Table 2.

Summary of studies included in the systematic review that investigated the effect of caffeine ingestion as compared to a placebo on serum markers of muscle damage.

Author/s	Population	Intervention	Outcomes Analyzed	Main Conclusion
Guttierres, A. P. et al. 2013 [26]	20 male young players (16.1 ± 0.7 years)	7.2 mg/kg of caffeinated sport drinks 20 min before and every 15 min during the test	Blood glucose Blood lactate Plasma caffeine Free fatty acids Urine caffeine	↑ Blood glucose ↑ Blood lactate ↑ Plasma caffeine † Free fatty acids † Urine caffeine
Machado, M. et al. 2010 [30]	15 male players (18.4 ± 0.8 years)	4.5mg/kg of caffeine capsules Immediately before the test	CK LDH ALT AST basophils, eosinophils, neutrophils, monocyte lymphocytes	† CK † LDH † ALT † AST † basophils, eosinophils, neutrophils, monocyte lymphocytes
Machado, M. et al. 2009 [31]	20 male players (18.8 ± 1 years)	4.5 mg/kg of caffeine capsules Immediately before the test	Basic hemogram CK LDH ALT AST AP γ-GT	† Basic hemogram † CK † LDH † ALT † AST † AP † γ-GT
Machado, M. et al. 2009 [32]	15 male professional players (19 ± 1 years)	5.5 mg/kg of caffeine capsules Immediately before the test	CK LDH ALT AST	† CK † LDH † ALT † AST
Bassini-Cameron, A. et al. 2007 [33]	22 male professional players (26.0 ± 1.6 years)	5 mg/kg of caffeine capsules 60 min before the start	CK LDH ALT AST	↑ CK † LDH ↑ALT † AST

↑: statistically significant increase; ^† change with no statistical significance; ↓: statistically significant decrease. CK: creatine kinase; LDH: lactate dehydrogenase; ALT: alanine aminotransferase; AST: aspartate aminotransferase; AP: alkaline phosphorylase; γ-GT: γ-glutamyl transferase.