Comparative analysis of related indexes of cardiopulmonary function between the two groups
Note: VO2 = oxygen uptake expressed in l/min, VO2 /kg = oxygen uptake expressed in ml/kg/min, VCO2 = carbon dioxide output expressed in l/min, HR = Heart rate, MET = Metabolic equivalent (MET = VO2 expressed in ml/kg/min divided 3.5), RER = Respiratory exchange ratio. Data are presented as mean ± SD. Compared to 25%VO2max, □ means P < 0.05;□□ means P < 0.01, compared to 35%VO2max,⁕ means P < 0.05; ⁕⁕ means P < 0.01, compared to 45%VO2max, * means P < 0.05; ** means P < 0.01, compared to 55%VO2max, △ means P < 0.05; △△ means P < 0.01; compared to 65%VO2max, # means P < 0.05; ## means P < 0.01.
Table 2 shows the determination of Oxygen pulse,VO2, VO2/kg, VCO2, HR, MET and RER values in individuals with C Group (a) and O (b) Group. With increasing exercise intensity, there were statistically significant differences in Oxygen pulse, VO2, VO2/kg, VCO2, HR, MET in two groups, and no significant differences were found between 25% and 35% of VO2max. RER values had no significant differences for individuals with both groups during 25%, 35% ,45% and 55% of VO2max.
Note: * means P < 0.05,** means P < 0.01.
Table 2. Determination of Oxygen pulse,VO2, VO2/kg, VCO2 , HR , MET and RER in individuals with C Group (a) and O (b) Group.
(a) individuals in C Group
charateristic
|
25%VO2max
|
35%VO2max
|
45%VO2max
|
55%VO2max
|
65%VO2max
|
75%VO2max
|
Oxygen pulse, ml
|
4.79±1.30
|
5.84±1.26
|
7.42±1.39□□
|
8.25±1.68□□⁕
|
8.77±1.73□□⁕⁕
|
9.52±1.81□□⁕⁕
|
VO2 , l.min-1
|
0.48±0.88
|
0.65±0.11
|
0.87±0.12□☑
|
1.09±0.20□□⁕⁕
|
1.28±0.21□□⁕⁕**
|
1.54±0.26□□⁕⁕**△△#
|
VO2/kg, ml.kg-1.min-1
|
9.30±1.40
|
12.52±1.88
|
16.92±2.19□□⁕
|
21.20±3.12□□⁕⁕*
|
24.85±3.51□□⁕⁕**
|
29.97±4.28□□⁕⁕**△△##
|
VCO2, l.min-1
|
0.41±0.09
|
0.55±0.11
|
0.76±0.11□□
|
0.98±0.18□□⁕⁕*
|
1.17±0.20□□⁕⁕**
|
1.48±0.26□□⁕⁕**△△##
|
HR , beats.min-1
|
104.74±16.50
|
112.45±14.46
|
118.43±13.43
|
133.43±10.46□□⁕
|
146.83±9.26□□⁕⁕**
|
162.93±10.20□□⁕⁕**△△
|
MET
|
2.82±0.51
|
3.72±0.64
|
5.07±0.72□□⁕
|
6.36±0.78□□⁕⁕
|
7.46±1.19□□⁕⁕**
|
8.98±1.37□□⁕⁕**△△#
|
RER
|
0.83±0.07
|
0.85±0.07
|
0.88±0.07
|
0.90±0.07
|
0.92±0.06
|
0.96±0.05□□⁕⁕
|
(b) individuals in O Group
charateristic
|
25%VO2max
|
35%VO2max
|
45%VO2max
|
55%VO2max
|
65%VO2max
|
75%VO2max
|
Oxygen pulse, ml
|
6.25±0.71
|
6.93±0.79
|
7.58±0.94□□
|
8.81±0.89□□⁕⁕*
|
9.71±0.63□□⁕⁕**
|
10.79±0.64□□⁕⁕**△△
|
VO2 , l.min-1
|
0.59±0.06
|
0.69±0.08
|
0.83±0.13□□⁕
|
1.05±0.16□□⁕⁕*
|
1.27±0.17□□⁕⁕**△
|
1.55±0.16□□⁕⁕**△△##
|
VO2/kg, ml.kg-1.min-1
|
7.17±0.69
|
8.58±1.08
|
10.34±1.58□□
|
13.16±2.35□□⁕⁕*
|
15.79±2.28□□⁕⁕**△
|
19.31±2.40□□⁕⁕**△△##
|
VCO2, l.min-1
|
0.46±0.05
|
0.53±0.08
|
0.67±0.12□□
|
0.87±0.17□□⁕⁕
|
1.11±0.20□□⁕⁕**△△
|
1.42±0.21□□⁕⁕**△△##
|
HR, beats.min-1
|
94.88±5.73
|
100.14±7.04
|
109.71±10.56□□
|
119.66±11.31□□⁕⁕
|
130.32±12.37□□⁕⁕**
|
143.46±10.70□□⁕⁕**△△
|
MET
|
2.14±0.22
|
2.53±0.40
|
3.71±1.13□□⁕
|
4.13±0.77□□⁕⁕
|
4.96±0.75□□⁕⁕*
|
6.06±0.80□□⁕⁕**△△#
|
RER
|
0.77±0.06
|
0.76±0.08
|
0.80±0.07
|
0.82±0.07
|
0.88±0.07□⁕
|
0.91±0.08□□⁕⁕*
|
In Fig. 1, VO2/kg (a), HR (b), MET (c), RER(d) were plotted against exercise intensity (% maximal oxygen uptake) for the short continue exercise during the C Group (open square) and O Group (filled square). Significant main effects of obesity class on VO2/kg (F1,16=46.26, P ≤ 0.01, η2 = 0.74), HR (F1,16=9.50, P = 0.007, η2 = 0.37), MET (F1,16=32.02, P ≤ 0.01, η2 = 0.67) and RER (F1,16=5.50, P = 0.032, η2 = 0.25) controlling for age were observed. Significant exercise intensity × obesity class interactions on VO2/kg (F2.20,35.11=25.34, P ≤ 0.01, η2 = 0.61) and MET (F1.76,28.08=10.66, P = 0.001, η2 = 0.40) controlling for age were observed. Moreover, significant main effects of exercise intensity on VO2/kg (F2.20,35.11=373.07, P ≤ 0.01, η2 = 0.96), HR (F1.97,31.53=137.66, P ≤ 0.01, η2 = 0.90), MET (F1.76,28.08=203.04, P ≤ 0.01, η2 = 0.93) and RER (F2.53,40.52=33.53, P ≤ 0.01, η2 = 0.68) controlling for age were observed.
Figure 1 shows that VO2/kg and MET were significantly lower in O Group than in C Group. Except for 25% and 45% VO2max, HR in C Group was significantly higher than O Group. During the 35%, 45% and 55% VO2max intensity, indeed, RER of the C Group was significantly higher than that of O Group.
Comparative analysis between the energy expenditure and substrate oxidation for the two groups
Note: CHO = carbohydrate oxidation, CHO/kg = carbohydrate oxidation expressed in mg.min− 1.kg− 1, FAT/kg = fat oxidation expressed in mg.min− 1.kg− 1, fat oxidation rate = ratio of energy contribution from fat, EE = energy expenditure expressed in cal.min− 1, EE/kg = energy expenditure expressed in cal.min− 1kg− 1. Data are presented as mean ± SD. Compared to 25%VO2max, □ means P < 0.05;□□ means P < 0.01, compared to 35%VO2max,⁕ means P < 0.05; ⁕⁕means P < 0.01, compared to 45%VO2max, * means P < 0.05; ** means P < 0.01, compared to 55%VO2max, △ means P < 0.05; △△ means P < 0.01; compared to 65%VO2max, #means P < 0.05; ## means P < 0.01.
In Table 3, with exercise intensity increasing, CHO and CHO/kg increased significantly, 25% and 35% VO2max excepted, carbohydrate oxidation increased dramatically during 75% of the VO2max compared with 65% of the VO2max in C Group.
Table 3. EE/kg in individuals with C Group (a) and O Group (b).
(a) individuals in C Group
charateristic
|
25%VO2max
|
35%VO2max
|
45%VO2max
|
55%VO2max
|
65%VO2max
|
75%VO2max
|
CHO,g.min-1
|
0.30±0.19
|
0.43±0.23
|
0.70±0.29
|
0.97±0.35□□⁕
|
1.25±0.39□□⁕⁕*
|
1.83±0.48□□⁕⁕**△△##
|
CHO/kg , mg.min-1.kg-1
|
5.79±3.72
|
8.44±4.56
|
13.61±5.36
|
18.90±6.85□□⁕
|
24.49±7.95□□⁕⁕*
|
35.53±9.20□□⁕⁕**△△#
|
fat oxidation,g.min-1
|
0.13±0.06
|
0.16±0.07
|
0.17±0.12
|
0.18±0.13
|
0.17±0.14
|
0.09±0.16⁕*△##
|
FAT/kg, mg.min-1kg-1
|
2.56±1.22
|
3.13±1.37
|
3.37±2.25
|
3.57±2.51
|
3.30±2.76
|
1.75±3.03⁕*△##
|
fat oxidation rate, %
|
52.67±24.15
|
47.33±22.43
|
35.89±23.36
|
30.44±22.03
|
23.78±19.16
|
10.44±16.23□□⁕⁕
|
EE , kcal.min-1
|
2.38±0.46
|
3.18±0.59
|
4.35±0.57□□
|
5.54±1.01□□⁕⁕
|
6.56±1.07□□⁕⁕**
|
8.12±1.38□□⁕⁕**△△##
|
EE/kg, cal.min-1kg-1
|
46.18±7.95
|
61.90±10.30
|
84.82±10.51□□⁕
|
107.72±16.07□□⁕⁕*
|
127.68±18.51□□⁕⁕**
|
157.91±22.71□□⁕⁕**△△##
|
(b) individuals in O Group
charateristic
|
25%VO2max
|
35%VO2max
|
45%VO2max
|
55%VO2max
|
65%VO2max
|
75%VO2max
|
CHO ,g.min-1
|
0.18±0.15
|
0.18±0.26
|
0.39±0.25
|
0.60±0.42
|
1.01±0.51□□⁕⁕*
|
1.50±0.60□□⁕⁕**△△
|
CHO/kg , mg.min-1.kg-1
|
2.28±2.03
|
2.39±3.45
|
4.89±3.43
|
7.64±5.71□⁕
|
12.74±6.89□□⁕⁕*
|
18.80±7.94□□⁕⁕**△△
|
fat oxidation , g.min-1
|
0.23±0.07
|
0.27±0.11
|
0.27±0.10
|
0.30±0.15
|
0.26±0.16△
|
0.21±0.20△
|
FAT/kg, mg.min-1kg-1
|
2.81±0.83
|
3.37±1.27
|
3.34±1.15
|
3.72±1.70
|
3.14±2.01△
|
2.65±2.46△
|
fat oxidation rate, %
|
74.00±22.42
|
77.89±30.59
|
62.22±21.22
|
55.22±25.92
|
38.00±22.64□⁕
|
26.11±24.54□□⁕⁕*
|
EE , kcal.min-1
|
2.77±0.27
|
3.20±0.40
|
3.99±0.64□
|
5.12±0.88□□⁕⁕*
|
6.36±0.96□□⁕⁕**△
|
7.94±0.97□□⁕⁕**△△##
|
EE/kg, cal.min-1kg-1
|
34.44±2.90
|
39.39±5.32
|
49.64±8.41□
|
64.04±13.12□□⁕⁕
|
79.26±13.63□□⁕⁕**△
|
99.03±14.46□□⁕⁕**△△##
|
while fat oxidation and FAT/kg, during 55% of VO2max, fat oxidation was more than in other workloads, but there was no statistical significance during 25%,35% and 45% of VO2max. Compared to 25% and 35% of VO2max, the percentage of energy supplied from fat during 75% of the VO2max was very significantly lower. With exercise intensity increasing, EE and EE/kg increased significantly and simultaneously.
In O Group, with exercise intensity increasing, carbohydrate oxidation and CHO/kg increased very significantly,but in 25%,35% and 45%of VO2max. When VO2max was 55%, the fat oxidation and FAT/kg were significantly higher than fat oxidation during other workloads. Although exercise intensity during 55% of VO2max had higher fat oxidation, other exercise intensities had no dramatic differences. With exercise intensity increasing, fat oxidation rate was reduced progressively and EE and EE/kg increased very significantly.
Comparative analysis of related indexes of cardiopulmonary fitness and fat oxidation between the two groups
The following are the results in Table 4:
Note: AT = Anaerobic Threshold. Data are presented as mean ± SD. Comprised to C Group, * means P < 0.05;** means P < 0.01. Compared to VO2max/kg, △△ means P < 0.01. Compared to AT-VO2/kg, ♦♦ means P < 0.01.
Note: Data are presented as mean ± SD (95%CI of mean). CI: confidence interval of 95%. Compared to C Group, P < 0.05.
Results of of ANOVA indicated that VO2max/kg (P ≤ 0.01), AT-VO2/kg (P = 0.003), Fatmax -VO2/kg (P = 0.024) and MFO (P = 0.010) expressed as g/min of O Group were significantly lower than those of C Group. Moreover, in both group Fatmax -VO2/kg was lower at MFO than AT.
In Fig. 2, fat oxidation (e) and FAT/kg (f) are plotted against exercise intensity (% maximal oxygen uptake) for the short, continued exercise for C Group (real line) and O Group (broken line).
In O group, for VO2max/kg values there was significant positive correlation in AT-VO2/kg (R = 0.827, P = 0.011) and Fatmax-VO2/kg (R = 0.767, P = 0.016) values. However, during C Group, VO2max/kg values had no correlation with AT-VO2/kg and Fatmax-VO2/kg values, furthermore, the value of AT-VO2 had found relationship with MFO expressed as g/min (R = 0.884, P = 0.002) and MFO expressed as g/min/kg ( R = 0.861, P = 0.003), and a positive correlation had found AT-%VO2max and MFO expressed as g/min (R = 0.803,P = 0.009), and MFO expressed as g/min/kg ( R = 0.814,P = 0.008). However, it did not found during O Group. As shown in Fig. 2(e) and Fig. 2(f), Significant main effects of exercise intensity on fat oxidation (F2.01,32.08=3.96, P = 0.03, η2 = 0.20) and FAT/kg (F2.14,34.25=4.15, P = 0.02, η2 = 0.21) controlling for age were observed. with exercise intensity increasing, fat oxidation at different exercise intensities were increased first, then decreased.
In both groups, EE and EE/kg had positive correlations with oxygen pluse (P ≤ 0.01), VO2 (P ≤ 0.01), VO2/kg (P ≤ 0.01), VCO2 (P ≤ 0.01), HR (P ≤ 0.01), MET (≤ 0.01) and RER (P ≤ 0.01), But EE and EE/kg had negative correlation with fat oxidation rate (P ≤ 0.01). Moreover, There were negative correlations between fat oxidation expressed as g/min or g/min/kg and RER (p ≤ 0.01).