The Effects of 17 Weeks of Ballet Training on the Autonomic Modulation, Hormonal and General Biochemical Profile of Female Adolescents

Systematic review of methods used to measure training load in dance

Dance is a popular physical activity. Increased dance training has been associated with an increased risk of injury. Given the established association between training load (TL) and injury in sport, knowledge of how TL is currently being measured in dance is critical. The objective of this study is to summarise published literature examining TL monitoring in dance settings. Six prominent databases (CINAHL, EMBASE, Medline, ProQuest, Scopus, SportDiscus) were searched and nine dance-specific journals were handsearched up to May 2022. Selected studies met inclusion criteria, where original TL data were collected from at least one dancer in a class, rehearsal and/or performance. Studies were excluded if TL was not captured in a dance class, rehearsal or performance. Two reviewers independently assessed each record for inclusion at title, abstract and full-text screening stages. Study quality was assessed using Joanna Briggs Institute Critical Appraisal Tool checklists for each study design. The 199 included studies reported on female dancers (61%), ballet genre (55%) and the professional level (31%). Dance hours were the most common tool used to measure TL (90%), followed by heart rate (20%), and portable metabolic systems (9%). The most common metric for each tool was mean weekly hours (n=381; median=9.5 hours, range=0.2-48.7 hours), mean heart rate (n=143) and mean oxygen consumption (n=93). Further research on TL is needed in dance, including a consensus on what tools and metrics are best suited for TL monitoring in dance.

Effects of Different Training Interventions on Heart Rate Variability and Cardiovascular Health and Risk Factors in Young and Middle-Aged Adults: A Systematic Review

Introduction: Heart rate variability (HRV), the beat-to-beat variation of adjacent heartbeats, is an indicator of the function of the autonomic nervous system (ANS). Increased HRV reflects well-functioning of autonomic control mechanism and cardiovascular health. The aim of this systematic review is to provide a systematic overview of the effects of different physical training modalities on resting HRV and cardiovascular health and risk factors (i.e., baroreflex sensitivity, body fat, body mass, body mass index, blood pressure, heart rate recovery, VO₂ max, and VO₂ peak) in young and middle-aged (mean age of the studies samples up to 44 years), healthy adults.

Methods: A systematic review in accordance with the PRISMA guidelines was performed. Studies investigating the effects of different physical interventions (endurance, resistance, high-intensity, coordinative, or multimodal training) on HRV were included. Trials were considered eligible if the intervention lasted for at least 4 weeks and participants were regarded as general healthy. Five electronic databases were searched from 2005 to September 8th, 2020. The methodological quality of eligible studies was assessed by two study quality and reporting assessment scales (TESTEX and STARD_HRV). PROSPERO registration number: CRD42020206606.

Results: Of 3,991 retrieved records, 26 were considered eligible and analyzed. Twelve studies used an endurance training (of which three included high-intensity sessions), six studies resistance training, four studies coordinative training, two studies high-intensity training, and two studies used a multimodal intervention. Overall, the results showed for all types of intervention an improvement in linear and non-linear HRV parameters and cardiovascular health and risk factors. However, quality assessment revealed some methodological and reporting deficits.

Conclusion: This systematic review highlights the benefits of different types of physical training interventions on autonomic function and health parameters in young and middle-aged, healthy adults. In conclusion, higher training intensities and frequencies are more likely to improve HRV. For future studies, we recommend adhering to the criteria of methodological standards of exercise interventions and HRV measurements and encourage the use of non-linear HRV parameters.

Injury, Illness, and Training Load in a Professional Contemporary Dance Company: A Prospective Study

CONTEXT

Professional dance is a demanding physical activity with high injury rates. Currently, no epidemiologic data exist regarding the incidence of injury and illness together with training load (TL) over a long period of time.

OBJECTIVE

To provide a detailed description of injury, illness, and TL occurring in professional contemporary dancers.

DESIGN

Descriptive epidemiology study.

SETTING

A single professional contemporary dance company during a 1-year period.

PATIENTS OR OTHER PARTICIPANTS

A total of 16 male and female professional contemporary dancers.

MAIN OUTCOME MEASURE(S)

Injury data consisted of medical-attention injury (Med-Inj) and time-loss injury (Time-Inj). Illness was measured using the Wisconsin Upper Respiratory Tract Infection Survey. Training load was collected for each dance session using the session rating of perceived exertion and classified into 3 groups based on individual and group percentiles: low, medium, or high.

RESULTS

Reported injuries totaled 79 (86.1% new, 6.3% reinjury, and 7.6% exacerbation). The Med-Inj incidence rate was 4.6 per 1000 hours (95% confidence interval [CI] = 3.8, 5.8), and the Time-Inj rate was 1.4 per 1000 hours (95% CI = 0.8, 2.1). The median time until injury for Med-Inj and Time-Inj was 3 months. The number of days dancers experienced illness symptoms was 39.9 ± 26.9 (range = 1-96), with an incidence rate of 9.1 per 1000 hours (95% CI = 7.7, 10.7). Mean weekly TL was 6685 ± 1605 (4641-10 391; arbitrary units). Inconsistent results were found for the incidence of injury and illness based on individual and group categorizations of TL.

CONCLUSIONS

Professional dancing is associated with high injury and illness rates. This is worrying from a health perspective and underlines the need for further studies to understand how to decrease the risk. The TL is higher than in other sport disciplines, but whether the high incidence of injuries and illnesses is related to high training demands needs additional investigation, possibly conducted as international, multicenter collaborative studies.

The Validity of the Session Rating of Perceived Exertion Method for Measuring Internal Training Load in Professional Classical Ballet Dancers

The aim of this study was to investigate the convergent validity of session rating of perceived exertion (s-RPE) with objective measures of internal training load (TL) in professional classical ballet dancers. Heart rate and s-RPE data were collected in 22 professional classical ballet dancers across a total of 218 ballet class or rehearsal sessions. Eleven participants completed at least 9 sessions, and were therefore included in analyses of individual relationships between s-RPE and objective measures. To calculate s-RPE, the session duration was multiplied by the RPE, measured using the modified Borg CR-10 scale. The Edwards summated heart rate zones (Edwards TRIMP) and Banister training impulse (Banister TRIMP) methods were used as criterion measures of internal TL. Pearson product-moment correlation coefficients were used to determine intra-individual relationships between s-RPE and objective measures. Repeated measures correlations were used to identify intra-individual relationships common across the cohort. Positive linear relationships were seen between s-RPE and objective measures across all session types [Edwards TRIMP: r rm (195) = 0.81, p < 0.001; Banister TRIMP: r rm (195) = 0.79, p < 0.001], in ballet class [Edwards TRIMP: r rm (58) = 0.64, p < 0.001; Banister TRIMP: r rm (58) = 0.59, p < 0.001], and in rehearsals [Edwards TRIMP: r rm (119) = 0.82, p < 0.001; Banister TRIMP: r rm (119) = 0.80, p < 0.001], as well as across both males [Edwards TRIMP: r rm (136) = 0.82, p < 0.001; Banister TRIMP: r rm (136) = 0.80, p < 0.001], and females [Edwards TRIMP: r rm (57) = 0.80, p < 0.001; Banister TRIMP: r rm (57) = 0.78, p < 0.001]. Intra-individual correlation coefficients ranged from 0.46-0.96 [Edwards TRIMP: mean r = 0.81 ± 0.11, p = 0.051 - < 0.001; Banister TRIMP: mean r = 0.78 ± 0.14, p = 0.13- < 0.001]. These results demonstrate that s-RPE is a valid and practical method for measuring internal TL in professional classical ballet dancers.

The Effectiveness of Classical Ballet Training on Health-Related Outcomes: A Systematic Review

BACKGROUND

Regular physical activity is of paramount importance to reduce chronic disease risk. Classical ballet training requires balance, strength, and range of motion. Participation in social ballet classes is increasing. Ballet training interventions may be an alternative method of regular, enjoyable activity. This review aimed to determine the effectiveness of classical ballet training interventions on physical and psychological health.

METHODS

Ten databases were searched until April 2019. The included studies investigated classical ballet training interventions of a ≥4-week duration, on any population (no restrictions on experience and clinical condition), measuring physical health or psychological outcomes.

RESULTS

Twenty-three studies (25 intervention groups) were included, comprising experienced (19 groups) and novice dancers (6 groups). In experienced populations, muscular strength was the most commonly reported outcome. However, only 25% of these studies reported improvements. With novice dancers, including clinical populations, balance showed the most positive change, improving in 75% of studies that reported this measure.

CONCLUSIONS

Classical ballet training may improve balance in novices and maintain physical activity across the life span. Experienced dancers showed no further improvement, perhaps due to an already greater ability. There was large heterogeneity between the included studies. A greater focus on classical ballet interventions for inexperienced populations is required.

Injuries during transition periods across the year in pre-professional and professional ballet and contemporary dancers: A systematic review and meta-analysis

OBJECTIVE

To consider the association of injuries with transition periods in the dance year, i.e., when dancers return at the start of the year, and when they transition from rehearsal to performance periods.

METHODS

Six electronic databases were searched to November 2019. All English language peer-reviewed studies, of any study design investigating ballet and contemporary pre-professional and professional dance populations were included. Only those studies reporting on the timing of injury were included.

RESULTS

Fifteen cohort and two case-series studies were included. A meta-analysis of seven studies revealed the rate of injuries to be significantly higher for the second and third months (1.52; 95% confidence interval [CI]:1.11-2.08; 1.26; 95%CI:1.07-1.48 respectively) after the return to dance. Two further studies report more injuries up to Week 13 of the year. One study showed an increase in injured dancers at three and four weeks after transition from rehearsals to a performance season. Four studies show an increase in injuries at performance times.

CONCLUSIONS

Meta-analyses of seven studies shows the second and third months after returning to dance have a significantly higher rate of injuries. More research is needed to quantify training loads in dance. Practitioners should be cognisant of the higher injury rates during periods of transition and consider modifying load, as it is a potential contributing factor.

Cross-validation of prediction equations for estimating body composition in ballet dancers

Introduction

In sports related to low body weight, such as classical ballet, the assessment of body composition is important for monitoring performance and health status. This study aimed to cross-validate anthropometry and bioelectrical impedance (BIA) predictive equations for estimating body composition of non-professional classical ballet dancers, using dual-energy-X-ray absorptiometry (DXA) as a reference method.

Materials and methods

Thirty-seven female non-professional classical dancers (median age of 19 years), at intermediate/advanced level, were evaluated in a cross-sectional study. Body composition was evaluated by DXA, anthropometry and tetrapolar BIA. Twenty different predictive equations of anthropometry (n = 8) and BIA (n = 12) were used to estimate Body Fat (BF) and Fat-Free Mass (FFM), testing their validity against DXA using the Bland-Altman statistics.

Results

For BF estimated by anthropometry equations, just one equation showed agreement with DXA (r = 0.852, p < 0.0005; p = 0.600 for one sample T-test). According to the Bland-Altman analysis, this equation also showed validity, with the absence of proportional bias. Regarding the predictive BIA equations tested, none were valid for our study group.

Conclusion

Only one of the anthropometric equations, the one proposed by Durnin and Womerley (1974), but none of the BIA equations analyzed, was valid for the evaluation of body composition of the studied classical dancers. Our results emphasize the importance of previous cross-validation of existing equations or the development of specific equations for body composition assessment in specific populations.

Physiological and Psychological Changes at the End of the Soccer Season in Elite Female Athletes

This study compares and describes relationships among stress-recovery indices, the heart rate variability index, and the Cooper and Yo-Yo IR1 tests among female soccer players during the last six weeks of the competitive season. Sixteen female soccer players engaged in a pre-test of all of the variables. After having their training monitored for six weeks, a post-test was administered. The results revealed significant (p < 0.05) differences in the specific stress-recovery scales of the RESTQ-sport and in the frequency-domain variables of the HRV, although there were no significant differences in the general stress or general recovery scales. The Yo-Yo IR1 test, the Cooper test scores, and the means of the time-domain HRV variables did not exhibit any significant differences between the pre- and the post-test. The RMSSD variations exhibited very large and large correlations with the performance test and the RESTQ-sport variables, respectively. The variations in the HRV frequency-domain variables exhibited significant moderate and large correlations among the variations of the RESTQ-sport scales. Monitoring athletes at the end of the season may reveal contradictions between some variables. To help with the interpretation of these scales, some external aspects, such as athlete strain and monotony of training, should be considered.