This study compared nutritional intake, body composition, bone mineral density, and isokinetic strength by dance type in collegiate female dancers. The study subjects included Korean dancers (n=12), ballet dancers (n=13), contemporary dancers (n=8), and controls (n=12). Nutritional intake was estimated using the Computer Aided Nutritional Analysis Program. Body composition and bone mineral density were measured using dual-energy X-ray absorptiometry. Isokinetic knee joint strength was measured by Cybex 770-NORM. All statistical analyses were performed by SAS 9.2. Means and standard deviations were calculated using descriptive statistics. One-way analysis of variance was applied to evaluate nutritional intake, body composition, bone mineral density, and isokinetic strength differences. Duncan multiple range test was used for post hoc testing. A level of significance was set at
While dance has evolved as a pure art, it has reached the level where professional dancers require intense practice to master challenging techniques and provide high-quality performances, which require physical strength (
Most professional dancers experience insufficient nutrient intake considering the amount of practice in which they engage to ensure high-quality performances and maintain their body shape (
In terms of BMD, approximately 83% of ballet dancers observed by
Furthermore, decreased BMD can expose dancers to increased risks of fall-induced bone fracture, resulting in musculoskeletal damage or sarcopenia, which can potentially limit a dancer’s ability to perform expressive movements (
As mentioned above, although previous studies suggested various implications about the study of dance, an investigation of nutritional intake and analysis of the individually required factors such as body composition, BMD, and isokinetic muscular function are required to further understand the physiological features of dance. Therefore, this study aimed to understand differences in these factors by dance type by investigating the nutritional intake, body composition, BMD, and isokinetic muscular function of students majoring in contemporary dance, ballet, and Korean dance. Furthermore, by comparing the physical features of students who were not dance majors with those who were dance majors, we obtained health-related information in an effort to provide approaches to solving dance performance problems and improve function.
The study subjects included 12 students majoring in Korean dance, 13 students majoring in ballet, eight students majoring in contemporary dance, and 12 nondance majors at Kyung Hee University located in Seoul through simple random sampling. Thus, a total of 45 students (age range, 18–20 yr) participated in this study after they volunteered to participate and signed an informed consent form. None of the participants had any physical defects or diseases and were not on any medication. The participants’ characteristics are shown in
Nutritional intake was self-recorded over 24 hr on a dietary record. Nutritional intake was recorded for a total of three days, including two weekdays and one weekend day. The survey employed the Computer Aided Nutrition Analysis Program generated by The Korean Nutrition Society and aimed to investigate the intakes of total calories, the three major nutrients, calcium, phosphorus, iron, and zinc.
Body composition was measured using dual X-ray absorptiometry (DXA; QDR-4500W; Hologic, Marlborough, MA, USA) to investigate lean tissue and body fat percentage.
BMD was measured with DXA assessing whole body BMD and it was recorded in g/cm2.
Isokinetic dynamometry (Cybex 770-NORM, Cybex International, Medway, MA, USA) was performed to evaluate flexion and extension of the right and left knees. Each test included three maximal contractions at 60°/sec for muscle strength. Each isokinetic contraction was performed through a full range of motion, and data were normalized to each participant’s body weight and calculated as torque (N·m/kg) × 100.
Statistical analyses were performed by using SAS ver. 9.2 (SAS Institute Inc., Cary, NC, USA), and mean and standard deviation for each variable were computed using descriptive statistics. One-way analysis of variance was performed to test the statistical significance of body build, nutritional intake, body composition, BMD, and isokinetic muscular function of the four groups according to sport type.
This study compared and analyzed nutritional intake, body composition, BMD, and isokinetic muscular function in collegiate female Korean dance majors (n=12), ballet majors (n=13), modern dance majors (n=8), and controls (n=12). The results are described below.
The nutritional intake analysis results for each group are listed in
The body composition analysis results in each group are summarized in
The results comparing whole body BMD among groups are shown in
The comparison result of isokinetic muscular function by group is shown in
No statistically significant difference was detected on the right or left side of the mean isokinetic extensor at 60°/sec among the dance groups or between any dance group and the control group. No statistically significant difference was detected on the right or left side of the mean isokinetic flexor at 60°/sec among the dance groups or between any dance group and the control group.
Although it is necessary for dancers to obtain sufficient nutrition to ensure their best performance, dancers experience limited nutritional intake to maintain their body image and shape because dance is an art expressed through body motions. Thus, dancers are at risk of minimal nutritional intake, which can lead to deficiencies of micronutrients such as iron, calcium, and vitamin D (
No difference was observed in any of the nutritional intake values among participants in this study. However, while the Korean National Health and Nutrition Examination Survey (KNHANES V-3) (
Systemic and proper body composition and its maintenance are essential for dancers to perform challenging and high-quality repetitive movements (
However, in the case of lean tissue, no statistically significant difference was observed compared to the control group, showing 39,329.7 ± 2,997.67 g/cm2 for the contemporary dance group, 36,772.4 ± 3,004.82 g/cm2 for the Korean dance group, 36,503.1 ± 2,849.29 g/cm2 for the ballet group, and 35,421 ± 4,631.5 g/cm2 for the control group. This result suggests that nondance and dance majors have similar levels of lean tissue. Therefore, it is necessary for dancers to increase their lean tissue to better their performance, for which weight training or weight-bearing exercise programs are highly recommended. When this training is pursued, dancers’ capacities to execute challenging movements that require artistic components and professional dancing techniques are expected to improve.
Eating disorders, menstruation disorders, and low BMD, either alone or in combination, are risk factors for female dancers (
In this study, we also observed a normal BMD range despite a continuous diet restriction and low nutritional intake, which is thought to be because dancing movements such as kicking, leaping, hopping, turning, jumping, and twisting apply intense mechanical stress to the bones through weight-bearing.
However,
The evaluation of muscular function using isokinetic measurement equipment can be a useful indicator to assess the efficacy of sports injury prevention and recovery and is a reliable measurement method for muscular strength and endurance (
No potential conflict of interest relevant to this article was reported.
Subject characteristics by study group
Characteristic | Female dance group | |||
---|---|---|---|---|
Korean (n=12) | Ballet (n=13) | Contemporary (n=8) | Control (n=12) | |
Body weight (kg) | 54.5 ± 6.45 | 51.0 ± 4.70 | 54.7 ± 6.89 | 53.0 ± 6.38 |
Standing height (cm) | 164.9 ± 3.29 | 163.3 ± 3.55 | 164.8 ± 3.42 | 160.3 ± 5.10 |
Values are presented as mean ± standard deviation.
Comparisons of nutritional intake condition parameters by dance types in collegiate female dancers
Variable | Female dance group | |||||
---|---|---|---|---|---|---|
Korean (n=12) | Ballet (n=13) | Contemporary (n=8) | Control (n=12) | |||
Total calories (kcal) | 1,100.9 ± 472.89 | 1,214.4 ± 390.32 | 1,454.1 ± 478.59 | 1,306.9 ± 332.53 | 1.26 | 0.30 |
Protein (g) | 43.3 ± 17.92 | 45.4 ± 15.31 | 55.3 ± 18.95 | 50.9 ± 15.37 | 1.06 | 0.38 |
Fat (g) | 35.8 ± 17.55 | 36.0 ± 10.87 | 49.8 ± 17.82 | 40.4 ± 11.57 | 1.90 | 0.14 |
Carbohydrate (g) | 151.9 ± 63.50 | 177.8 ± 63.70 | 196.3 ± 67.99 | 176.7 ± 46.17 | 0.93 | 0.44 |
Ca (mg) | 269.2 ± 150.14 | 364.6 ± 108.67 | 367.4 ± 144.18 | 350.2 ± 124.85 | 1.44 | 0.25 |
P (mg) | 557.5 ± 257.41 | 629.4 ± 215.38 | 736.9 ± 271.83 | 677.1 ± 206.70 | 1.05 | 0.38 |
Fe (mg) | 7.2 ± 3.53 | 8.1 ± 3.23 | 8.9 ± 2.74 | 9.7 ± 5.28 | 0.87 | 0.47 |
Zn (mg) | 5.1 ± 2.29 | 5.6 ± 2.08 | 6.5 ± 2.40 | 6.1 ± 2.20 | 0.81 | 0.50 |
Values are presented as mean ± standard deviation.
Comparisons of body composition parameters by dance type in collegiate female dancers
Parameter | Female dance group | |||||
---|---|---|---|---|---|---|
Korean (n=12) | Ballet (n=13) | Contemporary (n=8) | Control (n=12) | |||
Lean tissue (kg) | 36.8 ± 3.00 | 36.5 ± 2.85 | 39.3 ± 2.10 | 35.4 ± 4.63 | 2.07 | 0.12 |
Percent body fat (%) | 27.7 ± 4.64 |
24.8 ± 3.12 |
24.5 ± 4.57 | 30.0 ± 3.09 | 5.2 | 0.004 |
Values are presented as mean ± standard deviation.
Same alphabet indicates no significant difference among groups.
Comparisons of total body BMD by dance type in collegiate female dancers
Female dance group | ||||||
---|---|---|---|---|---|---|
Korean (n=12) | Ballet (n=13) | Contemporary (n=8) | Control (n=12) | |||
Total BMD (g/cm2) | 1.1 ± 0.06 | 1.1 ± 0.06 | 1.1 ± 0.06 | 1.1 ± 0.09 | 1.6 | 0.2 |
Values are presented as mean ± standard deviation.
BMD, bone mineral density.
Comparisons of isokinetic muscular strength at %BW 60°/sec by dance type in collegiate female dancers
Isokinetic muscular strength | Female dance group | |||||
---|---|---|---|---|---|---|
| ||||||
Korean (n=12) | Ballet (n=13) | Contemporary (n=8) | Control (n=12) | |||
Extensor peak torque %BW (N·m/kg) | ||||||
Right | 178.5 ± 19.48 | 176.0 ± 34.68 | 184.3 ± 19.16 | 160.5 ± 28.11 | 1.52 | 0.22 |
Left | 176.0 ± 23.38 | 170.6 ± 37.79 | 180.5 ± 18.49 | 151.5 ± 37.42 | 1.79 | 0.17 |
| ||||||
Flexor peak torque %BW (N·m/kg) | ||||||
Right | 112.0 ± 17.03 | 114.0 ± 20.72 | 114.3 ± 26.42 | 100.8 ± 18.41 | 1.14 | 0.35 |
Left | 110.1 ± 18.93 | 113.8 ± 26.57 | 112.6 ± 18.87 | 94.4 ± 23.37 | 1.87 | 0.15 |
Values are presented as mean ± standard deviation.
% BW, % body weight.