Journal of Exercise Nutrition & Biochemistry最新文献

Purpose: Despite numerous studies, the mechanisms underlying the effects of exercise on brain function are not yet fully understood. Adult hippocampal neurogenesis is one of the most well-known effects of exercise on the brain, but its physiological roles during exercise are still ambiguous, mostly due to the difference in the structure and composition of each part of the hippocampus.

Methods: In this study, we analyzed exercise-induced changes in gene expression in the subgranular zone (SGZ) and granular cell layer (GCL) of the hippocampus.

Results: Surprisingly, only about 10% of changes were common to both areas. Tollip expression, which is altered in the SGZ and in Engrailed-2 mutant mice following exercise, did not change in the GCL. Tollip levels were not changed in the whole hippocampus after two weeks of treadmill exercise, but immunofluorescence analysis showed that Tollip and Ki-67 co-localize in the hippocampal dentate gyrus . Through siRNA knockdown experiments, we found that levels of DCX and cellular survival rates were decreased in Tollip-deficient Neuro2A cells.

Conclusion: Taken together, these results suggest a role for Tollip in mediating the beneficial effects of exercise, probably affecting cellular health in the SGZ of the hippocampus.

Purpose: Studies of L-carnitine in healthy athletic populations have yielded equivocal results. Further scientific-based knowledge is needed to clarify the ability of L-carnitine to improve exercise capacity and expedite the recovery process by reducing oxidative stress. This study aimed to examine the 9-week effects of L-carnitine supplementation on exercise performance, anaerobic capacity, and exercise-induced oxidative stress markers in resistance-trained males.

Methods: In a double-blind, randomized, and placebo-controlled treatment, 23 men (age, 25±2y; weight, 81.2±8.31 kg; body fat, 17.1±5.9%) ingested either a placebo (2 g/d, n=11) or L-carnitine (2 g/d, n=12) for 9 weeks in conjunction with resistance training. Primary outcome measurements were analyzed at baseline and at weeks 3, 6, and 9. Participants underwent a similar resistance training (4 d/w, upper/lower body split) for a 9-week period. Two-way ANOVA with repeated measures was used for statistical analysis.

Results: There were significant increases in bench press lifting volume at wk-6 (146 kg, 95% CI 21.1, 272) and wk-9 (245 kg, 95% CI 127, 362) with L-carnitine. A similar trend was observed for leg press. In the L-carnitine group, at wk-9, there were significant increases in mean power (63.4 W, 95% CI 32.0, 94.8) and peak power (239 W, 95% CI 86.6, 392), reduction in post-exercise blood lactate levels (-1.60 mmol/L, 95% CI -2.44, -0.75) and beneficial changes in total antioxidant capacity (0.18 mmol/L, 95% CI 0.07, 0.28).

Conclusion: L-carnitine supplementation enhances exercise performance while attenuating blood lactate and oxidative stress responses to resistance training.

Purpose: We examined the effects of diet before endurance exercise on hepcidin response in young untrained females.

Methods: Ten young untrained females [age: 20.6 ± 0.8 y, height: 157.5 ± 1.0 cm, weight: 54.4 ± 1.5 kg, and maximal oxygen uptake (VO2max): 35.9 ± 1.1 mL/kg/min] were involved in two experimental conditions with a crossover design. The two conditions were separated by approximately 1 month, and each condition was performed during the follicular phase. Subjects completed 60 min of pedaling at 65% of VO2max after consuming a meal (FED) or not consuming a meal (CON). Blood samples were collected before, immediately after, and 3 h after exercise.

Results: Serum ferritin levels before exercise did not differ between the two conditions (P > 0.05). Blood glucose and lactate levels were significantly elevated immediately after exercise only under the FED condition (P < 0.05). Serum iron levels were significantly elevated after exercise under both conditions. However, the plasma interleukin-6 and serum hepcidin levels were not significantly different 3 h after exercise under either condition (P > 0.05).

Conclusion: Consuming a meal before endurance exercise at moderate intensity did not affect exercise-induced hepcidin elevation in young untrained females.

Purpose: Hemodynamic function is a parameter indicating oxygen delivery and utilization capacity and is an important determinant of exercise performance. The present study aimed to determine whether intermittent hypoxic training (IHT) ameliorates hemodynamic function and exercise performance in competitive swimmers.

Methods: Twenty competitive swimmers (10 men, 10 women) volunteered to participate in the study. Participants were divided into the normoxic training (NT) group and the hypoxic training (HT) group and were subjected to training in a simulated altitude of 3000 m. We evaluated hemodynamic function profiles over 30 min of submaximal exercise on a bicycle and exercise performance before and after 6 weeks of training, which involved continuous exercise at 80% maximal heart rate (HRmax) for 30 min and interval exercise at 90% of HRmax measured before training for 30 min (ten rounds comprising 2 min of exercise followed by 1 min of rest each round).

Results: Significant changes in oxygen consumption (decrease) and end-diastolic volume (increase) were observed only in the HT group. Heart rate (HR), cardiac output (CO), and ejection fraction (EF) were significantly reduced in both groups, but the reduction rates of HR and CO were greater in the HT group than in the NT group. Exercise performance measures, including maximal oxygen consumption and 400-m time trial, were significantly increased only in the HT group.

Conclusion: Our findings suggested that 6 weeks of IHT, which involved high-intensity continuous and interval exercise, can effectively improve exercise performance by enhancing hemodynamic function in competitive swimmers.

Purpose: This study aimed to study the protective effects and mechanism of Blue Honeysuckle (BH) extracts (Berries of Lonicera caerulea L.) on non-alcoholic fatty liver disease (NAFLD) and obesity risk factors in a high fat-diet (HFD) model.

Methods: Animals adapted to HFD were selected after 1 week of adaption period and divided into 6 groups (8 mice in each group; 40 HFD-fed mice and 8 normal fat pellet diet (NFD)-fed mice). After the end of 12 weeks of continuous oral administrations of 3 different dosages of BH extract, 400, 200 and 100 mg/kg, or metformin 250 mg/kg, dissolved in a volume of 10 mL/kg distilled water, the hepatoprotective, hypolipidemic, hypoglycemic, nephroprotective, and anti-obesity effects were analyzed.

Results: The BH extract improved fat density and mass, adipocyte histopathology, hepatocyte hypertrophy, hepatic enzyme activity, lipid metabolism, and related gene expression including ACC1, AMPK α1 and AMPK α2 in hepatic tissue, leptin, UCP2, adiponectin, C/EBP α, C/EBPβ and SREBP1c in adipose tissue. Especially, 200 mg/kg of BH extract constantly improved NAFLD and obesity risk factors through AMPK upregulation-mediated hepatic glucose enzyme activity, lipid metabolism-related gene expression, and activation of the antioxidant defense system, to a level comparable to that of metformin 250 mg/kg in HFD-fed mice.

Conclusion: BH extract has the potential to reduce the risk factors associated with obesity, in addition to the remarkable effect of preventing NAFLD. Future research will need to be done to determine whether these results are consistent in human studies.

Purpose: This study aimed to analyze the correlation between anxiety, salivary alpha amylase (sAA), and salivary cortisol (sC) changes in athletes showing a high or low level performance in an actual archery competition.

Methods: The participants were female university athletes who participated in the individual 50 m archery competition at the 21st Korean National Archery Team Trials, in July 2018. Based on their game record in the competition, 9 athletes were allocated to the high-performance group (HPG) and another 9 to the low-performance group (LPG). Anxiety caused by the competition was rated on a 1-10 point Likert scale at 30 min before competition (pre-30), 3 min before competition (pre-3), and 30 min after competition (post-30). This assessment method directly measured their cognitive anxiety. Saliva samples were collected in a tube by having the athletes chew on an absorber swab. For data analysis, two-way ANOVA with repeated measures was performed and Pearson's correlation method was applied to correlate the variables.

Results: In the actual competition, significant difference between the game records of the HPG (mean score 339.5±4.1) and the LPG (mean score 323.3±3.4) was observed. Competitive anxiety showed a significant decrease in the HPG compared to the LPG. Due to the competition, sAA and sC were significantly decreased in the HPG compared to the LPG. Analysis of correlations between competition scores, anxiety, sAA, and sC, revealed that lower anxiety was associated with higher scores in the HPG. Pre-3 anxiety positively correlated with pre-3 sAA and sC. In the LPG, lower scores were associated with persistent anxiety until the completion of the competition. Positive correlations were observed for pre-3 anxiety with post-30 sC, pre-3 sAA with post-30 sAA and sC, and pre-3 cortisol with post-30 sAA.

Conclusion: Increased anxiety in the actual archery competition was associated with significant increase in sAA and sC. Elevated sAA and sC from prior-competition to post-competition stage were associated with reduced performance. Significant correlations between the measured variables (game records, anxiety, sAA, and sC) were associated with worse performance.

Purpose: Sudden and exhaustive exercise causes muscle damage accompanied by oxidative stress and inflammation, leading to muscle fatigue and soreness. AmLexin contains a standardized blend of extracts from the heartwood of Acacia catechu and the root bark of Morus alba, and is known to possess antioxidant and anti-inflammatory properties. The aim of this study was to investigate the effects of this proprietary blend supplementation on muscular pain and redox balance in healthy runners, in comparison to a placebo.

Methods: A double-blind placebo-controlled clinical trial was carried out over 9 weeks in a single center. Thirty physically active male and female subjects within 18-70 years of age were randomized into AmLexin (mean age = 42.92 ± 2.48 and gender 7/5, male/female, respectively) and placebo (mean age = 41.15 ± 3.5 and gender 10/3, male/female, respectively) groups. Subjects were supplemented with 400 mg of AmLexin/day or a look-alike placebo during an 8-week training program, and for one week following a 13.1-mile half-marathon. Twenty-six subjects completed the 9-week supplementation trial.

Results: Results showed the AmLexin group experienced significantly lower levels of post-exercise pain on day 1-3 following the half-marathon compared to the placebo group. The AmLexin group also showed lower post-exercise oxidative stress and higher antioxidant capacity on days 1 and 6 following the half-marathon. These results demonstrated the rapid benefits of AmLexin on pain and oxidative stress within 1-6 days post-exercise.

Conclusion: Our data suggest that AmLexin could be a safe, effective botanical alternative for delayed onset muscle soreness.

Purpose: The purpose of this study was to investigate the impact of weight loss practices on nutritional status, bone health, and injury history among Korean professional jockeys.

Methods: Forty-three male jockeys completed a questionnaire to assess their weight loss practices. Of these, 10 jockeys were selected for in-depth assessment of their nutritional status, bone health, and injury history.

Results: The questionnaires revealed that 81.4% of jockeys lost weight every week mainly by dieting and/or exercising. None of the jockeys consumed enough food during the weight loss period. Two jockeys were diagnosed with osteopenia and one was diagnosed with osteoporosis. Only history of fracture showed a significant correlation with low bone mineral density. All jockeys had more than one injury experience throughout their career. Fracture was the most common type of injury, occurring during practice and/or competition and caused mainly by difficulties in handling the horses.

Conclusion: Professional jockeys in Korea use extreme weight loss methods. Their repeated periods of poor nutritional intake may result in seriously low bone mineral density, which may aggravate injuries sustained during horse races. Implementation of balanced dietary programs and delivery of health education on weight management are urgently required.

Purpose: Exercise effectively enhances physiological adaptation, performance, and health-related markers in healthy individuals and diseased populations. However, the type and amount of optimal exercise remain controversial. High-intensity interval training (HIIT) took the top spot in the American College of Sports Medicine worldwide survey on fitness trends in 2018.

Methods: We review information on the effect of HIIT on physiological adaptation and the novel role on brain functions.

Results: HIIT is a more cost-effective way to improve physiological adaptations with aerobic capacity, and it also enhances brain functions such as hippocampus-dependent learning and memory.

Conclusion: In this review, we provide insight on the utility of HIIT in improving performance and highlight suggestions for future research.

Purpose: Previous studies have indicated that Kv7 channels have an important role in the regulation of blood vessel reactivity, including in the coronary, renal, and cerebral arteries. The present studies examined whether Kv7 channels regulated vascular reactivity in the mouse aorta and investigated the mechanisms involved in the reactivity.

Methods: Wild-type (WT) male C57BL/6 mice, between 10 and 15 weeks old, were used in this study. The vascular function of the aorta in WT male mice was assessed by using a pin myography system (Model 620; DMT, Denmark).

Results: Vasorelaxation by an endothelial-dependent vasodilator, acetylcholine (ACh, 1 nM - 10 μM) and an endothelial-independent vasodilator, sodium nitroprusside (SNP, 1 nM - 10 μM) was induced in the aorta in a dose-dependent manner. Pre-incubation with the nitric oxide synthase inhibitor, L-NAME (100 μM, 20 min), completely abolished ACh-induced vasorelaxation, but did not block retigabine-induced vasorelaxation, which suggested that retigabine caused vasorelaxation in the aorta via smooth muscle activation rather than via endothelial cells. Pre-application of the Kv7 channel blocker, linopirdine (10 μM), resulted in a greater contractile response compared with that induced by vehicle in the aorta. In addition, pre-incubation with linopirdine (10 μM, 20 min) reduced retigabine-induced vasorelaxation (1-50 μM).

Conclusion: This study has provided evidence that Kv7 channels may play a role in the regulation of aortic blood flow via smooth muscle activation.