Differences in preseason aerobic fitness screening in professional and pre-professional modern dancers.
Preparticipation physical examinations are mandatory for all collegiate student-athletes in the USA. (2) Increasingly, pre-professional dance training programs are adopting preseason screens to assess incoming students' health status. (3-6) Results from dancer screenings are often incorporated into wellness programs within the dance curriculum (7-9) or as part of company healthcare. (10) Increased awareness of fitness, participation in injury prevention and cross training programs, and aerobic and technical (11) demands of today's repertoire on all dancers emphasize the importance of understanding the current cardiorespiratory fitness of these individuals. The relationship between fatigue and dance injury (12-14) suggests that aerobic fitness training to reduce fatigue is warranted. Although recent research in the UK has focused on fitness in the contemporary dancer, (15-20) it is currently unclear whether contemporary dance and modern dance are interchangeable or have differing training and performance requirements. Currently, data on the cardiorespiratory fitness levels of professional and pre-professional modern dancers are limited.
Two modern dance based pre-professional university programs and two modern dance companies have used a common demographic intake and preseason screen for over 10 years. The two companies and one of the university programs are housed within one organization. All four groups undergo common technique training that includes Horton, Graham, ballet, African, and other dance forms. When comparing dancers of different training levels, the investigators asked whether pre-professional dancers are undergoing adequate aerobic training to meet the demands of a professional career.
The purposes of this study were 1. to investigate differences in aerobic fitness parameters, such as peak and recovery heart rate (HR), between groups and genders using an accelerated 3-min step test and 2. to investigate the effects of training variables on dancers' aerobic fitness over time in repeated annual screenings. Aerobic fitness was defined using several variables, including resting HR ([HR.sub.rest]), peak heart rate ([HR.sub.peak]), heart rate recovery ([HR.sub.recov]), and fitness rating as defined by the accelerated 3-min step test. (21,22)
Data for this study were compiled from preseason annual screens occurring each year at the beginning of the professional dancers' rehearsal period or students' academic training. The screens were conducted from 1998 to 2012, either as 1. part of the larger 30-min post-hire Dance/USA screen for professional dancers (21) or 2. part of the incoming 60-min dance screening for pre-professional students enrolled in one of two Bachelor of Fine Arts (BFA) university programs. A priori calculations for four groups, with a power of 95% and [alpha] = 0.05, determined a total sample size of 372 dancers. The majority of participants were only screened one time. A subset of that group was re-screened in subsequent years, affording a snapshot of change over time.
The screen consisted of a demographic and medical history questionnaire, followed by physical assessment. The screens were conducted at the rehearsal studios of the companies and schools and were administered by healthcare professionals, mostly physical therapists involved in the creation of the standardized screen and its guidelines. These same trained individuals administered the assessments from year to year.
Participants were either employed by their dance company (Prof-Sr and Prof-Jr) or enrolled in their respective BFA program (BFA-1 and BFA-2) and participated voluntarily in the study. Screening of the Prof-Sr company, comprised of 30 dancers, was initiated in 2006 with the development of the Dance/USA Task Force screening project. All dancers were screened that first year. A subset of those dancers was re-screened in consecutive years (N = 15). Generally, due to time constraints and touring schedule, only newly hired dancers were screened in the Prof-Sr company. Therefore, in any given year, out of 30 company dancers, one to five new dancers were screened. In the Prof-Jr company, all 12 dancers were screened each year. As this is a training company, there is a turnover of approximately 50% each year. In exceptional circumstances, a dancer stayed a third year and was re-screened that year as well. The number of incoming freshmen in the BFA programs fluctuated from year to year, ranging from 19 to 34 in BFA-1 and 8 to 15 in BFA-2. Dancers in BFA-1 were generally not re-screened annually unless they specifically requested it. The BFA-1 dancers that were re-screened were included in the repeated measures analysis of screening at three time points (N = 13). Dancers at the BFA-2 school, because it is a small program, were re-screened annually throughout their 4 years (N = 38). For professional dancers, all screens were completed in a single session during the rehearsal period at the start of the company's contract year. For incoming students, all screens were completed in a single session at the onset of the fall semester. Each participant gave written informed consent, and the Institutional Review Board for Human Ethics granted ethical approval for this study.
Aerobic fitness was tested using an accelerated 3-min step test. (21,22) The accelerated step test was previously vali dated against an incremental treadmill test comparing [HR.sub.peak], [HR.sub.recov], maximal [VO.sub.2] (VU2max), and recovery [VO.sub.2] ([VO.sub.2]recov). (22) HR was measured using Polar USA (Warminster, PA) HR monitors secured to each dancer's chest, with a receiver-watch worn on the wrist. Dancers wore running shoes and sat quietly for 5-min before [HR.sub.rest] and blood pressure (BP) were recorded. Participants were tested using a 0.305 m (12") step for 3-min at a rate of 112 steps x [min.sup.-1], maintained by a metronome. The metronome was started prior to the test to allow the dancers to familiarize themselves with the tempo. They were instructed to step "up, up, down, down" to the beat of the metronome. [HR.sub.peak] was recorded at 3-min. Dancers were seated immediately after completing the test, and [HR.sub.recov] was recorded at 1-min following completion of the step test. After removing their footwear, each dancer's height (m) was measured using a wall-mounted rigid tape measure, and mass (kg) was measured with a digital scale (Omron Scale HBF-300, Omron Healthcare Inc., Lake Forest, IL).
BMI was calculated from each dancer's height and mass. Each dancer was assigned a fitness rating based on gender, age, and [HR.sub.recov] step test results, according to YMCA step test guidelines. (23,24) Previous validation of the accelerated step test in dancers found correlation of fitness rating to [HR.sub.recov] was very high (r = 0.98). (22) Because male and female [HR.sub.recov] can differ by age and gender, the fitness ratings differentiate these variables by gender. Fitness ratings, as defined by the YMCA and ACSM, (23,24) were applied to the accelerated step-test results as currently used in the Dance/ USA Post-hire Health Screen for Professional Dancers (25) and by a number of collegiate pre-professional dance programs throughout the USA. The seven-category rating is 0 = Excellent, 1 = Good, 2 = Above Average, 3 = Average, 4 = Below Average, 5 = Poor, and 6 = Very Poor.
Demographic information regarding age, height, mass, years of dance training, years as a professional dancer, and whether the individual had a history of asthma, smoking, or participated in supplemental cross training or aerobic training was entered into a database in Excel. Cross training was defined as all non-dance and non-aerobic activities such as strength training, stretching, Pilates, Gyrotonics, yoga, etc. Aerobic training was defined as activities such as biking, swimming, running, elliptical walker, speed walking, stair master, etc. The number of positive answers to smoking, asthma, cross training, and aerobic training was calculated as a percentage of total answers. For aerobic and cross training, participants were asked to give examples in each category to determine whether they understood the question, as well as number of hours and frequency of training each week, to validate that they met our criteria for a positive answer.
Comparisons were made between the two professional and two pre-professional groups, with respect to age, height, and mass, using a 4 (group) X 2 (gender) MANOVA for the three dependent variables in SPSS (21.0, IBM Corp, Armonk, NY). A second 4 X 2 MANOVA examined years of dance training and BP (systolic and diastolic). A third 4 X 2 MANOVA evaluated the outcome variables, [HR.sub.rest], [HR.sub.peak], [HR.sub.recov], and fitness rating. Each dependent variable was checked for outliers using Mahalanobis distance values. Those outliers exceeding the cut off determined by [X.sup.2] table were eliminated (N = 3). Multivariate variables were checked for linearity, multi-collinearity, and homogeneity of variance and covariance (Box's M test), and for individual variables, Levene's test was applied. As several assumptions were violated, Pillai's trace was used for unequal sample size. With a selected significance of p < 0.05, an adjusted significance value and confidence intervals were calculated using Bonferroni corrections (p < 0.0167 and 0.0125 for three and four dependent variables, respectively). Post hoc analyses were conducted using Scheffe's tests for unequal sample size.
Asthmatic and smoking status and aerobic and cross training were coded for presence or absence. Again, they were tested for assumptions of normality. As several assumptions were violated, adjustments were made as listed above, with a corrected significance value of p < 0.025.
Pearson product moment and Spearman's rho correlations were used to determine whether there was a relationship between dancers' [HR.sub.rest], [HR.sub.peak], fitness rating, BMI, age, BP, and [HR.sub.recov].
For those dancers who were r-escreened over several years, a repeated measures ANOVA for Group X Time was conducted to ascertain any changes in cardiorespiratory parameters, p < 0.05. Mauchly's test was examined for violations of sphericity. In the case of significance, the Huynh-Feldt correction was applied to the degrees of freedom (DOF) and F-value. There were no cases of sphericity. The analysis of 3 years included all four groups, and the analysis of 4 years examined BFA-2 only. Pairwise comparisons were conducted where there was a significant main effect.
Data were collected from 577dancers (452 female, 125 male) out of a potential 584 dancers (99%) in the four groups (Table 1). This included 98 professional and 479 pre-professional dancers. Those who did not participate were injured or unavailable during the screening period. Professional companies had an equal ratio of male to female dancers, while pre-professional programs had a greater number of females compared to males. Participants represented a diversity of ethnic backgrounds, including 44% African-American, 40% Caucasian, 9% Hispanics, 4% Asian, and less than 1% Native American, African, Middle Eastern, and Caribbean.
Professional dancers spent 7.5 hrs/ wk in technique class. The remainder of their time was spent either in rehearsal or performance (30 hrs/wk). In contrast, pre-professional dancers spent 21 (BFA-1) and 16.5 (BFA-2) hrs/wk, respectively, in technique classes. Both pre-professional semesters culminated in two performances at the end of the fall and spring semesters, with approximately 3.0 to 6.0 hrs/wk of rehearsal.
There were differences between groups in age (p < 0.001) but not gender. Post hoc analysis revealed Prof-Sr dancers were older than Prof-Jr dancers, followed by BFA-2 and BFA-1 (p [less than or equal to] 0.009). There were no differences between groups in height or mass, but there were differences between genders, with males greater than females for height (p < 0.001) and mass (p < 0.001).
There were differences between groups in years of dance training (p < 0.001). Prof-Sr dancers had a greater number of years of dance training than Prof-Jr dancers, BFA-1, and BFA-2 (p < 0.001); Prof-Jr had more dance training than BFA-2 (p = 0.014). There were no differences in years of training between the pre-professional groups, BFA-1 and BFA-2. There were also differences between genders in years of dance training: females greater than males (p < 0.001).
Of the dancers who answered the relevant questions, there were no differences in smoking (9%) or asthma rates (14%) between groups or genders (Table 2). Forty-three percent of dancers said that they performed cross training activities regularly (1 to 4 times per week for the past year), with no differences between groups or genders. Thirty-six percent of dancers said they performed aerobic training. There were differences between groups in aerobic training (p = 0.014) but no differences between genders. Post hoc analysis found no differences.
Mean BP was 114/71 mmHg (Table 3). There was a difference between groups and genders in systolic BP (p < 0.001) but not in diastolic BP. Females' systolic BPs were lower than males'. Post hoc, Prof-Sr, and Prof-Jr dancers' systolic BPs were lower than BFA-1 (p [less than or equal to] 0.002). There were also differences between groups in [HR.sub.rest] (p < 0.001). Post hoc, Prof-Sr, and Prof-Jr dancers' mean [HR.sub.rest] was lower than that of BFA-1 and BFA-2 dancers (p < 0.001), and BFA-1 was lower than BFA-2 (p < 0.001). There were no differences between genders in [HR.sub.rest].
Mean [HR.sub.peak] was 150 [+ or -] 18 beats-[min.sup.-1] (range 99 to 201 beats x [min.sup.-1]), with differences between groups (p < 0.001). Post hoc, Prof-Sr, and Prof-Jr dancers' [HR.sub.peak] was lower than that of BFA-1 and BFA-2 (p < 0.001), and BFA-1 was lower than BFA-2 (p = 0.004). There was also a gender difference, with [HR.sub.peak] lower in males compared to females (p < 0.001). [HR.sub.recov] followed a similar pattern, with differences between groups (p < 0.001). Post hoc, Prof-Sr, and Prof-Jr dancers' mean [HR.sub.recov] was lower than that of BFA-1 and BFA-2 (p < 0.001), and BFA-1 was lower than BFA-2 (p = 0.004). This pattern was also reflected in the differences between groups in fitness ratings (p < 0.001). Post hoc, Prof-Sr, and Prof-Jr dancers' fitness ratings (more fit) exceeded those of BFA-1 and BFA-2 dancers (p < 0.001), and BFA-1 fitness ratings exceeded those of BFA-2 (p < 0.001). There were no differences between genders in [HR.sub.recov] or fitness ratings.
Resting HR was strongly correlated to [HR.sub.recov] (r = 0.61, p < 0.001), fitness rating (r = 0.58, p < 0.001), and [HR.sub.peak] (r = 0.70, p < 0.001). [HR.sub.peak] was highly correlated to [HR.sub.recov] (r = 0.70, p < 0.001) and fitness rating (p = 0.62, p < 0.001), and [HR.sub.recov] was highly correlated to fitness rating (r = 0.94, p < 0.001). Age demonstrated a weak negative correlation to [HR.sub.recov] (r = -0.220, p < 0.001), but there was no relationship between BMI or BP and [HR.sub.recov].
Changes Over Time
Seventy-two dancers from the four groups were screened over 3 years (Table 4). There were changes in systolic BP between groups (p = 0.001). Systolic BP in Prof-Sr was lower than that of BFA-1 and BFA-2 dancers (post hoc Prof-Sr versus BFA-1, p = 0.017, Prof-Sr versus BFA-2, p < 0.001). There were differences across the 3 years (p = 0.044; pairwise comparisons year 1 versus year 2, p = 0.004, and year 1 versus year 3, p = 0.044), with systolic BP lowering over the 4 years, and a group-by-time interaction (p = 0.002). There were no differences between groups in diastolic BP, but there were differences due to time (p = 0.005; pairwise comparisons year 1 versus year 2, p = 0.003; year 2 versus year 3, p = 0.028).
There were differences due to group in [HR.sub.rest] (p < 0.001; pairwise comparisons BFA-2 dancers versus Prof-Sr and Prof-Jr, p < 0.007) and [HR.sub.peak] (p < 0.001; pairwise comparisons BFA-2 dancers versus Prof-Sr and Prof-Jr, p [less than or equal to] 0.012), but not time. There were differences in [HR.sub.recov] between groups (p < 0.001, pairwise comparisons Prof-Sr, Prof-Jr, BFA-1 vs. BFA-2, p < 0.001), and time (p = 0.023), with an interaction between time and group (p = 0.006). [HR.sub.recov] in BFA-2 dancers improved over time, declining over the 3 years (pairwise comparisons BFA-2 dancers versus other groups p < 0.001). Differences in fitness ratings were also found between groups (p < 0.001, pairwise comparisons ProfSr, Prof-Jr, BFA-1 versus BFA-2, p < 0.001), time (p = 0.001, pairwise comparisons year 1 versus year 2 and year 3, p = 0.004), with an interaction between time and group (p = 0.001). Overall fitness ratings improved over time (p < 0.001). While the aerobic fitness of Prof-Sr and Prof-Jr remained higher than that of the BFA dancers, change over time was seen in the BFA-2 dancers compared to the other groups (p < 0.001), improving consistently over the 3 years.
Twenty dancers from the BFA-2 group were screened consecutively over 4 years (Table 4). There were consistent decreases in [HR.sub.recov] (p < 0.001, pairwise comparisons year 1 versus years 2, 3, and 4, p [less than or equal to] 0.021) and improvement in fitness ratings (p = 0.001, pairwise comparisons year 1 versus years 2, 3, and 4, p [less than or equal to] 0.006) over the 4 years.
Professional dancers exhibited lower [HR.sub.rest], [HR.sub.peak], [HR.sub.recov], and better fitness ratings compared to pre-professional dancers. Fitness ratings did not change from year to year in professional dancers, but improved over time in pre-professional dancers. Correlations of HR variables, fitness ratings, age, BP, and BMI found positive relationships between [HR.sub.recov], [HR.sub.peak], [HR.sub.rest], and fitness ratings, and a negative relationship between [HR.sub.recov] and age, but no relationship between [HR.sub.recov] and BMI.
Professional and Pre-Professional Demographic Characteristics
The differences between groups in age and years of dance training but not in height, mass, or BMI were to be expected. There were no differences in years of training between the pre-professional groups, BFA-1, and BFA-2. Therefore, baseline characteristics of pre-professional dancers did not differ.
Similar rates of smoking and asthma were reported among groups. While the rate of smoking found in the Prof-Sr group in this study is higher than previously reported for this company, (21) this project reflects data collected from Prof-Sr from 2006 to 2012. Current rates in a recent single screening year are more in line with those previously reported. (21) According to the Center for Disease Control and Prevention, 19% of adults in the USA report smoking. (26) Although the overall rate of 9% in this study is lower than the national average, smoking cessation support remains an important issue to promote among all dancers. Studies report increased fatigue and decreased [VO.sub.2max] in smokers compared to non-smokers. (27,28) In 2013 Center for Disease Control and Prevention surveillance data, asthma prevalence was 7% of US adults, 6.2% males and 8.3% females, 9.9% blacks, 7.4% whites, and 5.9% Hispanics (note that the CDC reports ethnicity differently than we do here). (29) In a recent review, 7% to 8% of Olympic athletes suffered from exercise-induced asthma. (30) The asthma rate of 14% in this study was higher than both these reports. This may be explained by several factors, including the higher prevalence of asthma in black Americans (almost half of our population were African Americans) and the lower asthmatic stressors induced by dance training compared to endurance sports. It is thought that intense training regimens with the added factors of training outdoors in the cold, exposure to particulate matter, exposure to chloramines in the case of swimmers or other poor quality air produce a progressive process of exercise-induced airway hyper-responsiveness and asthma. (30) It may be that individuals with asthma are relatively more successful in dance, which is usually practiced indoors, compared to endurance sport athletes who are exposed to these other factors.
Systolic BP differed between groups and genders but not diastolic BP, and all BP results were within normal ranges. While lower BP has been found to be associated with lower resting HR and aerobic fitness, (31) we did not find this relationship.
Professional and Pre-Professional Aerobic Fitness
Aerobic training is an important determinant of maximal oxygen uptake ([VO.sub.2max]) as well as related HR variables. (32) Both [HR.sub.rest] and [HR.sub.recov] are risk factors for overall mortality. (31,33) Therefore, aerobic fitness becomes important not only as a factor in fatigue-related injury but for lifelong health. The fast phase of recovery following high intensity intermittent exercise includes a rapid decline in both [VO.sub.2] and HR. (34) The ability to recover quickly is critical in dance performance, which may require repeated episodes of high intensity dancing.
Both professional groups exhibited enhanced aerobic fitness, based on their [HR.sub.recov], compared to pre-professional dancers. Overall, professional dancers spent a great deal more time dancing, whether in class, rehearsal, or performance, compared to pre-professional students; and more Sr-Prof dancers performed cross training and aerobic training activities in comparison to the other groups. In a previous comparison of professional modern and ballet companies using the accelerated step test, modern dancers demonstrated enhanced aerobic fitness compared to their ballet counterparts. (21) This difference was also found in previous studies using [VO.sub.2max] tests of aerobic fitness in professional ballet and modern dancers. (22,35-40) (Note that we did not include the research reporting on aerobic fitness in contemporary dancers. Although modern and contemporary dance have common roots, it is not clear whether the current dance training and performance requirements of modern and contemporary dancers are the same.)
Age was negatively correlated to [HR.sub.recov], meaning that older dancers tended to have improved [HR.sub.recov]. This is an unusual finding, as generally fitness declines and [HR.sub.recov] is slowed with aging. However, comparisons of trained younger (in their 20's) and older athletes (in their 50's) found no differences in [HR.sub.recov]. (41) The age range of the dancers in the current study was a continuum of 18 to 35 years; therefore, the negative relationship between age and [HR.sub.recov] may be more reflective of the demands of professional dance.
A review of [VO.sub.2max] in dancers indicates that female dancers typically exhibit a range of 39 to 54 and males 45 to 67 ml x [kg.sup.-1] x [min.sup.-1] values. The greatest focus to date has been on assessing [VO.sub.2max] in professional ballet dancers (females 39 to 53, males 46 to 59 ml x [kg.sup.-1] x [min.sup.-1]). (18,35-38,42,43) Less well studied are modern and other dance forms in professional or university level dancers. A summary of [VO.sub.2max] findings includes professional modern (females 49 to 52 and males 67 ml x [kg.sup.-1] x [min.sup.-1]), (22,39) professional contemporary (46 ml x [kg.sup.-1] x [min.sup.-1]), (44) professional jazz (females 42, males 49 ml x [kg.sup.-1] x [min.sup.-1]), (45) professional competitive ballroom (females 42 to 54, males 53 to 61 ml x [kg.sup.-1] x [min.sup.-1]), (46-48) university ballet (females 41 to 47 ml x [kg.sup.-1] x [min.sup.-1]), (39,49) and university modern dancers (females 39 to 51, combined females and males 51 ml x [kg.sup.-1] x [min.sup.-1]). (22,49-51) This summary suggests that female modern dancers exhibit values similar to those of professional ballet and ballroom dancers, and male modern dancers exhibit higher values than their ballet and ballroom counterparts.
Comparisons of [VO.sub.2max] in professional and pre-professional modern dancers found no differences in one study. (52) However, in a second study, increased [VO.sub.2max] suggested higher aerobic fitness in female professional modern dancers compared to pre-professional students. (39) While this study did not investigate [VO.sub.2max], our findings of enhanced aerobic fitness (based on [HR.sub.recov] and fitness ratings) in the professional compared to preprofessional dancers support the findings of Chmelar and coworkers. (39) We also found differences in [HR.sub.recov] and fitness ratings between pre-professional groups. BFA-1 dancers had greater aerobic fitness compared to BFA-2 dancers. Demographic characteristics were similar between the two groups. While we are unable to identify the reason for this difference, one program is considered to be more demanding, with a difficult audition process for entry, than the other. It may be that students entered BFA-1 with a higher pre-existing baseline of fitness and skill-based training. By the second year of screening, all pre-professional students were undergoing relatively similar dance training; however, in addition, BFA-2 had weekly supplemental wellness classes. This may account for some of the improvement in fitness measures seen in BFA-2 over subsequent years.
The aerobic capacity of dancers is generally lower than other athletes and similar to active age-matched individuals. (49) While dance performance has been categorized as a high intensity intermittent exercise activity, (53,54) the cardiorespiratory response to modern dance and ballet technique classes is considered insufficient to promote the aerobic adaptation sought in higher levels of aerobic fitness. (54,55) Monitoring of dance class, rehearsal, and performance in both professional and pre-professional contemporary dancers found performance required significantly greater HR and oxygen consumption, (54) pointing to a need for supplemental training. Our results suggest there is a need for supplemental training in modern dancers as well.
Changes Over Time in Aerobic Fitness
All the groups we tested had access to aerobic and fitness equipment. When results of the screen were reviewed with each participant, the importance of supplemental training was always emphasized. In particular, dancers were counseled to add supplemental aerobic training if their fitness ratings were from 3 to 7.
We analyzed change in fitness variables over time in a subset of groups that underwent annual screening. The professionals' [HR.sub.recov] and fitness remained stable over time. Only one group, BFA-2, demonstrated improvements in [HR.sub.recov] and fitness. There are several explanations for this finding. First, both groups of professional dancers spend more hours per week dancing than both groups of pre-professional dancers. Second, based on their annual rehearsal and performance schedule, it is likely that Prof-Sr maintained a relatively steady state of fitness. Annually, there is only one long vacation break of 3 weeks following a rigorous New York season. All other breaks are 1 to 2 weeks in length. The Prof-Jr group had more time off, but the amount of dancing in which they participated may have been more rigorous, as there are only 12 dancers who perform in the majority of the repertory. In contrast, the pre-professional dancers were not in school all summer (approximately 16 weeks), and it is up to them to take technique classes and maintain their fitness. Third, it is possible that there was insufficient opportunity for pre-professionals to add supplemental training to their already rigorous dance and academic class schedule during the school year. However, the mandatory wellness class (50 min/wk) supplemented BFA-2 training. This may have played an important part in the fitness improvements measured over 4 years in the BFA-2 group. The weekly wellness classes emphasized the practice of sound dance biomechanics and developed individualized strengthening, stretching, and aerobic programs for each dancer to perform on their own. In contrast, BFA-1 dancers learned about injury prevention, including the practice of sound dance biomechanics and principles of effective aerobic conditioning, in a single workshop.
[HR.sub.recov] improves with aerobic training and is therefore considered to be a sensitive marker of change in aerobic fitness over time. (56) Pre-professional dancers demonstrated improvement in aerobic fitness over time. Professionals, while continuing to demonstrate greater fitness, did not change. Despite dancing fewer hours/wk compared to BFA-1, only the BFA-2 dancers demonstrated significant improvement compared to the other groups. Therefore, it is likely that the mandatory wellness classes were responsible for this difference. Researchers have demonstrated improvement in aerobic fitness with supplemental training of varying lengths from 6 weeks to 1 year in pre-professional and professional modern and contemporary dancers (17,50,57) as well as professional ballet dancers, (58,59) thus supporting our findings. In contrast, other researchers have reported no change in aerobic fitness in pre-professional dancers with a 4-month conditioning program. (60) We may have seen no change over time in the professional dancers as they were maintaining the aerobic fitness required for their workload, a level that exceeded that of the pre-professionals.
Preliminary investigations report that pre-professional ballet dancers with lower levels of aerobic fitness suffer more musculoskeletal injuries than those with higher levels. (14) Several other studies analyzed injury factors retrospectively from dance injury reports and found fatigue to be the most common variable cited by dancers. (12-14) Prospective studies of military trainees found that lower aerobic fitness is related to increased risk for musculoskeletal injury. (61) Greater cardiorespiratory fitness might serve to reduce the effects of fatigue; however, a clear relationship remains to be demonstrated for dance.
Supplemental Training Recommendations for Pre-Professional Dancers
It is now well established that dance technique classes by themselves do not sufficiently challenge the aerobic and anaerobic systems to attain the fitness level necessary for performance. (44,53,54,62) Studies suggest that dance performance requires energy expenditure up to 85% of VU2max and 80% to 95% of [HR.sub.max]. (37,63,64) Increasingly, recommendations are being made for dancers to supplement their dance training with aerobic conditioning. (20,53,65) Research suggests that a combination of high volume low to moderate intensity (HVL-MI) aerobic exercise combined with short-term high intensity interval training (HIIT) may provide optimal training. (66,67)
Aerobic exercise includes running, swimming, cycling, aerobics classes, or other continuous activities that result in an increased HR for 20 to 40 minutes. An optimal target training range is 70% to 90% of [HR.sub.max] ([HR.sub.max] is estimated as 220--age). (20,53) To make improvements, exercise frequency of 3 to 4 times/wk is recommended. When considering supplemental training to increase performance, the majority of focus is on (HVL-MI) aerobic exercise. This provides the platform upon which to introduce HIIT exercise. Maintenance programs, when HIIT activities are introduced or dancers have begun performance, require HVL-MI training one to two times per week.
HIIT involves intermittent exercise at "all-out" or "supra-maximal" intensity, (66) in which participants work at levels greater than or equal to 90% to 95% [VO.sub.2max] or 90% to 95% [HR.sub.max]. (67) The type of exercise may include bursts of sprint running, sprint cycling, jumping, or combinations thereof. HIIT exercise is comprised of anywhere from 1:1 to 1:5 ratios of exercise to active rest (active rest such as walking or slow jogging is encourage to promote faster recovery) depending on the age of the population, level of training, and type of training. A range of intervals have been suggested, for example, from 15 seconds of exercise and 15 seconds of active rest (1:1 ratio) to 30 seconds of exercise and 2 minutes of active rest (1:4 ratio). (66-69) These bouts of alternating exercise followed by active rest are repeated up to 10 times. Generally, based on the research literature, a limited period of HIIT exercise is recommended 2 to 4 weeks before the dancer wishes to reach peak performance levels. A ratio of 75% HVL-MI aerobic training to 10 to 15% HIIT activity is recommended (with less than 10% devoted to warm up and cool down low intensity activity). Too much HIIT exercise, particularly without adequate recovery, can lead to over-training and burnout. (66,70)
Dance performance is comprised of intermittent periods of varying lengths that range from low to high intensity, with some choreography comprised of greater periods of high intensity while others may fluctuate between various levels. Intense exercise performance requires both aerobic and anaerobic components. Both types of training, as outlined above, are important because different adaptations occur depending on the type of training.
Our annual screening does not assess [VO.sub.2max] due to the number of dancers that are screened in a relatively short time and equipment constraints. Although our results report preseason aerobic fitness in dancers, it should be noted that this estimate is relative to physical fitness criteria and does not indicate the participant's level of skill-related fitness.
Heart rate has a positive relationship to energy expenditure during physical activity and can serve as an accurate indirect measure to evaluate metabolic demand. (71) The 1-min [HR.sub.recov] variable represents the fast recovery phase, with more rapid recovery indicating individuals with a higher aerobic capacity. (41) [VO.sub.2max] is not required to estimate aerobic fitness, as [HR.sub.recov] has demonstrated a strong relationship with training in steady state, moderate, and high intensity exercise, as well as intermittent exercise. (34,71-73)
Recent research has focused on alternative ways of screening for aerobic fitness in dancers, such as the Dance Specific Aerobic Fitness Test (DAFT) for contemporary dancers and a ballet-specific test. (44,74-76) One argument against using dance-specific fitness tests is that a given test may only be appropriate for one dance form (e.g., contemporary dance or ballet), require a familiarization period, and can be lengthy (up to 20 minutes). (44,76) While these tests measure maximal HR, they do not report [HR.sub.recov] and therefore cannot be compared with the results of the accelerated step test. Furthermore, they do not allow for comparisons across genres.
Currently, the Dance/USA posthire health screen, used to evaluate the professional modern dancers in this study, provides only 20 minutes per dancer for the assessment of medical history, vital signs, fitness, and other physiologic measures. (1,77) These tests are administered onsite in the dance studio or physical therapy room. The accelerated step test, requiring a total of 4-min, is efficient and utilizes minimal, low cost equipment.
As greater numbers of dancers at all levels of training are screened, we will be able to establish norms for various parameters. In the future, this will enable researchers, dance faculty, healthcare providers, and company artistic staff to establish best practice to optimize training and conditioning for dancers of all ages.
The ability to conduct large studies on dancers is limited. Here, we report screening results from the largest group of professional and pre-professional modern dancers tested to date in the USA. Screening programs will not by themselves decrease injuries; it is through the information gathered from screening that change may be studied and implemented. Differences between pre-professional and professional dancer aerobic fitness suggest it remains particularly important to emphasize aerobic training at the pre-professional level as preparation for the demands of professional careers. If we classify dance as having components of high-intensity intermittent exercise, aerobic fitness enhances recovery from these recurrent periods. The ability to recover quickly is critical to enable optimal performance in subsequent choreographic sequences. Greater aerobic conditioning during pre-professional training is imperative to meet the increasing demands of choreography at the professional level. Future study of the relationship between aerobic fitness and implementation of more stringent training programs on the incidence of injury is necessary.
* Professional modern dancers display greater aerobic fitness than pre-professional dancers.
* Supplemental aerobic training is recommended for pre-professional modern dance students to prepare themselves for the demands of a professional career.
* Wellness programs that include aerobic exercise appear to be effective in improving aerobic fitness in pre-professional dancers.
(1.) Southwick H, Gibbs R, Bronner S, Cassella M. Update on the annual post-hire health screen for professional dancers: Dance/USA Taskforce on Dancer Health. Presented at: XVIII Annual Meeting of International Association for Dance Medicine & Science 2008. Cleveland, OH: IADMS, 2008.
(2.) Klossner D. National Collegiate Athletic Association. 2013-14 NCAA Sports Medicine Handbook (24th ed). Indianapolis, IN: National Collegiate Athletic Association, 2013. Available at: www.ncaa.org/sites/default/files/2013-14 Sports Medicine Handbook.pdf.
(3.) Fuller M, Peirce D. Screening practices in dance: applying the research. Presented at: Dance Dialogues: Conversations across Cultures, Artforms and Practices. Brisbane, Australia, 2008.
(4.) Gamboa JM, Roberts LA, Maring J, Fergus A. Injury patterns in elite preprofessional ballet dancers and the utility of screening programs to identify risk characteristics. J Orthop Sports Phys Ther. 2008 Mar;38(3):126-36.
(5.) Molnar M, Esterson J. Screening students in a pre-professional ballet school. J Dance Med Sci. 1997;1(3):118-21.
(6.) Southwick H, Cassella M. Boston ballet student screening clinic: an aid to injury prevention. Orthop Phys Ther Practice. 2002;14(2):14-6.
(7.) Department of Performing Arts LIUB. Dance Wellness. Available at: www.liu.edu/Brooklyn/Academics/ Schools/CLAS/Programs/Div4/PA/ Dance2/Dance-Wellness. Accessed September 14, 2014, 2014.
(8.) Department of Dance Case Western Reserve. Dancer Wellness Program. dance.case.edu/dancer-wellnessprogram/. Accessed February 23, 2015.
(9.) Texas A&M Dance Program. Dancer Wellness Clinic. dance.tamu.edu/ about/dance-wellness. Accessed February 23, 2015.
(10.) Clark T, Gupta A, Ho CH. Developing a dancer wellness program employing developmental evaluation. Front Psychol. 2014 Jul 10;5:731.
(11.) Deprati E, Iosa M, Haggard P. A dance to the music of time: aesthetically-relevant changes in body posture in performing art. PlosOne. 2009;4(3):e5023.
(12.) Laws H. Fit to Dance2--Report of the Second National Inquiry Into Dancers' Health and Injury in the UK. London, UK: Dance UK, 2005.
(13.) Liederbach M, Compagno J. Physiological aspects of fatigue-related injuries in dancers. J Dance Med Sci. 2001;5(3):116-20.
(14.) Twitchett E, Brodrick A, Nevill AM, et al. Does physical fitness affect injury occurrence and time loss due to injury in elite vocational ballet students? J Dance Med Sci. 2010;14(1):26-31.
(15.) Angioi M, Metsios GS, Koutedakis Y, et al. Physical fitness and severity of injuries in contemporary dance. Med Probl Perform Art. 2009;24(1):26-9.
(16.) Angioi M, Metsios GS, Koutedakis Y, Wyon MA. Fitness in contemporary dance: a systematic review. Int J Sports Med. 2009 Jul;30(7):475-84.
(17.) Angioi M, Metsios GS, Twitchett EA, et al. Effects of supplemental training on fitness and aesthetic competence parameters in contemporary dance. Med Probl Perform Art. 2012 Mar;27(1):3-8.
(18.) Brinson P, Dick F. Fit to Dance? London: Calouse Gulbenkian Foundation, 1996.
(19.) Redding E, Wyon M, Shearman J, Doggart L. Validity of using heart rate as a predictor of oxygen consumption in dance. J Dance Med Sci. 2004;8(3):69-72.
(20.) Wyon MA. Cardiorespiratory training for dancers. J Dance Med Sci. 2005;9(1):7-12.
(21.) Bronner S, Ojofeitimi S, Bailey Lora J, et al. A preseason cardiorespiratory profile of dancers in nine professional ballet and modern companies. J Dance Med Sci. 2014;18(2):72-81.
(22.) Bronner S, Rakov S. An accelerated step test to assess dancer preseason aerobic fitness. J Dance Med Sci. 2014;18(1):12-21.
(23.) American College of Sports Medicine. ACSM's Guidelines for Exercise Testing and Prescription (8th ed). Philadelphia: Lippincott Williams & Wilkins, 2009.
(24.) Golding L, Myers C, Sinning WE. The YMCA Physical Fitness Test Battery. Y's Way to Physical Fitness (4th ed). Champaign, IL: Human Kinetics, 1989, pp. 61-138.
(25.) Gibbs R, Bronner S, Cassella M, et al. Annual Post-Hire Health Screen for Professional Dancers Guidelines. 2006. Available at: Available at: www2.dance-usa.org/uploads/Dancer_Health/ resources_HealthScreenGuidelines. pdf.
(26.) Schiller JS, Lucas JW, Peregory JA. Summary Health Statistics for U.S. Adults: National Health Interview Survey. Washington, DC: National Center for Health Statistics. Vital Health Stat 10(252), 2012.
(27.) Klausen K, Andersen C, Nandrup S. Acute effects of cigarette smoking and inhalation of carbon monoxide during maximal exercise. Eur J Appl Physiol Occup Physiol. 1983;51(3):371-9.
(28.) Lee C-L, Chang W-D. The effects of cigarette smoking on aerobic and anaerobic capacity and heart rate variability among female university students. Int J Womens Health. 2013 Oct 17;5:667-79.
(29.) Asthma surveillance data. US Dept. of Health and Human Services; 2013. Available at: www.cdc.gov/ asthma/asthmadata.htm. Accessed February 26, 2015.
(30.) Kippelen P, Fitch KD, Anderson SD, et al. Respiratory health of elite athletes--preventing airway injury: a critical review. Br J Sports Med. 2012 Jun;46(7):471-6.
(31.) Tell GS, Vellar OD. Physical fitness, physical activity, and cardiovascular disease risk factors in adolescents: the Oslo youth study. Prev Med. 1988 Jan;17(1):12-24.
(32.) Uth N, Sorensen H, Overgaard K, Pedersen PK. Estimation of [VO.sub.2max] from the ratio between [HR.sub.max] and [HR.sub.rest]--the Heart Rate Ratio Method. Eur J Appl Physiol. 2004 Jan;91(1):111-15.
(33.) Watanabe J, Thamilarasan M, Blackstone EH, et al. Heart rate recovery immediately after treadmill exercise and left ventricular systolic dysfunction as predictors of mortality: the case of stress echocardiography. Circulation. 2001 Oct 16;104(16):1911-16.
(34.) Tomlin DL, Wenger HA. The relationship between aerobic fitness and recovery from high intensity intermittent exercise. Sports Med. 2001;31(1):1-11.
(35.) Cohen JL, Segal KR, Witriol I, McArdle WD. Cardiorespiratory responses to ballet exercise and the [VO.sub.2max] of elite ballet dancers. Med Sci Sports Exerc. 1982;14(3):212-17.
(36.) Micheli LJ, Gillespie WJ, Walaszek A. Physiologic profiles of female professional ballerinas. Clin Sports Med. 1984 Jan;3(1):199-209.
(37.) Schantz P, Astrand P. Physiologic characteristics of classical ballet. Med Sci Sports Exerc. 1984 Oct;16(5):472-6.
(38.) Wyon MA, Deighan MA, Nevill AM, et al. The cardiorespiratory, anthropometric, and performance characteristics of an international/national touring ballet company. J Strength Cond Res. 2007 May;21(2):389-93.
(39.) Chmelar RD, Schultz BB, Ruhling RO, et al. A physiologic profile comparing levels and styles of female dancers. Phys Sportsmed. 1988;16(7):87-94.
(40.) Kirkendall DT, Calabrese LH. Physiological aspects of dance. Clin Sports Med. 1983 Nov;2(3):525-37.
(41.) Darr KC, Bassett DR, Morgan BJ, Thomas DP. Effects of age and training status on heart rate recovery after peak exercise. Am J Physiol. 1988 Feb;254(2 Pt 2):H340-3.
(42.) Mostardi RA, Porterfield JA, Greenberg B, et al. Musculoskeletal and cardiopulmonary characteristics of the professional ballet dancer. Phys Sportsmed. 1983;11(12):53-61.
(43.) Rimmer JH, Jay D, Plowman SA. Physiological characteristics of trained dancers and intensity level of ballet class and rehearsal. Impulse. 1994 Apr;2(2):97-105.
(44.) Redding E, Weller P, Ehrenberg S, et al. The development of a high intensity dance performance fitness test. J Dance Med Sci. 2009;13(1):3-9.
(45.) Lavoie JM, Lebe-Neron RM. Physiological effects of training in professional and recreational jazz dancers. J Sports Med Phys Fitness. 1982 Jun;22(2):231-6.
(46.) Kline GM, Porcari JP, Hintermeister R, et al. Estimation of [VO.sub.2max] from a one-mile track walk, gender, age, and body weight. Med Sci Sports Exerc. 1987 Jun;19(3):253-9.
(47.) Bria S, Bianco M, Galvani C, et al. Physiological characteristics of elite sport-dancers. J Sports Med Phys Fitness. 2011 Jun;51(2):194-203.
(48.) Liiv H, Jurimae T, Maestu J, et al. Physiological characteristics of elite dancers of different dance styles. Eur J Sport Sci. 2014 Jan;14(Suppl 1):S429-36.
(49.) White SB, Philpot A, Green A, Bemben MG. Physiological comparison between female university ballet and modern dance students. J Dance Med Sci 2004;8(1):5-10.
(50.) Koutedakis Y, Hukam H, Metsios G, et al. The effects of three months of aerobic and strength training on selected performance- and fitness-related parameters in modern dance students. J Strength Cond Res. 2007 Aug;21(3):808-12.
(51.) Wyon M, Head A, Sharp C, Redding E. The cardiorespiratory responses to modern dance classes: differences between university, graduate, and professional classes. J Dance Med Sci. 2002;6(2):41-5.
(52.) Chatfield SJ, Byrnes WC, Lally DA, Rowe SE. Cross-sectional physiologic profiling of modern dancers. Dance Res J. 1990 Spring;22(1):13-20.
(53.) Rafferty S. Considerations for integrating fitness into dance training. J Dance Med Sci. 2010;14(2):45-9.
(54.) Wyon MA, Abt G, Redding E, et al. Oxygen uptake during modern dance class, rehearsal, and performance. J Strength Cond Res. 2004 Aug;18(3):646-9.
(55.) Cohen JL, Segal KR, Witriol I, McArdle WD. Cardiorespiratory responses to ballet exercise and the [VO.sub.2max] of elite ballet dancers. Med Sci Sports Exerc. 1982;14(3):212-17.
(56.) Lamberts RP, Swart J, Noakes TD, Lambert MI. Changes in heart rate recovery after high-intensity training in well-trained cyclists. Eur J Appl Physiol. 2009 Mar;105(5):705-13.
(57.) Redding E, Irvine S, Quin E, Rafferty S. Dance science: scientific investigations into the effect of dance specific fitness training and its impact upon pedagogic practices and dance performance. Presented at: International Symposium on Performance Science. Auckland, New Zealand, 2009.
(58.) Smol E, Fredyk A. Supplementary low-intensity aerobic training improves aerobic capacity and does not affect psychomotor performance in professional female ballet dancers. J Hum Kinet. 2012 Mar;31:79-87.
(59.) Ramel E, Thorsson O, Wollmer P. Fitness training and its effect on musculoskeletal pain in professional ballet dancers. Scand J Med Sci Sports. 1997 Oct;7(5):293-8.
(60.) Roussel NA, Vissers D, Kuppens K, et al. Effect of a physical conditioning versus health promotion intervention in dancers: a randomized controlled trial. Man Ther. 2014 Dec;19(6):562-8.
(61.) Lisman P, O'Connor FG, Deuster PA, Knapik JJ. Functional movement screen and aerobic fitness predict injuries in military training. Med Sci Sports Exerc. 2013 Apr;45(4):63643.
(62.) Wyon MA, Head A, Sharp NC, Redding E. The cardiorespiratory responses to modern dance classes: differences between university, graduate, and professional classes. J Dance Med Sci. 2002;6(2):41-5.
(63.) Cohen JL, Segal KR, McArdle WD. Heart rate response to ballet stage performance. Phys Sportsmed. 1982;10(11):120-33.
(64.) Twitchett EA, Koutedakis Y, Wyon MA. Physiological fitness and professional classical ballet performance: a brief review. J Strength Cond Res. 2009 Dec;23(9):2732-40.
(65.) Irvine S, Redding E, Rafferty S. Dance fitness. IADMS Resource Paper. Available at: c.ymcdn.com/sites/ www.iadms.org/resource/resmgr/ resource_papers/dance_fitness.pdf. Accessed February 23, 2015.
(66.) Laursen PB. Training for intense exercise performance: high-intensity or high-volume training? Scand J Med Sci Sports. 2010 Oct;20(Suppl 2):1-10.
(67.) Wisloff U, Ellingsen O, Kemi OJ. High-intensity interval training to maximize cardiac benefits of exercise training? Exerc Sport Sci Rev. 2009 Jul;37(3):139-46.
(68.) Billat LV. Interval training for performance: a scientific and empirical practice. Special recommendations for middle- and long-distance running. Part II: anaerobic interval training. Sports Med. 2001 Feb;31(2):7590.
(69.) Tabata I, Nishimura K, Kouzaki M, et al. Effects of moderate-intensity endurance and high-intensity intermittent training on anaerobic capacity and [VO.sub.2max]. Med Sci Sports Exerc. 1996 Oct;28(10):1327-30.
(70.) Billat VL, Flechet B, Petit B, et al. Interval training at [VO.sub.2max]: effects on aerobic performance and overtraining markers. Med Sci Sports Exerc. 1999 Jan;31(1):156-63.
(71.) Strath SJ, Swartz AM, Bassett DR Jr, et al. Evaluation of heart rate as a method for assessing moderate intensity physical activity. Med Sci Sports Exerc. 2000 Sep;32(9 Suppl):S465-70.
(72.) Bernard T, Gavarry O, Bermon S, et al. Relationships between oxygen consumption and heart rate in transitory and steady states of exercise and during recovery: influence of type of exercise. Eur J Appl Physiol Occup Physiol. 1997;75(2):170-6.
(73.) Short KR, Sedlock DA. Excess postexercise oxygen consumption and recovery rate in trained and untrained subjects. J Appl Physiol (1985). 1997 Jul;83(1):153-9.
(74.) Olson MS, Williford HN, Blessing DL, et al. A test to estimate [VO.sub.2max] in females using aerobic dance, heart rate, BMI, and age. J Sports Med Phys Fitness. 1995 Sep;35(3):159 68.
(75.) Wyon M, Redding E, Abt G, et al. Development, reliability, and validity of a multistage dance specific aerobic fitness test (DAFT). J Dance Med Sci. 2003;7(3):80-4.
(76.) Twitchett E, Nevill A, Angioi M, et al. Development, validity, and reliability of a ballet-specific aero bic fitness test. J Dance Med Sci. 2011;15(3):123-7.
(77.) Kadel N, Southwick H, Cole HH. Update on the annual post-hire health screen for professional dancers: Dance/USA Taskforce on Dancer Health. Annual Dance USA Conference. Chicago, IL: Dance/USA, 2011.
Shaw Bronner, P.T., Ph.D., O.C.S., Emma Codman, Dana Hash-Campbell, M.F.A., and Sheyi Ojofeitimi, D.P.T., C.F.M.T., O.C.S.
Shaw Bronner, P.T., Ph.D., O.C.S., Director, ADAM Center and Associate Professor, Dept. of Physical Therapy, Movement and Rehabilitation Sciences, Northeastern University, Boston, Massachusetts; and Director, Physical Therapy Services, Alvin Ailey American Dance Theater, New York, New York. Emma Codman, ADAM Center, Department of Physical Therapy, Movement and Rehabilitation Sciences, Northeastern University, Boston, Massachusetts. Dana Hash-Campbell, M.F.A., Chair, Dept. of Performing Arts, Long Island University, Brooklyn, New York. Sheyi Ojofeitimi, D.P.T., C.F.M.T., O.C.S., Senior Research Associate, ADAM Center; Senior Physical Therapist, Alvin Ailey American Dance Theater, New York, New York; Synthesis Physical Therapy, Brooklyn, New York.
Correspondence: Shaw Bronner, P.T., Ph.D., O.C.S., ADAM Center, 308B Robinson Hall, Northeastern University, 360 Huntington Avenue, Boston, Massachusetts 021150; email@example.com.
Table 1 Group Demographics: Part 1 Group Gender Age (years) * Height (m) ([dagger]) Prof-Sr 20 F 27.35 [+ or -] 3.83 1.66 [+ or -] 0.06 18 M 26.67 [+ or -] 3.48 1.80 [+ or -] 0.06 38 Total 27.03 [+ or -] 3.64 1.73 [+ or -] 0.09 Prof-Jr 30 F 21.17 [+ or -] 1.56 1.65 [+ or -] 0.05 30 M 21.63 [+ or -] 1.79 1.77 [+ or -] 0.07 60 Total 21.40 [+ or -] 1.68 1.71 [+ or -] 0.09 BFA-1 333 F 18.02 [+ or -] 0.85 1.65 [+ or -] 0.08 65 M 18.33 [+ or -] 1.00 1.76 [+ or -] 0.05 401 Total 18.07 [+ or -] 0.87 1.67 [+ or -] 0.08 BFA-2 69 F 19.16 [+ or -] 3.12 1.62 [+ or -] 0.06 9 M 19.22 [+ or -] 1.20 1.77 [+ or -] 0.06 78 Total 19.17 [+ or -] 2.96 1.64 [+ or -] 0.08 Total 452 F 18.82 [+ or -] 2.62 1.64 [+ or -] 0.07 125 M 20.35 [+ or -] 3.39 1.77 [+ or -] 0.06 577 All 19.17 [+ or -] 2.88 1.67 [+ or -] 0.09 Group Gender Mass (kg) ([section]) BMI ([double dagger]) Prof-Sr 20 F 55.08 [+ or -] 3.52 19.98 [+ or -] 1.36 18 M 75.48 [+ or -] 5.14 23.27 [+ or -] 1.33 38 Total 64.75 [+ or -] 11.18 21.54 [+ or -] 2.13 Prof-Jr 30 F 54.39 [+ or -] 5.19 19.97 [+ or -] 1.43 30 M 70.46 [+ or -] 8.67 22.37 [+ or -] 2.20 60 Total 62.43 [+ or -] 10.76 21.17 [+ or -] 2.13 BFA-1 333 F 56.09 [+ or -] 5.58 20.68 [+ or -] 1.99 65 M 68.82 [+ or -] 6.27 22.16 [+ or -] 2.20 401 Total 58.33 [+ or -] 7.49 21.43 [+ or -] 1.99 BFA-2 69 F 58.65 [+ or -] 8.58 22.27 [+ or -] 2.49 9 M 67.48 [+ or -] 7.11 21.62 [+ or -] 1.91 78 Total 59.67 [+ or -] 8.85 22.20 [+ or -] 2.43 Total 452 F 56.35 [+ or -] 6.12 20.85 [+ or -] 2.10 125 M 70.06 [+ or -] 7.15 22.33 [+ or -] 1.73 577 All 59.37 [+ or -] 8.52 21.17 [+ or -] 2.11 Group Gender Training (years) Prof (years) ([parallel]) Prof-Sr 20 F 19.85 [+ or -] 6.11 7.35 [+ or -] 3.69 18 M 14.44 [+ or -] 4.06 8.39 [+ or -] .05 38 Total 17.29 [+ or -] 5.85 7.84 [+ or -] 3.85 Prof-Jr 30 F 13.83 [+ or -] 5.11 1.07 [+ or -] 0.98 30 M 10.73 [+ or -] 3.42 0.93 [+ or -] 0.78 60 Total 12.28 [+ or -] 4.58 1.00 [+ or -] 0.88 BFA-1 333 F 11.72 [+ or -] 3.38 0 [+ or -] 0 65 M 7.10 [+ or -] 4.11 0 [+ or -] 0 401 Total 10.91 [+ or -] 3.93 0 [+ or -] 0 BFA-2 69 F 10.62 [+ or -] 4.80 0 [+ or -] 0 9 M 5.89 [+ or -] 5.21 0 [+ or -] 0 78 Total 10.07 [+ or -] 5.04 0 [+ or -] 0 Total 452 F 12.06 [+ or -] 4.30 0.39 [+ or -] 1 .72 125 M 8.91 [+ or -] 4.85 1.41 [+ or -] 3.26 577 All 11.36 [+ or -] 4.61 0.62 [+ or -] 2.19 Abbreviations: body mass index, BMI; training, dance training; professional experience, Prof; senior professional company, Prof-Sr; junior professional company, Prof-Jr; Bachelors of Fine Arts program #1, BFA-1; Bachelors of Fine Arts program #2, BFA-2; female, F; male, M. * Differences between groups in age [F(3,569) = 319.6527, p < 0.001]. Post hoc Prof-Sr versus Prof-Jr, BFA-1, BFA-2, p < 0.001; Prof-Jr versus BFA-1, BFA-2, p < 0.001; BFA-1 versus BFA-2, p = 0.009. Gender: no differences. ([dagger]) Differences between genders in height [F(1,569) = 177.303, p < 0.001]. ([section]) Differences between genders in mass [F(1,569) = 275.7028, p < 0.001]. ([double dagger]) Differences between genders in BMI [F(1,569) = 35.791, p < 0.001]. ([parallel]) Differences between groups in years of dance training [F(3,566) = 49.382, p < 0.001]. Post hoc Prof-Sr versus Prof-Jr, BFA-1, and BFA-2, p < 0.001; Post hoc Prof-Jr versus BFA-2, p = 0.014. Differences between genders in years of dance training [F(1,566) = 65.279, p < 0.001]. Table 2 Group Demographics: Part II Group Gender Smoking Asthma Cross Aerobic Training (%) * Prof-Sr Female 2 (10%) 6 (30%) 7 (70%) 5 (56%) Male 5 (29%) 3 (18%) 6 (60%) 6 (60%) Total 7 (19%) 9 (24%) 13 (67%) 12 (60%) Prof-Jr Female 2 (7%) 7 (23%) 7 (50%) 5 (36%) Male 4 (13%) 3 (10%) 8 (53%) 4 (27%) Total 6 (10%) 10 (17%) 15 (50%) 9 (30%) BFA-1 Female 25 (8%) 41 (12%) 134 (42%) 115 (36%) Male 3 (4%) 13 (19%) 20 (32%) 14 (22%) Total 28 (7%) 54 (13%) 154 (40%) 129 (34%) BFA-2 Female 10 (15%) 5 (7%) 28 (42%) 25 (37%) Male 1 (11%) 4 (44%) 5 (50%) 5 (56%) Total 11 (14%) 9 (13%) 33 (44%) 30 (39%) Total Female 39 (9%) 59 (13%) 176 (43%) 150 (37%) Male 13 (10%) 23 (18%) 39 (40%) 29 (30%) Total 52 (9%) 82 (14%) 217 (43%) 179 (36%) * There were differences between groups in aerobic training [F(3,514) = 3.588, p = 0.014]. Abbreviations: Number of positive responses out of total, % smoking, % asthma, % cross training, and % aerobic training, aerobic; senior professional company, Prof-Sr; junior professional company, Prof-Jr; Bachelors of Fine Arts program #1, BFA-1; Bachelors of Fine Arts program #2, BFA-2. Table 3 Mean [+ or -] SD for Blood Pressure, Heart Rate, and Fitness Variables Group Gender BP [HR.sub.rest] (mm/Hg) * (beats x [min.sup.-1]) ([dagger]) Prof-Sr Female 103/66 67 [+ or -] 9 Male 113/76 69 [+ or -] 11 Total 107/71 68 [+ or -] 10 Prof-Jr Female 107/67 69 [+ or -] 8 Male 117/76 71 [+ or -] 11 Total 112/72 71 [+ or -] 10 BFA-1 Female 112/70 79 [+ or -] 14 Male 128/74 80 [+ or -] 13 Total 114/71 79 [+ or -] 14 BFA-2 Female 113/69 81 [+ or -] 13 Male 116/70 84 [+ or -] 14 Total 113/69 81 [+ or -] 13 Total Female 111/70 78 [+ or -] 14 Male 123/74 77 [+ or -] 13 All 114/71 77 [+ or -] 13 Group [HR.sub.peak] [HR.sub.recovery] (beats x (beats x [min.sup.-1]) [min.sup.-1]) ([double dagger]) ([section]) Prof-Sr 140 [+ or -] 10 82 [+ or -] 15 132 [+ or -] 16 85 [+ or -] 15 136 [+ or -] 13 83 [+ or -] 15 Prof-Jr 141 [+ or -] 13 85 [+ or -] 13 132 [+ or -] 15 84 [+ or -] 12 136 [+ or -] 14 84 [+ or -] 12 BFA-1 153 [+ or -] 16 103 [+ or -] 20 145 [+ or -] 17 103 [+ or -] 19 152 [+ or -] 17 103 [+ or -] 20 BFA-2 162 [+ or -] 18 124 [+ or -] 23 141 [+ or -] 17 109 [+ or -] 21 160 [+ or -] 19 122 [+ or -] 23 Total 153 [+ or -] 17 104 [+ or -] 23 139 [+ or -] 17 95 [+ or -] 19 150 [+ or -] 18 102 [+ or -] 22 Group Fitness ([parallel]) Prof-Sr 0.60 [+ or -] 0.94 1.22 [+ or -] 1.11 0.89 [+ or -] 1.06 Prof-Jr 0.80 [+ or -] 0.85 1.07 [+ or -] 0.94 0.93 [+ or -] 0.90 BFA-1 2.17 [+ or -] 1.70 2.91 [+ or -] 1.97 2.30 [+ or -] 1.78 BFA-2 3.84 [+ or -] 1.85 3.33 [+ or -] 1.87 3.77 [+ or -] 1.84 Total 2.26 [+ or -] 1.86 2.20 [+ or -] 1.86 2.25 [+ or -] 1.86 Abbreviations: blood pressure, BP; heart rate, HR; resting HR, [HR.sub.rest]; peak HR, [HR.sub.peak]; 1-min recovery HR, [HR.sub.recovery]; fitness rating, Fitness; senior professional company, Prof-Sr; junior professional company, Prof-Jr; Bachelors of Fine Arts program #1, BFA-1; Bachelors of Fine Arts program #2, BFA-2. Fitness ratings were determined by [HR.sub.recov], gender, and age range and were comprised of 0 to 7 groupings. (23,24) * Differences between groups in systolic BP [F(3,558) = 11.748, p < 0.001]. Post hoc, Prof-Sr and Prof-Jr dancers systolic BP were lower than BFA-1 (p [less than or equal to] 0.002); differences between genders in systolic BP F(1,558) = 27.208, p < 0.001]. ([dagger]) Differences between groups in [HR.sub.rest] [F(3,453) = 13.942, p < 0.001]; post hoc Prof-Sr and Prof-Jr dancers versus BFA-1 and BFA-2 dancers, p < 0.001; BFA versus BFA-2, p < 0.001; there were no differences between genders in [HR.sub.rest]. ([double dagger]]) Differences between groups in [HR.sub.peak] [F(3,453) = 14.947, p < 0.001]; post hoc Prof-Sr and Prof-Jr dancers versus BFA-1 and BFA-2, p < 0.001; BFA-1 versus BFA-2, p = 0.004. Differences between genders in [HR.sub.peak] [F(3,455) = 25.733, p < 0.001]. ([section]) Differences between groups in [HR.sub.recov] [F(3,455) = 30.799, p < 0.001]; post hoc Prof-Sr and Prof-Jr dancers versus BFA-1 and BFA-2, p < 0.001; BFA-1 versus BFA-2, p = 0.004; there were no differences between genders in [HR.sub.recov]. ([parallel]) Differences between groups in fitness categories [F(3,453) = 28.687, p < 0.001]; post hoc Prof-Sr and Prof-Jr versus BFA-1 and BFA-2, p < 0.001; BFA-1 versus BFA-2, p < 0.001; there were no differences between genders in fitness categories. Table 4 Mean [+ or -] SD Change in Aerobic Fitness Group # BP Subjects (mm Hg) * Year 1 Prof-Sr 15 108/73 Prof-Jr 6 111/72 BFA-1 13 123/74 BFA-2 38 115/69 Total 72 115/71 Year 2 Prof-Sr 15 101/61 Prof-Jr 6 99/52 BFA-1 13 108/67 BFA-2 38 116/70 Total 72 110/67 Year 3 Prof-Sr 15 114/77 Prof-Jr 6 104/72 BFA-1 13 112/71 BFA-2 38 111/69 Total 72 110/69 Year 4 BFA-2 38 116/71 Group [HR.sub.rest] [HR.sub.peak] (beats x (beats x [min.sup.-1]) [min.sup.-1]) ([dagger]) ([double dagger]) Year 1 Prof-Sr 70 [+ or -] 7 133 [+ or -] 12 Prof-Jr 67 [+ or -] 4 135 [+ or -] 11 BFA-1 83 [+ or -] 16 156 [+ or -] 12 BFA-2 84 [+ or -] 14 164 [+ or -] 17 Total 80 [+ or -] 14 153 [+ or -] 20 Year 2 Prof-Sr 68 [+ or -] 8 131 [+ or -] 13 Prof-Jr 70 [+ or -] 8 149 [+ or -] 16 BFA-1 74 [+ or -] 8 142 [+ or -] 7 BFA-2 80 [+ or -] 14 159 [+ or -] 18 Total 75 [+ or -] 13 149 [+ or -] 19 Year 3 Prof-Sr 68 [+ or -] 8 131 [+ or -] 13 Prof-Jr 68 [+ or -] 11 143 [+ or -] 13 BFA-1 73 [+ or -] 11 144 [+ or -] 8 BFA-2 83 [+ or -] 15 155 [+ or -] 16 Total 77 [+ or -] 14 146 [+ or -] 17 Year 4 BFA-2 78 [+ or -] 14 153 [+ or -] 14 Group [HR.sub.recovery] Fitness ([parallel]) (beats x [min.sup.-1]) ([section]) Year 1 Prof-Sr 81 [+ or -] 13 0.73 [+ or -] 0.88 Prof-Jr 74 [+ or -] 8 0.33 [+ or -] 0.51 BFA-1 105 [+ or -] 25 3.23 [+ or -] 2.27 BFA-2 126 [+ or -] 23 4.16 [+ or -] 1.73 Total 108 [+ or -] 29 2.96 [+ or -] 2.24 Year 2 Prof-Sr 79 [+ or -] 11 0.67 [+ or -] 0.82 Prof-Jr 85 [+ or -] 15 0.47 [+ or -] 0.92 BFA-1 89 [+ or -] 10 1.23 [+ or -] 1.09 BFA-2 120 [+ or -] 21 3.61 [+ or -] 1.67 Total 103 [+ or -] 25 2.28 [+ or -] 1.98 Year 3 Prof-Sr 79 [+ or -] 11 0.47 [+ or -] 0.92 Prof-Jr 83 [+ or -] 12 0.83 [+ or -] 0.98 BFA-1 87 [+ or -] 11 1.08 [+ or -] 1.19 BFA-2 114 [+ or -] 20 3.24 [+ or -] 1.70 Total 99 [+ or -] 23 2.07 [+ or -] 1.89 Year 4 BFA-2 109 [+ or -] 22 2.09 [+ or -] 1.94 Abbreviations: blood pressure, BP; heart rate, HR; resting HR, [HR.sub.rest]; peak HR, [HR.sub.peak]; 1-min recovery HR, [HR.sub.recovery], fitness category, Fitness; senior professional company, Prof-Sr; junior professional company, Prof-Jr; Bachelors of Fine Arts program #1, BFA-1; Bachelors of Fine Arts program #2, BFA-2. * Differences in systolic BP between groups [F(3,56) = 6.021, p = 0.001]; post hoc Prof-Sr versus BFA-1, p=0.017, Prof-Sr versus BFA-2, p < 0.001; differences in systolic BP due to time [F(1,56) = 4.261, p = 0.044]; post hoc pairwise comparisons year 1 versus year 2, p = 0.004, and year 1 versus year 3, p = 0.044; interaction between group and time [F(3,56) = 5.398, p = 0.002]. ([dagger]) Differences in diastolic BP due to time [F(1,56) = 8.546, p = 0.005]; post hoc pairwise comparisons year 1 versus year 2, p=0.003; year 2 versud year 3, p = 0.028; no differences between groups in diastolic BP. ([dagger]) Differences in [HR.sub.rest] between groups [F(3,68) = 10.276, p < 0.001]; post hoc pairwise comparisons BFA-2 dancers versus Prof-Sr and Prof-Jr, p [less than or equal to] 0.007; no differences due to time. ([double dagger]) Differences in [HR.sub.peak] between groups [F(3,60) = 17.839, p < 0.001]; post hoc pairwise comparisons BFA-2 dancers versus Prof-Sr and Prof-Jr, p < 0.012; no differences due to time. ([section]) Differences in [HR.sub.recov] between groups [F(3,68) = 31.414, p < 0.001]; post hoc pairwise comparisons Prof-Sr, Prof-Jr, BFA-1 versus BFA-2, p < 0.001; differences in [HR.sub.recov] due to time [F(1,71) = 5.436, p = 0.023], interaction between time and group [F(3,68) = 4.472, p = 0.006]. ([parallel]) Differences in Fitness between groups [F(3,68) = 26.773, p < 0.001]; post hoc pairwise comparisons Prof- Sr, Prof-Jr, BFA-1 versus BFA-2, p < 0.001; differences in Fitness due to time [F(1,68) = 11.259, p=0.001]; post hoc pairwise comparisons year 1 versus year 2 and year 3, p = 0.004; interaction between time and group [F(3,68) = 5.980, p = 0.001]. Four year analysis of BFA-2: differences in [HR.sub.recov] over time [F(1,19) = 23.818, p < 0.001]; post hoc pairwise comparisons year 1 versus years 2, 3, and 4, p [less than or equal to] 0.021; differences in fitness category over time [F(1,19) = 15.035, p = 0.001]; post hoc pairwise comparisons year 1 versus years 2, 3, 4, p < 0.006.
|Printer friendly Cite/link Email Feedback|
|Author:||Bronner, Shaw; Codman, Emma; Hash-Campbell, Dana; Ojofeitimi, Sheyi|
|Publication:||Journal of Dance Medicine & Science|
|Date:||Jan 1, 2016|
|Previous Article:||Femoral shaft torsion in injured and uninjured ballet dancers and its association with other hip measures: a cross-sectional study.|
|Next Article:||Attentional focus in classical ballet a survey of professional dancers.|