Integrative effects of resistance training and endurance training on mitochondrial remodeling in skeletal muscle.

Resistance training activates mammalian target of rapamycin (mTOR) pathway of hypertrophy for strength gain, while endurance training increases peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α) pathway of mitochondrial biogenesis benefiting oxidative phosphorylation. The conventional view suggests that resistance training-induced hypertrophy signaling interferes with endurance training-induced mitochondrial remodeling. However, this idea has been challenged because acute leg press and knee extension in humans enhance both muscle hypertrophy and mitochondrial remodeling signals. Thus, we first examined the muscle mitochondrial remodeling and hypertrophy signals with endurance training and resistance training, respectively. In addition, we discussed the influence of resistance training on muscle mitochondria, demonstrating that the PGC-1α-mediated muscle mitochondrial adaptation and hypertrophy occur simultaneously. The second aim was to discuss the integrative effects of concurrent training, which consists of endurance and resistance training sessions on mitochondrial remodeling. The study found that the resistance training component does not reduce muscle mitochondrial remodeling signals in concurrent training. On the contrary, concurrent training has the potential to amplify skeletal muscle mitochondrial biogenesis compared to a single exercise model. Concurrent training involving differential sequences of resistance and endurance training may result in varied mitochondrial biogenesis signals, which should be linked to the pre-activation of mTOR or PGC-1α signaling. Our review proposed a mechanism for mTOR signaling that promotes PGC-1α signaling through unidentified pathways. This mechanism may be account for the superior muscle mitochondrial remodeling change following the concurrent training. Our review suggested an interaction between resistance training and endurance training in skeletal muscle mitochondrial adaptation.

[Exercise regulates lipid metabolism via lipophagy and its molecular mechanisms].

Lipophagy is a kind of selective autophagy, which can selectively identify and degrade lipid droplets and plays an important role in regulating cellular lipid metabolism and maintaining intracellular lipid homeostasis. Exercise can induce lipophagy and it is also an effective means of reducing body fat. In this review, we summarized the relationship between exercise and lipophagy in the liver, pancreas, adipose tissue, and the possible molecular mechanisms to provide a new clue for the prevention and treatment of fatty liver, obesity and other related metabolic diseases by exercise.

Hypoxic training upregulates mitochondrial turnover and angiogenesis of skeletal muscle in mice.

AIMS: Hypoxic training promotes human cardiopulmonary function and exercise performance efficiently, but the myocellular mechanism has been less studied. We aimed to examine the effects of hypoxic trainings on mitochondrial turnover and vascular remodeling of skeletal muscle. MAIN METHODS: C57BL/6 J mice were divided into control, hypoxic exposure, exercise training, "live high-train low" (LHTL), and "live low-train high" (LLTH) groups (n = 8/group). Western blot and immunohistochemistry were used to evaluate mitochondrial turnover of gastrocnemius and angiogenesis of quadriceps after six weeks interventions. KEY FINDINGS: Compared with control group, both LHTL and LLTH increased phosphorylation levels of p38 MAPK markedly (p < 0.05). LLTH also elevated PGC-1α protein expression significantly (p < 0.05). All interventions did not influence Bnip3 and Drp-1 proteins levels (p > 0.05), while LLTH enhanced Parkin and Mff protein contents significantly (p < 0.05). Immunohistochemical analysis showed both LHTL and LLTH promoted CD31 and VEGF expressions (p < 0.05). ATP content, citrate synthase activities of gastrocnemius were robustly elevated in LHTL and LLTH groups (p < 0.01). The exercise training increased Mff protein and ATP content in gastrocnemius as well as VEGF expression in quadriceps (p < 0.05). The hypoxic exposure also increased ATP content, citrate synthase, and ATP synthase activities in gastrocnemius as well as VEGF expression in quadriceps (p < 0.01). SIGNIFICANCE: Our results suggested that hypoxic trainings, especially LLTH, promoted mitochondrial turnover and angiogenesis of skeletal muscle, which may be an underlying mechanism of hypoxic training-induced exercise capacity.

[Effects of the combination of tangeretin and whey protein on testosterone and cortisol in sprinters at winter training season].

Objective: To evaluate the regulation efficacy of oral tangeretin on testosterone and cortisol in sprinters at winter training season. Methods: Twenty-four sprinters were paired and randomly divided into experimental group (EG) and control group (CG). During winter training season, EG were treated with 200 mg tangeretin by oral, and CG were treated with placebo for 4 weeks. Blood samples were collected on the first day of each week (T1, T2, T3, T4) and after the intervention (T5) to detect serum levels of testosterone, cortisol, superoxide dismutase (SOD), and adrenocorticotropic hormone (ACTH). The body composition was tested at T1 and T5. Results: After 4 weeks, ①the serum cortisol level of CG was increased, and the serum levels of testosterone and SOD were decreased significantly (P＜0.05). ②In EG, the serum levels of cortisoland ACTH were decreased significantly (P＜0.05, P＜ 0.01), while the serum testosterone level was remained stable, and the level of SOD was increased slightly. ③The muscle mass of EG and CG were increases, but that of EG was increased higher than that of CG. Conclusion: Tangeretin reduces the oxidative stress response that caused by high-intensity exercise during winter training, which maintain the serum testosterone level and inhibit cortisol excessive secretion and promote muscle synthesis.

[Effects of Tangeretin on cortisol stress response induced by high-intensity resistance exercise].

Objective: To investigate the effects of 4-week tangeretin supplementation on cortisol stress response induced by high-intensity resistance exercise. Methods: Twenty-four sprinters were paired and randomly divided into experimental group (EG) and control group (CG). EG orally took supplement with tangeretin (200 mg/day) and CG took placebo for 4 weeks. Before and after the 4-week intervention, all sprinters performed a set of high-intensity resistance exercise (shoulder press, squat, bench press and deadlift, 10 RM, 4 sets per movement) to stimulate their cortisol stress responses. Serum levels of cortisol, adreno-corticotropic hormone (ACTH), superoxide dismutase (SOD), white blood cell count (WBC) and blood glucose were obtained by collecting blood sample before the exercise (PRE), immediately after the exercise (P0), and at 10 (P10), 20 (P20), and 30 minutes (P30) after the exercise. Results: Compared with the same period before the intervention, after the 4-week tangeretin intervention, EXP showed significantly reduced serum cortisol level at PRE (P=0.017), P10 (P=0.010), P20 and P30 (P＜0.05 or P＜0.01), and significantly reduced WBC at PRE, ACTH at P10 (P=0.037) and WBC and ACTH at P30 (P＜0.05). Compared with CTROL, EXP showed significantly lower levels of the serum cortisol at PRE and P10 (P＜0.05), and significantly lower levels of the ACTH (P＜0.05) and WBC (P＜0.01) at P30, and significantly increased level of the SOD activity at P30 (P＜0.05). Conclusion: Tangeretin supplementation can significantly alleviate the cortisol stress response induced by high-intensity resistance exercise, inhibit the excessive secretion of cortisol, enhance antioxidant capacity, accelerate the elimination of inflammation in the body, and promote the recovery of body functions.

[Unfolded protein response signaling in mitochondria].

The mitochondrial unfolded protein response is an important component of the mitochondrial protein quality control program. It can effectively remove unfolded or misfolded proteins under stress, and maintain a stable and healthy mitochondrial pool. The mitochondrial unfolded protein response is coordinated by multiple signaling pathways. The classical ATF4/ATF5-CHOP pathway is induced by accumulation of unfolded or misfolded proteins in the mitochondrial matrix, which reduces stress toxicity by regulating molecular chaperones and proteases. Sirt3-FOXO3a-SOD2 pathway, located in the mitochondrial matrix, plays an important role in anti-oxidative damage. The ERα-NRF1-HTRA2 pathway mainly removes unfolded proteins in the mitochondrial membrane space and improves the quality control of mitochondrial proteins. These three signaling pathways work both independently and cooperatively to enhance mitochondrial capacity and maintain health under stress.

[Research advances in relationship between mitochondrial dynamics and cellular energy metabolism and exercise intervention].

Mitochondrial dynamics, involving mitochondrial fusion, fission and autophagy, plays an important role in maintaining cellular physiological function and homeostasis. Mitochondria are the "energy plant" of human body, so the changes of mitochondrial fusion, division and autophagy are important for cell respiration and energy production. On the other hand, energy metabolism influences mitochondrial dynamics in turn. This paper reviewed the recent advances in studies on the relationship between energy metabolism and the proteins regulating mitochondrial fusion, fission and autophagy. The association of mitochondrial dynamics with electron chain complex expression, oxidative phosphorylation and ATP synthesis upon exercise intervention will provide theoretical references for the further studies in sports training and disease intervention.

[The effects of lower limb intermittent negative pressure therapy on the skin microcirculation perfusion of quadriceps in male rowers].

OBJECTIVE: To investigate the effects of intermittent negative pressure therapy on the skin microcirculation perfusion of quadriceps in male rowers, and to provide basis for the practical application of this method. METHODS: Fourteen male rowers were selected from the national rowing team and randomly divided into experimental and control groups. The daily training plans of two groups were the same. The recovery intervention for experimental group was implemented by 20 minutes in the cube of Vacusport Regeneration System (German), 5 times per week for 4 weeks, no recovery intervention for control group. Microcirculation markers were collected by PeriFlux5000 system before and after the 4-week intervention. The markers included microcirculatory blood perfusion(MBP), average velocity of blood cells(AVBC), concentration of moving blood cells (CMBC), and values of the markers included basic values and post-heating values (44℃), difference before and after heating of the values was considered as the reserve capacity of those markers. RESULTS: The test results before the 4 weeks intervention showed there was no statistical difference between the two groups(P＞0.05). After the 4 weeks intervention: ①MBP: The post-heating value and the difference of the experimental group were significantly higher than those of the control group (P＜0.05). But there was no statistical inner-group difference. ②AVBC: The post-heating values and the difference in the experimental group were significantly lower than those in the control group (P＜0.05). Intra-group comparison found that the post-heating values after post-intervention were significantly reduced, compared with those of pre-intervention (P＜ 0.01); the difference after post-intervention was reduced significantly, compared with those in the pre-intervention (P＜0.05). ③CMBC: The post-heating values and the difference in the experimental group were significantly higher than those in the control group (P＜0.01). There were no statistical significant inner-group difference. CONCLUSION: Lower limb intermittent negative pressure therapy can improve the skin microcirculation of the quadriceps of the male rowers, which has a positive effect on the rapid recovery of physical fitness.

[Effects of different intensity exercise training on apoptosis-related microRNAs and the targeted proteins in cardiomyocytes].

OBJECTIVE: To detect the levels of miR-1, miR-21 and their targeted proteins in hearts of mice after different exercise training, and discuss potential molecular mechanism. METHODS: Male C57BL/6 mice were randomly divided to 3 groups:sedentary (SE), exercise training 1(ET1) and exercise training 2 (ET2). SE did not do any exercise; ET1 undertook swimming training for 8 weeks, once a day, 5 days/week. Swimming 30 min in the 1st week, and the duration was increased 10 min per week to 90 min and maintained in the 7th and 8th week. ET2 performed the same work as ET1 and switched to twice a day by the end of the 5th week. TUNEL assay was applied to test myocardial apoptosis. Western blot and RT-PCR were used to detect proteins and miRs levels respectively. RESULTS: Compared with SE, in ET1, myocardial apoptosis and miR-1 level did not change, but its targeted protein Bcl-2 increased significantly(P<0.01). miR-21 and its targeted protein PDCD4 did not change significantly. In ET2, myocardial apoptosis and miR-1 level were decreased significantly(P<0.05). Bcl-2 was increased significantly(P<0.01). miR-21 also increased significantly (P<0.05), but PDCD4 did not decrease significantly. CONCLUSIONS: Exercise training in ET2 other than ET1 could down-regulate myocardial apoptosis. Alterations of miR-1 and Bcl-2 may be responsible for this cardioprotection. PDCD4 is not sensitive to exercise training, it is likely that miR-21 and other targeted proteins participate in exercise-regulative apoptosis.

[The relationship between reserve capacity of microcirculatory blood perfusion and related biochemical indices of male rowers in six weeks' pre-competition training].

OBJECTIVE: To study the change of reserve capacity of microcirculatory blood perfusion (MBP) and the relationship between some conventional function indices of elite male rowers in 6 weeks before the Olympic Games. The feasibility of the MBP using for athletes fu nctional status monitoring was also discussed. METHODS: Eight male lightweight rowers of Chinese National Rowing Team were selected as the subjects. Blood samples were taken every Monday morning before eating breakfast (6:30-7:00). The indices including hemoglobin (Hb), red blood cells (RBC),blood urea (BU) and creatine kinase (CK) were tested,while reserve capacity of MBP were collected with PeriFlux 5000 system on the same day. Meanwhile,the venous blood samples were collected and the levels of testosterone (T) and cortisol (C) were deter-mined in the high load training week and last two weeks before the Olympic Games. RESULTS: All presented a certain relevance between the re-serve capacity of MBP and conventional function indices. There was significant positive correlation with T (P < 0.05), and it was correlated with Hb, C and T/C positively, negative correlation with CK, and they all did not have significant difference(P > 0.05), but there was sig-nificant negative correlation with BU (P < 0.05). CONCLUSIONS: There is a certain consistency between change of reserve capacity of MBP and the characteristic of conventional function indices. And reserve capacity of MBP is more sensitive in fatigue monitoring after intensity training. In a certain extent, reserve capacity of MBP as a non-invasive indices can be used for evaluating the functional state and judging the degree of fat igue.

[Study on the biceps brachii microcirculation blood flow reserve capacity of the Chinese rowers].

OBJECTIVE: To investigate the effect of chronic endurance exercise on microcirculatory reserve capacity of biceps brachii in Chinese rowers and provide a certain basis for the date standard foundation of monitoring of functional status and the foundation of database of reserve capacity of blood of Chinese rowers. METHODS: Empty stomach in the morning, 77 rowers from different groups and 24 common health people were noninvasive tested by using PeriFlux System 5000, the test indexes include the microcirculatory reserve capacity and other related indexes of biceps brachii. The test sites of all athletes were the same space in biceps brachii of the right side of body, there was no space differences of all athletes . All athletes were tested in the relatively stable functional status, common people were healthy. The test value included basic values and heating values, put the before and after heating of microcirculatory blood perfusion (MBP) as the microcirculatory reserve capacity. RESULTS: Heavyweight female (198. 97 ± 98. 81) > heavyweight male (183. 45 ± 64. 31) > lightweight male (151. 01 ± 65. 96) > lightweight female(140.53 ± 43.22) > common male people(127.21 ± 56.38) > common female people(103.54 ± 33.41), the microcirculatory reserve capacity of each group athletes were higher than common people, except the comparison between lightweight female and common male people, and there was no significant difference among the different group athletes. CONCLUSION: Chronic endurance exercise can improve the microcirculatory reserve capacity of rowers, especially the heavyweight rowers; the normal value of microcirculatory reserve capacity of heavy weight rowers should be more than 160, and lightweight rowers should be more than 120. There was no significant difference among different sex athletes, if the value of microcirculatory reserve capacity is significant lower than normal, it shows that athletes are in the state of fatigue.

[Effects of HiLo for two weeks on erythrocyte immune adhesion and leukocyte count of swimmers].

OBJECTIVE: To investigate the effects of living high-training low (HiLo) on innate immunity in blood of elite swimmers. METHODS: Six female swimmers undertook HiLo for two weeks, erythrocyte adhesion function and counts of leukocyte were tested in different time of training period. RESULTS: Red blood cell C3b receptor ring rate (RBC-C3bRR) decreased and red blood cell immune complex matter ring rate (RBC-ICR) increased significantly (P < 0.05), the two markers returned to base line 1 week after training. Counts of leukocyte and granulocyte decreased significantly (P < 0.05), and they recovered 1 week after training; Counts of lymphocyte and monocyte decreased without significance during training and did not recovered after training. CONCLUSION: Immunity of erythrocyte and granulocyte decreased quickly, but lymphocyte and monocyte recovered slowly, swimmers were adaptive to the training.