No abstract

The prevailing model of osteology is that bones constantly undergo a remodeling process, and that the differentiation and functions of osteoblasts are partially regulated by leptin through different central hypothalamic pathways. The finding that bone remodeling is regulated by leptin suggested possible endocrinal effects of bones on energy metabolism. Recently, a reciprocal relationship between bones and energy metabolism was determined whereby leptin influences osteoblast functions and, in turn, the osteoblast-derived protein osteocalcin influences energy metabolism. The metabolic effects of bones are caused by the release of osteocalcin into the circulation in an uncarboxylated form due to incomplete γ-carboxylation. In this regard, the Esp gene encoding osteotesticular protein tyrosine phosphatase is particularly interesting because it may regulate γ-carboxylation of osteocalcin. Novel metabolic roles of osteocalcin have been identified, including increased insulin secretion and sensitivity, increased energy expenditure, fat mass reduction, and mitochondrial proliferation and functional enhancement. To date, only a positive correlation between osteocalcin and energy metabolism in humans has been detected, leaving causal effects unresolved. Further research topics include: identification of the osteocalcin receptor; the nature of osteocalcin regulation in other pathways regulating metabolism; crosstalk between nutrition, osteocalcin, and energy metabolism; and potential applications in the treatment of metabolic diseases.

[Purpose] The aim of this study was to investigate the impact of different marathon running distances (10 km, 21 km, and 42.195 km) on muscle and lymphocyte DNA damage in amateur marathon runners. [Subjects and Methods] Thirty male amateur runners were randomly assigned to 10 km, 21 km, and 42 km groups, with 10 subjects in each group. Blood samples were collected before and after the races and on the 3rd day of recovery to examine levels of muscle damage (creatine kinase and lactate dehydrogenase) and lymphocyte DNA damage (DNA in the tail, tail length, and tail moment). [Results] Serum creatine kinase, serum lactate dehydrogenase, and tail moment were significantly higher after the races compared with before the races in all groups. In addition, the 42 km group showed significantly higher levels of creatine kinase, lactate dehydrogenase, and tail moment than the 10 km and 21 km groups after the races. [Conclusion] Strenuous endurance exercise can cause muscle and lymphocyte DNA damage, and the extent of such damage can increase as running distance increases.

Objective: Orbotron training is a popular training method for fighter pilots because it replicates a high-acceleration environment with excessive G-force. The purpose of this study was to investigate the effects of 9 weeks of orbotron training on oxidative DNA damage and antioxidant capacity in humans during 3-dimensional space exercise. Subjects and Methods: The subjects comprised 15 senior cadets from the Korea Air Force Academy who had no record of medical disorders and who participated in a regular exercise program (3 times per week). They were randomly divided into three groups consisting of 5 subjects each: a weight training group (21.97 ± 1.12 years), a running training group (21.53 ± 0.18 years) and an orbotron training group (21.48 ± 0.29 years). Three-dimensional exercise tests were performed before and after training, and blood samples were taken to measure the concentration of plasma lactate, malondialdehyde (MDA), erythrocyte superoxide dismutase (SOD) activity, and leukocyte DNA damage. Results: Plasma lactate concentrations decreased in all three groups when measured after training and after 30 min of recovery compared to before training (p < 0.05). The concentration of plasma MDA also decreased after training in all blood samples compared to the values obtained before training although there was no significant difference in the weight training and orbotron training groups. In contrast, the activity of erythrocyte SOD increased for all three groups compared to before training (p < 0.05). In the comet assay results, the greatest lymphocyte DNA damage was demonstrated at the end of exercise compared to the other three samples under all conditions, and these aspects were commonly observed in all three parameters of lymphocyte DNA damage (tail DNA, tail length and tail moment) (p < 0.05). Conclusion: It can be concluded that the three types of exercise training reduced plasma lactate concentration, improved antioxidant enzyme activity, and further protected the body against oxidative stress (lipid peroxidation and DNA damage). Although we have identified an effect of exercise training on the levels of antioxidants and oxidants, our cohort was small, so further studies are needed to evaluate the different types of exercise training.

PurposeThe aim of this study was to investigate the effects of fluid replacement by water or sports drinks on serum heat shock protein 70 (HSP70) levels and DNA damage during exercise at a high ambient temperature.MethodsTen male college athletes with an athletic career ranging from 6 to 11 years were recruited from Yonsei University. The subjects ran on a treadmill at 75% of heart rate reserve during 4 different trials: thermoneutral temperature at 18°C (T), high ambient temperature at 32°C without fluid replacement (H), high ambient temperature at 32°C with water replacement (HW), and high ambient temperature at 32°C with sports drink replacement (HS). During each condition, blood samples were collected at the pre-exercise baseline (PEB), immediately after exercise (IAE), and 60 min post-exercise.ResultsSkin temperature significantly increased during exercise and was significantly higher in H compared to T and HS at IAE. Meanwhile, serum HSP70 was significantly increased in all conditions at IAE compared to PEB and was higher in H compared to T at the former time point. Significantly increased lymphocyte DNA damage (DNA in the tail, tail length, tail moment) was observed in all trials at IAE compared to PEB, and attenuated DNA damage (tail moment) was observed in HS compared to H at IAE.ConclusionAcute exercise elevates serum HSP70 and induces lymphocyte DNA damage. Fluid replacement by sports drink during exercise at high ambient temperature can attenuate HSP response and DNA damage by preventing dehydration and reducing thermal stress.