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Immediate Effect of Whole Body Vibration on Saute Height and Balance in Female Professional Contemporary Dancers A Randomized Controlled Trial.

As dancers often prepare for the physical and aesthetic demands of a performance season by engaging in supplemental training, the goal of such training should be to increase physical capacity while maintaining or improving aesthetic quality. Angioi et al. (1) examined the correlation between fitness and aesthetic competence in contemporary dancers. Their fitness components were anthropometrics, flexibility, muscular power, muscular endurance, and aerobic capacity, while aesthetic competence included movement control, spatial skills, accuracy of movement, technique, dynamic and rhythmic accuracy, performance qualities, and overall performance. While there was a moderate correlation (r = 0.55) between jump ability and aesthetic competence, there was no demonstrable causality. Angioi (2) followed up with a randomized controlled trial on the effects of 6 weeks of supplemental training on fitness and aesthetic competence in contemporary dancers. The intervention group significantly improved in lower body muscular power (11%), upper body muscular endurance (22%), aerobic fitness (11%), and aesthetic competence (12%), while the control group declined in aesthetic competence and in all fitness parameters except aerobic condition. This study demonstrated that supplemental training can have a causal effect on fitness and aesthetics in contemporary dancers. Because most injuries among professional dancers are the result of overuse, (3,4) there is ample reason to seek methods for improving physical fitness in this population. However, as professional contemporary dancers can spend up to 44 hours in class and rehearsal each week, (5) any additional training regimen must be highly time-efficient.

The countermovement jump (CMJ) is considered to provide a useful measurement of muscular power, which is a component of fitness. (1) The CMJ is a single jump that begins while standing on both feet with straight knees and lower limbs in parallel position. A demi-plie is then performed, followed by a quick straightening of the knees to propel the body vertically into the air, with a return to the ground in reverse sequence (Fig. 1). For the dancer, the CMJ is also known as saute, a jump that is part of the training regimen of many dance genres. Increased CMJ height after whole body vibration (WBV) intervention for 4 to 8 weeks has been reported in collegiate, (6) conservatory, (7) and pre-professional ballet dancers, (8) and in national-level competitive rhythmic gymnasts (9) immediately after one 75-second intervention. The intensity of WBV is determined by the frequency, amplitude, acceleration, and duration of the intervention and the exercises being performed while receiving WBV. (10) The frequency used in intervention studies has varies from 30 Hz with gymnasts (9,11) and ballet dancers (6-8) to 35 Hz and 40 Hz with collegiate and conservatory student dancers. (6,7) Because the 75-second intervention with a 30 Hz frequency and 2 to 4 mm peak-peak (p-p) amplitude has been found to have an acute effect on CMJ height, it was selected as the lowest effective dose frequency for this study. No studies to date have examined the effect on first position saute height in professional contemporary dancers of static versus dynamic demi-plie during WBV as separate intervention conditions.

Dancers may require both static and dynamic balance during performance. (12,13) The effect of WBV on balance has been studied in terms of postural sway, (14) dynamic balance, (15) and static balance (among athletes). (9,16,17) Unfortunately, these studies involve force plates (14,16,17) or other bulky measurement tools. (9,15) Missing in the literature is the study of the immediate effects of WBV on balance using validated, reliable, quick, and clinically reproducible tests. The Star Excursion Balance Test (SEBT) is considered to be a test of dynamic balance, and the Balance Error Scoring System (BESS) a test of static balance. (18) Batson (19) adapted the SEBT to the dance studio setting by taping the star configuration to a Marley floor and normalized the dancer's achieved composite reach score to his or her leg length. The BESS can be used to test participants with ankle instability and is performed in barefeet. (20) Ambegaonkar et al. (21) used the BESS to distinguish static balance differences between female dancers and active female non-dancers and found dancers had significantly fewer errors (12.0 [+ or -] 6.9 vs. 25.3 [+ or -] 9.1; p < 0.001).

The purpose of this study was to assess the immediate effect of WBV and moving versus non-moving first position demi-plie on first position saute height and both static and dynamic balance in female professional contemporary dancers.

Methods

The Texas Woman's University (TWU) Institutional Review Board approved the study, and a minimum sample size of 48 was calculated with G*Power 3.1, MANOVA special effects and interactions, using the SPSS option for calculating effect size with Pillal V, [[eta].sup.2] = 34.7% from the Despina et al. (9) study. Sixty 18- to 35-year-old female professional contemporary dancers were recruited by e-mail and word of mouth from Brockus Project Studios (BPS) in Los Angeles, California, USA, and MetDance and Ad Deum Dance companies in Houston, Texas, USA. The study was conducted onsite at BPS and in the TWU research lab. Exclusion criteria were as follows: current pregnancy, active cancer, lower extremity fracture within the past year, ligament sprain or musculotendinous strain in the past 3 months, surgery within the past year, metal plates in the body, prior history of migraines, and resting blood pressure greater than 200 mmHg systolic or greater than 100 mmHg diastolic. The participants signed a consent form after receiving an explanation and demonstration of the study protocol. Heart rate and blood pressure were taken, and leg length was measured from the anterior superior iliac spine to the medial malleolus to normalize values on the SEBT. Participant demographics can be found in Table 1.

Participants were randomly assigned to one of four WBV conditions: static demi-plie (0 Hz), static demi-plie (30 Hz), dynamic demi-plie (0 Hz), or dynamic demi-plie (30 Hz). For the static demi-plie, the dancer held the turned out demi-plie position for 75 seconds; for the dynamic demi-plie she moved slowly, as she might in ballet class. Dynamic demi-plie cadence was 3 seconds down and 3 seconds up, and turnout was self-selected by each dancer. Depth of both the static and dynamic demi-plie was expected to be the furthest the dancer could go comfortably while still performing the movement correctly. Each participant completed the study on the same day in a pre-test, intervention, and immediate post-test format. The primary investigator conducted the study and collected the data over a 6-month time period. Of the original 60 participants, one dropped out, and her data were excluded from the analysis, which was done by the primary investigator 1 month after data collection.

A warm-up sequence was completed by all participants. First they rode a stationary bike for five minutes, while maintaining a heart rate between 120 and 140 beats per minute. Then they performed 5 minutes of dynamic and static stretching similar to the protocol introduced in the WBV study among dancers by Wyon et al. (6)

After the warm-up, the participants were given a practice session with each of the study's testing modalities and then preceded to the testing itself in the following sequence.

1. Three first position CMJs performed on the Just Jump Mat System* (Probotics, Huntsville, Alabama, USA). The Just Jump Mat System (*) calculates jump height from flight time between takeoff and landing.

2. The SEBT, repeated three times for a mean score, since prior studies support good to excellent test-retest reliability ([ICC.sub.(2,1)] = 0.82 to 0.90) for the average of three trials. (22) The composite score for this test was normalized to leg length as composite score = (sum of directions)/(leg length x number of directions) x 100.

3. The BESS, done once, since this is a structured test with moderate to excellent test-retest reliability (G = 0.64 - 0.91). (20)

The CMJ, SEBT, and BESS were all performed in bare feet, with hands placed on hips.

After the BESS, the participants received a 75-second intervention of a randomly assigned WBV condition. As previously noted, there were four conditions: static demi-plie (0 Hz), static demi-plie (30 Hz), dynamic demi-plie (0 Hz), and dynamic demi-plie (30 Hz). The Power Plate[R] pro5[TM] (Performance Health Systems, LLC, Northbrook, Illinios, USA) AIRdaptive[R] vibration plate (PP) was used for the WBV intervention conditions. The PP provides triplanar oscillating vibration, and as the body on the plate moves in and out of phase with the vibration it experiences an acceleration. (10) The plate serves as a vibration actuator while the body acts as a resonator. (10) The PP provides a 25 to 50 Hz range in frequency, a 4-mm or 8-mm amplitude, starting at 30 seconds of time with the ability to add 15-second increments. Whole body vibration intensity can be increased in terms of frequency or amplitude, while dosage depends on time, position, rest, and number of interventions.

Immediately following the intervention, participants performed three CMJs on the Just Jump Mat System[R], then completed the SEBT and BESS, in the same sequence as prior to the intervention.

Data Analysis

For the primary analysis of the effect of the WBV intervention on CMJ height and on balance, the alpha level was split to control for the possibility of a type I error accounting for the effect of the CMJ testing on balance testing. The effect of intervention on CMJ height was separated into three analyses using a two-way split plot ANOVA with a multivariate approach (each held at [alpha] = 0.025): 1. condition x time on CMJ height; 2. position alone on CMJ height; and 3. frequency alone on CMJ height. The effect of WBV intervention on balance was separated into three groups for analysis: 1. condition x time x balance test type, a 4 x 2 x 2 MANOVA ([alpha] = 0.025); 2. dynamic balance, as tested by the SEBT ([alpha] = 0.0125); and 3. static balance, as tested by the BESS ([alpha] = 0.0125). As balance as a construct was separated into dynamic and static balance, the alpha level was further split to control for a type I error. For each type of balance, there were two analyses using the two-way split-plot ANOVA with a multivariate approach: 1. position alone on balance and 2. frequency alone on balance. For the ANOVAs, the Lavene's test was used to establish homogeneity of variance (HOV), and for the MANOVA, Mahalanobis distance, Lavene's test, linearity, Box's test for homoscedasticity, and multicollinearity were used. In all analyses HOV was found to be tenable.

Results

There was no significant increase in CMJ height for any of the four conditions of WBV intervention (Table 2). When the effect of position was analyzed separately, regardless of frequency, the interaction of position x time was significant [F(1, 57) = 7.17; p = 0.01], (Tables 3 and 4). Simple effects analysis found a statistically significant increase in CMJ height for the static first position demi-plie after intervention, with a small effect size [F(1, 57) = 11.89; p = 0.001, d = 0.22, 95% CI: 11.28-12.78], (Table 5 and Fig. 2). There was no increase in CMJ height for the effect of frequency alone (Table 6).

For the MANOVA using the four conditions of WBV intervention, the two balance tests, and two time factors, there were no significant differences (Table 7). When the effect of position was analyzed separately, regardless of frequency, for the SEBT, there was a significant increase in dynamic balance for both positions after intervention, with a small effect size for each [F(1, 57) = 23.00; p < 0.001, d = 0.25, 95% CI: 88.35-96.89 for the static first position demi-plie, and d = 0.26, 95% CI: 88.07-97.39 for the dynamic first position demi-plie], (Tables 8 and 9). The same occurred when the effect of frequency was analyzed separately, regardless of position, for the SEBT, with a significant increase in dynamic balance after intervention for both frequencies and small effect sizes for each [F(1, 57) = 23.31; p < 0.001, d = 0.21, 95% CI: 88.50-97.64 for the 0 Hz frequency, and d = 0.31, 95% CI: 87.90-96.64 for the 30 Hz frequency], (Tables 10 and 11). Because all WBV conditions improved post-intervention, the results are questionable. As there was no position x time interaction and no frequency x time interaction, there was no need for further analysis of simple effects.

When the effect of position was analyzed separately, regardless of frequency, for the BESS, there was no significant improvement in static balance (Table 12). When the effect of frequency was analyzed separately, regardless of position, there was a significant interaction of frequency x time [F(1, 57) =9.04; p = 0.004], (Tables 13 and 14). Simple effects analysis found a significant improvement in static balance after the 30 Hz intervention, with a medium effect size [F(1, 57) = 13.39; p = 0.001, d = 0.68, 95% CI: 8.72-11.83], (Table 15 and Fig. 3).

Discussion

The results of this study are especially noteworthy in two ways: 1. the use of a 75-second static first position demi-plie intervention resulted in an immediate increase in CMJ jump height, regardless of WBV frequency; and 2. the 30 Hz WBV frequency improved static balance. The statistically significant improvements must be interpreted in light of what is clinically important to the dancer, as there is no proof of a biological change. Future studies could assess self-report outcomes and muscle EMG data.

It is important to note the small to medium effect sizes in the current study when considering dosage in future WBV studies with dancers. While the current study found immediate improvement in static balance after 75-second use of 30 Hz WBV, the dosage did not improve CMJ height. The lack of improvement is surprising, as Despina et al. (9) found improvements in both CMJ height and dynamic balance using this dosage, albeit in rhythmic gymnasts. This dissimilarity may be due to differences in population or in the turned out first position demi-plie. Da Silva-Grigoletto et al. (23) found the 60-second exposure of 30 Hz frequency to be the optimum dosage in healthy men in a parallel squat position, with a 4% increase in CMJ height, as compared to a 90-second exposure of 30 Hz, which resulted in a 3% decrease in CMJ height. While Annino et al. (8) found the first position static demi-plie at 30 Hz improved CMJ in pre-professional ballet dancers, the intervention was administered over 8 weeks. Wyon et al. (6) and Marshall et al. (7) also used the first position demi-plie and found significant improvement in CMJ height among collegiate dancers, but in both studies additional intervention positions (such as lunges and maximal heel raise) were considered, and the vibration frequencies were 35 Hz and 35 and 40 Hz, respectively.

In the current study, CMJ height improved with the static demi-plie position. Similarly, Armstrong et al. (24) found a significant increase in CMJ height among collegiate men and women after 1 minute of WBV intervention in a parallel squat position. Because both the control group with no vibration and all intervention groups improved, it appears the use of the parallel static squat position may have been causal to the increase in CMJ height, which would support the finding of the current study. In future studies, it would be useful to know if a turned out static demi-plie alone would yield an equal or better improvement in CMJ height.

A possible explanation for the improvement in CMJ height in the current study after performing the static demi-plie is muscular co-contraction, in this case the vastus lateralis and vastus medialis. When a dancer is maintaining the demi-plie position she is pushing against gravity to prevent herself from sinking lower, possibly introducing a post-activation potentiation. Use of the 75-second first position demi-plie intervention in the stage wings prior to performance and as part of class may be a worthwhile addition to typical dance training, although additional evidence of physiological change is warranted.

One possible contribution to improved static balance that was not explored in the current study is the amount of stimulation at the hind-foot and forefoot. Prior research (25-28) supports a forward sway of the body when the hindfoot is stimulated, a backward sway when the forefoot is stimulated, and the leg muscles acting as antagonists when the hindfoot and forefoot are stimulated equally. During the 30 Hz frequency, the dancers Caption: Figure 3 Effect of intervention and frequency on Balance Error Scoring System Score (*significant difference). in the present study may have adjusted their weight to share the WBV stimulus. When these dancers were resting on their heels, or only on the balls of the feet, the vibration was transmitted through bone and felt uncomfortable at the ears and jaw. The stimulus of the 30 Hz frequency may have inadvertently provided postural feedback, as opposed to the 0 Hz frequency. During the 0 Hz frequency, the dancers held the handles of the vibration plate, which may have caused an alteration in their weightbearing support and sustained posture. To avoid this potentially confounding factor, future studies should consider eliminating the use of the handles during WBV.

The dancers in the present study expressed that they did not find the floor balance positions of the BESS test challenging (as compared, for example, to the same positions held on a foam pad). Simmons et al. (25) found their dancers were most challenged in static stance by balance tests that altered somatosensory input, as compared to visual and vestibular input, when compared to non-dancer controls. Because changes in balance as a function of somatosensory challenge create balance difficulties in dancers, future studies should consider using only BESS foam balance positions for testing static balance.

In regard to dynamic balance, there is a need for standardization of the testing protocols for the SEBT. Specifically, there should be a requirement that the dancer keep her pelvis and shoulders in the transverse plane during testing. In the present study, the dancers were not given postural limits, and this may have been a confounding factor.

Because all conditions improved after intervention, the results are questionable, though it is noteworthy that the greatest improvement occurred in the static demi-plie 30 Hz condition, as the static demi-plie was found to increase CMJ height and the 30 Hz frequency improved static balance. The short duration of holding a static demi-plie during 30 Hz WBV intervention further recommends its use both for improving dancers' performance and in future studies with female professional dancers. Although few studios currently have a vibration platform, with time more affordable and portable WBV platforms may become available.

Conclusion

The clinical and studio applications of this study are as follows: 1. the female professional contemporary dancer may be able to improve her first position saute by maintaining the static demi-plie position for 75 seconds with any WBV frequency; 2. one-time use of a 75-second 30 Hz frequency WBV intervention may be an effective way of immediately improving static balance; and 3. the 75-second use of the static demi-plie 30 Hz condition may be worthy of consideration as a quick method of improving dynamic balance. While this study yielded statistically significant results, clinically meaningful changes should be investigated in future studies.

References

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(2.) Angioi M. Effects of supplemental training on fitness and aesthetic competence parameters in contemporary dance: a randomised controlled trial. Med Probl Perform Art. 2012 Mar;27(1):3-8.

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(5.) Weiss DS, Shah S, Burchette RJ. A profile of the demographics and training characteristics of professional modern dancers. J Dance Med Sci. 2008 Jun;12(2):41-6.

(6.) Wyon M, Guinan D, Hawkey A. Whole-body vibration training increases vertical jump height in a dance population. J Strength Cond Res. 2010 Mar;24(3):866-70.

(7.) Marshall LC, Wyon MA. The effect of whole-body vibration on jump height and active range of movement in female dancers. J Strength Cond Res. 2012 Mar;26(3):789-93.

(8.) Annino G, Padua E, Castagna C, et al. Effect of whole body vibration training on lower limb performance in selected high-level ballet students. J Strength Cond Res. 2007 Nov;21(4):1072-6.

(9.) Despina T, George D, George T, et al. Short-term effect of whole-body vibration training on balance, flexibility and lower limb explosive strength in elite rhythmic gymnasts. Hum Mov Sci. 2014 Feb;33:149-58.

(10.) Rittweger J. Vibration as an exercise modality: how it may work, and what its potential might be. Eur J Appl Physiol. 2010 Mar;108(5):877-904.

(11.) Kinser AM, Ramsey MW, O'Bryant HS, et al. Vibration and stretching effects on flexibility and explosive strength in young gymnasts. Med Sci Sports Exerc. 2008 Jan;40(1):133-40.

(12.) Lott MB, Laws KL. The physics of toppling and regaining balance during a pirouette. J Dance Med Sci. 2012 Dec;16(4):167-74.

(13.) Gerbino PG, Griffin ED, Zura-kowski D. Comparison of standing balance between female collegiate dancers and soccer players. Gait Posture. 2007 Oct;26(4):501-7.

(14.) Dickin DC, McClain MA, Hubble RP, et al. Changes in postural sway frequency and complexity in altered sensory environments following whole body vibrations. Hum Mov Sci. 2012 Oct;31(5):1238-46.

(15.) Cloak R, Nevill A, Wyon M. The acute effects of vibration training on balance and stability amongst soccer players. Eur J Sport Sci. 2016 Jan;16(1):20-6.

(16.) Chen C, Liu C, Chuang L, et al. Chronic effects of whole-body vibration on jumping performance and body balance using different frequencies and amplitudes with identical acceleration load. J Sci Med Sport. 2014 Jan 1;17(1):107-12

(17.) Fort A, Romero D, Bagur C, Guerra M. Effects of whole-body vibration training on explosive strength and postural control in young female athletes. J Strength Cond Res. 2012 Apr;26(4):926-36.

(18.) Clark RC, Saxion CE, Cameron KL, Gerber JP. Associations between three clinical assessment tools for postural stability. N Am J Sports Phys Ther. 2010 Sep;5(3):122-30.

(19.) Batson G. Validating a dance-specific screening test for balance. Med Probl Perform Art. 2010 Sep;25(3):110-5.

(20.) Bell DR, Guskiewicz KM, Clark MA, Padua DA. Systematic review of the balance error scoring system. Sports Health. 2011 May;3(3):287-95.

(21.) Ambegaonkar JP, Caswell SV, Winchester JB, et al. Balance comparisons between female dancers and active nondancers. Res Q Exerc Sport. 2013 Mar;84(1):24-9.

(22.) Kinzey SJ, Armstrong CW. The reliability of the star-excursion test in assessing dynamic balance. J Orthop Sports Phys Ther. 1998 May;27(5):356-60.

(23.) Da Silva-Grigoletto ME, De Hoyo M, Sanudo B, et al. Determining the optimal whole-body vibration dose-response relationship for muscle performance. J Strength Cond Res. 2011 Dec;25(12):3326-33.

(24.) Armstrong WJ, Grinnell DC, Warren GS. The acute effect of whole-body vibration on the vertical jump height. J Strength Cond Res. 2010 Oct;24(10):2835-9.

(25.) Simmons RW. Sensory organization determinants of postural stability in trained ballet dancers. Int J Neurosci. 2005 Jan;115(1):87-97.

(26.) Kavounoudias A, Roll R, Roll J. Foot sole and ankle muscle inputs contribute jointly to human erect posture regulation. J Physiol (Lond). 2001 Jun;532(3):869-78.

(27.) Kavounoudias A, Roll R, Roll J. Specific whole-body shifts induced by frequency-modulated vibrations of human plantar soles. Neurosci Lett. 1999 May 14;266(3):181-4.

(28.) Polonyova A, Hlavacka F. Human postural responses to different frequency vibrations of lower leg muscles. Physiol Res. 2001;50(4):405-10.

Annette Karim, MSPT, DPT, PhD, OCS, FAAOMPT, Toni Roddey, PhD, PT, OCS, FAAOMPT, Katy Mitchell, PT, PhD, Alexis Ortiz, PT, PhD, SCS, CSCS, FASCM, and Sharon Olson, PT, PhD

Annette Karim, MSPT, DPT, PhD, OCS, FAAOMPT, Azusa Pacific University, Azusa, California, USA. Toni Roddey, PhD, PT, OCS, FAAOMPT, Katy Mitchell, PT, PhD, and Sharon Olson, PT, PhD, Texas Woman's University, Houston, Texas, USA. Alexis Ortiz, PT, PhD, SCS, CSCS, FASCM, University of Texas Health Science San Antonio, San Antonio, Texas, USA.

Correspondence: Annette Karim, MSPT, DPT, PhD, OCS, FAAOMPT, Department of Physical Therapy, Azusa Pacific University, 901 Easet Alosta Avenue, PO Box 7000, Azusa, California 91702-7000, USA; akarim@apu.edu.

Caption: Figure 1 Execution of the first position CMJ (saute).

Caption: Figure 2 The effect of intervention and plie position on countermovement jump (CMJ) height (*significant difference).

https://doi.org/10.12678/1089-313X.23.1.3
Table 1 Participant
Demographics (N = 59)

Characteristics    M (SD)

Age               25.78 (3.78)
Weight (kg)       58.55 (7.12)
Height (cm)      163.81 (1.72)
BMI               21.87 (2.06)
Leg Length (cm)   85.34 (4.88)

Table 2 Effect of Time in Condition on Countermovement Jump Height

                                           Time
                            Pre-Intervention  Post-Intervention
Condition                  N   M(SD) inches   N   M(SD) inches

Static demi-plie (0 Hz)    15  11.58 (2.07)   15  11.98 (2.29)
Static demi-plie (30 Hz)   14  11.57 (2.00)   14  12.08 (1.66)
Dynamic demi-plie (0 Hz)   15  11.25 (1.46)   15  11.15 (1.43)
Dynamic demi-plie (30 Hz)  15  11.41 (1.83)   15  11.25 (1.87)

Table 3 Effect of Time in Position on Countermovement Jump Height

                                   Time
                   Pre-Intervention  Post-Intervention
Position           N   M(SD) inches  N   M(SD) inches

Static demi-plie   29  11.58 (2.00)  29  12.02 (1.97)
Dynamic demi-plie  30  11.24 (1.66)  30  11.20 (1.64)

Table 4 Omnibus Analysis for the Effect of Position and Time on
Countermovement Jump Height ([alpha] = 0.025)

                                F     df     P-value

Main Effect of Position         1.56  1, 57  0.22
Main Effect of Time             5.02  1, 57  0.03
Interaction of Position x Time  7.17  1, 57  0.01 (*)

(*) Statistically significant.

Table 5 Simple Effects of Position and Time on Countermovement Jump
Height ([alpha] = 0.0125)

                      F       df     P-value

Time Within Position
  Static demi-plie    11.89   1, 57  0.001 (*)
  Dynamic demi-plie    0.097  1, 57  0.76
Position Within Time
  Pre-Intervention     0.50   1, 57  0.49
  Post-Intervention    3.07   1, 57  0.85

(*) Statistically significant.

Table 6 Effect of Time in Frequency on Countermovement Jump Height

                            Time
            Pre-Intervention   Pos-Intervention
Frequency  N    M(SD) inches  N    M(SD) inches

0 Hz       30   11.42 (1.77)  30   11.56 (1.92)
30 Hz      29   11.39 (1.91)  29   11.65 (1.79)

Table 7 Effect of Time in Condition and Test Type on Balance

Condition         SEBT              SEBT               BESS
                  Pre-Intervention  Post-Intervention  Pre-Intervention
                  M(SD) inches      M(SD) inches       M(SD) errors

Static demi-plie  91.80 (10.47)     93.40 (12.12)      12.60 (4.24)
(0 Hz) N = 15
Static demi-plie  88.07 (8.91)      91.79 (10.58)      12.93 (5.77)
(30 Hz) N = 14
Dynamic demi      89.60 (10.49)     92.73 (12.78)      11.47 (4.19)
(plie-0 Hz)
N = 15
Dynamic demi      90.13 (9.18)      92.73 (12.62)      14.13 (5.36)
(plie-30 Hz)
N = 15

Condition         BESS
                  Post-Intervention
                  M(SD) errors

Static demi-plie  12.4 (5.25)
(0 Hz) N = 15
Static demi-plie  10.43 (4.77)
(30 Hz) N = 14
Dynamic demi      12.67 (6.75)
(plie-0 Hz)
N = 15
Dynamic demi      10.13 (3.50)
(plie-30 Hz)
N = 15

Table 8 Effect of Time in Position on Star Excursion Balance Test
Results

                                Time
                   SEBT              SEBT
                   Pre-Intervention  Post-Intervention
Position           N   M(SD) inches  N   M(SD)inches

Static demi-plie   29  90.00 (9.76)  29  92.62 (11.23)
Dynamic demi-plie  30  89.87 (9.69)  30  92.73 (12.4)

Table 9 Omnibus Analysis of the Effect of Position and Time on Star
Excursion Balance Test Results ([alpha] = 0.0125)

                                 F      df      P-value

Main Effect of Position          0.00  1, 57   0.99
Main Effect of Time             23.00  1, 57  <0.001 (*)
Interaction of Position x Time   0.05  1, 57   0.83

(*) Statistically significant.

Table 10 Effect of Time in Frequency on Star Excursion Balance Test
Results

                            Time
            SEBT             SEBT
           Pre-Intervention   Post-Intervention
Frequency  N   M(SD) inches   N   M(SD) inches

 0 Hz      30  90.70 (10.36)  30  93.07 (12.24)
30 Hz      29  89.14 (8.95)   29  92.28 (11.48)

Table 11 Omnibus Analysis of the Effect of Frequency and Time on Star
Excursion Balance Test Results ([alpha] = 0.0125)

                                   F     df     P-value

Main Effect of Frequency          0.18  1, 57   0.67
Main Effect of Time              23.31  1, 57  <0.001 (*)
Interaction of Frequency x Time   0.46  1, 57   0.50

(*) Statistically significant

Table 12 Effect of Time in Position on Balance Error Scoring System
Results

                                   Time
                       BESS                BESS
                   Pre-Intervention  Post-Intervention
Position           N   M(SD) errors  N   M(SD) errors

Static demi-plie   29  12.76 (4.95)  29  11.45 (5.03)
Dynamic demi-plie  30  12.80 (4.92)  30  11.40 (5.44)

Table 13 Effect of Frequency on Balance Error Scoring System Results

                             Time
                BESS               BESS
           Pre-Intervention  Post-Intervention
Frequency  N   M(SD) errors  N   M(SD) errors

 0 Hz      30  12.03 (4.18)  30  12.53 (5.94)
30 Hz      29  13.56 (5.49)  29  10.28 (4.09)

Table 14 Omnibus Analysis Results for the Effect of Position and Time
on the Balance Error Scoring System ([alpha] = 0.0125)

                                  F     df     P-value

Main Effect of Frequency         0.11  1, 57  0.75
Main Effect of Time              4.89  1, 57  0.03
Interaction of Frequency x Time  9.04  1, 57  0.004 (*)

(*) Statistically significant.

Table 15 Simple Effects of Frequency and Time on Balance Error Scoring
System Results ([alpha] = 0.0063)

                        F      df     P-value

Time Within Frequency
   0 Hz                 0.32  1, 57  0.57
  30 Hz                13.39  1, 57  0.001 (*)
Frequency Within Time
  Pre-Intervention      1.43  1, 57  0.24
  Post-Intervention     2.87  1, 57  0.096

(*) Statistically significant.


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Author:Karim, Annette; Roddey, Toni; Mitchell, Katy; Ortiz, Alexis; Olson, Sharon
Publication:Journal of Dance Medicine & Science
Article Type:Report
Date:Jan 1, 2019
Words:5052
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