The maximal aerobic power is the most important criterion of physical endurance and is the mechanism which covers the energy demand of most of daily life activities. This component is generally accepted as the most important criterion of an individual's fitness for physical effort of the endurance type, and is determined by measurements of maximal oxygen intake during performance of dynamic work. The physioligical basis for this test has been evaluated by many investigators who can be refered to for details (Robinson, 1938; Astrand, 1952), and also comparison of maximal oxygen intaken of different populations should be made in terms of age and sex (Astrand, 1952; 1960; Ikai, 1967; Robinson, 1938; Ekblom and Gjessing 1968; Anderson and Smith-Sivertsen, 1965). Moreover, one of the items in the human adaptability project of the international biological problem (Ikai et al., 1967; Meshizuka, 1966; Wyndham et al., 1965) is the estimation of the maximal oxygen intake of samples of different populations.
Any type of exercise can be recommended to provide ot bring into play the larger muscle groups of the body. Bicycling on an ergometer, running on a treadmill, stepping on or off a bench or field running method are commonly uwed in tests to measure the maximal oxygen intake.
In Korea, the maximal oxygen intake of adults and athletes have been reported by many investigators (Lee at al., 1967; Yoo et al., 1967; Choi and Nam , 1967; Lee at al., 1968) but there is a deficiency of information for younger age groups below the age of 17 and it has been required to evaluate the physical fitness of Korean youngsters.
The purpose of the present study, therefore, was to determine the maximal oxygen intake and muscular power between the age of 9 and 17, and to compare with the previously reported data. The subjects participating in this study consisted of 399 normal and healthy Korean Youngsters (196 males, 203 females), 9∼17 of age
randomly selected from 24 school childrens, each 8 of primary, middle and high school in Seoul and Kyunggi province.
The maximal oxygen intake was measured by means of field running method (Yoo et al., 1967). Expired air was collected in Douglas bag through one way Douglas valve or face mask at last 30 sec. and during three minute maximal running exercise performance. aliquots of the expired air were analyzed according to Scholander micro gas analyzer and leg and arm muscular power was measured by means of inertia ergometer (Ikai, 1965). The calculated oxygen intake was corrected to STPD and also expressed in kg of body weigh.
The results are summarized as follows:
1) Physical characteristics were absolutely the same as those of reported Korean youngsters and Japanese at same ages.
2) The maximal minute ventilation was increased considerably with age and maximum values were 103.2(boys) and 74.4 L/min. (girls) at the age of 17 and 16, respectively.
3) The maximal oxygen intake was increased with age in boys while there was a little increments in girls above the age of 13 and maximum values were 2.93(boys) and 2.09 L/min. (girls) at the age 17.
4) The maximal oxygen intake expressed per kg of body weight was slightly decreased with ages and the values were 51.0 (boys) and 41.7ml/min./kg (girls) at the age of 17. these results were almost the same as those of the Japanese, but the values were lower than those of European and Americans and higher than those of the Easter Island populations at the same ages.
5) Muscular power was increased linearly with age in boys while there was relatively a little increment in girls above the age of 13. The maximum values of legs in boys and girls at the age of 17 were 0.168 and 0.088 horse power, respectively.
According to the above results, it was concluded that Korean youngsters have a good physical fitness, but in girls improvements of their physical fitness almost stopped at the age of about 13∼14 as well as their growth.