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Original Article

Indian Pediatrics 2003; 40:105-114 

A Comparative Study of Maximal Aerobic Power of School Boys of East and North-East Regions of India


S.K. Dey and Parthasarathi Debray

From Sports Authority of India, Netaji Subhas Eastern Center, Kolkata 700 098, India.

Correspondence to: Dr. S.K. Dey, Human Performance Laboratory, Sports Authority of India, Netaji Subhas Eastern Center, Salt Lake City, Kolkata 700 098, West Bengal, India.

Manuscript received: November 8, 2001, Initial review completed: January 20, 2002,
Revision accepted: December 20, 2002.

Objective: The evaluation of physiological responses during graded ergometry in children has been proven to be useful to determine the growth and development of cardio-respiratory and musculo-energetic systems and is also essential in sports and games. In India few attempts have been made to determine the peak oxygen consumption (VO2) of children from different regions. This study aims to investigate peak VO2 and its relation to other anthropometric parameters of school boys (8 to 14 years age) from east region (ER) and north east region (NER) of India. Also, this stucdy attempts to find out the effect of regional variation, including their growth and development in comparison with the boys of other countries. Design: Boys were selected from east and north-east states of India and then subdivided according to their age. Subjects: The present study was carried out on 394 boys of 8 to 14 years of age, from three different states of ER and five states of the NER on the Indian subcontinent. Methods:The habitual physical activity, socio-cultural characteristics were assessed by standard questionnaires. The sexual maturity status (age at puberty stage 2) was calculated by standard indices. Height, body weight and skinfold thickness were assessed by standard procedures. Peak oxygen uptake (peak VO2) of boys was measured by computerized motor driven treadmill by standard procedure. Results: The results showed that the body size and peak VO2 of the boys from both regions increased significantly from 8 to 14 years of age. Peak VO2 of the subjects was less than untrained Japanese, European and American boys. The weight related and lean body weight (LBW) related peak VO2 was also changed from 8 years to 14 years boys in both the regions. It was also observed that peak VO2 was significantly and negatively correlated with the sum of skin fold thickness. Body size and peak VO2 were found to be significantly higher in the ER boys than their NER counterparts at 13 and 14 years of age only. Peak VO2 remained the same up to 12 years of age and then became significantly higher in the ER boys at 13 and 14 years of age as compared with their NER counterparts. Conclusions: There was a significant difference in peak VO2 of children from ER and NER. The high VO2 may be due to late sexual maturation and higher body size of the ER boys at that age. The difference in body size and sexual maturation may be due to genetic, racial, geographical, climatic and nutritional diversity in the east )ER) and north-eash (NER) regions of India.

Key words: Body size, East & North-east India, Maximal aerobic power, Peak VO2 .

THE highest rate of oxygen consumption by the body in a given period of time is considered to be the best single index of cardio-respiratory fitness and it has therefore been widely studied in both adults (maximum oxygen consumption, VO2 max) and children (peak oxygen consumption, peak VO2)(1,2). Peak VO2 of children, which indicates the aerobic energy yielding system or aerobic power, starts to develop during the elementary school ages, between 10-12 years, and continues to develop during puberty(2). Peak VO2 in children has been proven to be useful in determining the growth and development of cardio-respiratory and musculoenergetic systems. It has been shown that the absolute value of peak VO2 differes from country to country(3). But the trend of development is almost the same. It increases with chronological age. There is no doubt, therefore, that the VO2 max is related to the maturity of the children at any given chronological age. However, there exists a great deal of variation not only in peak VO2 but also in such physical dimensions as height and weight.

India is a vast country with unique cultural, social, geographical, ethnic and climatic differences. The morphological characteristics of Indian children vary according to regional variations of this country. The sexual maturation also varies from one region to another, which ultimately affects physical growth and development. Sodhi(4) and Pathmanathan and Prakash(5) have reported that the regional variation of morphological characteristics of Indian children occur due to socioeconomic, climatic and genetical variations. Swaminathan et al.(6) have worked on aerobic power and cardiopulmonary response of exercise in healthy South Indian children and concluded that nutritional and socio-cultural factors may play an important role in determining peak VO2 of children from different populations rather than ethnic differences alone. Investigations have been made in India only regarding the development of physical growth parameters and maximal aerobic power of children only from east region of India(7), however, no study has been reported on north-east Indian children, who are basically of Mongoloid origin. This study was aimed to find out the peak VO2 values and their relation to general growth parameters of school boys (8-14 years of age) from India’s east (ER) and north-east (NER) regions and to investigate the effect of regional variation on the same. Further, the study was also aimed to examine the development of maximal aerobic power of east and north-east regions boys(8-14 years) in comparison with the boys of other countries.

Subjects and Methods

Boys of average age of 8 to 14 years, from three states of the east region (ER) viz., West Bengal, Bihar, Orissa and five states of the north-east region (NER) viz., Assam, Meghalaya, Arunachal Pradesh, Manipur and Tripura of the Indian sub-contient, were invited to participate in a research project at Human Performance Laboratory, Sports Authority of India, Eastern Center, Kolkata. Prior to the tests clinical examinations by a physician were made and medically fit boys were included in this study. The total number of selected boys was 394 from three different states of the east region and five states of the north-east region (NER) of India. Out of 394 boys 191 boys were from ER region and 203 boys were from NER region. The boys were subdivided according to regions and ages. The criteria for selection of subjects were medical fitness, age range 8-14 years and their habitual physical activity.

The habitual physical activity and time spent in physical education (PE) classes in school were also surveyed on the school questionnaires and verified by interviews with boys and their parents. Depending on the school curriculum the compulsory physical education program varied between 1 and 3 hours per week. Those who participated in not more than 1.5 h/wk in running, swimming, football, cycling outside of compulsory school physical education programs were includecd in this study.

The climate and environment of the ER states are generally hot and humid as compared to the NER states. The ER states are located in the plane area of the eastern part of the Indian subcontinent with similar races, socio-economic status, cultures, food habits and geographic and climatic conditions. The boys belonging to the states of ER were considered as a homogenous group in respect to the factors mentioned above. On the other hand the climatic and environmental conditions of the NER states are generally cool and temperate as compared to the ER states because geographically these are located slightly above the sea level and in the mountain (Himalaya) range of north-east part of the Indian subcontinent. NER states are largely inhabited by dozens of tribes who are basically Mongoloid in origin with short to medium stature and muscular body. These states have similar races, socio-economic status, cultures, food habits and geographic, climatic conditions. Thus, the boys of NER states were considered as a homogenous group in respect to the factors mentioned.

Prior to initial testing all selected boys and their parents were given a complete explanation of the purposes, procedures, and potential risks and benefits involved in the study. They were asked to read and sign a statement. In the case of the children, written consent by parents or legal guardian was required in addition to the children’s written assent. Physical characterstics of the boys and medical tests were performed at their respective places (states) and for peak VO2 max they were called at the Human Performance Laboratory, Sports Authority of India, Kolkata.

Anthropometric rod (FITKIT, USA), skinfold caliper (Harpenden, Switzerland), steel measuring tape, weighing machine (FITKIT, USA), sphygmomonometer, computerized treatdmill and analyzer (Oxycon Champion, Jaeger, Germany) were procured from reliable companies. All the instruments were calibrated before use. The instruments were available and were in frequent use in routine testings and research.

Decimal age was computed from date of birth and date of tests. Body weight was recorded using an electronic weighing machine when boys were without shoes and wearing minimum clothes. Height was measured by the anthropometric rod. Harpenden skinfold caliper was used for skinfold measurements at the site of biceps, triceps, subscapular and suprailliac by standard procedures(8). Body density was calculated by using standard formula(9). The body fat percentage was calculated by using the formula of Siri(10).

The pubertal stage was assessed according to the indices developed by Marshal and Tanner(11) by averaging pubic hair ratings with genetalia ratings to find out the sexual maturity status of the boys. Based on the Marshal and Tanners’ classification, we considered only ‘stage 2’ of pubic hair and genetalia rating. It was calculated that of the 394 boys, 76 of the ER boys and 67 of the NER boys were passing through ‘stage 2’. The observed mean age at pubertal stage 2 was 12.9 ± 0.3 years in the ER boys and 12.6 ± 0.5 years in the NER boys.

Peak oxygen uptake (peak VO2) or maximum aerobic power of the subjects was determined using a continuous graded exercise test, on a motorized treadmill (LE 6000, Erich Jaeger, Germany). All the subjects were instructed to avoid heavy exercise and food intake at least 2 hrs before the treadmill exercise test. The detailed procedure of the test was explained to the subjects and the demonstration of the test was given to them. Subjects were first familiarized with the treadmill running by allowing them to run with the mouthpiece (with Triple ‘V’ volume Transducer, dead space less than 50 mL).

The testing protocol began with initial speed and inclination of the treadmill being 4 km per hour and 2% respectively. The speed was increased by 2 kmh–1 at every 2 minutes till complete exhaustion while the inclination was kept constant. The subject was verbally encouraged to perform the maximal limits and the test was terminated when the subject could not maintain the pace with further increments in exercise intensity. Oxygen uptake (VO2), CO2 production (VCO2), heart rate (HR) etc. were monitored in every 30 seconds.

The main criterion for the attainment of VO2 max is a leveling off or plateau of VO2 despite an increase in exercise intensity. Only the minority of children exhibit a true VO2 plateau(3). The appropriate term to use with children is peak VO2 that represents the highest VO2 elicited during an increase test to exhaustion(12). So, two of the three following criteria was followed for establishment of peak VO2 as a maximal index: (a) failure of VO2 to increase more than 2.1 ml.kg–1 mm–1 despite a further increase in work load, (b) respiratory exchange ratio (RER) greater than 1.0 and (c) maximal heart rate greater than the age predicted maximum heart rate ±5%. Additionally the appearance of signs of exhaustion, i.e., extreme forced ventilation, fatigue, facial flushing, dyspnea and unsteady gait was observed as subjective criteria of peak effort(13).

The whole experiment was performed at room temperature varying from 23 to 25 degree centrigrade with the relative humidity varying between 50 to 60 per cent.

The collected data were analyzed using the Statistical Package for the Social Sciences (SPSS, version 6.0, 1993). Mean, standard deviation (SD) and analysis of variance (ANOVA) were used to see the significant difference among the groups and multiple groups. The level of significance was set at p <0.05. Pearson product moment correlation coefficients were calculated as appropriate.

Results

The physical characteristics and peak cardiopulmonary response to treadmill exercise of boys from the ER and NER regions in relation to age are displayed in Table I. It appears that height and body weight increased significantly (p <0.01) from the age of 8 to 14 years in both ER and NER boys. However, no such significant changes were observed in body fat% in both the ER and NER boys. But the peak VO2 increased significantly (p <0.01) from the ages of 8 to 14 years in both the ER and NER boys. Peak VO2 of the boys from both the regions were positively and significantly correlated with age (ER, r = 0.68; NER, r = 0.61). A significant positive correlation (p <0.01) between peak VO2 (L/min) and body size (height & weight) was noted in both the regions (height, weight: ER r = 0.81, 0.79 and NER r = 0.75, 0.72). Peak VO2 expressed in relation to body weight showed a significant relationship with age (p <0.05) in both the regions. The peak VO2 and also weight related peak VO2 were significantly correlated with the body fat% (peak VO2: ER r = – 0.50, NER r = – 0.48 and weight related peak VO2; ER r = –0.55, NER r = – 0.41). Peak VO2 related to lean body weight (LBW) also changed significantly with age (p <0.05).

Table I	Mean, SD and Level of Significance of Physical Characteristics, Sum of Skinfolds
and Peak Cardiopulmonary Response to Treadmill Exercise of the Boys from East and North-east 
Regions of India.
Age
groups
 
 
 
Age
(years)
 
 
 
No. of
subjects
(n)
 
 
Height
(cm)
 
 
 
Body 
weight
(kg)
 
 
Body
fat%
 
 
 
Peak
Oxygen
Uptake
(1.min–1)
 
Peak
Oxygen
Uptake
(ml.kg–1)
 
Peak
Oxygen
Uptake
(ml.LBW–1)
 
Peak
Heart
Rate
(beats min–1)
(min–1)

East Region
 8
8.2
24
1.32
26.0
7.8
1.19
45.76
49.4
204
 
(0.75)
 
(0.75)
(4.2)
(0.27)
(0.12)
(2.8)
(2.6)
(5)
 9
9.3
27
1.37
28.2
8.0
1.32
46.80
50.2
203
 
(0.5)
 
(0.92)
(5.7)
(0.5)
(0.15)
(4.1)
(3.0)
(5)
10
10.4
22
1.40
31.5
8.4
1.47
46.66
50.1
202
 
(0.3)
 
(0.91)
(6.2)
(0.54)
(0.18)
(4.8)
(4.2)
(9)
11
11.5
29
1.46
33.5
8.6
1.62
46.35
52.3
199
 
(0.5)
 
(0.62)
(3.9)
(0.61)
(0.20)
(5.1)
(3.2)
(8)
12
12.7
30
1.49
36.2
8.8
1.70
47.22
51.4
202
 
(0.8)
 
(0.85)
(5.2)
(0.56)
(0.25)
(4.8)
(3.0)
(5)
13
13.6
31
1.55
40.2
8.9
1.91
47.51
52.2
198
 
(0.3)
 
(0.76)
(6.9)
(0.91)
(0.34)
(3.9)
(5.4)
(7)
14
14.5
28
1.64
45.0
9.0
2.14
47.55
52.7
195
 
(0.2)
 
(0.64)
(5.5)
(1.0)
(0.39)
(4.2)
(4.9)
(8)
Analysis
of variance
(all age group)
p <0.01
 
p <0.01
p <0.01
ns
p <0.01
p <0.05
p <0.05
ns
North-East Region
 8
8.5
31
1.34
27.2
8.0
1.20
44.11
48.2
208
 
(0.2)
 
(0.31)
(2.1)
(0.61)
(0.19)
(3.5)
(3.1)
(8)
 9
9.5
28
1.36
29.1
8.3
1.33
45.70
49.9
208
 
(0.3)
 
(0.43)
(3.2)
(0.56)
(0.2)
(4.2)
(3.0)
(7)
10
10.7
27
1.39
32.5
8.5
1.45
44.61
49.2
205
 
(0.1)
 
(0.21)
(2.9)
(0.39)
(0.14)
(3.9)
(4.1)
(8)
11
11.2
32
1.44
34.8
9.0
1.61
46.26
51.2
200
 
(0.4)
 
(0.52)
(3.1)
(0.71)
(0.71)
(5.2)
(3.0)
(7)
12
12.6
27
1.46
36.0
9.3
1.68
46.66
51.5
199
 
(0.3)
 
(0.39)
(5.2)
(0.61)
(0.15)
(4.5)
(4.1)
(6)
13
13.4
28
1,52*
39.0**
8.8
1.83**
46.92**
51.4*
188
 
(0.2)
 
(0.61)
(2.8)
(0.56)
(0.43)
(4.8)
(5.7)
(5)
14
14.4
30
1.56*
43.5*
9.6
2.05*
47.12*
52.0*
195
 
(0.5)
 
(0.58)
(3.9)
(0.42)
(0.35)
(3.9)
(5.1)
(6)
Analysis
of variance 
(all age groups)
p <0.01

p <0.01
p <0.01
ns
p <0.01
p <0.05
p <0.05
ns
Values are means (standard deviations), ns = not significant, * P <0.01 and **P < 0.05, 
when analysis of variance were done between same age groups of two different regions.

Mean values of height and body weight were found to be significantly higher in ER boys at 13 and 14 years of age as compared to their NER counterparts. It is evident from the table that the peak VO2 and weight related peak VO2 remained constant upto 12 years of age in both the regions and then the values increased significantly in ER boys (at 13 and 14 years) as compared to NER boys. Signficant changes were found in LBW related peak VO2 in case of 13 and 14 years of boys (p <0.05).

Table II represents the comparative values of peak VO2 of children (boys) of the present study with their international counterparts. By and large the present values of peak VO2 were found to be well comparable with their international counterparts. Figures 1 and II present changes in VO2 max of ER and NER boy in respect to body weight and lean body bweight (LBW) respectively.

 

TABLE II - Comparison of cross sectional peak VO2 values of untrained boys of different countr5ies with the present study

Country Age
(Years)
Mode** Peak VO2
(L/min)
Peak VO2
(ml/kg/min)
Country Age
(Years)
Mode** Peak VO2
(L/min)
Peak VO2
(ml/kg/min)
Sweden 7-9 T 1.75 56.9 13.0 B 2.19 44.3
10-11 T 2.04 56.1 8-9 T 1.56 57.7
12-13 T 2.46 56.5 South Africa* 10-11 T 2.01 56.1
14-4.5 T 3.53 59.5 12-13 T 2.35 59.4
France* 11 B 1.74 49.2 Finland* 12.1 B 2.13 51.1
12 B 1.77 47.8 14.6 B 3.11 56.0
13 B 2.10 47.8 Japan* 10.2 B 1.10 38.6
14 B 2.34 43.9 11.2 B 1.34 39.7
15 B 2.68 48.9 12.3 B 1.43 39.8
Netherlands* 13 T 2.54 59.3 13.4 B 2.05 44.5
14 T 2.82 58.8 14.3 B 2.38 50.5
Great Britain* 9.0 B 1.38 48.9 Present study (east boys) 8.2 T 1.19 45.76
10.8 B 1.63 46.2 9.3 T 1.32 46.80
12.8 B 2.05 49.6 10.4 T 1.47 46.66
Australia* 11.5 B 1.71 47.5 11.5 T 1.62 46.35
12.6 B 2.05 46.5 12.7 T 1.70 47.22
13.5 B 2.24 49.0 13.6 T 1.91 47.51
14.5 B 2.75 50.5 14.5 T 2.14 47.55
United States* 10.1 B 1.74 49.8 Present Study (north-east boys) 8.5 T 1.20 44.11
11.4 B 1.97 45.8 9.5 T 1.33 45.70
12.5 B 1.85 45.9 10.7 T 1.45 44.61
13.4 B 2.51 48.8 11.2 T 1.61 46.26
Columbia* 8-8.9 T 1.43 52.0 12.6 T 1.68 46.66
10-11.9 T 1.74 52.5 13.4 T 1.83 46.92

12-13.9 T 2.17 51.8 14.4 T 2.05 47.12
Canada* 10.0 B 1.59 55.4

** VO2 measured by B. Bicycle Ergometer, T. Treadmill, * Krahenbuhl et al., 1985(3).

Fig.1. Changes in Peak VO2 max (ml.kg-1.min-1) of ER & NER boys with age

Fig. 2. Changes in Peak VO2 max (ml.LBW–1. min–1) of ER & NER boys with age.

Discussion

Regardless of region, boys peak VO2 increased with age and this is in accordance with reports from other studies(1,3,14). The peak VO2 of the ER and NER boys was found to be lower than those reported of American, European and Japanese untrained boys(3,12,15). These differences are, however, largely due to the difference in body size of the subjects. The present study further reveals that the boys’ peak VO2 expressed relative to body weight slightly increased from 8 to 14 years of age in ER and NER boys. Similar observations were also reported by various researchers(3). The peak VO2 expressed relative to body weight of the ER and NER boys was found to be well comparable with those of American, European and Japanese untrained boys(3). This finding is also corroborated with the different findings from India(6). They have also reported that the peak VO2 expressed as relative to body weight of South Indian boys was found to be similar to those of North American boys.

Peak VO2 of the present study was positively correlated to body size (body weight and height) in both the ER and NER boys and the correlation was almost similar to those as reported by various authors(16,17).

The present study revealed that the peak VO2 was significantly higher in the ER boys at 13 and 14 years of age only. This may be due to the larger body size of the ER boys at 13 and 14 years of age as compared to their NER counterparts. The present study further reveals that the ER boys were late maturers as compared to their NER counterparts (as indicated by average pubic hair ratings with genetalia ratings). This may be due to the difference in genetic, racial, maturational, climatic and geographical factors. However, it has been reported that those who mature early are shorter in height that the late maturers(18). This hypothesis was also found to be true in the present investigation. It has also been observed that body size and proportion varies considerably with the maturity status of an individual (developing stage) during the adolescent period, but maturity related variation in physique is also noted during childhood(19). Reports show that sexual maturation varies from one region to another of India, which ultimately affects the physical growth and development in terms of height and body weight(20). The growth and development are influenced by the variation of climatic condition, which is also in agreement of the present study as the climatic conditions of the regions are different(21).

It may be concluded from this study that body size and peak VO2 increases from 8 years to 14 years of age in both the ER and NER boys. The peak VO2 values are less than those of untrained American, European and Japanese boys. But the peak VO2 expressed as relative to body weight has been found to be well comparable with their international counterparts. The maximal aerobic power remained the same up to 12 years of age and then was significantly higher in the ER boys at 13 and 14 years of age as compared with their NER counterparts. The peak VO2 related with lean body weight was also significantly higher in ER boys in 13 and 14 years of age. The underlying factors may be due to the late sexual maturation and greater body size of the ER boys at that age. These differences including maturity status may be due to the diversity in the genetic, racial, climatic, geographical and nutritional factors in the east (ER) and north-eash (NER) regions of India.

Acknowledgement

The authors express their sincere gratitude to the Sports Authority of India, Eastern Center, Salt Lake City, Kolkata for providing facilities, funds and the subjects who were volunteers for the present study. The authors are also grateful to Prof. S.P. Chatterjee, Department of Physiology, Calcutta Univer-sity, Kolkata, Dr. S. Nag, Department of Physiology, M.B.B. College, Tripura for their valuable suggestions and cooperation. The authors are also thankful to D.I.C., Bose Institute, Kolkata for Medline searching.

Contributors: Both authors were involved in designing, data collection, analysis and writing the paper. SKD shall act as guarantor.

Funding: Sports Authority of India.

Competing interests: None stated.

Key Messages

• Peak VO2 of the boys from east and north-east India is less than untrained Japanese, European and American boys.

• Peak VO2 is significantly and positively correlated with age and body size.

• Height, weight and peak VO2 at 13 & 14 years of ages are higher in boys from Eastern India as compared to the north-east region.

 

 

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