. 2014 Nov 15;7(11):4461–4465.

Table 2.

Exhausted swimming time index comparison between experimental group and control group before and after intervention (n = 20, x̅± s)

Group	Case number (piece)	Mean time of exhausted swimming (min)

		Before experiment	After experiment
Control group	20	253.14 ± 45.60	276.57 ± 45.97
Mild smoking group	20	253.57 ± 38.97	215.57 ± 29.49^a,^b
Heavy smoking group	20	252.39 ± 47.83	176.54 ± 21.79^a,^b

Note: compared with the pre-intervention;

P < 0.05, compared with the control group;

P < 0.05.