Table 2.

Comparison of tidal volume by sex and grade.

Tidal volume (mL)	Sex (n = 72)		t	p	Grade (n = 72)		t	p
	Male (n = 21)	Female (n = 51)			3rd (n = 43)	4th (n = 29)
0 g	356.48 ± 148.48	330.12 ± 142.02	0.71	0.482	347.40 ± 131.06	323.59 ± 161.31	0.69	0.493
100 g	377.48 ± 78.04	357.27 ± 128.35	0.67	0.505	359.91 ± 126.04	368.00 ± 100.57	− 0.29	0.773
200 g	392.62 ± 119.33	376.47 ± 119.23	0.52	0.603	395.58 ± 117.31	359.83 ± 119.43	1.26	0.212
300 g	419.52 ± 74.90	358.84 ± 137.19	1.91	0.061	380.88 ± 134.40	370.10 ± 111.38	0.36	0.722

Data are expressed as mean ± standard deviation.