European Journal of
Europ. J. Appl. Physiol. 36, 93-99 (1977)
Applied
Physiology
and OccuoationalPhysiology
9 by Springer-Verlag1977
Oxygen Transport System during Exhaustive Exercise in Japanese Boys Keiji Yamaji I and Mitsumasa Miyashita2 1 Laboratory for Exercise Physiology, Faculty of Education, Toyama University, Toyama, Japan 2 Laboratory for Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan
Summary. The study was designed to investigate the age-related increase in maximal oxygen uptake with special reference to the other physiological parameters (ventilation, pulmonary diffusing capacity, cardiac output etc.). 77 normal boys aged 10-18 years were tested by the progressive loading method on a bicycle ergometer. VO2 max increased by approximately 55% with age from 10-18 years. The increase in [zO2 max was accompanied with increase in ventilation (49%), pulmonary diffusing capacity (45%) and cardiac output (5%). Key words: Age-related increase - Boys - Maximal oxygen uptake - Pulmonary diffusing capacity - Cardiac output. Introduction Aerobic work capacity (maximal oxygen uptake: f/tO 2 max) is currently considered to be the best measure of physical fitness, and considerable data have been reported relating to age, sex, race and training. Although the existing information for aerobic work capacity is fairly extensive and complete, there is a deficiency of information for physiological parameters behind maximal overall oxygen transport, and in particular for the case of adolescents. Since ventilation is obtained in the process of determining VO2 max and respiratory frequency and heart rate are also easily measured, their maximal values have been reported together with VO 2 max. On the other hand, data regarding the determination of cardiac output at leO 2 max were very few (Eriksson, 1971; Miyamura and Honda, 1973) in the case of adolescents. Also pulmonary diffusing capacity has been reported only at mild or moderate exercise (Filley et al., 1954; Turino et al., 1959). Aerobic work capacity is most remarkably improved in the case of boys from 10-18 years of age. Therefore, the present study was designed to investigate the age-related increase in P'O2 max with special reference to the other physiological parameters such as ventilation, pulmonary diffusing capacity and cardiac output.
94
K. Yamaji and M. Miyashita
Methods The subjects tested were 77 normal boys livingin Tokyo, aged 10-18 years. All subjects did not participate in any extracurricular physical activity. Their anthropometric data are shown in Table 1. The exhaustive exercise was performed on a friction-type bicycle ergometer (Monark-Sweden). The pedal length and seat height were adjusted for use with boys. The pedaling rate was kept constant at 50 rpm for 10-12 years old boys and 60 rpm for older boys. After 2 min of pedaling with constant load (150-1080 kgm/min), work intensity was increased by 180 kgm/miu (75 kgm/min for 10-12 years old boys) every minute up to exhaustion. The initial work load was chosen from the preliminary test so that the subject reached exhaustion within 5-7 min. VO2 max was determined by the Douglas bag technique: Expired gas was collected with a face mask and connecting tube (diameter : 33 ram) in the bag every minute until exhaustion. The volume of collected gas was measured by a dry gasometer and gas analysis was performed with the Scholander micro-gas analyzer. Cardiac output was estimated by a CO2 rebreathing method (Jernerus et al., 1963): The partial pressure of CO2 in arterial blood was estimated from the mean of two determinations of partial pressure of CO 2 in the alveolar gas measured with the end-tidal method immediately after exhaustion. The partial pressure of CO2 in the mixed venous blood was estimated by rebreathing a gas mixture of CO2 (4-6%) in Oz (Klausen, 1965). This process was completed within 17 s after exhaustion. The values of the content of CO2 in the arterial blood and the mixed venous blood were read on a standard CO2 dissociation curve from the partial pressure of COz in the arterial and in the mixed venous blood, respectively. The steady state method (Filley et al., 1954) was used for determining the pulmonary diffusing capacity: The subject inspired 0.05% CO in air for 75 s before exhaustion from a Douglas bag and expired in another Douglas bag. The CO uptake was determined from the volumes and CO concentrations of inspired and expired gas measured by Beckman CO Analyzer. Alveolar CO was computed from the alveolar CO2 (Bates et at., 1971). Heart rate was obtained from ECG recorded with bipolar chest leads and respiratory frequency was determined with the aid of thermister attached to the inside of the mask. Vital capacity was measured by a Benedict respirometer before the exercise.
Results Table 1 summarizes average values and standard deviations for physical characteristics, maximal oxygen uptake and other physiological parameters during determination of (10 z max on boys of different ages. Body height, body weight, VO z max, p u l m o n a r y diffusing capacity, ventilation, respiratory frequency, cardiac output and heart rate at VO2 max in relation to age are presented in % ratio to the average values of 18 years old boys in Figure 1. The increase in body height is a smooth process through 1 0 - 1 8 years of age. This increment was approximately 20%. O n the other hand, body weight showed an almost twofold increase in step-wise curve from 28.7 kg at 10 years of age to 57.5 kg at 18 years of age. leO 2 max increased by approximately 55% with age from 1 0 - 1 8 years. But in this increasing curve the first peak appeared at 14 years of age. The highest value of fzO z max per body weight was 50.5 ml/kg/min at 14 years of age. As for ventilatory function, vital capacity increased linearly with age. Ventilatory frequency was almost constant from 41--52/rain over a wide range of ages from 10--18 years, while ventilation increased in the same way as (10 z max. P u l m o n a r y diffusing capacity increased almost linearly with age by approximately 45%.
8 mean SD
8 mean SD
10 mean SD
9 mean SD
10 m e a n SD
8 mean SD
8 mean SD
8 mean SD
8 mean SD
11 + 2
12 + 4
13 + 5
14 + 3
15 + 1
16 + 4
17 + 2
18 + 4
No.
10 + 2
Age (years + months)
168.7 2.2
167.8 1.4
166.2 1.0
161.9 1.2
159.4 4.5
156.4 1.5
144.2 3.9
139.4 4.4
131.9 2.2
Height (cm)
57.5 2.1
57.5 0.9
55.8 1.2
46.1 3.0
47.5 2.1
47.6 7.4
36.2 4.2
36.5 4.0
28.7 3.0
1.66 0.08
1.66 0.02
1.61 0.01
1.47 0.09
1.47 0.08
1.44 0.10
1.20 0.10
1.18 0.07
1.03 0.07
Weight B.S.A. (kg) (m z)
4.47 0.74
4.25 0.40
3.74 0.34
3.95 0.33
3.37 0.14
2.98 0.18
2.60 0.32
2.32 0.22
2.12 0.16
(1)
VC
1.07 0.06
1.02 0.00
1.02 0.06
1.14 0.07
1.08 0.07
1.02 0.06
1.09 0.06
1.00 0.07
1.05 0.09
RQ
2,46 0.25
2,40 0.13
2.20 0.23
2.17 0.29
2.38 0.14
2.05 0.24
1.43 0.20
1.34 0.22
1.10 0.17
42,8 3.4
41.9 2.1
39.9 5.1
47.1 4.1
50.5 3.6
44.5 10.0
39.8 4.7
39.7 6.7
38.6 4.6
P'O 2 m a x (l/min) (ml/kg/ rain)
93.5 10.3
81.0 5.7
77,2 12.2
84.2 14.2
91.1 14.0
73.0 12.5
56.2 8.3
54.5 9.7
45.9 4.8
(l/rain)
Ve
42.6 3.5
39..4 3.2
35.7 4.5
32.8 5.5
32.4 5.8
30.9 3.2
27.2 5.4
28.5 4.5
23.9 4.1
(ml/min/ m m Hg)
DLco
47.4 9.5
47.6 10.0
41.3 10.4
47.6 7.8
49.7 7.6
50.9 3.9
52.1 8.3
50.7 2.8
49.4 1.6
(l/rain)
f
19.7 1.2 21.4 2.0
1.79 0.50 2.02 0.28
18.7 2.0
17.9 2.4
1.78 0.18 2.02 0.72
20.2 1.7
1.82 0.29
13.0 2.2
1.11 0.21 17.0 1.6
12,3 1,3
1.14 0.25
1,43 0.19
11.0 1.1
0.95 0.08
(~ (l/rain)
(l)
P~
114.3 11.9
107.8 5.3
100.2 11.4
87.3 12.1
93.9 11.0
84.3 8.7
67.0 13.2
64.9 5.8
59.8 5.6
(ml)
sv
187.8 7.4
183.8 6.0
186.8 4.7
190.1 8.0
190.7 9.4
183.7 15.2
199.0 7.7
190.1 8.1
192,8 6.7
(beats/ min)
;If
115.1 3.6
122.3 4.4
118.3 6.9
131.5 3.2
132.6 12.7
132.7 7.3
110.9 10.3
116.1 10.8
103.6 7.8
diff. (ml/1)
a-~o2
Table 1. Average values and standard deviations for physical characteristics, maximal oxygen uptake (120 a max) and other physiological parameters during determination of f/O 2 max. B.S.A.: body surface area, VC: vital capacity, RQ: respiratory quotient, r ventilation, DLco: pulmonary diffusing capacity,f: respiratory frequency, Vr: tidal volume, Q: cardiac output, SV: stroke volume, Hf: heart rate, a-f/Oz diff.: arterio-venous oxygen content difference
o
t~
"
Europ. J. Appl. Physiol. 36, 93-99 (1977)
Applied
Physiology
and OccuoationalPhysiology
9 by Springer-Verlag1977
Oxygen Transport System during Exhaustive Exercise in Japanese Boys Keiji Yamaji I and Mitsumasa Miyashita2 1 Laboratory for Exercise Physiology, Faculty of Education, Toyama University, Toyama, Japan 2 Laboratory for Exercise Physiology and Biomechanics, Faculty of Education, University of Tokyo, Hongo 7-3-1, Bunkyoku, Tokyo, Japan
Summary. The study was designed to investigate the age-related increase in maximal oxygen uptake with special reference to the other physiological parameters (ventilation, pulmonary diffusing capacity, cardiac output etc.). 77 normal boys aged 10-18 years were tested by the progressive loading method on a bicycle ergometer. VO2 max increased by approximately 55% with age from 10-18 years. The increase in [zO2 max was accompanied with increase in ventilation (49%), pulmonary diffusing capacity (45%) and cardiac output (5%). Key words: Age-related increase - Boys - Maximal oxygen uptake - Pulmonary diffusing capacity - Cardiac output. Introduction Aerobic work capacity (maximal oxygen uptake: f/tO 2 max) is currently considered to be the best measure of physical fitness, and considerable data have been reported relating to age, sex, race and training. Although the existing information for aerobic work capacity is fairly extensive and complete, there is a deficiency of information for physiological parameters behind maximal overall oxygen transport, and in particular for the case of adolescents. Since ventilation is obtained in the process of determining VO2 max and respiratory frequency and heart rate are also easily measured, their maximal values have been reported together with VO 2 max. On the other hand, data regarding the determination of cardiac output at leO 2 max were very few (Eriksson, 1971; Miyamura and Honda, 1973) in the case of adolescents. Also pulmonary diffusing capacity has been reported only at mild or moderate exercise (Filley et al., 1954; Turino et al., 1959). Aerobic work capacity is most remarkably improved in the case of boys from 10-18 years of age. Therefore, the present study was designed to investigate the age-related increase in P'O2 max with special reference to the other physiological parameters such as ventilation, pulmonary diffusing capacity and cardiac output.
94
K. Yamaji and M. Miyashita
Methods The subjects tested were 77 normal boys livingin Tokyo, aged 10-18 years. All subjects did not participate in any extracurricular physical activity. Their anthropometric data are shown in Table 1. The exhaustive exercise was performed on a friction-type bicycle ergometer (Monark-Sweden). The pedal length and seat height were adjusted for use with boys. The pedaling rate was kept constant at 50 rpm for 10-12 years old boys and 60 rpm for older boys. After 2 min of pedaling with constant load (150-1080 kgm/min), work intensity was increased by 180 kgm/miu (75 kgm/min for 10-12 years old boys) every minute up to exhaustion. The initial work load was chosen from the preliminary test so that the subject reached exhaustion within 5-7 min. VO2 max was determined by the Douglas bag technique: Expired gas was collected with a face mask and connecting tube (diameter : 33 ram) in the bag every minute until exhaustion. The volume of collected gas was measured by a dry gasometer and gas analysis was performed with the Scholander micro-gas analyzer. Cardiac output was estimated by a CO2 rebreathing method (Jernerus et al., 1963): The partial pressure of CO2 in arterial blood was estimated from the mean of two determinations of partial pressure of CO 2 in the alveolar gas measured with the end-tidal method immediately after exhaustion. The partial pressure of CO2 in the mixed venous blood was estimated by rebreathing a gas mixture of CO2 (4-6%) in Oz (Klausen, 1965). This process was completed within 17 s after exhaustion. The values of the content of CO2 in the arterial blood and the mixed venous blood were read on a standard CO2 dissociation curve from the partial pressure of COz in the arterial and in the mixed venous blood, respectively. The steady state method (Filley et al., 1954) was used for determining the pulmonary diffusing capacity: The subject inspired 0.05% CO in air for 75 s before exhaustion from a Douglas bag and expired in another Douglas bag. The CO uptake was determined from the volumes and CO concentrations of inspired and expired gas measured by Beckman CO Analyzer. Alveolar CO was computed from the alveolar CO2 (Bates et at., 1971). Heart rate was obtained from ECG recorded with bipolar chest leads and respiratory frequency was determined with the aid of thermister attached to the inside of the mask. Vital capacity was measured by a Benedict respirometer before the exercise.
Results Table 1 summarizes average values and standard deviations for physical characteristics, maximal oxygen uptake and other physiological parameters during determination of (10 z max on boys of different ages. Body height, body weight, VO z max, p u l m o n a r y diffusing capacity, ventilation, respiratory frequency, cardiac output and heart rate at VO2 max in relation to age are presented in % ratio to the average values of 18 years old boys in Figure 1. The increase in body height is a smooth process through 1 0 - 1 8 years of age. This increment was approximately 20%. O n the other hand, body weight showed an almost twofold increase in step-wise curve from 28.7 kg at 10 years of age to 57.5 kg at 18 years of age. leO 2 max increased by approximately 55% with age from 1 0 - 1 8 years. But in this increasing curve the first peak appeared at 14 years of age. The highest value of fzO z max per body weight was 50.5 ml/kg/min at 14 years of age. As for ventilatory function, vital capacity increased linearly with age. Ventilatory frequency was almost constant from 41--52/rain over a wide range of ages from 10--18 years, while ventilation increased in the same way as (10 z max. P u l m o n a r y diffusing capacity increased almost linearly with age by approximately 45%.
8 mean SD
8 mean SD
10 mean SD
9 mean SD
10 m e a n SD
8 mean SD
8 mean SD
8 mean SD
8 mean SD
11 + 2
12 + 4
13 + 5
14 + 3
15 + 1
16 + 4
17 + 2
18 + 4
No.
10 + 2
Age (years + months)
168.7 2.2
167.8 1.4
166.2 1.0
161.9 1.2
159.4 4.5
156.4 1.5
144.2 3.9
139.4 4.4
131.9 2.2
Height (cm)
57.5 2.1
57.5 0.9
55.8 1.2
46.1 3.0
47.5 2.1
47.6 7.4
36.2 4.2
36.5 4.0
28.7 3.0
1.66 0.08
1.66 0.02
1.61 0.01
1.47 0.09
1.47 0.08
1.44 0.10
1.20 0.10
1.18 0.07
1.03 0.07
Weight B.S.A. (kg) (m z)
4.47 0.74
4.25 0.40
3.74 0.34
3.95 0.33
3.37 0.14
2.98 0.18
2.60 0.32
2.32 0.22
2.12 0.16
(1)
VC
1.07 0.06
1.02 0.00
1.02 0.06
1.14 0.07
1.08 0.07
1.02 0.06
1.09 0.06
1.00 0.07
1.05 0.09
RQ
2,46 0.25
2,40 0.13
2.20 0.23
2.17 0.29
2.38 0.14
2.05 0.24
1.43 0.20
1.34 0.22
1.10 0.17
42,8 3.4
41.9 2.1
39.9 5.1
47.1 4.1
50.5 3.6
44.5 10.0
39.8 4.7
39.7 6.7
38.6 4.6
P'O 2 m a x (l/min) (ml/kg/ rain)
93.5 10.3
81.0 5.7
77,2 12.2
84.2 14.2
91.1 14.0
73.0 12.5
56.2 8.3
54.5 9.7
45.9 4.8
(l/rain)
Ve
42.6 3.5
39..4 3.2
35.7 4.5
32.8 5.5
32.4 5.8
30.9 3.2
27.2 5.4
28.5 4.5
23.9 4.1
(ml/min/ m m Hg)
DLco
47.4 9.5
47.6 10.0
41.3 10.4
47.6 7.8
49.7 7.6
50.9 3.9
52.1 8.3
50.7 2.8
49.4 1.6
(l/rain)
f
19.7 1.2 21.4 2.0
1.79 0.50 2.02 0.28
18.7 2.0
17.9 2.4
1.78 0.18 2.02 0.72
20.2 1.7
1.82 0.29
13.0 2.2
1.11 0.21 17.0 1.6
12,3 1,3
1.14 0.25
1,43 0.19
11.0 1.1
0.95 0.08
(~ (l/rain)
(l)
P~
114.3 11.9
107.8 5.3
100.2 11.4
87.3 12.1
93.9 11.0
84.3 8.7
67.0 13.2
64.9 5.8
59.8 5.6
(ml)
sv
187.8 7.4
183.8 6.0
186.8 4.7
190.1 8.0
190.7 9.4
183.7 15.2
199.0 7.7
190.1 8.1
192,8 6.7
(beats/ min)
;If
115.1 3.6
122.3 4.4
118.3 6.9
131.5 3.2
132.6 12.7
132.7 7.3
110.9 10.3
116.1 10.8
103.6 7.8
diff. (ml/1)
a-~o2
Table 1. Average values and standard deviations for physical characteristics, maximal oxygen uptake (120 a max) and other physiological parameters during determination of f/O 2 max. B.S.A.: body surface area, VC: vital capacity, RQ: respiratory quotient, r ventilation, DLco: pulmonary diffusing capacity,f: respiratory frequency, Vr: tidal volume, Q: cardiac output, SV: stroke volume, Hf: heart rate, a-f/Oz diff.: arterio-venous oxygen content difference
o
t~
"
