Background: Intense physical exercise leads to inflammation, oxidative stress and muscle damage, and these responses are of greater magnitude in people with obesity. Melatonin (MLT) is considered an endogenous antioxidant which may have beneficial effects against inflammation, oxidative stress and promote tissue repair after exercise. The aim of this study was to examine the effect of MLT on inflammatory parameters, oxidative stress and muscle damage in people with overweight/obesity after a high-intensity interval exercise (HIIE). Methods: A total of 23 subjects with obesity (9 men and 14 women) age: 33.26 ± 9.81 years, BMI: 37.75 ± 8.87 kg.m⁻² were randomized to participate in two experimental sessions: HIIE + Placebo and HIIE + MLT (3 mg). The HIIE protocol corresponds to 8 intervals of 1 min (90% of the maximal aerobic power (MAP)) alternating with 2 min recovery (45% of the MAP). Blood samples were drawn before and 5 min after each exercise session. Results: MLT ingestion attenuated the increase of inflammation (C-reactive protein, white blood cells (P < 0.001, ηp² = 0.45; for both) and Neutrophils (P < 0.01, ηp² = 0.36)) and hepatic and muscle damage (Aspartate aminotransferase (P < 0.01, ηp² = 0.25), Alanine aminotransferase (P < 0.01, ηp² = 0.27) and Creatine kinase (P = 0.02, ηp² = 0.23). MLT also attenuated the exercise induced lipid and protein peroxidation (i.e., Malondialdehyde (P = 0.03, ηp² = 0.19) and AOPP (P < 0.001, ηp² = 0.55)). Concerning the antioxidant status, MLT intake increased Thiol (P < 0.01, ηp² = 0.26) and Catalase (P < 0.01, ηp² = 0.32) and decreased Uric acid (P = 0.02, ηp² = 0.2) and Total bilirubin (P < 0.01, ηp² = 0.33). Conclusions: MLT intake before HIIE reduced muscle damage by modulating oxidative stress and preventing overexpression of the pro-inflammatory mediators in people with obesity.

Background: This study aimed to investigate the effects of intradialytic concurrent (resistance–endurance) training combined with melatonin (MEL) supplementation on oxidative stress, inflammation, and cellular damage in hemodialysis (HD) patients. Methods: Thirty-two HD patients were randomly assigned to three groups: Exercise (EX)-MEL, EX-Placebo (PLA), and Control (C)-PLA. Participants in the EX-MEL and EX-PLA groups underwent 12 weeks of concurrent training. Before nocturnal sleep, they ingested either 3 mg of MEL (EX-MEL) or a placebo (EX-PLA and C-PLA). Blood samples were collected at baseline and after 12 weeks of intervention to assess lipid peroxidation [malondialdehyde (MDA)], antioxidant biomarkers [ferric-reducing antioxidant power (FRAP), reduced glutathione (GSH), total thiol (THIOL)], total bilirubin (TBIL), uric acid (UA), biomarkers of muscle and liver damage [aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), creatine kinase (CK), lactate dehydrogenase (LDH), and Gamma-glutamyltransferase (Gamma-GT)], and inflammation [C-reactive protein (CRP)]. Results: EX-MEL demonstrated a decrease in MDA (p < 0.05) and CRP (p < 0.05), and an increase in FRAP (p < 0.05) pre- and post-training. Both EX-MEL and EX-PLA showed an increase in GSH (p < 0.001, and p < 0.05, respectively) and THIOL (p < 0.01, and p < 0.05, respectively) pre- and post-training. No significant changes were observed in TBIL, UA, ASAT, ALAT, CK, LDH, or Gamma-GT pre- and post-training across all groups. Conclusion: Concurrent training combined with MEL supplementation enhances oxidant–antioxidant balance and reduces inflammation in HD patients more effectively than intradialytic concurrent training alone.

Purpose: The present study aimed to investigate for the first time the effects of melatonin (MEL) intake on oxidative stress and cellular damage during intradialytic exercise (IEX). Methods: Thirteen hemodialysis (HD) patients volunteered to participate in the current randomized crossover trial. Participants performed four HD sessions in four different conditions: (Exercise (EX)-MEL), (EX-Placebo (PLA)), (Control (C)-MEL), and (C-PLA). 3 mg of MEL or PLA were taken 60 min before starting exercise, or at the equivalent time in the C conditions. Blood samples were taken before HD (T0), immediately after the end of IEX (T1), 60 min after IEX (T2), or at the corresponding times in the C conditions to measure free radicals damage, antioxidant biomarkers, as well as biomarkers of muscle and liver damage. Results: Malondialdehyde and Advanced Oxidation Protein Products decreased in (C-MEL) ( p < 0.05, d = 2.19; p < 0.01, d = 0.99, respectively) at T2 compared to T0. Catalase and total thiol levels increased in (C-MEL) ( p < 0.01, d = 1.51; p < 0.01, d = 1.56, respectively) and in (EX-MEL) ( p = 0.01, d = 1.28; p < 0.01, d = 1.52, respectively) at T1 compared to T0. Total bilirubin levels increased in (EX-MEL) and (C-MEL) at T2 compared to T0 ( p < 0.001, d = 2.77; p < 0.001, d = 1.36, respectively), but only at T2 compared to T1 in (EX-MEL) ( p < 0.001, d = 1.67). In all conditions, uric acid levels decreased at T1 compared to T0 and at T2 compared to T1, while biomarkers of muscle and liver damage remained unchanged. Conclusion: This pilot study is the first to show that MEL ingestion, alone or combined with IEX, could improve oxidant-antioxidant balance during HD.

Background: This study aimed to investigate the effects of intradialytic concurrent (resistance-endurance) training combined with melatonin (MEL) supplementation on oxidative stress, inflammation, and cellular damage in hemodialysis (HD) patients. Methods: Thirty-two hemodialysis (HD) patients were randomly assigned to three groups: Exercise (EX)-MEL, EX-Placebo (PLA), and Control (C)-PLA. Participants in the EX-MEL and EX-PLA groups underwent 12 weeks of concurrent training. Before nocturnal sleep, they ingested either 3 mg of MEL (EX-MEL) or a placebo (EX-PLA and C-PLA). Blood samples were collected at baseline and after 12 weeks of intervention to assess lipid peroxidation [malondialdehyde (MDA)], antioxidant biomarkers [ferric reducing antioxidant power (FRAP), reduced glutathione (GSH), total thiol (THIOL)], total bilirubin (TBIL), uric acid (UA), biomarkers of muscle and liver damage [aspartate aminotransferase (ASAT), alanine aminotransferase (ALAT), creatine kinase (CK), lactate dehydrogenase (LDH), Gamma-glutamyltransferase (Gamma-GT)], and inflammation [C-reactive protein (CRP)]. Results: EX-MEL demonstrated a decrease of MDA (p<0.05) and CRP (p<0.05), and an increase of FRAP (p<0.05) pre- and post-training. Both EX-MEL and EX-PLA showed an increase in GSH (p<0.001, and p<0.05, respectively) and THIOL (p<0.01, and p<0.05, respectively) pre- and post-training. No significant changes were observed in TBIL, UA, ASAT, ALAT, CK, LDH, and Gamma-GT pre- and post-training across all groups. Conclusion: Concurrent training combined with MEL supplementation enhances oxidant-antioxidant balance and reduces inflammation in HD patients more effectively than intradialytic concurrent training alone.