Effects of Habitual Low-Impact Dance on the Balance and Torque of the Knees of Older Female Individuals

doi:10.4236/ape.2012.22007

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Advances in Physical Education

2012. Vol.2, No.2, 39-43

Published Online May 2012 in SciRes (http://www.SciRP.org/journal/ape) http://dx.doi.org/10.4236/ape.2012.22007

Effects of Habitual Low-Impact Dance on the Balance and Torque

of the Knees of Older Female Individuals

Huiying Wu1, Jungsheng Gau2, Chin Hsing Hsu1, Jui Hung Tu3, Te Hung Tsao4

1Department of Rec reation Sport and Health Promotion,

National Pingtung University of Science & Technology, Pingtung, Chinese Taipei

2Office of Physical E ducation, Chang Gung Unive rsity of Science and Technology, Tauyau, Chinese Taipei

3Department of Phys ical Education, National Pingtung University of Education, Pingtung, Chinese Taipei

4Physical Education Section of General Education, National Sun Ya t-sen University, Kaohsiung, Chinese Tai pei

Email: [email protected], [email protected]

Received March 22nd, 2012; revised April 18th, 2012; accepted May 2nd, 2012

Backgroud: Despite of many people engaging in aerobic dance activities, little knowledge was reported

regarding the effects of low-impact dance on the balance, torque and range of motion (ROM) of joints of

the lower extremities. Thus, the aim of this study was to examine whether any differences existed in terms

of the aforementioned variables between older females who regularly engaged in low-impact dance and

those who were physically inactive. Method: In total, 38 older females comprised the subjects of this

study, which consisted of a dance group (DG) and a control group (CG). The extension torque of the

knees, dynamic and static balance, and ROMs of the hip and ankles of all participants were measured.

Results: Dynamic balance in the DG was significantly higher than that in the CG (13.0 ± 4.7 vs. 5.5 ± 7.8

times, p < 0.05). Although the knee extension torque for both legs was higher in the DG than in the CG, a

significant difference was only found in the non-dominant leg. A few ROMs of lower-extremities joints in

the dominant leg, ankle inversion, plantiflexion and dorsiflexion were significantly higher in the DG than

the CG (p < 0.05). In addition, ankle inversion of the non-dominant leg in the DG was also significantly

higher than that in the CG. Conclusions: Compared to their physically inactive counterparts, older fe-

males who habitually engage in low-impact dance had significantly higher dynamic balance, knee exten-

sion in the non-dominant leg, and ROMs of several joints of the lower extremities. Although this research

was not an intervention study, these positive results should encourage further studies, because the afore-

mentioned parameters are associated with risk factors for and reductions in falls.

Keywords: Low-Impact Dance; Fall; Balance; Knee Joint Torque

Introduction

Similar to many countries worldwide, the aging population

(over 65 years) is increasing, and a “silver society” seems to be

an unavoidable trend in Taiwan. The aging population is esti-

mated to be 10% of the population in Taiwan. Negative phe-

nomena with respect to physiology and psychology, such as

weak muscular strength, a decline in the balance capacity,

slower metabolism, and depression, become more prevalent in

aging individuals. Everyone alive will face the aging pheno-

menon; however, these negative influences of aging can be

somewhat attenuated through regular physical activities and

exercise (American College of Sports Medicine (ACSM), 1998;

Steffen et al., 2002). As a result, the American Collage of

Sports Medicine (ACSM) and American Heart Association

(AHA) jointly recommend that older adults under 65 years of

age need a minimum of 30 min of moderate-intensity aerobic

phy sical activity 5 days a week or a minimum of 20 min of vi g o r-

ous-intensity aerobic activity 3 days a week to promote and

maintain health (Haskell et al., 2007).

Although the majority of exercises are beneficial for mental

and physical health, extra attention should be paid to older

adults engaged in physical activities, especially older women.

The reason is that they are close to or in the period of meno-

pause (Asikainen et al., 2004; Roberts, 2007). Due to loss of

estrogen during menopause, a declines in balance and muscle

strength in female adults might be faster compared to premeno-

pausal women. Menopause is associated with loss of estrogen

(Greeves et al., 1999; Hammar et al., 1996). Loss of balance

and weak strength in the lower extremities are risk factors for

falls in older individuals (Rubenstein, 2006; Yokoya et al.,

2008). As a result, in addition to improving those negative phe-

nomena by hormone replacement therapy (Carville et al., 2006;

Götherström et al., 2010), interventions with of a battery of

physical activities or exercises are effective in reducing of fall

risk factors and fall cases (Bocalini et al., 2009; Shigematsu et

al., 2008).

Among a variety of physical activities, aerobic dance is one

of the recommended physical activities and is widely enjoyed

by women. Although aerobic dance can enhance and improve

cardiorespiratory fitness, the maximal oxygen capability, and

submaximal aerobic power of older adults (Dowdy et al., 1985),

higher peak impact forces, higher mean loading rate, and a higher

mean impact impulse with aerobic dance pose potential risks to

the strength, joints, and soft tissues of the lower extremities of

participants (Ricard & Veatch, 1990; Janis, 1990). As a result,

older or sedentary women who wish to engage in this activity

should carefully consider the risks. On the other hand, several

studies (Hopkins et al., 1990; Shimamoto et al., 1998) reported

that low-impact dance can improve cardiopulmonary fitness,

and muscular strength and endurance. In addition to lower-impact

H. Y. WU ET AL.

forces on the lower extremities with low-impact dance, an obvious

difference between low- and high-impact dance is that with

low-impact aerobic dance, one foot maintains contact with the

floor at all times, which differs from both feet sometimes syn-

chronously leaving the ground in high-impact dance (Ricard &

Veatch, 1990). Consequently, as long as the influences of impact

on the lower extremities is considered, the characteristics of

low-impact dance seem to be more appropriate for those who

are weak strength in the lower extremities or sedentary when

they begin an exercise program. Despite the benefits ascer-

tained in previous studies and seemingly positive features from

our assumptions, there are few studies of the effects of low-impac t

dance on balance, torque, and ROM of joints of the lower ex-

tremities. However, those parameters are significantly related to

risk factors for falling. As a result, the aim of this study was to

investigate the effects of low-impact dance on balance and knee

torque in participants and to compare the above-mentioned

parameters with those of a physically inactive cohort. In addi-

tion, the ROM of several joints in the lower extremities, such as

the hip and ankles, were also measured and analyzed in this

study. We hypothesized that these parameters in women who

engage in regular low-impact dance would significantly differ

compared to those of their physically inactive counterparts.

Methods

Participants

The design of this research was a comparative of cross-sectional

study. The age range of participating females in this study was

50 - 70 years. All female participants were screened by a physi-

cian to ensure that they had no cardiovascular, metabolic, or

pulmonary diseases. In addition, individuals who had such

problems or diseases related to the musculoskeletal system and

had taken any hormone-related medicine for menopause within

6 months before the study were excluded. Individuals who had

engaged in low-impact aerobic dance for at least 3 years, 30

min each time, five times per week were included in the dance

group (DG). These conditions with respect to regular physical

activity matched recommendations of the ACSM (Haskell et al.,

2007). On the other hand, individuals who did not exceed 20

min of structured physical activity at most in a week and those

who did not engage in physical labor in their occupations were

included in the control group (CG). Originally, numbers of

individuals with the intention of participating in this research

were 33 in t he DG and 19 in the CG, resp ectively. After scr eening

all of these potential persons for their regular low-impact dance

habits and health conditions in the DG and whether they had

engaged in regular exercise or physical activity within the last 6

months in the CG, 26 low-impact dancers in the DG and 12

individuals in the CG matched the conditions of the study.

However, those who were not subjects in this study did not

differ from participants in age or BMI. All eligible subjects

provided written informed consent before they were allowed to

participate in the study. According to the instructor’s records,

the compliance rate for low-impact dance participants exceeded

85% in each month. Approval for this study was obtained from

the Human Subject Internal Review Board of the local hospital.

All measurements in the present study were conducted in a

sports biomechanics laboratory.

Participants’ Anthropometric Measurements

The height and weight of all participants were measured with

an electronic stadiometer (Seca, Model 242, Hanover, MD) and

digital scale (Tanita, Model BWB-627A, Hong Kong, China),

respectively. The BMI was calculated by dividing the weight

(kg) by the height (m) squared (kg/m2). In addition, the percent

body fat was measured by InBody 720 (BIOSPACE, Seoul,

South Korea). The measurement was carried out in the morning

after an overnight fast.

The Program of Low-Impact Aerobic Dance

The general program of low-impact dance consisted of three

parts: warming up, reviewing actions in the previous sessions

and practicing all of the actions with the music, and teaching

new actions. Of these, reviewing and practicing occupied the

most time in a given program. The main exercises for the lower

extremities were side-stepping, walking forward and backward,

circling, lifting the legs, tiptoeing with the foot to the front, side,

and rear, and heel rises. The main exercises for the upper extremi-

ties were stretching, circling, shrugging, abduction, adduction,

and circumduction.

Balance

The balance measurement was divided into two parts: dy-

namic and static balance. The former was measured with a

stabilometer (Model 1630, Lafayette Instrument Inc., IN). A

participant stood on the stabilometer with a fixed width be-

tween the medial borders of the feet, and balance was deter-

mined by maintaining one’s position within ± 5° relative to the

horizontal plane. The balance times in 30 s were calculated and

recorded by the program of the stabilometer. Static balance was

measured by balancing on one leg with eyes closed. The time

for this measurement was recorded from when one foot left the

ground to when the person touched a support (wall, chair, or

protectors). The time interval between measurements on the

two legs was 1 min.

Knee-Joint Extension Torque Test

The mean peak torque for each knee extension of all partici-

pants was determined by averaging peak torque values from

three maximal trials with an intervening 2-min rest period be-

tween trials. Subjects were tightly secured to a fixed chair using

waist, chest, and thigh straps. The knee was positioned in 120°

of flexion and the hip in 90˚ flexion. The lateral condyle of the

tibia was aligned with the axis of the torque sensor. The force

measurement device can measure the force generated by the

knee extension using a torque sensor (Jihsense RT-100, Taipei,

Taiwan). When the knee torque measurement of one leg was

completed, the assessment for the other leg began after a 3-min

rest period. This torque instrument was calibrated according to

the manufacturer’s instructions before the measurement. The

inter- and intra-individual coefficients of variation for all vari-

ables in this study were <7%.

ROM of the Hip and Ankle Joints

Parameters related to the lower extremities in the current

study were separately analyzed for the dominant and non-domi-

nant legs in order to examine differences between legs for those

who were habitual low-impact dancers because some actions,

for example, being supported by a single leg, circling, and step-

ping to the side, might subconsciously be executed using the

do minant leg. To identify the domi nant leg, we asked partici pa nt s

H. Y. WU ET AL.

with which leg they preferred to kick a ball (Ricotti & Rava-

schio, 2011). Hip joint flexion, extension, internal rotation, and

external rotation and ankle joint inversion, eversion, plantir-

flexion, and dorsiflexion ROMs of all participants were meas-

ured using a goniometer (NexGen Ergonomics, Quebec, Can-

ada) by an experienced physiotherapist, who was blinded to the

group categories. The methods of Norkin and White (1995) for

hip and ankle joint ROMs were adopted in the current study.

Before testing, participants were asked to warm up for 3 - 5 min.

All values of ROM measured for these joints were obtained

from the mean of two measurements. If the difference between

these two measurements of any variable exceeded 2°, a third

measurement was performed.

Statistical Analysis

Results of all parameters are expressed as the mean ± stan-

dard deviation (SD). Variables in the two different groups were

compared by an independent Student’s t-test. All data analyses

were performed with SPSS vers. 15.0 (SPSS, Chicago, IL,

USA). The significance level was set to p < 0.05.

Results

For the knee-extension torque, the sample size of 38 subjects

was sufficient to give a statistical power of 80% with a signify-

cance level of p < 0.05 after a statistical power analysis

(G*Power 3.0, Franz Faul, Kiel University, Germany). The

average number of days in a week in which participants en-

gaged in low-impact dance in the DG group was 5.9 ± 0.8 days,

which agreed with the physical activity recommendations of the

ACSM for adults. The age, BMI, body fat percentage, and

waist-to-hip ratio (WHR) of participants in these two groups

are presented in Table 1. Participants in this study were catego-

rized as being overweight according to the BMI value (>25).

Although the BMI value and percentage of body fat were

slightly higher in the CG than the DG, the results showed no

significant differences between the two groups.

The balance times on the stabilometer were significantly

higher in the DG than in the CG (Table 1), although no sig-

nificant difference was detectable in static balance of either leg

between the two groups (Table 2). For knee-extension torque,

although this variable in the dominant (DG: 57.9 ± 20.6 vs. CG:

43.3 ± 13.9 Newton [N]·m, p = 0.053) and non-dominant legs

(DG: 57.2 ± 22.2 vs. 40.3 ± 16.5 N·m, p < 0.05) was higher in

the DG than the CG, a significant difference was only found in

the non-dominant leg between these two groups (Table 2).

The ROMs of the hip and ankle joints of participants in these

two groups are given in Table 3. The DG group had signify-

cantly higher values for inversion of the ankle than the CG for

both the dominant and non-dominant legs (p < 0.05). In addi-

tion, ankle plantiflexion and dorsiflexion in the dominant leg

were significantly higher in the DG than the CG (p < 0.05). For

ROMs of the hip, hip extension in both legs of the DG was

significantly higher than that of the CG. However, the hip external

rotation of the non-dominant leg in the CG was significantly

higher than that in the DG.

Discussion

Although previous studies on aerobic dance indicated that

both low- and high-impact aerobic dancing were beneficial for

cardiorespiratory fitness (CRF) of overweight females (Dodwy

et al., 1985; Shimamoto et al., 1998), data on the balance, torque,

and ROM of joints of the lower extremities from low-impact

Table 1.

Participant’s characteristics and dynamic balance between the Dance

Group (DG) and Control Group (CG).

DG (n = 26) CG (n = 12)

Age (year) 59.1 ± 8.3 62.0 ± 5.3

BMI (kg/m2) 24.7 ± 3.0 25.9 ± 3.0

Body fat percentage (% ) 36.5 ± 5.5 37.8 ± 5.2

Waist-to-hip ratio 0.95 ± 0.05 0.97 ± 0.03

Dynamic balance (times)13.0 ± 14.7* 5.5 ± 7.8

*significa ntly differs from the CG, p < 0.05.

Table 2.

The static balance and knee extension torque in the Dance Group (DG)

and Control Group (C G ) .

Dominant l eg Non-dominant leg

Item DG CG p DG CG p

Single-leg

with eyes

closed (s)7.1 ± 10.97.4 ± 4.80.63 7.6 ± 14.8 7.1 ± 6.10.25

Torque

(N·m) 57.9 ± 20.643.3 ± 13.90.05 3 57.2 ± 22.2* 40.3 ± 16.5<0.05

*significa ntly differs from the CG, p < 0.05.

Table 3.

Characteristics of the study population and descriptive statistics.

Dominant l eg Non-domin ant leg

Item DG CG p DG CG p

Ankle inversion 17.2 ± 4.9* 8.3 ± 4.6 <0.01 15.7 ± 3.9* 8.6 ± 2.6 <0.01

Ankle eversion 12.9 ± 5.0 11.7 ± 4.8 0.89 13.6 ± 4.0 11.6 ± 2.7 0.25

Ankle plantiflexion 37.6 ± 5.6* 33.2 ± 5.2 0.04 35.1 ± 4.4 34.8 ± 7.4 0.81

Ankle dorsi f l exion 18.3 ± 5.0* 14.0 ± 5.7 0.03 17.1 ± 5.0 15.1 ± 4.3 0.52

Hip extensi o n 21.0 ± 6.9* 15.0 ± 3.3 <0.05 22.9 ± 7.8* 14.0 ± 3.9 < 0.05

Hip flexion 108.5 ± 9.6 104.0 ± 17.61 0.14 109.0 ± 12.0 107.5 ± 19.5 0.20

Hip internal rotation 31. 6 ± 8.9 34.6 ± 5.5 0.73 27.8 ± 7.0 28.0 ± 7.0 0.51

Hip external r otation 30.6 ± 7.6 30.0 ± 5.9 0.19 31.9 ± 6.4* 37.8 ± 5.3 <0.05

H. Y. WU ET AL.

dance are scarce. Results of the current study support older

females who habitually engage in low-impact dance having a

higher dynamic balance capacity, greater knee extension torque,

and larger ROMs of most of the lower-extremities joints com-

pared to those who are physically inactive.

Longitudinal and cross-sectional studies reported that main-

tenance or interventions with physical activities or exercise that

enhance muscle strength and balance in older individuals (Bird

et al., 2009; Chandler et al., 1998; Hortobágyi et al., 2001),

even exercises of low intensity such as walking, cycling, and tai

chi (Huang et al., 2011; Macaluso et al., 2003; Melzer et al.,

2003; Qin et al., 2005), were also corroborated with effective-

ness in improvement in muscle strength and balance. In this

study, the knee extension torque of the non-dominant leg in the

DG was significantly higher than that in the CG. Moreover, the

knee torque of the dominant leg tended to be higher in the DG

than in the CG, even though not statistically significant (p =

0.053). We know that low-impact dance practitioners perform

their dance steps by maintaining contact with the ground. These

repetitive movements reinforce muscle groups of the lower

extremities through the impact of hitting the ground in addition

to increasing muscle contractions. We suggest that this model

of low-impact dance is a possible reason for the significant

difference in the non-dominant leg between the DG and CG. In

fact, the above-mentioned stimulations resemble weight-bearing

exercises in several studies (Bravo et al., 1996; Kukuljan et al.,

2009), which supported the beneficial effects of impact from

exercise on muscles.

On the other hand, previous literature (Engels et al., 1998;

Hopkins et al., 1990) reported that low-impact dance benefited

balance and muscle strength of the lower extremities. From the

results of dynamic balance, this study also supports conclusions

of the related studies on low-impact dance. However, no signi-

ficant differences were evident in the static balance of the dominant

or non-dominant leg between these two groups. In addition,

after associations between knee extension torque and static

balance of the dominant and non-dominant legs in the respect-

tive groups were further analyzed, no significant relationships

were evident. As a result, although low-impact dance displayed

a positive result on dynamic balance, further studies regarding

the influence of low-impact dance on balance are warranted,

because the results for static balance seemed counter to the

hypothesis of this study.

Several studies indicated that the ROMs of joints in the

lower extremities of women and men decrease with age (James

& Parker, 1989; Sepic et al., 1986), and the ROMs of these

joints in women, such as the ankles, knees and hips, declined

more obviously and faster than those of men (Vandervoort et al.,

1992). These negative developments, of reduced ROMs of

joints in the lower extremities, are likely to increase the chances

of losing one’s balance and lead to falls (Mecagni et al., 2000;

Vandervoort et al., 1990). Several studies reported that the in-

tervention of a battery of physical activities or exercises im-

proved the ROMs of joints, and those positive changes could

contribute to a decline in the incidence of falls (Cao et al., 2007;

Katzman et al., 2007). In the current study, in addition to a few

ROMs of joints in the non-dominant leg of the DG tending to

be higher compared to those of the CG, most ROMs of joints in

the dominant leg, ankle inversion, plantiflexion, and dorsiflex-

ion, were significantly higher in the DG than the CG. These

results are in agreement with a study by Cao et al., (2007),

which supported the positive influence of exercise on ROMs of

joints in the lower extremities. We inferred that diverse dance

steps, such as side-stepping, walking forward and backward,

circling, lifting the legs, tiptoeing with the foot to the front, side,

and rear, and raising the heels, were frequently executed with

the fixed dominant leg. This bias of utilization is likely to be

the reason for the difference between the two groups. On the

other hand, although a few movements, such as side-stepping

and circling, seem to be useful for the ROM of these joints, no

significant difference was found in the ROMs of the hips be-

tween the DG and the CG, except for hip external rotation. It is

difficult for us to speculate on the reason for this. Accordingly,

further studies are needed to explore possible reasons why the

ROMs of these joints were higher in the DG than the CG ac-

cording to the current results. However, maintaining a certain

degree of ROMs of lower-extremity joints from low-impact

dance is a novel finding in this study, especially of the domi-

nant leg, compared to sedentary counterparts. Studies on older

persons reported that maintenance or improvement of the ROM

of the lower extremities with exercise can boost the perform-

ance of activities of daily living (Alexander et al., 2001; Stan-

ziano et al., 2009). Low-impact dancers enjoy this benefit fea-

ture because the ROMs of their lower limbs are superior to

those of physically inactive individuals.

Limitations

A few limitations exist in this study. The data regarding fall

cases in this study were not investigated, although the parame-

ters were related to risk factors for falls. In addition, because

this study was not an intervention type of experiment, we can-

not infer causality from the aforementioned results, such as

balance and torque of knee extension. As a result, further stud-

ies are warranted to examine associations between falls and

related parameters for regular participants of low-impact dance

and the comparisons between low-impact dancers and seden-

tary individuals.

Conclusion

Regular low-impact dancers showed positive features com-

pared to individuals who were physically inactive, such as sig-

nificantly higher torque and ROM of the lower extremities. In

addition, the balance capacity, especially dynamic balance, was

obviously higher in participants of low-impact dance. These

promising findings should prompt further direct studies to in-

vestigate changes in related parameters and fall cases in the

elderly who participate in low-impact dance interventions.

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