Assessment of cardiovascular endurance in Bharatanatyam dancers

Nithyakalyani Mohan,Jahnanvi Narayanan

1Apollo Hospitals,Tamil Nadu,India.2Rasa Arpita,Tamil Nadu,India.

Abstract Background:The nature and duration traditional Bharatanatyam training bring about a wholesome physiological improvement in terms of balance,flexibility,stamina,and respiratory efficiency.Aerobic fitness is essential in sustaining endurance exercise,like a long dance performance,as it keeps the muscle fatigue away for longer.Regular practice improves the aerobic metabolic pathway of dancers,which is characterized by increased oxygen delivery and carbon dioxide removal in the muscles.The current study sought to assess the aerobic fitness and cardiovascular endurance of Bharatanatyam dancers compared to non-dancers.Methods:The study population included 30 females in the age group of 16-25 years,including 15 dancers(Group I)and 15 non-dancers(Groups II).Their VO2max,or peak oxygen consumption,was assessed using the modified Canadian aerobic fitness test,a sub-maximal step test.The two groups were compared based on demographics,BMI,VO2max,pre-and post-test heart rate.Statistical analysis was performed using Microsoft Excel.All test results were two-tailed,and a probability value(P-value)less than 0.05 was taken to be statistically significant.Results:The analysis revealed that Bharatanatyam dancers had a significantly lower BMI(P-value = 0.002),post-test heart rate(P-value =0.01),and difference in the pre and post-test heart rate(P-value = 0.019);and higher VO2max(P-value = 0.000)when compared to the control group.There was a significant association between the practice of Bharatanatyam and VO2max(Fisher exact test; P-value =0.000).Within the Group I(dancers;n = 15),there was a significant inverse correlation between BMI and VO2max(rs=-0.546, P-value = 0.001),post-test heart rate and VO2max(rs=-0.461, P-value = 0.01);and difference in the pre-and post-test heart rate and VO2max(rs=-0.412, P-value = 0.02).Finally,there was a mild positive correlation between practice days/week and VO2max,although not statistically significant(rs= 0.3841, P-value = 0.157).Conclusion:The overall higher level of aerobic capacity of dancers when compared to non-dancers can be attributed to the way Bharatanatyam training is traditionally designed with graded training protocols and gradually increasing intensities of performance pieces;as well as the individual's initial fitness level and the frequency,intensity and duration of the training.Thus,we conclude that Bharatanatyam has the framework necessary for improving various aspects of the dancer's health.

Keywords:Bharatanatyam;aerobic capacity;VO2max;heart rate

Introduction

Bharatanatyam is an Indian classical dance form that derives its roots from the Natya Shastra,an ancient Indian text on performing arts,said to be compiled by sage Bharata around 200 BCE.Bharatanatyam effectively combines nirtta,nritya,and natya to communicate mythological stories and social messages.Like other Indian classical dance forms,Bharatanatyam recruits many different body parts in each movement.The dance items often include a complex string of movements performed at different speeds and energy levels.Traditionally,Bharatanatyam training involves years of perfecting the dance moves and regular practice.Although different styles,or Banis,exist,the fundamental element of Bharatanatyam is the‘Adavu.’These are primarily performed in a semi-seated posture,called Araimandi,which provides balance,stability,and also allows for a broader range of movements[1].

The nature and duration of the training and performance period bring about a wholesome physiological improvement in terms of flexibility,stamina or cardiorespiratory efficiency.Over time,exercising the muscles improves vascularization,which further increases the oxygen delivery and carbon dioxide removal in the muscles[2].These physiological effects of Bharatnatyam and the fitness level of dancers can be analyzed through parameters like body composition,heart rate,aerobic capacity,anaerobic threshold,muscular power,and strength[3].

During any sustained period of activity like dancing,the body derives energy through various metabolic pathways like the aerobic and anaerobic pathways[3].At a basic level,the aerobic pathway is where oxygen is used to break down food substances to generate energy.On the other hand,the anaerobic pathway occurs in the absence of oxygen to generate energy,along with the production of metabolites like lactic acid,which contributes to quicker fatigue.The aerobic pathway is essential in sustaining endurance exercise,like a long dance performance,as it keeps the muscle fatigue away for longer.Measuring an individual’s aerobic capacity,which is the capacity of the cardiorespiratory system to supply oxygen and the capacity of the skeletal muscles to utilize it,assesses the aerobic pathway.The aerobic capacity is influenced by both genetic as well as environmental factors,including lifestyle factors like smoking,exercising[4,5].Years of research have established the fact that exercising has an exponential effect on improving one’s aerobic capacity[6-8].The gold standard for assessing aerobic capacity is VO2max,a measure of maximal oxygen consumption or cardiovascular endurance,which can be measured by direct as well as indirect methods.The direct method is a complex process requiring equipment that is expensive and not routinely available.Hence,indirect methods like the modified Canadian Aerobic Fitness tests,and Queen’s College step test are good alternatives[9,10].

Previously published papers on the physiology and fitness levels of dancers have mostly focused on western dance forms like ballroom dancing,ballet,high-land dance,and aerobic dance workouts.These studies found that the aerobic capacity of dancers is average and comparable to individuals practicing non-endurance sports[3-8,11-19].These results can be attributed to the dance style,gender,level of technical ability,and status in a dance company[3].However,the scientific literature is still lacking in terms of Indian dance forms like Bharatanatyam and their physiological effects.Hence,the current study aims to assess the aerobic fitness and cardiovascular endurance of Bharatanatyam dancers compared to non-dancers.

Materials and methods

The study was conducted on female Bharatanatyam dancers and non-dancers with the age group of 16-25 years after obtaining informed written consent for data collection from all participants/guardians.Inclusion criteria for dancers included those with Bharatanatyam dance training of 5 years or more.Exclusion criteria for dancers included athletes,presence of chronic pulmonary diseases like chronic obstructive pulmonary disease,asthma,lung fibrosis,and respiratory distress.Demographic data including age,years since beginning to dance,frequencies of practice sessions per week have also been included.Participants were divided into two groups-Group I with experience practicing Bharatanatyam and Group II,with no experience in Bharatanatyam dancing.VO2maxwas assessed using the modified Canadian Aerobic fitness test(mCAFT),a sub-maximal step test,in both groups.In brief,participants were asked to step on two 20.3-cm steps at a fixed cadence according to the mCAFT stage.The stepping cadence for each stage was standardized based on age and gender.At the end of each stage,heart rate was measured by palpating the radial pulse.Participants were allowed to progress to the next stage(with increased cadence)if their postexercise heart rate was below 85% of their age-predicted maximal heart rate(220-age in years).If a participant only partially completed a stepping stage their final score reflected the last completed stage.VO2maxwas calculated using the CSEP-PATH equation(CSEP 2013)[9,10,20,21].

Estimated VO2max(mL·kg-1·min-1)

=[17.2+(1.29×O2cost of last completed stage)-(0.09×body weight in kg)-(0.18× age in years)][20,21]

Statistical analysis was performed using Microsoft Excel and the results were interpreted in terms of percentage,mean,chi-square/Fisher exact test.Comparison of the means of continuous variables between the two groups was done using an independent sample’st-test.Spearman's Correlation test was used to analyze the relationship between variables.All test results were two-tailed and a probability value(P-value)less than 0.05 was taken to be statistically significant.

Results

The study population included a total of 30 females,including 15 dancers(Group I)and 15 non-dancers(Group II).The overall age group ranged from 15 to 25,and the mean age was 19.9 ± 3.1 years.There was no significant difference in the age distribution between the two groups(P-value = 0.954).With respect to the physical characteristics,there was no significant difference between the two groups in the height(162.26 ± 5.58 vs 162.4 ± 3.39 cm;P-value =0.93).The two groups showed a significant difference in the body weight(58.58 ± 6.16 vs 63.68 ± 3.25 Kg;P-value = 0.001)

There was a significantly lower BMI,post-test heart rate,and difference in the pre and post-test heart rate in dancers compared to non-dancers(Table 1).Among the dancers,the average duration of dance training was 12.6 ± 3.17 years,and the average number of practice days per week was 4.26 ± 1.16 days/week.

Around 53.33% of dancers fell into the VO2maxcategory of 'very good'[21](Figure 1).There was a significantly higher VO2maxGroup I when compared to Group II(Table 1).Further analysis showed a significant association between the practice of Bharatanatyam and VO2max(Fisher exact test;P-value = 0.000)

Table 1 Demographic profile between dancers and non-dancers

Within the Group I(dancers;n = 15),there was a significant inverse correlation between BMI and VO2max(rs=-0.546,P-value =0.001),post-test heart rate and VO2max(rs=-0.461,P-value = 0.01);and difference in the pre-and post-test heart rate and VO2max(rs=-0.412,P-value = 0.02).Finally,there was a mild positive correlation between practice days/week and VO2max,although not statistically significant(rs= 0.3841,P-value = 0.157).However,there was no significant correlation between VO2maxand the no.of years of dance training.

Discussion

Bharatanatyam initially began as a temple dance form in ancient India but has since then evolved into a globally performed theatre art form.In addition to its original intent of devotion and religious purposes,Bharatanatyam also has scope for becoming the harbinger of mental,physical,and emotional well-being for the dancer.Many studies have demonstrated the beneficial effects of different dance forms in terms of physiological and psychological perspectives[3-8,11-19,22-26].Moreover,as Bharatanatyam fits into the category of aerobic exercise,it can be beneficial in preventing cardiovascular diseases,improving lipid profile,and increasing levels of good cholesterol-HDL[4,8,14,19,25,26].

In our study,we compared the parameters of aerobic fitness,VO2max,the pre-and post-test heart rate in Bharatanatyam dancers and non-dancers(Figure 2).Bharatanatyam dancers were found to have a statistically significant higher cardiovascular endurance,VO2max(46.17 ± 3.71)than non-dancers.The result was similar to the study done by Saba Ananth which compared the cardiopulmonary parameters in amateur and professional Bharatanatyam dancers.Professional dancers had a VO2maxof 46.67 ± 2.57 and amateur dancers had 44.33 ± 2.98.Our analysis further showed that VO2maxshowed a positive correlation between the number of practice days per week and along with sporadically higher values(up to 52.62 ml/kg/min)in dancers who practiced for 4 days or more per week(Figure 3).However,VO2maxdid not correlate with the duration of dance training(in years).This could also be a reason for the higher aerobic capacity of professional Bharatanatyam dancers[5].Moreover,the finding reinforces the necessity for regularly placed training days in contrast to distantly placed training days despite longer years of training.

Figure 1 Distribution of VO2max grades in dancers and non-dancer

Figure 2 Representation of mean VO2max in dancers and non-dancers

Figure 3 Correlation between VO2max in dancers and practice days per week

Figure 4 Post-test heart rate trend in dancers and non-dancers

Siva Jyothi et al demonstrated a similarity in the VO2maxof Bharatanatyam and Kuchipudi dancers[19].Our results also largely correlate with the aerobic capacity of professional dancers of other dance styles.Various studies have found the VO2maxof dancers to be in the range of 40 to 47 mL/kg/min,regardless of dance style[3,6,11,16].This trend can be extrapolated to indicate a moderately increased aerobic capacity and increased anaerobic threshold of the dancers.It has been recommended that dancers receive additional training targeted at improving their aerobic capacity beyond the average range[7].Shankarashis Mukherjee et al.demonstrated that Bharatanatyam training for at least a period of five years,contributes to achieving healthier body composition and increasing physical fitness[27].Studies have also shown that Bharatanatyam and related dancing styles effectively improve the pulmonary function and respiratory efficiency of female dancers[5,25,26].Bharatanatyam dance form in its repertoire already contains the necessary movements that can provide effective aerobic training.For example,factoring in a combination of adavu session as a daily routine,or practicing a Varnam,a delicately woven piece of nritta and abinaya a 2-3 a week.Thus,we can postulate that effectively designing a training session could increase the aerobic capacity of dancers.However,targeted prospective interventional studies are necessary to assess the effect of such training regimens.

Our study also showed that Bharatanatyam dancers had a significantly lower post-test heart rate(164.2 ± 19.72 vs 181.33 ±13.48;P-value:0.01)and lesser variability between the resting heart rate and peak heart rate(87.46 ± 20.62 vs 103.2 ± 12.8;P-value:0.01)(Figure 4).Long-term Bharatanatyam dancers,quite similar to young athletes,have been shown to have a lower resting heart rate[5].Furthermore,the Bharatanatyam dancers were able to ascend to higher testing stages of the mCAFT test and took longer to reach the target HR(85% HRmax),which indicates a better overall cardiovascular fitness during submaximal exercise.

The overall higher level of aerobic capacity of dancers when compared to non-dancers can be attributed to the way Bharatanatyam training is traditionally designed with graded training protocols and gradually increasing intensities of performance pieces;as well as the individual’s initial fitness level and the frequency,intensity and duration of the training[3,5,26-28].

Conclusion

Although our study had a small sample size,the results provide an overall favorable result in terms of aerobic capacity and cardiopulmonary fitness in Bharatanatyam dancers,suggesting a role in improving the health of dancers.Bharatanatyam dance involves multiple muscle groups in all four limbs,as well as the tiny facial muscles,in continuous rhythmical movements.Thus,we conclude that Bharatanatyam has the framework necessary for improving all aspects of an individual’s health.So,it's important to go down the right path while training to reap its benefits.Regular sustained training is essential to see the full extent of the cardiopulmonary effects.There is a need for larger-scale interventional studies to establish the health benefits of Bharatanatyam.