60°/s. Pelvic and lower body kinematics and kinetics were measured pre- and 48 h post-eccentric exercise. The examination of muscle damage indicators included isometric torque, muscle soreness, and serum creatine kinase (CK) activity. The results revealed that all indicators changed significantly following eccentric exercise (p &lt; 0.05). Peak knee and hip joint flexion as well as peak anterior pelvic tilt significantly increased, whereas vertical ground reaction force (GRF), internal knee extension moment, and knee joint stiffness significantly decreased during landing (p &lt; 0.05). Therefore, the participants displayed a softer landing pattern following knee-localized eccentric exercise while being in a muscle-damaged state. This observation provides new insights on how the DVJ landing kinematics and kinetics alter to compensate the impaired function of the knee extensors following exercise-induced muscle damage (EIMD) and residual muscle soreness 48 h post-exercise

Bone mineral density in vocational and professional ballet dancers

Summary: According to existing literature, bone health in ballet dancers is controversial. We have verified that, compared to controls, young female and male vocational ballet dancers have lower bone mineral density (BMD) at both impact and non-impact sites, whereas female professional ballet dancers have lower BMD only at non-impact sites. Introduction: The aims of this study were to (a) assess bone mineral density (BMD) in vocational (VBD) and professional (PBD) ballet dancers and (b) investigate its association with body mass (BM), fat mass (FM), lean mass (LM), maturation and menarche. Methods: The total of 152 VBD (13 ± 2.3 years; 112 girls, 40 boys) and 96 controls (14 ± 2.1 years; 56 girls, 40 boys) and 184 PBD (28 ± 8.5 years; 129 females, 55 males) and 160 controls (27 ± 9.5 years; 110 female, 50 males) were assessed at the lumbar spine (LS), femoral neck (FN), forearm and total body by dual-energy X-ray absorptiometry. Maturation and menarche were assessed via questionnaires. Results: VBD revealed lower unadjusted BMD at all anatomical sites compared to controls (p < 0.001); following adjustments for Tanner stage and gynaecological age, female VBD showed similar BMD values at impact sites. However, no factors were found to explain the lower adjusted BMD values in VBD (female and male) at the forearm (non-impact site), nor for the lower adjusted BMD values in male VBD at the FN. Compared to controls, female PBD showed higher unadjusted and adjusted BMD for potential associated factors at the FN (impact site) (p < 0.001) and lower adjusted at the forearm (p < 0.001). Male PBD did not reveal lower BMD than controls at any site. Conclusions: both females and males VBD have lower BMD at impact and non-impact sites compared to control, whereas this is only the case at non-impact site in female PBD. Maturation seems to explain the lower BMD at impact sites in female VBD