Dynamic, Not Isometric Resistance Training Improves Muscle Inflammation, Oxidative Stress and Hypertrophy in Rats

Renoprotection Induced by Aerobic Training Is Dependent on Nitric Oxide Bioavailability in Obese Zucker Rats

Aerobic training (AT) promotes several health benefits that may attenuate the progression of obesity associated diabetes. Since AT is an important nitric oxide (NO⁻) inducer mediating kidney-healthy phenotype, the present study is aimed at investigating the effects of AT on metabolic parameters, morphological, redox balance, inflammatory profile, and vasoactive peptides in the kidney of obese-diabetic Zucker rats receiving L-NAME (N(omega)-nitro-L-arginine methyl ester). Forty male Zucker rats (6 wk old) were assigned into four groups (n = 10, each): sedentary lean rats (CTL-Lean), sedentary obese rats (CTL-Obese), AT trained obese rats without blocking nitric oxide synthase (NOS) (Obese+AT), and obese-trained with NOS block (Obese+AT+L-NAME). AT groups ran 60 min in the maximal lactate steady state (MLSS), five days/wk/8 wk. Obese+AT rats improved glycemic homeostasis, SBP, aerobic capacity, renal mitochondria integrity, redox balance, inflammatory profile (e.g., TNF-α, CRP, IL-10, IL-4, and IL-17a), and molecules related to renal NO⁻ metabolism (klotho/FGF23 axis, vasoactive peptides, renal histology, and reduced proteinuria). However, none of these positive outcomes were observed in CTL-Obese and Obese+AT+L-NAME (p < 0.0001) groups. Although Obese+AT+L-NAME lowered BP (compared with CTL-Obese; p < 0.0001), renal damage was observed after AT intervention. Furthermore, AT training under conditions of low NO⁻ concentration increased signaling pathways associated with ACE-2/ANG1-7/MASr. We conclude that AT represents an important nonpharmacological intervention to improve kidney function in obese Zucker rats. However, these renal and metabolic benefits promoted by AT are dependent on NO⁻ bioavailability and its underlying regulatory mechanisms.

Influence of Angiotensin Converting Enzyme I/D Polymorphism on Hemodynamic and Antioxidant Response to Long-Term Intradialytic Resistance Training in Patients With Chronic Kidney Disease: A Randomized Controlled Trial

ABSTRACT

Corrêa, HdL, Deus, LA, Neves, RVP, Reis, AL, de Freitas, GS, de Araújo, TB, da Silva Barbosa, JM, Prestes, J, Simões, HG, Amorim, CE, dos Santos, MAP, Haro, A, de Melo, GF, Gadelha, AB, Neto, LS, and Rosa, TdS. Influence of angiotensin converting enzyme I/D polymorphism on hemodynamic and antioxidant response to long-term intradialytic resistance training in patients with chronic kidney disease: a randomized controlled trial. J Strength Cond Res 35(10): 2902-2909, 2021-The aim of the study was to verify the influence of Angiotensin-converting enzyme (ACE) I/D genotype on blood pressure, muscle mass, and redox balance response to long-term resistance training (RT) in end-stage renal disease patients. Three hundred and twenty subjects were randomized into 4 groups: II + ID control (II + ID CTL, n = 80), II + ID RT (II + ID RT, n = 79), DD control (DD CTL n = 83), and DD RT (DD RT, n = 78). The RT lasted 24 weeks with a frequency of 3 times per week, on alternative days. Each section consisted of 3 sets of 8-12 repetitions in 11 exercises, with training loads at 6 point (somewhat hard) to 8 point (hard) based on OMNI-RES scale and was prescribed during dialysis (intradialytic). Statistical significance was accepted with p < 0.05. The most relevant benefits in blood pressure were found for DD homozygotes (p < 0.0001), whereas allele I carriers displayed a higher increase in muscle mass (p < 0.0001). Hemodialysis clinics that already use RT for their patients could include the genotyping of ACE to identify the predisposal of the patients to respond to RT and to counteract kidney disease-related comorbidities.

Strength training improves insulin resistance and differently affects mitochondria in skeletal muscle and visceral adipose tissue in high-fat fed mice

AIMS

Strength training (ST) improves insulin resistance and glucose tolerance by yet unknown mechanisms. The aims of this study were to investigate the effects of ST on mitochondrial adaptation in skeletal muscle and adipose tissue, on heat shock protein 72 (Hsp72) in skeletal muscle, and on visceral adipocyte size in mice with high-fat diet (HFD)-induced insulin resistance.

MATERIALS AND METHODS

Male Balb/c mice were divided into sedentary control-chow (C-chow), strength trained-chow (ST-chow), sedentary control-HFD (C-HFD) and strength trained-HFD (ST-HFD). Diet was provided for 12 weeks, while ladder climbing ST was performed for the final six weeks of the study at a frequency of three days per week.

KEY FINDINGS

Strength training led to increased strength, muscular endurance, and skeletal muscle hypertrophy. Compared to the C-HFD group, mice in the ST-HFD group decreased their whole-body insulin resistance, improved their glucose tolerance, and had higher activation of the insulin pathway in skeletal muscle. ST increased citrate synthase (CS) activity in skeletal muscle, but this increase was blunted in ST-HFD. Conversely, HFD reduced adipose tissue CS activity regardless of training status. Hsp72 content was reduced in C-HFD, but returned to control levels in ST-HFD. Finally, reduced epididymal adipocyte size was observed in ST-HFD.

SIGNIFICANCE

These results suggest that the improvement in insulin resistance induced by ST is related to mitochondrial adaptation in skeletal muscle, but not in adipose tissue. Moreover, this improvement might be related to increased skeletal muscle Hsp72 and reduced epididymal adipocyte size.

Effects of dynamic and isometric resistance training protocols on metabolic profile in hemodialysis patients: a randomized controlled trial

The aim of this study was to compare the effect of dynamic (DRT) and isometric (IRT) resistance training on glycemic homeostasis, lipid profile, and nitric oxide (NO) in hemodialysis (HD) patients. Patients were randomly distributed into 3 groups: control (n = 65), DRT (n = 65), and IRT (n = 67). Patients assessed before and after the intervention period were tested for fasting blood glucose, glycated hemoglobin, oral glucose tolerance test, insulin resistance, lipid profile, leptin, insulin, adiponectin, C-reactive protein, and NO . Patients underwent to strength and body composition assessments. Subjects allocated in both DRT and IRT groups took part in a 24-week resistance training program, 3 times per week. Each training session was approximately 1 hour before dialysis and consisted of 3 sets of 8-12 repetitions at low intensity. Total workload was higher in the DRT as compared with the IRT. This heightened workload related to better glycemic homeostasis in HD patients as measured by regulation of insulin, adiponectin, and leptin, while improveing triglycerides, free-fat mass, and muscle strength. Additionally, NO levels were increased in the DRT group. NO was significantly correlated with glucose intolerance (r = -0.42, p = 0.0155) and workload (r = 0.46, p = 0.0022). The IRT group only improved strength (p < 0.05). Twenty-four weeks of DRT improved glycemic homeostasis, lipid profile, and NO in HD patients. Although IRT seems to play an important role in increasing strength, DRT might be a better choice to promote metabolic adjustments in HD patients. Clinical trial: http://www.ensaiosclinicos.gov.br/rg/RBR-3gpg5w. Novelty: DRT might be a better choice for metabolic improvements in patients with chronic kidney disease (CKD). Exercise-training might treat metabolic imbalance in CKD patients.

Biomarkers and Redox Balance in Aging Rats after Dynamic and Isometric Resistance Training

Aging muscle is prone to sarcopenia and its associated telomere shortening and increased oxidative stress. Telomeres are protected by a shelterin protein complex, proteins expressed in response to DNA damage. Aerobic exercise training has shown to positively modulate these proteins while aging, but the effects of resistance training are less clear. This investigation was to examine the role of dynamic and isometric RT on markers of senescence and muscle apoptosis: checkpoint kinase 2, 53 kDa protein, shelterin telomere repeat binding 1 and 2, DNA repair, telomere length and redox state in the quadriceps muscle. Fifteen 49-week-old male rats were divided into three groups: control, dynamic resistance training, and isometric resistance training. Dynamic and isometric groups completed five sessions per week during 16 weeks at low to moderate intensity (20-70% maximal load). Only dynamic group decreased expression of 53 kDa protein, proteins from shelterin complex, oxidative stress, and improved antioxidant defense. There was no difference among groups regarding telomere length. In conclusion, dynamic resistance training was more effective than isometric in reducing markers of aging and muscle apoptosis in elderly rats. This modality should be considered as valuable tool do counteract the deleterious effects of aging.

Strength Training Reduces Cardiac and Renal Oxidative Stress in Rats with Renovascular Hypertension

Fundamento

O treino de força tem efeitos benéficos em doenças renais, além de ajudar a melhorar a defesa antioxidante em animais saudáveis.

Objetivo

Verificar se o treino de força reduz o dano oxidativo ao coração e rim contralateral para cirurgia de indução de hipertensão renovascular, bem como avaliar as alterações na atividade das enzimas antioxidantes endógenas superóxido dismutase (SOD), catalase (CAT) e glutationa peroxidase (GPx).

Métodos

Dezoito ratos machos foram divididos em três grupos (n=6/grupo): placebo, hipertenso e hipertenso treinado. Os animais foram induzidos a hipertensão renovascular através da ligação da artéria renal esquerda. O treino de força foi iniciado quatro semanas após a indução da hipertensão renovascular, teve 12 semanas de duração e foi realizada a 70% de 1RM. Depois do período de treino, os animais foram submetidos a eutanásia e o rim esquerdo e o coração foram retirados para realizar a quantificação de peróxidos de hidrogênio, malondialdeído e grupos sulfidrílicos, que são marcadores de danos oxidativos. Além disso, foram medidas as atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase. O nível de significância adotado foi de 5% (p < 0,05).

Resultados

Depois do treino de força, houve redução de danos oxidativos a lipídios e proteínas, como pode-se observar pela redução de peróxidos de hidrogênio e níveis sulfidrílicos totais, respectivamente. Além disso, houve um aumento nas atividades das enzimas antioxidantes superóxido dismutase, catalase e glutationa peroxidase.

Conclusão

O treino de força tem o potencial de reduzir danos oxidativos, aumentando a atividades de enzimas antioxidantes. (Arq Bras Cardiol. 2021; 116(1):4-11)

Isometric blood flow restriction exercise: acute physiological and neuromuscular responses

Background

Numerous studies have demonstrated that the addition of blood flow restriction (BFR) to low-load (LL) resistance exercise leads to elevated levels of muscle hypertrophy and strength gains. In terms of main underlying mechanisms, metabolic accumulation and increased neuromuscular adaptations seem to play a primary role. However, this evidence is largely based on dynamic exercise conditions. Therefore, the main objective was to investigate the acute physiological adaptations following isometric LL-BFR exercise.

Methods

Fifteen males participated in this cross-over trial and completed the following sessions in a random and counterbalanced order: isometric LL-BFR exercise (20% maximum voluntary contraction, MVC) and load matched LL exercise without BFR. Lactate levels, muscle activation as well as muscle swelling were recorded during the whole exercise and until 15 min post completion. Additionally, changes in maximal voluntary torque and ratings of perceived exertion (RPE) were monitored.

Results

During exercise, EMG amplitudes (72.5 ± 12.7% vs. 46.3 ± 6.7% of maximal EMG activity), muscle swelling and RPE were significantly higher during LL-BFR compared to LL (p < 0.05). Lactate levels did not show significant group differences during exercise but revealed higher increases 15 min after completion in the LL-BFR condition (LL-BFR: + 69%, LL: + 22%) (p < 0.05). Additionally, MVC torque significantly decreased immediately post exercise only in LL-BFR (~ − 11%) (p < 0.05) but recovered after 15 min.

Conclusions

The present results demonstrate that isometric LL-BFR causes increased metabolic, neuromuscular as well as perceptual responses compared to LL alone. These adaptations are similar to dynamic exercise and therefore LL-BFR represents a valuable type of exercise where large joint movements are contraindicated (e.g. rehabilitation after orthopedic injuries).

Muscle hypertrophy and ladder-based resistance training for rodents: A systematic review and meta-analysis

This study aimed to review the effects of ladder-based resistance training (LRT) on muscle hypertrophy and strength in rodents through a systematic review with meta-analysis. We systematically searched PubMed/Medline, SportDiscuss, Scopus, Google Scholar, Science Direct, and Scielo database on May 18, 2020. Thirty-four studies were included measuring total (mCSA) or mean muscle fibers cross-sectional area (fCSA) or maximum load-carrying capacity (MLCC) or muscle mass (MM). About the main results, LRT provides sufficient mechanical stimulation to increase mCSA and fCSA. Meta-analysis showed a significant overall effect on the fCSA (SMD 1.89, 95% CI [1.18, 2.61], p < .00001, I2  = 85%); however, subgroup analysis showed that some muscle types might not be hypertrophied through the LRT. Meta-analysis showed a significant training effect on the MM (SMD 0.92, 95% CI [0.52, 1.32], p < .00001, I2  = 72%). Sub-group analysis revealed that soleus (SMD 1.32, 95% CI [0.11, 2.54], p = .03, I2  = 86%) and FHL (SMD 1.92, 95% CI [1.00, 2.85], p < .0001, I2  = 71%) presented significant training effects, despite moderate heterogeneity levels (I2  = 72%). MLCC increases considerably after a period of LRT, regardless of its duration and the characteristics of the protocols (SMD 12.37, 95% CI [9.36, 15.37], p < .00001, I2  = 90%). Through these results, we reach the following conclusions: (a) LRT is efficient to induce muscle hypertrophy, although this effect varies between different types of skeletal muscles, and; (b) the ability of rodents to carry load increases regardless of the type and duration of the protocol used.

Transcriptome profiling of muscle in Nelore cattle phenotypically divergent for the ribeye muscle area

This study aimed to use RNA-Seq to identify differentially expressed genes (DEGs) in muscle of uncastrated Nelore males phenotypically divergent for ribeye muscle area (REA). A total of 80 animals were phenotyped for REA, and 15 animals each with the highest REA and the lowest REA were selected for analyses. DEGs found (N = 288) belonging to families related to muscle cell growth, development, motility and proteolysis, such as actin, myosin, collagen, integrin, solute carrier, ubiquitin and kelch-like. Functional analysis showed that many of the significantly enriched gene ontology terms were closely associated with muscle development, growth, and degradation. Through co-expression network analysis, we predicted three hub genes (PPP3R1, FAM129B and UBE2G1), these genes are involved in muscle growth, proteolysis and immune system. The genes expression levels and its biological process found this study may result in differences in muscle deposition, and therefore, Nelore animals with different REA proportions.