Table 2.

Subgroup analysis results regarding the effects of H₂ on anti-oxidative stress.

Outcomes	Variables	No. of experiments	Hedges’ g (95%CI)	p value	Test of heterogeneity
					χ2	p value	I2 (%)
d-ROMs	Performance levels
	Untrained	6	−0.08 (−0.55, 0.39)	0.69	0	0.42	0.11
	Recreationally trained	1	0.35 (−0.50, 1.19)	-	0	-	-
	Period of H 2 implementation
	Single or multiple doses in 1 day	5	−0.08 (−0.49, 0.34)	0.63	0	0.58	0
	Multiple doses lasting more than 1 day	2	0.21 (−7.31, 7.72)	0.79	0.47	0.08	67.87
	Exercise types
	Continuous exercises	4	−0.06 (−0.67, 0.54)	0.76	0	0.52	0
	Intermittent exercises	3	0.08 (−1.46, 1.61)	0.85	0.15	0.18	41.64
BAP	Performance Levels
	Untrained	6	0.30 (−0.00, 0.61)	0.05	0	0.83	0
	Recreationally trained	1	0.19 (−0.65, 1.03)	-	0	-	-
	Period of H2 implementation
	Single or multiple doses in 1 day	5	0.18 (−0.99, 0.44)	0.14	0	0.92	0
	Multiple doses lasting more than 1 day	2	0.59 (−0.13, 1.32)	0.06	0	0.86	0
	Exercise types
	Continuous exercises	4	0.13 (−0.21, 0.47)	0.31	0	0.87	0
	Intermittent exercises	3	0.52 (0.16, 0.87)	0.02	0	0.91	0