Caffeine Does Not Alter Performance, Perceptual Responses, and Oxidative Stress After Short Sprint Interval Training.

Despite the abundance of research investigating the efficacy of caffeine supplementation on exercise performance, the physiological and biochemical responses to caffeine supplementation during intermittent activities are less evident. This study investigated the acute effects of caffeine supplementation on measures of exercise performance, ratings of perceived exertion, and biomarkers of oxidative stress induced by an acute bout of sprint interval training. In a randomized crossover design, 12 healthy males (age: 26 ± 4 years, height: 177.5 ± 6 cm, body mass: 80.7 ± 7.6 kg) ingested 6 mg/kg of caffeine or placebo 60 min prior to performing sprint interval training (12 × 6 s "all-out sprints" interspersed by 60 s of rest). Performance scores and ratings of perceived exertion were assessed after every sprint. Blood samples were collected before supplementation, prior to and following each sprint, and 5 and 60 min after the last sprint. Caffeine had no effect on any performance measures, ratings of perceived exertion, or biomarkers of oxidative stress (p > .05). In conclusion, caffeine supplementation does not improve performance or decrease oxidative stress after an acute bout of sprint interval training.

Salivary profile of children with erosive tooth wear: a transversal study

Abstract The aim of the present transversal study was to evaluate the clinical and biochemical salivary parameters of children with and without erosive tooth wear (ETW). The study population was children aged 4 to 9 years. A trained and calibrated examiner (kappa value for intraexaminer reliability = 0.89) classified the children into ETW (n = 24) and control groups (n = 24), and applied the O'Brien index. The salivary flow rate was initially evaluated by stimulated sialometry (paraffin chewing). Afterwards, the collected saliva was submitted to biochemical analyses of pH, uric acid, total buffering capacity, ferric-reducing antioxidant power, reduced glutathione, calcium, and phosphorus. Among the ETW children, 20 (83%) had dental lesions restricted to enamel, and 4 (17%) presented lesions affecting both enamel and dentin. A statistically significant difference between the groups was obtained only for the pH values (t-test; p = 0.004), with averages of 7.31 and 7.56 for the control and the ETW groups, respectively. Considering the parameters evaluated in general, it is suggested that the salivary profile of children with ETW does not differ considerably from that of children without ETW. However, the pH mean value seems to be slightly higher in ETW children, but is still within the normal physiological range.

Twice-weekly exercise training reduces oxidative stress and proinflammatory cytokine levels in elder women

Aim: Reactive oxygen species and high concentrations of proinflammatory cytokines are related to diseases that are often triggered during the aging process. This study aimed to investigate the effect of moderate-intensity physical exercise, twice a week, on oxidative stress and inflammation biomarkers. Methods: Participants were older women aged 60-70 years, engaged in a moderate-intensity exercise program carried out in 60 minutes sessions, twice a week, for 24 weeks. Exercise sessions consisted of step, resistance and stretch exercises. Thiobarbituric acid reactive substances (TBARS), serum iron and cytokines IL-6, IL-1β and IL-1ra were determined using specific kits. Physical fitness was assessed using tests provided by AAPHERD. A paired t test was performed. Results: Moderate-intensity exercise program provided a reduction in lipid peroxidation (27%) and in the serum release of prooxidant iron ions (40%). Cytokine levels were reduced by 37% for IL-6, 16% for IL-1β and 32% for IL-1ra. Improvements in cardiorespiratory fitness (13%), muscular endurance (11%) and flexibility (12%) were also observed. Conclusion: Diminished redox state and inflammation were obtained using a twice-weekly exercise program. These results have important implications for older adults who are unable or unwilling to attend exercise programs more than twice a week. Moreover, these results could re-establish the minimum exercise activity necessary for obtaining health benefits in the elderly population.(AU)

Astaxanthin ameliorates the redox imbalance in lymphocytes of experimental diabetic rats

Diabetes mellitus is a syndrome of impaired insulin secretion/sensitivity and frequently diagnosed by hyperglycemia, lipid abnormalities, and vascular complications. The diabetic 'glucolipotoxicity' also induces immunodepression in patients by redox impairment of immune cells. Astaxanthin (ASTA) is a pinkish-orange carotenoid found in many marine foods (e.g. shrimp, crabs, salmon), which has powerful antioxidant, photoprotective, antitumor, and cardioprotective properties. Aiming for an antioxidant therapy against diabetic immunodepression, we here tested the ability of prophylactic ASTA supplementation (30 days, 20mg ASTA/kg BW) to oppose the redox impairment observed in isolated lymphocytes from alloxan-induced diabetic Wistar rats. The redox status of lymphocytes were thoroughly screened by measuring: (i) production of superoxide (O2•-), nitric oxide (NO•), and hydrogen peroxide (H2O2); (ii) cytosolic Ca2+; (iii) indexes of oxidative injury; and (iv) activities of major antioxidant enzymes. Hypolipidemic and antioxidant effects of ASTA in plasma of ASTA-fed/diabetic rats were apparently reflected in the circulating lymphocytes, since lower activities of catalase, restored ratio between glutathione peroxidase and glutathione reductase activities and lower scores of lipid oxidation were concomitantly measured in those immune cells. Noteworthy, lower production of NO and O2•- (precursors of peroxynitrite), and lower cytosolic Ca2+ indicate a hypothetical antiapoptotic effect of ASTA in diabetic lymphocytes. However, questions are still open regarding the proper ASTA supplementation dose needed to balance efficient antioxidant protection and essential NO•/H2O2-mediated proliferative capacities of diabetic lymphocytes.