3.1. Body size, composition and VO2 max

Persons of larger size in general appear to function better than those with smaller stature (CALLOWAY, 1982) in relation to reproduction (THOMSON, 1980), disease (REDDY et al., 1976), cognition (KLEIN, 1972), and work performance (SPURR, 1983; 1984). Because physical work capacity is a function of body size (ÅSTRAND and RODAHL, 1970), i.e., the mass of muscle tissue involved in the maximum effort, and muscle constitutes about 40% of the body weight and 50% of the LBM (CLARYS, MARTIN and DRINKWATER, 1984; BUSKIRK and MENDEZ, 1985), it is interesting to note the correlations between three components of body size and VO₂ max presented in Table 3. The correlations in boys are higher than those in men, probably because of a threefold greater range in values, but in either case it is clear that in non-obese subjects there are significant correlations between parameters of body size and PWC as measured by VO₂ max. Taller individuals have more LBM and higher VO₂ max values (Figure 7). Similar relationships exist for adult women, but the correlation coefficients are lower (VON DÖBELN, 1956).

All of the data presented in Figure 7 are from various studies in our laboratory (BARAC-NIETO et al., 1978; 1979; 1980; SPURR et al., 1975; 1977; 1983; 1984; SPURR et REINA, 1986) and permit a comparison between Colombian boys and men, and between the latter and a small group of North American adult males. The differences in height between adults of developing and developed countries are well known (Interdepartmental Committee on Nutrition for National Defense, 1963; SPURR, BARAC-NIETO and MAKSUD, 1978; Figure 1). The average value of the C group of men in Figure 7 is very close to that published for low-income Colombian men (Figure 1) and probably reflects some period(s) of undernutrition during the period of growth. The heights of the three groups of malnourished (M, I and S) men were not significantly different from each other but were lower than the C group. This is probably a result of more severe nutritional deprivation in Groups M, I and S during growth than occurred in Group C. It is difficult to predict the adult height of the oldest boys, but it is likely that the nutritionally normal children will be taller (Figure 7A) and perhaps have a higher VO₂ max (L/min) than Group C (Figure 7D), while the undernourished group of boys in adulthood will most likely resemble more closely Group M.

Table 3. Correlation coefficients of weight, height, lean body mass (LBM) and maximal oxygen consumption VO₂ maxi L/min) in nutritionally normal boys 6-16 years of age (SPURR et al., 1983; BARAC-NIETO et al., 1984) and adult males (BARAC-NIETO et al., 1978). All are statistically significant (p< 0.01).

The lower values of aerobic capacity per kg of body weight and of LBM in adults than in boys is also well known and, at least in part, this probably reflects the progressive decline in these measurements with age from the youngest ages (DEHN and BRUCE, 1972). The differences also may reflect differences in the states of physical training in the boys and men.