Endurance Running Exercise Research Articles

Differential Mitochondrial Adaptation of the Slow and Fast Skeletal Muscles by Endurance Running Exercise in Streptozotocin-Induced Diabetic Mice.

The skeletal muscle is the main organ responsible for insulin action, and glucose disposal and metabolism. Endurance and/or resistance training raises the number of mitochondria in diabetic muscles. The details of these adaptations, including mitochondrial adaptations of the slow and fast muscles in diabetes, are unclear. This study aimed to determine whether exercise training in streptozotocin (STZ)-induced mice leads to differential adaptations in the slow and fast muscles, and improving glucose clearance. Eight-week-old mice were randomly distributed into normal control (CON), diabetes (DM), and diabetes and exercise (DM+Ex) groups. In the DM and DM+Ex groups, mice received a freshly prepared STZ (100 mg/kg) intraperitoneal injection on two consecutive days. Two weeks after the injection, the mice in the groups ran on a treadmill for 60 min at 20 m/min for a week and subsequently at 25 m/min for 5 weeks (5 days/week). The analyses indicated that running training at low speed (25 m/min) enhanced mitochondrial enzyme activity and expression of lactate and glucose transporters in the plantaris (low-oxidative) muscle that improved whole-body glucose metabolism in STZ-induced diabetic mice. There were no differences in glucose transporter expression levels in the soleus (high-oxidative) muscle. The endurance running exercise at 20-25 m/min was sufficient to induce mitochondrial adaptation in the low-oxidative muscles, but not in the high-oxidative muscles, of diabetic mice. In conclusion, the present study indicated that running training at 25 m/min improved glucose metabolism by increasing the mitochondrial enzyme activity and glucose transporter 4 and monocarboxylate transporter 4 protein contents in the low-oxidative muscles in STZ-induced diabetic mice.

Sex Differences in Endurance Running.

In recent years, there has been a significant expansion in female participation in endurance (road and trail) running. The often reported sex differences in maximal oxygen uptake (VO2max) are not the only differences between sexes during prolonged running. The aim of this narrative review was thus to discuss sex differences in running biomechanics, economy (both in fatigue and non-fatigue conditions), substrate utilization, muscle tissue characteristics (including ultrastructural muscle damage), neuromuscular fatigue, thermoregulation and pacing strategies. Although males and females do not differ in terms of running economy or endurance (i.e. percentage VO2max sustained), sex-specificities exist in running biomechanics (e.g. females have greater non-sagittal hip and knee joint motion compared to males) that can be partly explained by anatomical (e.g. wider pelvis, larger femur-tibia angle, shorter lower limb length relative to total height in females) differences. Compared to males, females also show greater proportional area of type I fibres, are more able to use fatty acids and preserve carbohydrates during prolonged exercise, demonstrate a more even pacing strategy and less fatigue following endurance running exercise. These differences confer an advantage to females in ultra-endurance performance, but other factors (e.g. lower O2 carrying capacity, greater body fat percentage) counterbalance these potential advantages, making females outperforming males a rare exception. The present literature review also highlights the lack of sex comparison in studies investigating running biomechanics in fatigue conditions and during the recovery process.

The Effects of 8-week Acetic Acid Feeding on Endurance Performance and Fat Metabolism in Skeletal Muscle of Mice

PURPOSE:The combined effect of acetic acid supplementation and endurance exercise training on fatty acid metabolism and skeletal muscle functions are not well known. Therefore, the purpose of this study was to investigate the effects of 8-week acetic acid administration with or without endurance exercise training on fatty acid metabolism and skeletal muscle functions using mice.METHODS: Fourty-eight male wild-type ICR mice (10-week old) were randomly divided into 4 groups: sedentary control (Sed+Con), sedentary sodium acetate (Sed+NaAc), exercise control (Exe+Con) and exercise sodium acetate (Exe+NaAc) groups. For acetic acid diet, sodium acetate was incorporated into the chow diet at 5% (w/w). For the exercise training, mice performed 4 days/week of 20 min treadmill running exercise training for 8 weeks. Following 8 weeks of combined treatments of acetic acid and endurance running exercise training, visceral fat mass and skeletal muscle mass, blood parameters, and the markers for fatty acid metabolism were analyzed. The results were analyzed with one-way ANOVA (p<.05) using the SPSS 21 program.RESULTS: Eight weeks of Exe+NaAc treatment significantly increased maximal running time compared with Sed+Con and Exe+Con groups (p<.05). Eight weeks of Exe+NaAc treatment significantly decreased fatty acid synthesis-related FAS (fatty acid synthase) protein levels compared with the Sed+Con group, and increased fatty acid oxidation-related CPT1B (carnitine palmitoyltransferase 1B) protein levels compared with Sed+Con and Sed+NaAc groups (p<.05). This combined treatment of acetic acid and endurance exercise training also increased AMPK activation compared with the Sed+Con and the Sed+NaAc groups (p<.05).CONCLUSIONS: It was concluded that there were synergistic effects of the treatment of 8-week acetic acid supplementation and endurance exercise training on the reductions of body weight and visceral fat mass and an increase in endurance performance.

Endurance running exercise is an effective alternative to estradiol replacement for restoring hyperglycemia through TBC1D1/GLUT4 pathway in skeletal muscle of ovariectomized rats.

Menopause is a risk factor for impaired glucose metabolism. Alternative treatment of estrogen for postmenopausal women is required. The present study was designed to investigate the effects of 5-week endurance running exercise (Ex) by treadmill on hyperglycemia and signal pathway components mediating glucose transport in ovariectomized (OVX) placebo-treated rats, compared with 4-week 17β-estradiol (E2) replacement or pair-feeding (PF) to the E2 group. Ex improved the hyperglycemia and insulin resistance index in OVX rats as much as E2 or PF did. However, Ex had no effect on body weight gain in the OVX rats. Moreover, Ex enhanced the levels of GLUT4 and phospho-TBC1D1 proteins in the gastrocnemius of the OVX rats, but E2 or PF did not. Instead, the E2 increased the Akt2/AS160 expression and activation in the OVX rats. This study suggests that endurance Ex training restored hyperglycemia through the TBC1D1/GLUT4 pathway in muscle by an alternative mechanism to E2 replacement.

Contribution of branched-chain amino acids to purine nucleotide cycle: a pilot study

Branched-chain amino acids (BCAAs) and purine nucleotide cycle (PNC) are both associated with energy metabolism. The purpose of this study was to explore the influences of BCAA supplementation on the PNC activity of male athletes in response to a bout of endurance running exercise. Twelve male athletes (20.3±1.4 years) participated in the study. Each of the athletes received 12 g of a BCAA supplement (leucine 54%, isoleucine 19% and valine 27%) per day during the study. They performed two identical 60-min running exercises (65-70% maximum heart rate reserved) before and after receiving the BCAA supplements for 15 days. In addition to body composition measurement, plasma and urinary samples were also collected. Plasma samples were examined for the concentrations of glucose, lactate, BCAAs, alanine, glutamine, aspartate, hypoxanthine and uric acid. Urinary samples were examined for the concentrations of urea nitrogen, hydroxyproline, 3-methylhistidine and creatinine. Body composition and the concentrations of urinary metabolites were not affected by BCAA supplementation, whereas clearance of plasma lactate after recovery from exercise was enhanced by BCAA supplementation (P<0.05). Plasma aspartate concentration was increased (P<0.05), whereas plasma glutamine, hypoxanthine and uric acid concentrations were decreased (P<0.05) by BCAA supplementation. The findings suggest that BCAA supplements not only provided additional substrate to meet the energy demands of the athletes during endurance exercise but also reduced their PNC activity, and subsequently decreased uric acid production and reduced the incidence of gout in a person engaging in endurance exercise.

The effect of recreational soccer training and running on postural balance in untrained men

The aim of this study was to examine the effect of intense intermittent exercise performed as soccer training or interval running in comparison with continuous endurance running exercise on postural balance in young healthy untrained males. Young sedentary men were randomized to soccer training (SOC, n = 10), continuous running (RUN; n = 9), high-intensity interval running (INT; n = 7) or no training (CON; n = 9). Postural balance was evaluated pre and post 12 weeks of training using a 30-s single-leg stance test on a force plate (AMTI) to yield center of pressure (CoP) sway path and 1-min beam standing (Flamingo test). CoP sway length decreased by 18.2% (p < 0.01), 14.6% (p < 0.05) and 12.8% (p < 0.05) in SOC, INT and RUN, respectively. CoP sway area decreased in SOC (-30.2%; p < 0.01) and INT (-23.4%; p < 0.01) but remained unaffected in RUN. Acceleration parameters (Mean CoP acc, SD accX, SD accY) decreased in SOC only (17-19%, p < 0.05). All training groups demonstrated fewer falls (37-41%, p < 0.01) in the Flamingo test. No changes were observed in CON. Relationships (r > 0.40) were observed between pre-training values in CoP sway area versus muscle fiber area, explosive muscle strength and countermovement jump velocity. Postural control was improved in response to 12 weeks of soccer training and high-intensity interval running, respectively, while less-marked changes were observed following continuous running. Notably, the reduced variability in CoP acceleration after soccer training indicates that this training regimen may produce superior improvements in postural sensory-motor function.

Effects of Long-term Regular Exercise on Cognitive Function, Lipid Profile and Atherogenic Biomarkers in Middle-aged Men

Effects of Long-term Regular Exercise on Cognitive Function, Lipid Profile and Atherogenic Biomarkers in Middle-aged Men Several studies on exercise and its effect on cognitive function in human and animal populations have documented the beneficial impact of regular physical activity on maintenance of good cognitive abilities and satisfactory health-related quality of life well into older age. The aim of the study was to evaluate the effects of long-term regular running on metabolic profile and cognitive function in middle-aged men. A total of 24 regularly exercising, middle-age men (Group A), all being members of the Runners Club, and 22 age-matched sedentary subjects (Group B), as the control group, were enrolled in this study. The control group included 8 non-overweight (BMI=23.5±5.2) individuals (Group C) and 14 overweight/obese (BMI=30.7±1.6) subjects (Group D). Serum lipid profile, glucose and homocysteine concentrations were assessed by routine laboratory methods. Subjects' cognitive function was evaluated based on Trail Making Test (TMT) and Digit Symbol Test (DST) scores. In a majority of runners (Group A), the BMI and the parameters of lipid profile (TC, HDL, LDL, TG, glycerol) were close to those recorded in non-overweight controls (Group C) and, in both groups, results were ideally within the reference ranges for healthy male subjects. However, as compared to the whole control group (Group B), which may be considered as an average population sample of sedentary middle-age men, significant differences were observed in BMI and concentrations of TC and LDL, as well as in the pro-atherogenic biomarkers (TC/HDL, LDL/HDL), which were lower in runners. A similar tendency was found in concentrations of TG (independent cardiovascular risk factor), glycerol and TG/HDL ratio (surrogate measure of insulin resistance), however the differences did not reach the level of significance. The level of homocysteine (pro-atherogenic biomarker) was comparable in all groups, and in most cases, within the reference range for male adults. Results of cognitive function tests did not reveal any significant between-group differences. The TMT score was found to be correlated positively (r=0.492, p&lt;0.05), whereas DST score was correlated negatively (r=-0.549, p&lt;0.005), with age. The DST performance, as evaluated in the group of runners (Group A), appeared to be strongly dependent (r=0.809, p&lt;0.005) on the educational level of the subject. These data provided evidence of beneficial effects of a long-term regular endurance running exercise on lipid profile and cardiovascular health in middle-aged men. However, we failed to confirm the findings of a favorable impact of regular physical activity on improvement in cognitive abilities.

Impaired voluntary running capacity of creatine kinase‐deficient mice

The creatine kinase system (CK) is important for energy delivery in skeletal and cardiac muscles. The two main isoforms of this enzyme, cytosolic MM-CK and mitochondrial mi-CK, are expressed in a developmental and muscle-type specific manner. Mice deficient in one or both of these isoforms are viable and fertile but exhibit profound functional, metabolic and structural muscle remodelling that primarily affects fast skeletal muscles, which show an increased contribution of oxidative metabolism to contractile function. However, the consequences of these alterations in terms of physical capabilities have not yet been characterized. Consequently, we compared the voluntary exercise capacity of 9-month-old male wild-type (WT), M-CK knockout (M-CK(-/-)), and M-CK and mi-CK double knockout (CK(-/-)) mice, using cages equipped with running wheels. Exercise performance, calculated by total distance covered and by work done during the training period, was more than 10-fold lower in CK(-/-) mice than controls, with M-CK(-/-) mice exhibiting intermediate performance. Similarly, the mean distance run per activation was lower in M-CK(-/-) and even lower in CK(-/-) mice. However, the maximal running speed (V(max)) was lower only for CK(-/-) mice. This was accompanied by severe skeletal muscle mass decrease in CK(-/-) mice, with signs of histological damage that included enlarged interstitial areas, aggregations of mononuclear cells in the interstitium, heterogeneity of myofibre size and the presence of very small fibres. No overt sign of cardiac dysfunction was observed by magnetic resonance imaging during dobutamine stimulation. These results show that metabolic failure induced by CK deficiency profoundly affects the ability of mice to engage in chronic bouts of endurance running exercise and that this decrease in performance is also associated with muscle wasting.

Immune and Inflammatroy Responses to a 246 KM Ultraendurance Running Race

1750 Endurance exercise represents a great challenge for the immune system. It is believed that the release of cytokines provide the communication between the immune system and all other body systems in order to maintain homeostasis. PURPOSE: To evaluate the effect of a continuous ultra endurance running exercise on immune and inflammatory responses immediately after and 48 hours after the end of exercise. METHODS: Blood samples were obtained before, at the end and 48h after the end of the race from 11 runners of the Spartathlon 2002 ultramarathon race (a 246 km continuous race from Athens to Sparta that takes place annually in Greece), who finished the race in less than 36 h. White blood cells were measured using an automatic analyzer, inflammatory markers C-reactive Protein (CRP) and Serum Amyloid Protein (SAA) were determined by nephelometric assays (BN-Prospec Dade-Behring), while the assessment of cytokines Intereukin-6 (IL-6) and Tumor Necrosis Factor a (TNFa) were determined using an enzyme-linked immunosorbent assay (ELISA). RESULTS: Moderate leukocytosis was observed immediately after the race (mean value of WBC: 15,042 ± 1,013/mm3), accompanied by a significant increase in plasma IL-6 (9,767 ± 2,654 pg/mL). However, we failed to detect TNFa in plasma before, during or after exercise. CRP and SAA levels were increased significantly 150- and 110-fold, respectively at the end of the race (97.4 ± 17.4 mg/L and 340.8 ± 62.2 mg/L, respectively). CRP levels tended to decrease 48 hours after the end of the race while SAA increased further. CONCLUSIONS: Post-race CRP, SAA, and IL-6 levels were dramatically elevated after the 246 km continuous foot race, indicating a serious inflammation, and remained elevated even 48 h post exercise. However, WBC count returned to baseline level within 48 h after the end of the race. These values are the highest reported as a result of prolonged exercise. The study was partially supported by the Ministry of Culture.

Loss of desmin leads to impaired voluntary wheel running and treadmill exercise performance.

We examined voluntary wheel running and forced treadmill running exercise performance of wild-type mice and mice null for the desmin gene. When given access to a cage wheel, desmin null mice spent less time running and ran less far than wild-type mice. Wild-type mice showed a significant training effect with prolonged voluntary wheel running, as evidenced by an increase in mean running speed across the 3-wk exercise period, whereas desmin null mice did not. Desmin null mice also performed less well in acute treadmill stress and endurance tests compared with wild-type mice. We also evaluated serum creatine kinase (CK) activity in wild-type and desmin null mice in response to running. Voluntary running did not result in elevated CK activity in either wild-type or desmin null mice, whereas downhill treadmill running caused significant increases in serum CK activity in both wild-type and desmin null mice. However, the increase in serum CK was significantly less in desmin null mice than in wild-type mice. These results suggest that the lack of desmin adversely affects the ability of mice to engage in both chronic and acute bouts of endurance running exercise but that this decrement in performance is not associated with an increase in serum CK activity.

The effects of chronic alcohol consumption and exercise on the skeleton of adult male rats

Background Lifestyle factors are known to affect skeletal development and integrity. Specifically, running has been reported to increase risk of fatigue fractures, whereas chronic alcohol consumption has been shown to reduce bone formation and bone mass. The combined effect of exercise and alcohol on the skeleton has yet to be explored, although alcohol consumption is common among certain physically active populations (e.g., military recruits, college athletes). It was hypothesized that chronic alcohol consumption would accentuate the inherent risk associated with endurance running exercise. Methods Six-month-old male Sprague Dawley® rats were assigned to one of five groups: baseline, exercise-alcohol diet, exercise-normal diet, sham-alcohol diet, and sham-normal diet. Alcohol-fed rats (35% caloric intake) received a liquid diet ad libitum. Normal animals were pair-fed the identical diet with a maltose dextrin caloric substitute. Exercise was conducted on a motorized treadmill 5 days/wk for 16 weeks. Sham rats were placed on a stationary treadmill for matching time periods. Fluorochrome labels were administered 3 days before baseline and at 10 and 2 days before animals were killed. Heart, soleus, and rectus femoris muscles were wet weighed to assess the effects of training. Tibiae were collected for static and dynamic histomorphometric measurements on cancellous and cortical bone. Results Muscle weights were larger in the exercised rats versus the sham rats. Alcohol had no significant effect on skeletal muscle weight but did result in larger heart weights in both alcohol-treated groups. Cancellous and periosteal bone formation rates were significantly decreased in the alcohol-fed rats versus rats on the normal diet and were associated with a significant reduction in trabecular thickness in the tibial metaphysis. Cortical and cross-sectional areas were also significantly lower in the alcohol-fed groups compared with the non-alcohol-fed groups. Exercise had no significant effect on cancellous or cortical bone measurements. Conclusions Chronic alcohol consumption significantly reduced bone formation. Exercise had no effect on the bone and did not attenuate any of the negative effects of alcohol. The results suggest that alcohol consumption weakens the skeleton and increases the incidence of endurance-exercise-related bone injuries. Thus, individuals who are participating in endurance exercise and consuming alcohol may be at greater risk for exercise-related skeletal injuries. Further investigation of the potential for alcohol to induce detrimental effects on the hearts of individuals participating in endurance exercise is indicated.

Changes in lactate dehydrogenase and 3-hydroxyacetyl-CoA dehydrogenase activities in rat skeletal muscle by the administration of Eucommia ulmoides OLIVER leaf with spontaneous running-training.

We examined the effect of Eucommia ulmoides OLIVER leaf on rat skeletal muscles together with spontaneous running-training in terms of the isozyme profile and specific activity of lactate dehydrogenase (LDH; EC 1.1.1.27) and 3-hydroxyacetyl-CoA dehydrogenase (HAD; EC 1.1.1.35). On the twenty-ninth day of the experimental period, a mandatory endurance running exercise (treadmill, 7 degrees grade) was conducted. Twenty-four hours later, the rats were sacrificed and the skeletal muscles and other organs were dissected. Due to the training, the HAD specific activity in the skeletal muscles had increased and a more oxidative metabolism had developed, which was further enhanced by the administration of the leaf. In soleus (SOL) muscle in the Eucommia leaf treated running-training group (ET), the LDH specific activity in the skeletal muscle was significantly higher than in the sedentary control group (SC). The isozyme profile of the group ET was significantly different when compared with the group SC. The changes in the LDH isozyme profile were larger in the SOL than that in extensor digitorum longus (EDL) muscle. The results show that mechanical training and the use of the leaf cooperatively increase the ability to avoid lactate accumulation in skeletal muscle. This effect is supported by the group where 67% of rats accomplished the endurance running exercise. Theses results suggest that the administration of Eucommia ulmoides OLIVER leaf along with light intensity training enhances the ability of a muscle to resist fatigue.

Study of 5-HT release with a chronically implanted microdialysis probe in the ventral horn of the spinal cord of unrestrained rats during exercise on a treadmill

The ventral horn of the spinal cord is profusely innervated by serotonin (5-hydroxytryptamine, 5-HT) which presumably modulates locomotor activity through motoneurons. However, direct evidence of correlation between 5-HT release and activation of motoneurons is still lacking. In order to appreciate the functional characteristics of this innervation, we have used microdialysis to monitor the release of 5-HT in the spinal cord of rats spontaneously running on a treadmill. For this purpose, we developed an original surgical procedure adapted for the chronic implantation of a microdialysis probe in the lumbar spinal cord. The probe was kept in place for 40 days, and microdialysis experiments were carried out at days 8, 16, 20 and 32. 5-HT was detected with HPLC coupled to electrochemistry. This technique demonstrated that release of 5-HT is not increased during exercise. However, a significant decrease was measured during postexercise rest. 5-HT could still be detected 32 days after probe implantation. Detailed histological and immunocytochemical analysis based on glial fibrillary acidic protein and 5-HT immunocytochemistry showed minimal gliosis and the presence of serotonergic varicose fibers, respectively, at the probe contact. It thus appears that microdialysis can be performed through a probe implanted chronically in the spinal cord of unrestrained rat during an endurance running exercise.