Low-intensity Endurance Training Research Articles

Endurance training volume cannot entirely substitute for the lack of intensity.

Very low intensity endurance training (LIT) does not seem to improve maximal oxygen uptake. The purpose of the present study was to investigate if very high volume of LIT could compensate the lack of intensity and is LIT affecting differently low and high intensity performances. Recreationally active untrained participants (n = 35; 21 females) cycled either LIT (mean training time 6.7 ± 0.7 h / week at 63% of maximal heart rate, n = 16) or high intensity training (HIT) (1.6 ± 0.2 h /week, n = 19) for 10 weeks. Two categories of variables were measured: Low (first lactate threshold, fat oxidation at low intensity exercise, post-exercise recovery) and high (aerobic capacity, second lactate threshold, sprinting power, maximal stroke volume) intensity performance. Only LIT enhanced pooled low intensity performance (LIT: p = 0.01, ES = 0.49, HIT: p = 0.20, ES = 0.20) and HIT pooled high intensity performance (LIT: p = 0.34, ES = 0.05, HIT: p = 0.007, ES = 0.48). Overall, very low endurance training intensity cannot fully be compensated by high training volume in adaptations to high intensity performance, but it nevertheless improved low intensity performance. Therefore, the intensity threshold for improving low intensity performance is lower than that for improving high intensity performance. Consequently, evaluating the effectiveness of LIT on endurance performance cannot be solely determined by high intensity performance tests.

Biseasonal Changes in Aerobic Capacity and Sports Performance in Highly Trained Mountain Bike Cyclists Applying Elements of the Polarized Training Programme

Abstract Introduction. This study assessed maximal oxygen uptake (VO2max), power output and sports performance in mountain bike cyclists applying elements of the polarized training programme (POL) Material and Methods. Seven cyclists participated in the study. Immediately before the 2-year experiment (T1), and five times during the experiment (T2, T3, T4, T5, T6), incremental and verification tests were performed to assess VO2max, peak aerobic power (Ppeak) and power at the second ventilatory threshold (PVT2). During the experiment, sports performance in mountain bike cyclists at National Championships, European Championships, World Championships, and World Cup were analyzed. The cyclists performed POL for seven months in each year of the experiment. POL included sprint interval training, high-intensity interval training, and low-intensity endurance training. Results. In the group of cyclists VO2max [l∙min−1] increased in T6 (4.14 ± 1.13) compared to T1 (3.74 ± 0.95), Ppeak [W] increased in T4, T5 and T6 (353 ± 78.45; 350.14 ± 87.96; 360.23 ± 93.83; respectively) compared to T1 (324.14 ± 90.24), and PVT2 [W] increased in T3, T4, T5 and T6 (265.57 ± 80.66; 267.29 ± 63.74; 266.43 ± 69.29; 276.71 ± 78.99; respectively) compared to T1 (229.29 ± 62.91). Cyclists’ sports performance improved during the experiment, and one of them won bronze medal at the World Championships. Conclusions. During the biseasonal experiment using elements of the polarized training programme, improvements in VO2max, Ppeak and PVT2 were observed in cyclists, which was accompanied by better sports performance in cycling races.

Restricted nasal-only breathing during self-selected low intensity training does not affect training intensity distribution.

Introduction: Low-intensity endurance training is frequently performed at gradually higher training intensities than intended, resulting in a shift towards threshold training. By restricting oral breathing and only allowing for nasal breathing this shift might be reduced. Methods: Nineteen physically healthy adults (3 females, age: 26.5 ± 5.1years; height: 1.77 ± 0.08m; body mass: 77.3 ± 11.4kg; VO2peak: 53.4 ± 6.6mL·kg-1min-1) performed 60min of self-selected, similar (144.7 ± 56.3 vs. 147.0 ± 54.2 W, p = 0.60) low-intensity cycling with breathing restriction (nasal-only breathing) and without restrictions (oro-nasal breathing). During these sessions heart rate, respiratory gas exchange data and power output data were recorded continuously. Results: Total ventilation (p < 0.001, ηp 2 = 0.45), carbon dioxide release (p = 0.02, ηp 2 = 0.28), oxygen uptake (p = 0.03, ηp 2 = 0.23), and breathing frequency (p = 0.01, ηp 2 = 0.35) were lower during nasal-only breathing. Furthermore, lower capillary blood lactate concentrations were found towards the end of the training session during nasal-only breathing (time x condition-interaction effect: p = 0.02, ηp 2 = 0.17). Even though discomfort was rated marginally higher during nasal-only breathing (p = 0.03, ηp 2 = 0.24), ratings of perceived effort did not differ between the two conditions (p ≥ 0.06, ηp 2 = 0.01). No significant "condition" differences were found for intensity distribution (time spent in training zone quantified by power output and heart rate) (p ≥ 0.24, ηp 2 ≤ 0.07). Conclusion: Nasal-only breathing seems to be associated with possible physiological changes that may help to maintain physical health in endurance athletes during low intensity endurance training. However, it did not prevent participants from performing low-intensity training at higher intensities than intended. Longitudinal studies are warranted to evaluate longitudinal responses of changes in breathing patterns.

Durability is improved by both low and high intensity endurance training.

Introduction: This is one of the first intervention studies to examine how low- (LIT) and high-intensity endurance training (HIT) affect durability, defined as 'time of onset and magnitude of deterioration in physiological-profiling characteristics over time during prolonged exercise'. Methods: Sedentary and recreationally active men (n = 16) and women (n = 19) completed either LIT (average weekly training time 6.8 0.7h) or HIT (1.6 0.2h) cycling for 10 weeks. Durability was analyzed before and after the training period from three factors during 3-h cycling at 48% of pretraining maximal oxygen uptake (VO2max): 1) by the magnitude and 2) onset of drifts (i.e. gradual change in energy expenditure, heart rate, rate of perceived exertion, ventilation, left ventricular ejection time, and stroke volume), 3) by the 'physiological strain', defined to be the absolute responses of heart rate and its variability, lactate, and rate of perceived exertion. Results: When all three factors were averaged the durability was improved similarly (time x group p = 0.42) in both groups (LIT: p = 0.03, g = 0.49; HIT: p = 0.01, g = 0.62). In the LIT group, magnitude of average of drifts and their onset did not reach statistically significance level of p < 0.05 (magnitude: 7.7 6.8% vs. 6.3 6.0%, p = 0.09, g = 0.27; onset: 106 57min vs. 131 59 min, p = 0.08, g = 0.58), while averaged physiological strain improved (p = 0.01, g = 0.60). In HIT, both magnitude and onset decreased (magnitude: 8.8 7.9% vs. 5.4 6.7%, p = 0.03, g = 0.49; onset: 108 54min vs. 137 57 min, p = 0.03, g = 0.61), and physiological strain improved (p = 0.005, g = 0.78). VO2max increased only after HIT (time x group p < 0.001, g = 1.51). Conclusion: Durability improved similarly by both LIT and HIT based on reduced physiological drifts, their postponed onsets, and changes in physiological strain. Despite durability enhanced among untrained people, a 10-week intervention did not alter drifts and their onsets in a large amount, even though it attenuated physiological strain.

Uphill versus downhill high-intensity training effectiveness in preserving vascular function and exercise performance in runners who reduce their regular endurance training.

The COVID-19 restrictions have limited outdoor physical activities. High-intensity training (HIT) may be a valid indoor alternative. We tested whether an indoor HIT is effective in maintaining vascular function and exercise performance in runners who reduce their usual endurance training, and whether a downhill HIT is as effective as an uphill one for such purposes. Sixteen runners performed the same 6-week HIT either uphill (UP, eight runners) or downhill (DOWN, eight runners). Eight runners continuing their usual endurance training acted as a control group (CON). The following data were collected before vs after our HIT: vascular conductance during rapid leg vasodilation to assess vasodilation capacity; V̇O2max through running incremental test to exhaustion; 2000m running time; neuromuscular indexes related to lower-limb muscle strength. Both uphill and downhill HIT failed in maintaining the pre-HIT leg vasodilation capacity compared to CON, which was, however, blunted more after uphill than downhill HIT. V̇O2max and 2000m time were similar after downhill HIT compared to CON, and augmented after uphill HIT compared to CON and DOWN. Indexes of lower-limb muscle strength were similar before vs after HIT and among groups. Our HIT was ineffective in maintaining the pre-HIT leg vasodilation capacity compared to runners continuing their usual low-intensity endurance training, but did not lead to reductions in V̇O2max, 2000m time performance, and indexes related to lower-limb muscle strength. Our data show an appealing potential for preserving exercise performance with low cardiorespiratory effort via downhill running.

The weight-lowering effect of low-intensity endurance training targeted at the level of maximal lipid oxidation (LIPOX max) lasts for more than 8 years, and is associated with improvements in body composition and blood pressure

The weight-lowering effect of low-intensity endurance training targeted at the level of maximal lipid oxidation (LIPOX max) lasts for more than 8 years, and is associated with improvements in body composition and blood pressure

Effect of Training Intensity on HIF-1a Gene Expression and Cardiac TG Content in Rats with Non-Alcoholic Fatty Liver Disease

Introduction: HIF-1a is an important regulator in response to hypoxia that affects various genes involved in energy metabolism. The aim of this study was to investigate the effect of exercise intensity on HIF-1a gene expression and cardiac TG content in rats with non-alcoholic fatty liver disease.&#x0D; Methods: The present study was performed experimentally on 40 male Wistar rats. Mice were randomly divided into 4 groups. The control groups, low-intensity endurance training and intense interval training, consumed high-fat food for 16 weeks, and then the two training groups participated in exercise for 8 weeks. Furthermore, sham group, which used standard food during this period, at the end of training, the expression level of HIF-1a and the amount of intra-tissue fat of the heart were measured in 4 groups. HIF-1a expression was assessed using real-time PCR and TG assay on an auto-analyzer. SPSS software version 16 and analysis of variance were used to analyze the data.&#x0D; Results: The results showed that there was a significant difference in the expression of HIF-1a gene between the control and the sham groups, HIIT and LIET groups (P=0.001). Moreover, there was a significant difference in triglyceride between HIIT and LIET groups compared to the sham and control groups, but no significant difference was observed between HIIT and LIET groups (P=0.0001).&#x0D; Conclusion: The results showed that intense intermittent exercise and low-intensity continuous exercise may reduce cardiac triglyceride content by decreasing HIF-1a expression and increasing fatty acid oxidation.

Physiological, Perceptual, and Performance Responses to the 2-Week Block of High- versus Low-Intensity Endurance Training.

This study examined the physiological, perceptual, and performance responses to a 2-wk block of increased training load and compared whether responses differ between high-intensity interval (HIIT) and low-intensity training (LIT). Thirty recreationally trained males and females performed a 2-wk block of 10 HIIT sessions (INT, n = 15) or 70% increased volume of LIT (VOL, n = 15). Running time in the 3000 m and basal serum and urine hormone concentrations were measured before (T1) and after the block (T2), and after a recovery week (T3). In addition, weekly averages of nocturnal heart rate variability (HRV) and perceived recovery were compared with the baseline. Both groups improved their running time in the 3000 m from T1 to T2 (INT = -1.8% ± 1.6%, P = 0.003; VOL = -1.4% ± 1.7%, P = 0.017) and from T1 to T3 (INT = -2.5% ± 1.6%, P < 0.001; VOL = -2.2% ± 1.9%, P = 0.001). Resting norepinephrine concentration increased in INT from T1 to T2 (P = 0.01) and remained elevated at T3 (P = 0.018). The change in HRV from the baseline was different between the groups during the first week (INT = -1.0% ± 2.0% vs VOL = 1.8% ± 3.2%, P = 0.008). Muscle soreness increased only in INT (P < 0.001), and the change was different compared with VOL across the block and recovery weeks (P < 0.05). HIIT and LIT blocks increased endurance performance in a short period. Although both protocols seemed to be tolerable for recreational athletes, a HIIT block may induce some negative responses such as increased muscle soreness and decreased parasympathetic activity.

Resistance Training Affects Neuromuscular Fatigue But Not Efficiency in Elite Rowers.

To investigate how resistance training (RT) in a regular training program affects neuromuscular fatigue (NMF) and gross efficiency (EGROSS) in elite rowers. Twenty-six elite male rowers performed 4 RTsessions within 10 days. At baseline and after the first and fourth RT, EGROSS and NMF were established. From breathing gas, EGROSS was determined during submaximal rowing tests. Using a countermovement jump test, NMF was assessed by jump height, flight time, flight-to-contraction-time ratio, peak power, and time to peak power. Muscle soreness was assessed using a 10-cm-long visual analog scale. No significant differences were found for EGROSS (P = .565, ω2 = .032). Muscle soreness (P = .00, ω2 = .500) and time to peak power (P = .08, ω2 = 0.238) were higher compared with baseline at all test moments. Flight-to-contraction-time ratio, jump height, and peak power after the fourth RT differed from baseline (P < .05, ω2 = .36, ω2 = .38, and ω2 = .31) and from results obtained after the first RT (P < .05, ω2 = .36, ω2 = .47, and ω2 = .22). RT in general does not influence EGROSS, but large individual differences (4.1%-14.8%) were observed. NMF is affected by RT, particularly after multiple sessions. During periods of intensified RT, imposed external load for low-intensity endurance training need not be altered, but rowers are recommended to abstain from intensive endurance training. Individual monitoring is strongly recommended.

Effect of Pre-conditioning of Endurance Training with Different Intensities on Soleus Muscle Atrophy in a Period of Inactivity: The Role of PGC-1α4 Gene

Background: This study aimed to measure PGC-1α4 soleus muscle and to investigate the effect of endurance training pre-conditioning with different intensities on the atrophy response of the soleus muscle to a period of inactivity. Methods: In this experimental study, 24 male Wistar rats were randomly divided into equal groups of control (C), control inactivity (CI), high-intensity endurance training group (HE) (treadmill speed 30 km/h), and low-intensity endurance training (LE) (treadmill’s speed: 10 km/h). After two weeks of familiarization, the endurance training group ran on a treadmill for two weeks (five sessions each week). The animal’s lower limbs were then immobilized for seven days. Then the soleus muscle was extracted, and after weighting, the expression of the PGC-1α4 gene was measured using the real-time polymerase chain reaction (realtime PCR) technique. Data were analyzed using SPSS software, version 24. Results: The expression of the PGC-1α4 gene was significantly higher in the HE group than the CI group. However, compared to the C group, all groups with inactivity intervention showed significantly lower PGC-1α4 gene levels. The ratio of muscle mass to body weight in the C group was significantly higher than the LE and CI groups, and higher in the HE group than the CI group. Conclusion: Endurance training seems to be able to reduce the destructive effects of inactive atrophy. The higher intensity of these exercises was more effective, which was associated with increased expression of the PGC-1α4 gene.

Effects of Wearing the Elevation Training Mask During Low-intensity Cycling Exercise on Intraocular Pressure.

Low-intensity aerobic exercise is recommended to reduce intraocular pressure (IOP) levels. However, this effect depends on several factors. We found that using an elevation training mask (ETM) during low-intensity aerobic exercise causes an IOP rise. The aim was to assess the influence of wearing an ETM on IOP during low-intensity endurance training. Sixteen physically active young adults (age=23.9±2.9 y) cycled during 30 minutes at 10% of maximal power production with and without an ETM in 2 different days and randomized order. A rebound tonometer was used to measure IOP at baseline, after a warm-up of 5 minutes, during cycling (6, 12, 18, 24, and 30 min), and recovery (5 and 10 min) by rebound tonometry. The use of an ETM significantly affects the IOP behaviour during exercise (P<0.001, ηp²=0.66). In the ETM condition, there was an IOP increment during exercise (P<0.001, ηp²=0.28) whereas an IOP-lowering effect was observed in the control condition (P<0.001, ηp²=0.41). Post hoc comparisons showed that there were greater IOP values during exercise in the ETM condition in comparison to the control condition (average IOP difference=3.7±2.2 mm Hg; corrected P<0.01, and the Cohen d's >1.10, in all cases). Low-intensity endurance exercise causes an increment in IOP when it is performed wearing an ETM and a decrease in IOP when the air flow is not restricted (control condition). Therefore, the ETM should be discouraged during low-intensity endurance exercise for individuals who need to reduce IOP levels (eg, glaucoma patients or those at risk). However, the external validity of these results needs to be addressed in future studies with the inclusion of glaucoma patients.

Effect of Low-Intensity Endurance Training and High-Intensity Interval Training on Sperm Quality in Male Rats with Fatty Liver.

BackgroundWe aimed to investigate the effect of low-intensity endurance training (LIET) and high-intensity inter- val training (HIIT) on sperm parameters, chromatin status, and oxidative stress in a rat model of non-alcoholic fatty liver disease (NAFLD).Materials and MethodsFor this experimental study, we divided 40 male Wistar rats into four groups (control, sham, HIIT and LIET) according to diet treatment and exercise training protocol. Liver triglycerides, sperm parameters, sperm lipid peroxidation (BODIPY C11 probe) and chromatin status [chromomycin A3 (CMA3)], and acridine orange [AO] staining) were assessed in these groups at the end of the study.ResultsThe mean liver triglyceride values significantly improved in both the LIET and HIIT groups compared to the control and sham groups. The mean of testicular volume, sperm concentration, motility, intensity of sperm lipid peroxidation and DNA damage were similar within groups. While, the mean percentage of sperm lipid peroxidation and protamine deficiency were significantly higher in the LIET and HIIT groups compared to the control group.ConclusionBoth LIET and HIIT in the rat NAFLD model had no adverse effects on testicular morphometric param- eters, sperm concentration, motility, and DNA integrity. However, the mean sperm lipid peroxidation and protamine deficiency were significantly higher in both exercise groups. Our study suggests that exercise or antioxidant supple- mentation could minimise the adverse effects of oxidant by-products of exercise.

The weight-lowering effect of low intensity endurance training targeted on the level of maximal lipid oxidation (LIPOX MAX) persists over more than 6 years and is associated with improvements in body composition and lipid oxidation

Rationale: Among varieties of training that have been proposed in obesity, endurance targeted at low to moderate intensity on the level of maximal lipid oxidation (LIPOX max) has been shown to decrease body fat stores and to improve fat and carbohydrate metabolism, blood pressure and eating behavior [1]. Our aims in this study was to investigate the effect of this type of exercise on body composition and lipid oxidation over 6 years.

Interval Training Is Not Superior to Endurance Training With Respect to Bone Accrual of Ovariectomized Mice.

Physical exercise is considered to delay bone loss associated with post-menopausal estrogen deficiency in women. However, the optimal training regimen for maximal bone accrual has not yet been defined. We, therefore, turned to ovariectomized (OVX) C57BL/6 mice and directly compared a low intensity endurance training on the treadmill to medium and high intensity interval trainings tailored to the individual performance limits. Trainings lasted 30 min each and were performed five times/week. After a 5-week training period, mice were sacrificed, and the hind legs were analyzed for assessment of (i) biomechanical stability (three-point bending test), (ii) bone microarchitecture [micro-computed tomography (μCT)], (iii) mineral apposition rate (MAR; histomorphometry), and (iv) muscle volume (MRI). Increased running speeds and quadriceps femoris muscle volumes in trained mice confirmed positive impacts on the cardiopulmonary system and myoinduction; however, none of the treadmill training regimens prevented ovariectomy induced bone loss. Our results provide evidence that treadmill training impacts differentially on the various members of the musculoskeletal unit and call for further experiments investigating frequency and duration of training regimens.

The Annual Periodization of Training Volumes of International-Level Cross-Country Skiers and Biathletes.

To compare the training-volume (TrV) distribution of Russian international-level male biathletes, female biathletes, and cross-country skiers (XC) during an annual cycle. Day-to-day TrVs were recorded and averaged for a 5-year period for male biathletes (n = 6), female biathletes (n = 8), and XC (n = 14) with VO2max values of 77.7 (3.8), 64.6 (1.9), and 79.4 (3.5)mL·min-1·kg-1, respectively. The volumes of low- and moderate-intensity endurance training and all types of nonspecific endurance and strength training gradually decreased toward the competition period. However, the volumes and proportions of high-intensity endurance training and specific exercises (roller skiing, skiing, and shooting during high-intensity endurance training) increased by the time of the competition period. The total volume of training, volumes of low- and moderate-intensity endurance training, moderate- and high-load strength training (70%-95% 1RM), and power/speed loads did not increase gradually but reached their maximum immediately after a short stage of initial training. All teams employed the "pyramid" model of intensity distribution. Compared with the biathletes, XC demonstrated a larger (P < .01) annual volume of endurance training (~190h), low-intensity endurance training (~183h), and strength training (~818 sets). They also engaged in more upper-body and core-strength exercises (~769 sets), and they reached their maximum aerobic TrVs in June, while the biathletes reached theirs in July. In recent decades, the traditional model of periodization has been altered. The Russian XC and biathletes had significant differences in TrVs.

The Effect of Endurance Training Intensity on the Expression of Perlipin a Protein of Subcutaneous Adipose Tissue and Pancreatic B cells Function in Diabetic Rats

Objective: The aim of this study was to compare the three endurance training intensities on the expression of Perlipin A protein in subcutaneous adipose tissue and pancreatic B-cells function in male diabetic rats. Materials and Methods: In this study, 40 healthy male wistar rats were divided into five groups, including diabetic with low intensity endurance training, diabetic with moderate intensity endurance training, diabetic with high intensity endurance training, diabetic control and healthy control. After diabetic induction with streptozotocin, endurance training was performed with low intensity, moderate and severe for eight weeks, three sessions per week. The relative expression of Perilipin A was measured by western blot technique. Results: The results indicated a significant effect of endurance training with three intensities on serum levels of insulin and glucose and pancreatic B-cells function ( P -value: 0.001). Also the results showed that there was no significant difference between Perlipin A expression in healthy and diabetic control groups with endurance training groups (with low, moderate and high intensity) ( P -value: 0.07). Conclusion: However, Moderate and high intensity endurance training compared to low-intensity training can compensate for the loss caused by diabetes in the expression of the Perlipin A protein but the difference was not significant. It seems that more intensity endurance training lead to more increase in Perlipin A expression in diabetic rats.

Both high-intensity interval training and low-intensity endurance training decrease intrahepatic lipid deposits via alterations of the expression of HIF-1α, HIG2 in a murine model of non alcoholic fatty liver disease (NAFLD)

Non-alcoholic fatty liver disease (NAFLD) is known as a serious disease associated with malnutrition and overweight habits. The aim of this study was to investigate the effect of the eight-week high-intensity interval training (HIIT) and the low-intensity endurance training (ET) on the expression of HIF-1α, HIG2 and intrahepatic lipid content (IHL) in the rats suffering from non-alcoholic fatty liver disease (NAFLD). To this aim, forty Wistar rats were selected randomly and divided into four groups: NAFLD, NAFLD + HIIT (N + HIIT), NAFLD + ET (N + ET), and control groups. The protocol of the N + HIIT group consisted of high-intensity running separated with light running; the protocol of the N + ET group was matched with the whole ran distance of the N + HIIT group with a lower intensity. After eight weeks, a portion of the liver of each rat was excised and frozen in liquid nitrogen for assessment of HIF-1α, HIG2 mRNA levels, and IHL. The results showed that there was a significant difference between the groups in terms of the expression of HIF-1α (X 2 = 16.42, P = 0.001), HIG2 (X 2 = 12.43, P = 0.006) and IHL content (X 2 = 32.84, P = 0.001). Moreover, HIF-1α and HIG2 mRNA levels were found to be decreased in N + HIIT vs. NAFLD ( P = 0.024 and P = 0.031) and N + ET vs. NAFLD ( P = 0.012 and P = 0.012), respectively. There was no significant difference in the expression of HIF-1α and HIG2 between N + HIIT and N + ET groups ( P = 0.895 and P = 0.453). There were also significant differences in terms of IHL between NAFLD and N + HIIT groups ( P = 0.001), and between NAFLD and N + ET groups ( P = 0.001). A significant difference was also observed in the IHL content between N + HIIT and N + ET groups ( P = 0.003). Overall, it could be concluded that both N + HIIT and N + ET protocols reduced the content of liver fat, thereby decreasing fatty liver disease by reducing the expression of HIF-1α and HIG2 genes. It seems that the decrease of hypoxia and lipid droplet-associated with proteins in hepatocytes could lead to the improvement of fatty liver disease. La stéatose hépatique non alcoolique (SHNA)/(NAFLD) est connue comme une maladie grave associée à la malnutrition et aux habitudes de surpoids. Le but de cette étude était d’étudier l’effet de l’entraînement par intervalles de huit semaines à haute intensité (EIHI)/(HIIT) et l’entraînement à faible intensité en endurance (EE)/(ET) sur l’expression de HIF-lα, HIG2 et teneur en lipides intrahépatiques (TLI)/(IHL) chez les rats souffrant de stéatose hépatique non alcoolique (SHNA)/(NAFLD). Dans ce but, quarante rats Wistar ont été sélectionnés au hasard et divisés en quatre groupes: NAFLD, NAFLD + HIIT (N + HIIT), NAFLD + ET (N + ET) et groupes témoins. Le protocole du groupe N + HIIT consistait en une course à haute intensité séparée avec une course légère, le protocole du groupe N + ET était apparié avec la distance parcourue totale du groupe N + HIIT avec une intensité plus faible. Après 8 semaines, une partie du foie de chaque rat a été excisée et congelée dans de l’azote liquide pour l’évaluation du HIF-1α, des niveaux d’ARNm de HIG2 et du IHL. Les résultats ont montré qu’il y avait une différence significative entre les groupes en termes d’expression de HIF-lα (X 2 = 16,42, p = 0,001), HIG2 (X 2 = 12,43, p = 0,006) et contenu en IHL (X 2 = 32,84, p = 0,001). De plus, les niveaux de HIF-lα et de HIG2 mRNA ont diminué respectivement dans N + HIIT vs NAFLD ( p = 0,024 et p = 0,031) et N + ET vs NAFLD ( p = 0,012 et p = 0,012) respectivement. Il n’y avait pas de différence significative dans l’expression de HIF-lα et HIG2 entre les groupes N + HIIT et N + ET ( p = 0,895 et p = 0,453). Il y avait également des différences significatives en termes de IHL entre les groupes NAFLD et N + HIIT ( p = 0,001), et entre les groupes NAFLD et N + ET ( p = 0,001). Une différence significative a également été observée dans la teneur en DIH entre les groupes N + HIIT et N + ET ( p = 0,003). Dans l’ensemble, on a pu conclure que les protocoles N + HIIT et N + ET ont réduit la teneur en graisse hépatique, diminuant ainsi la stéatose hépatique en réduisant l’expression des gènes HIF-lα et HIG2. Il semble que la diminution de l’hypoxie et des protems associés aux gouttelettes lipidiques dans les hépatocytes pourrait entraîner une amélioration de la stéatose hépatique.

LOW-INTENSITY ENDURANCE TRAINING AND RIGHT VENTRICULAR MYOCYTES OF HYPERTENSIVE RATS

ABSTRACT Introduction The structural and mechanical adaptations of the right ventricular (RV) myocytes in response to hypertension associated with low-intensity endurance training (LIET) have not been studied in experimental models. Objective To determine the effects of LIET on the structural and mechanical properties of RV myocytes in spontaneously hypertensive rats (SHRs). Methods Male SHRs and normotensive Wistar rats (age: 16 weeks) were allocated to groups (n=7): WIS (Wistar Controls); SHR-C (SHR Controls) and SHR-T (SHR Trained; 60 min/day, 50-60% of maximal exercise capacity, 5 days/week for 8 weeks). Systolic arterial pressure (SAP), isolated RV myocyte dimensions, contractility, intracellular Ca2+ transient ([Ca2+]i), and ventricular Ca2+ regulatory proteins were measured. The statistical analysis was performed by one-way ANOVA followed by the Tukey post hoc test (α=5%). Results LIET reduced the SAP in SHR animals (SHR-C, 164 ± 2 mmHg vs. SHR-T, 152 ± 4 mmHg; P&lt;0.05). Hypertension increased cell length (WIS, 156.8 ± 2.7 µm; SHR-C, 166.6 ± 3.1 µm; P&lt;0.05) but did not affect cell width or volume (P&gt;0.05). LIET did not change the cell dimensions in the SHR-T. Neither hypertension nor LIET affected myocyte contractility or the expression of Ca2+ regulatory proteins in the RV of the SHR-C and SHR-T groups. Hypertension did not affect the amplitude of the [Ca2+]i transient or the time to half resting level (P&gt;0.05), but increased the time to peak (WIS, 58 ± 1 ms vs. SHR-C, 79 ± 2 ms; P&lt;0.05). LIET increased the amplitude of the [Ca2+]i transient (WIS, 2.28 ± 0.07 F/F0 and SHR-C, 2.48 ± 0.08 F/F0 vs. SHR-T, 2.87 ± 0.08 F/F0 P&lt;0.05), but did not alter the times to peak or to half resting level. Conclusion LIET had no effect on the structural and mechanical properties of RV myocytes in the SHRs, although it increased the amplitude of the [Ca2+]i transient and reduced the SAP. Level of evidence I, Therapeutic Studies - Investigating the Results of Treatment.

Augmented Anabolic Responses after 8-wk Cycling with Blood Flow Restriction.

Low-intensity endurance training (ET) performed with blood flow restriction (BFR) can improve muscle strength, cross-sectional area (CSA) and cardiorespiratory capacity. Whether muscle strength and CSA as well as cardiorespiratory capacity (i.e., V˙O2max) and underlying molecular processes regulating such respective muscle adaptations are comparable to resistance and ET is unknown. To determine the respective chronic (i.e., 8 wk) functional, morphological, and molecular responses of ET-BFR training compared with conventional, unrestricted resistance training (RT) and ET. Thirty healthy young men were randomly assigned to one of three experimental groups: ET-BFR (n = 10, 4 d·wk, 30-min cycling at 40% of V˙O2max), RT (n = 10, 4 d·wk, 4 sets of 10 repetitions leg press at 70% of one repetition maximum with 60 s rest) or ET (n = 10, 4 d·wk, 30-min cycling at 70% of V˙O2max) for 8 wk. Measures of quadriceps CSA, leg press one repetition maximum, and V˙O2max as well as muscle biopsies were obtained before and after intervention. Both RT and ET-BFR increased muscle strength and hypertrophy responses. ET-BFR also increased V˙O2max, total cytochrome c oxidase subunit 4 isoform 1 abundance and vascular endothelial growth factor mRNA abundance despite the lower work load compared to ET. Eight weeks of ET-BFR can increase muscle strength and induce similar muscle hypertrophy responses to RT while V˙O2max responses also increased postintervention even with a significantly lower work load compared with ET. Our findings provide new insight to some of the molecular mechanisms mediating adaptation responses with ET-BFR and the potential for this training protocol to improve muscle and cardiorespiratory capacity.

【論文摘要】The Effect of Low Intensity Endurance Training on Lung Cancer Combine Dermatomyositis-A Case Report

【論文摘要】The Effect of Low Intensity Endurance Training on Lung Cancer Combine Dermatomyositis-A Case Report