Table 2.

Comparison of perceptions of dyspnea between non-smokers and smokers

	Non-smokers	Smokers	P- value
Number	14	14
R = 10 (point)	2.3 ± 1.0	1.9 ± 1.3	n.s.
R = 20 (point)	3.1 ± 1.4	2.9 ± 1.5	n.s.
R = 30 (point)	4.4 ± 1.5	4.8 ± 1.8	n.s.
Sum (point)	9.7 ± 3.8	9.8 ± 4.8	n.s.
Slope (point • L/g)	0.14 ± 0.05	0.15 ± 0.05	n.s

Data are mean ± S.D. R = 10, R = 20 and R = 30 indicates the Borg score at R = 10, R = 20 and R = 30 cmH₂O/L/s, respectively. Sum indicates the summation of Borg scores at R = 10, R = 20 and R = 30 cmH₂O/L/s. Slope indicates the linear regression slope when estimated Borg scores were plotted against the corresponding values of resistive loads. P-values were calculated by the Mann-Whitney U test. n.s. denotes not significant.