Table 2. The results of the categorical comparison between study groups in terms of heart tissue levels of MDA, 3-NT, CAT, GPx and SOD.

Parameters	Study groups			Comparisons
	Control (n = 10)	Acute exercise (n = 10)	Melatonin (n=10)	Control/acute exercise	Control/melatonin	Acute exercise/melatonin
MDA (nmol/mg protein)	22.4 (21.8-23.0)	29.5 (28.7-30.1)	23.7 (22.4-24.0)	p < 0.001	p > 0.05	p < 0.001
3-NT (nmol/g tissue protein)	-	0.090 ± 0.01	0.032 ± 0.01	-	-	p < 0.001
CAT (μmol/g tissue protein)	4.10 (4.08-4.12)	3.09 (3.06-3.10)	3.91 (3.90-3.93)	p < 0.001	p < 0.001	p < 0.001
GPx (U/mg tissue protein)	1.6 (1.59-1.62)	0.80 (0.79-0.82)	1.44 (1.42-1.46)	p < 0.001	p < 0.001	p < 0.001
SOD (U/mg tissue protein)	1.56 (1.54-1.58)	1.10 (1.2-1.14)	1.52 (1.50-1.53)	p < 0.001	p < 0.001	p < 0.001

CAT, catalase; GPx, glutathione peroxidase; MDA, malondialdehyde; SOD, superoxide dismutase; 3-NT, 3-nitrotyrosine.

Data are expressed as mean ± SD or median (25th-75th percentile) for continuous variables.