Short-term Resistance Exercise Research Articles

The Effects of a Short-Term Combined Exercise Program on Liver Steatosis Indices and the Lipidemic and Glycemic Profile in NAFLD Individuals: A Pilot Study.

Non-alcoholic fatty liver disease (NAFLD) is a very common liver disease associated with obesity, unhealthy diet, and lack of physical exercise. Short-term aerobic or resistance exercise has been shown to result in reduced liver fat in patients with NAFLD; however, the impact of the combination of these types of exercise has received less attention. This study investigated the effect of a short-term (7 days) concurrent exercise training program performed daily on liver steatosis indices, as well as the glycemic and lipidemic profile of overweight/obese sedentary volunteers. Twenty adult patients (age: 47.3 ± 12.3 yrs, body mass index: 32.4 ± 3.4 kg/m2) with NAFLD, detected by ultrasound and hematological indices, participated in the study. Pre- and post-exercise intervention assessment included body weight (BW), waist circumference (WC), hip/waist ratio (H/W), Homeostasis Model Assessment Insulin Resistance (HOMA-IR), blood lipids, and steatosis indices. Fatty Liver Index, Lipid Accumulation Index, WC, H/W, triglycerides, and total cholesterol were improved (p < 0.05) post-exercise, while no differences (p > 0.05) were observed in BW, HOMA-IR, HDL, LDL, Hepatic Steatosis Index, and Framingham Steatosis Index compared to pre-exercise values. It is concluded that a 7-day combined exercise program can have beneficial effects on hepatic steatosis and central adiposity indices, independently of weight loss, in patients with NAFLD.

No effect of five days of bed rest or short-term resistance exercise prehabilitation on markers of skeletal muscle mitochondrial content and dynamics in older adults.

Bed rest (BR) results in significant impairments in skeletal muscle metabolism. Mitochondrial metabolism is reportedly highly sensitive to disuse, with dysregulated fission‐fusion events and impaired oxidative function previously reported. The effects of clinically relevant short‐term BR (≤5 days) on mitochondrial protein expression are presently unclear, as are the effects of exercise prehabilitation as a potential counteractive intervention. The present study examined the effects of a 5‐day period of BR and short‐term resistance exercise prehabilitation (ST‐REP) on mitochondrial‐protein content. Ten older men (71 ± 4 years) underwent 5 days of BR, completing four sessions of high‐volume unilateral resistance exercise prehabilitation over 7 days beforehand. Muscle biopsies were obtained from the vastus lateralis in the non‐exercised control and exercised legs, both pre‐ and post‐prehabilitation and pre‐ and post‐BR, to determine changes in citrate synthase enzyme activity and the expression of key proteins in the mitochondrial electron transport chain and molecular regulators of fission‐fusion dynamics, biosynthesis, and mitophagy. We observed no significant effect of either BR or ST‐REP on citrate synthase protein content, enzyme activity, or ETC complex I‐V protein content. Moreover, we observed no significant changes in markers of mitochondrial fission and fusion (p‐DRP1S616, p‐DRP1S637, p‐DRP1S616/S637 ratio, p‐MFFS146, Mitofillin, OPA1, or MFN2 (p > 0.05 for all). Finally, we observed no differences in markers of biosynthesis (p‐AMPKT172, p‐ACCS79, PGC1a, TFAM) or mitophagy‐related signaling (ULK‐1, BNIP3/NIX, LC3B I/II) (p > 0.05 for all). In contrast to previous longer‐term periods of musculoskeletal disuse (i.e., 7–14 days), a clinically relevant, 5‐day period of BR resulted in no significant perturbation in muscle mitochondrial protein signaling in healthy older adults, with no effect of ST‐REP in the week prior to BR. Accordingly, disuse‐induced muscle atrophy may precede alterations in mitochondrial content.

Obesity and exercise training alter inflammatory pathway skeletal muscle small extracellular vesicle microRNAs.

New Findings What is the central question of this study? Is 1 week of exercise training sufficient to reduce local and systemic inflammation?Do obesity and short‐term concurrent aerobic and resistance exercise training alter skeletal muscle extracellular vesicle (EV) contents? What is the main finding and its importance? Obesity alters skeletal muscle small EV microRNAs targeting inflammatory and growth pathways. Exercise training alters skeletal muscle small EV microRNAs targeting inflammatory pathways, indicative of reduced inflammation. Our findings provide support for the hypotheses that EVs play a vital role in intercellular communication during health and disease and that EVs mediate many of the beneficial effects of exercise. Obesity is associated with chronic inflammation characterized by increased levels of inflammatory cytokines, whereas exercise training reduces inflammation. Small extracellular vesicles (EVs; 30–150 nm) participate in cell‐to‐cell communication in part through microRNA (miRNA) post‐transcriptional regulation of mRNA. We examined whether obesity and concurrent aerobic and resistance exercise training alter skeletal muscle EV miRNA content and inflammatory signalling. Vastus lateralis biopsies were obtained from sedentary individuals with (OB) and without obesity (LN). Before and after 7 days of concurrent aerobic and resistance training, muscle‐derived small EV miRNAs and whole‐muscle mRNAs were measured. Pathway analysis revealed that obesity alters small EV miRNAs that target inflammatory (SERPINF1, death receptor and Gαi) and growth pathways (Wnt/β‐catenin, PTEN, PI3K/AKT and IGF‐1). In addition, exercise training alters small EV miRNAs in an anti‐inflammatory manner, targeting the IL‐10, IL‐8, Toll‐like receptor and nuclear factor‐κB signalling pathways. In whole muscle, IL‐8 mRNA was reduced by 50% and Jun mRNA by 25% after exercise training, consistent with the anti‐inflammatory effects of exercise on skeletal muscle. Obesity and 7 days of concurrent exercise training differentially alter skeletal muscle‐derived small EV miRNA contents targeting inflammatory and anabolic pathways.

Safety and efficacy of short-term structured resistance exercise in Gulf War Veterans with chronic unexplained muscle pain: A randomized controlled trial

AimsChronic widespread musculoskeletal pain (CMP) is a primary condition of Veterans suffering from Gulf War illness. This study evaluated the influence of resistance exercise training (RET) on symptoms, mood, perception of improvement, fitness, and total physical activity in Gulf War Veterans (GWV) with CMP. Main methodsFifty-four GWV with CMP were randomly assigned to 16 weeks of RET (n = 28) or wait-list control (n = 26). Supervised exercise was performed twice weekly starting at a low intensity. Outcomes, assessed at baseline, 6, 11 and 17 weeks and 6- and 12-months post-intervention, were: pain, fatigue, mood, sleep quality, perception of improvement, and physical activity via self-report and accelerometry. Muscular strength was assessed at baseline, 8 and 16 weeks. Accelerometer data yielded estimates of time spent in sedentary, light, and moderate-to-vigorous physical activities. Analyses used separate linear mixed models with group and time point as fixed effects. All models, except for perceived improvement, included baseline values as a covariate. Key findingsParticipants assigned to RET completed 87% of training sessions and exhibited strength increases between 16 and 34% for eight lifts tested (Hedges' g range: 0.47–0.78). The treatment by time interaction for perceived improvement (F1,163 = 16.94, p < 0.001) was characterized by greater perceived improvement since baseline for RET at each time point, until the 12-month follow-up. Effects were not significant for other outcomes (p > 0.05). RET caused no adverse events. SignificanceAfter 16 weeks of RET, GWV with CMP reported improvements in their condition and exhibited increases in muscular strength, without symptom exacerbation or reductions in total physical activity.

Effects of a Short-Term Resistance-Training Program on Heart Rate Variability in Children With Cystic Fibrosis-A Randomized Controlled Trial.

Background: Cystic fibrosis (CF) affects the autonomic nervous system (ANS) and exercise in healthy children modulates the interaction between sympathetic and parasympathetic activity. This study aimed to evaluate the effects of a short-term resistance exercise program on heart rate variability (HRV) in children and adolescents with CF.Methods: A randomized controlled trial was carried out in children diagnosed with CF aged 6–18 years. Individuals were divided into two groups: control (CON) and resistance-training (EX). Individuals in the EX group completed an individualized guided resistance program (5-RM—60–80%) for 8 weeks (3 sessions of 60 min/week). Upper and lower limbs exercises (seated bench press, seated lateral row, and leg press) were used. HRV was measured using a Suunto watch with subjects in lying position.Results: Nineteen subjects (13 boys) were included (CON = 11; and EX = 8). Mean age was 12.2 ± 3.3, FEV1 (forced expiratory volume in the first second) z-score was 1.72 ± 1.54 and peak oxygen consumption (VO2peak) 42.7 ± 7.4 mL.Kg–1.min–1. Exercise induced significant changes in the frequency-domain variables, including a decrease in LF power (p = 0.001, d = 0.98) and LF/HF ratio (p = 0.020, d = 0.92), and an increase in HF power (p = 0.001, d = −0.97), compared to the CON group. No significant changes were found for time-domain variables, although increases with a moderate effect size were seen for SDNN (p = 0.152, d = −0.41) and RMSSD (p = 0.059, d = −0.49) compared to the CON group.Conclusion: A short-term resistance exercise-training program was able to modulate HRV in children and adolescents with CF presenting mild to moderate lung function impairment and good physical condition.Clinical Trial Registration: www.ClinicalTrials.gov, identifier NCT04293926.

Effect of Short Term Resistance and Endurance Exercise Training on Resting Heart Rate and Inflammatory Marker in Young Adults: A Cross-sectional Study

Introduction: In a normal healthy adult, sympathetic and parasympathetic system should be in synergy. Measuring resting heart rate is a one of the methods to assess health condition. It can be affected by different factors such as exercise, mental health, any disease, etc. Normal subjects with reduced heart rate are associated with better cardiovascular health. Physical inactivity is associated with high level of inflammatory markers. Increased inflammatory markers are related to inflammation and chronic diseases. The C-Reactive Protein (CRP) is a biomarker of inflammatory diseases. High CRP level is a potent risk factor for obesity, diabetes, atherosclerosis, etc. Aim: To study the effect of short term resistance and endurance exercise training on resting heart rate in healthy young adults, CRP, Body Mass Index (BMI) and also to compare the changes between two exercise groups. Materials and Methods: A cross-sectional study was conducted from May 2019 to May 2020 in the Department of Physiology at King George’s Medical University, Lucknow, Uttar Pradesh, India. The study included 60 healthy young adults with normal BMI (18.5-24.9 kg/m2) and age between 18-25 years. Subjects were equally divided into Group I- Resistance exercise and Group II endurance groups. Subjects did moderate intensity exercise (based on maximum heart rate) for five days in a week for eight weeks. Endurance group did jogging. Resistance group did push-up, pull-up and squats. Target heart rate during moderate intensity of activities was 64-76% of maximum heart rate. Heart rate measurement was done before the start of exercise and after five to seven minutes of exercise when it reached 64-76% of maximum heart rate. It was measured by pulse oximeter. Follow-up was done after eight weeks of exercise training in both the groups. Evaluation was done by comparing resting heart rate and CRP level before the start of training and after the completion of training programme. Statistical analysis was done using student t-test and paired t-test. Results: Mean age of subjects of group I was found to be higher (19.98±1.26 years) as compared to group II (19.97±0.98 years). Mean pre intervention BMI of both the groups was found to be similar (21.97±1.78 kg/m2). No statistically significant change in resting heart rate was found in both resistance group (p=0.096) and endurance group (p=0.326) after exercise training. Statistically significant increase in CRP was found in resistance group (p&lt;0.001) and endurance group (p&lt;0.001). The increment in CRP was more in endurance group (55.04%) than resistance group (35.34%). Conclusion: Short duration of exercises increase inflammation but no significant effect on resting heart rate was seen.

The effect of short-term exercise prehabilitation on skeletal muscle protein synthesis and atrophy during bed rest in older men.

BackgroundPoor recovery from periods of disuse accelerates age‐related muscle loss, predisposing individuals to the development of secondary adverse health outcomes. Exercise prior to disuse (prehabilitation) may prevent muscle deterioration during subsequent unloading. The present study aimed to investigate the effect of short‐term resistance exercise training (RET) prehabilitation on muscle morphology and regulatory mechanisms during 5 days of bed rest in older men.MethodsTen healthy older men aged 65–80 years underwent four bouts of high‐volume unilateral leg RET over 7 days prior to 5 days of inpatient bed rest. Physical activity and step‐count were monitored over the course of RET prehabilitation and bed rest, whilst dietary intake was recorded throughout. Prior to and following bed rest, quadriceps cross‐sectional area (CSA), and hormone/lipid profiles were determined. Serial muscle biopsies and dual‐stable isotope tracers were used to determine integrated myofibrillar protein synthesis (iMyoPS) over RET prehabilitation and bed rest phases, and acute postabsorptive and postprandial myofibrillar protein synthesis (aMyoPS) rates at the end of bed rest.ResultsDuring bed rest, daily step‐count and light and moderate physical activity time decreased, whilst sedentary time increased when compared with habitual levels (P < 0.001 for all). Dietary protein and fibre intake during bed rest were lower than habitual values (P < 0.01 for both). iMyoPS rates were significantly greater in the exercised leg (EX) compared with the non‐exercised control leg (CTL) over prehabilitation (1.76 ± 0.37%/day vs. 1.36 ± 0.18%/day, respectively; P = 0.007). iMyoPS rates decreased similarly in EX and CTL during bed rest (CTL, 1.07 ± 0.22%/day; EX, 1.30 ± 0.38%/day; P = 0.037 and 0.002, respectively). Postprandial aMyoPS rates increased above postabsorptive values in EX only (P = 0.018), with no difference in delta postprandial aMyoPS stimulation between legs. Quadriceps CSA at 40%, 60%, and 80% of muscle length decreased significantly in EX and CTL over bed rest (0.69%, 3.5%, and 2.8%, respectively; P < 0.01 for all), with no differences between legs. No differences in fibre‐type CSA were observed between legs or with bed rest. Plasma insulin and serum lipids did not change with bed rest.ConclusionsShort‐term resistance exercise prehabilitation augmented iMyoPS rates in older men but did not offset the relative decline in iMyoPS and muscle mass during bed rest.

Moderate-to-high intensity inspiratory muscle training improves the effects of combined training on exercise capacity in patients after coronary artery bypass graft surgery: A randomized clinical trial

BackgroundThe effects of adding moderate-to-high intensity inspiratory muscle training (IMT) to short-term aerobic and resistance exercise (combined training [CT]), after coronary artery bypass grafting (CABG) are not established. This study aimed to determine the effects of moderate-to-high intensity IMT + CT on exercise capacity, respiratory muscle strength, inspiratory muscle endurance, quality of life (QoL), and laboratory biomarkers in patients after CABG who were participants of a phase II cardiac rehabilitation program. MethodsTwenty-four patients were randomly assigned to either the IMT + CT group (n = 12), who performed moderate-to-high intensity IMT with CT or the sham-IMT + CT group (n = 12). Patients completed two sessions per week for 12 weeks. Each patient underwent a cardiopulmonary exercise test, six-minute walk test (6MWT), respiratory muscle strength and endurance evaluation, QoL questionnaire, and serum advanced oxidation protein products, ferric reducing antioxidant power [FRAP], nitrate/nitrate, and high-sensitivity C-reactive protein, before and after the 12-week intervention. ResultsThe IMT + CT group showed significantly greater improvements in peak oxygen uptake (1.3 mL∙kg−1∙min−1; 95% confidence interval [95% CI], 0.5 to 2.2), distance covered during the 6MWT (78.8 m; 95% CI, 28.1 to 129.5), maximal inspiratory pressure (23.0 cmH2O; 95% CI, 9.3 to 36.7), QoL (−15.1 points; 95% CI, −26.9 to −3.3), and FRAP (83.7 μmol/L; 95% CI, 20.2 to 147.1) compared to the sham-IMT + CT group as a result of the intervention. ConclusionsShort-term moderate-to-high intensity IMT with CT provided additional benefits in exercise capacity, inspiratory muscle strength, QoL, and antioxidant profile in patients after CABG.Trial Registration clinicaltrials.gov Identifier: NCT02885077

Acute, short-, and long-term effects of different types of exercise in central arterial stiffness: a systematic review and meta-analysis.

The independent predictor of cardiovascular mortality, central arterial stiffness (CAS), is modulated by exercise depending on type of exercises, arteries assessed, sample features and time to exposure. Thus, this study aim to determine the endurance, resistance and combined exercise effects on CAS over time in humans. MEDLINE database for studies published between January 1st, 1990 and February 3rd, 2015. Studies measuring the effects of exercise on CAS, measured by aortic pulse wave velocity or carotid arterial compliance measured by ultrasound were included. Two independent reviewers extracted the 56 studies meta-analyzed and allocated among type of exercise and time effects categories: acute (10 minutes to 24 hours post-exercise session effect), short-term (interventional studies testing basal CAS from 1 to 24 weeks of exercise) and long-term (cross-sectional studies comparing trained and untrained individuals). We calculated standard difference in means 95% CIs, applying random or fixed-effects models, according to presence or absence of true heterogeneity, respectively. Endurance exercise reduced CAS in short and long-term analysis (-0.42 [-0.53 to -0.31] and -0.62 [-0.95 to -0.29], respectively), however it did not modify CAS acutely; higher magnitude of reduction occurred in normal weight individuals, with longer duration, higher weekly frequency and continuous (rather than interval) protocols. Resistance exercise increases CAS acutely (0.30 [0.01 to 0.58]) and after long-term (0.47 [0.19 to 0.75]), while short-term resistance exercise did not modify CAS significantly. No significant effect was found for short-term combined exercises and there was not enough number of studies for acute and long-term effects to be meta-analysed. Endurance and resistance exercise have opposite long-term effects, being beneficial and deleterious, respectively, while the combined exercise showed to be innocuous.

Absence of Functional Left Ventricular Adaption With Short-Term Resistance Exercise Training in Young Men

Absence of Functional Left Ventricular Adaption With Short-Term Resistance Exercise Training in Young Men

Effects of Intra-dialytic, Short-term Resistance Exercise on Physical Fitness, Depression and Dialysis Adequacy

This study aims to identify effects of intra-dialytic, short-term strength exercises on physical fitness, depression and dialysis adequacy. In addition, we aim to examine the minimum level of momentum that positive effect is displayed for each part. The subjects were 27 hemodialysis patients who have no disability in free living. They were allocated to a moderate amount exercise group and a low amount exercise group. Both groups joined strength exercise program during hemodialysis which was set three times a week for 4 weeks. The exercise program was progressed by warm up, main exercise, and cool down that was designed to use low limb and core muscles. Measurements were taken before and after the intervention. In physical factor, body composition, physical fitness, physical function, physical activity level and, dialysis adequacy was measured. In psychological part, depression was measured. As a results, body composition, physical function, physical activity and dialysis adequacy were not changed by exercise intervention. However, leg strength and agility was increased (p＜0.05) after 4-week moderate amount exercise program. Also, depression was significantly improved (p＜0.05) in both exercise group.

Resistance training improves capacity to delay neuromuscular fatigue in older adults

The purpose of this study was to investigate the effects of short term resistance exercise on neuromuscular fatigue threshold (PWCFT), strength, functional performance, and body composition in older adults. Twenty-three participants (71.2±6.0yr) were randomly assigned to 6 weeks of resistance exercise (EXE) or control (CONT). A submaximal cycle ergometer test, physical working capacity at fatigue threshold, was used to determine PWCFT. Strength was assessed with predicted leg extension 1-RM and functional performance with time to complete 5 chair rises (CHAIR) and walk an 8-ft course (WALK). PWCFT, 1-RM and CHAIR significantly (p<0.05) improved in the EXE (27%, 24%, 27%) compared with CONT (−0.1%, 7%, 6%), respectively. The results of this study suggest that short term EXE improved strength, functionality and the capacity to delay the onset of neuromuscular fatigue in older adults.

Effects of Aerobic Plus Resistance Exercise on Body Composition Related Variables in Pediatric Obesity: A Systematic Review and Meta-Analysis of Randomized Controlled Trials.

The purpose of this meta-analysis of randomized trials was to determine the effectiveness of aerobic plus resistance exercise interventions on body composition related to variables in overweight and obese youth. A computerized search was made of 7 databases. The analysis was restricted to randomized controlled trials that examined the effect of aerobic and resistance exercise on body composition (body weight, body mass index, fat mass, fat-free mass, and waist circumference) in obese youth. Two independent reviewers screened studies and extracted data. Weighted mean differences (WMD) and 95% confidence intervals were calculated. Nine studies were selected for meta-analysis as they fulfilled the inclusion criteria (n = 365). Aerobic plus resistance exercise interventions (8-24 weeks duration) produced a decrease in body weight (WMD=-3.31 kg), body mass index (WMD=-1.05 kg/m2), and fat mass (WMD=-1.93% and 5.05 kg), but changes in fat-free mass and waist circumference were not observed. These changes were accentuated through programs of at least 60 min of exercise per session, generating greater reductions in body weight (WMD=-4.11 kg), fat mass (WMD=-4.07%), and increase in fat-free mass (WMD = 2.45 kg). This meta-analysis provides insight into the effectiveness of short-term aerobic plus resistance exercise interventions for decreasing body weight, body mass index, and fat mass in pediatric obesity.

Bio-active peptides (Biogro™) supplementation improves work capacity during short-term resistance exercise in men

Background Inadequate recovery between training sessions leads to fatigue and imposes a hindrance on exercise performance. Bio-Active Peptides (BAPs) supplementation has been shown to reduce recovery time between strenuous exercise bouts and improve work capacity during subsequent bouts in athletes. However, few investigations have explored the efficacy of BAP supplementation on early performance adaptations in previously untrained men.

SLC30A8 Nonsynonymous Variant Is Associated With Recovery Following Exercise and Skeletal Muscle Size and Strength

Genome-wide association studies have identified thousands of variants that are associated with numerous phenotypes. One such variant, rs13266634, a nonsynonymous single nucleotide polymorphism in the solute carrier family 30 (zinc transporter) member eight gene, is associated with a 53% increase in the risk of developing type 2 diabetes (T2D). We hypothesized that individuals with the protective allele against T2D would show a positive response to short-term and long-term resistance exercise. Two cohorts of young adults-the Eccentric Muscle Damage (EMD; n = 156) cohort and the Functional Single Nucleotide Polymorphisms Associated with Muscle Size and Strength Study (FAMuSS; n = 874)-were tested for association of the rs13266634 variant with measures of skeletal muscle response to resistance exercise. Our results were sexually dimorphic in both cohorts. Men in the EMD study with two copies of the protective allele showed less post-exercise bout strength loss, less soreness, and lower creatine kinase values. In addition, men in the FAMuSS, homozygous for the protective allele, showed higher pre-exercise strength and larger arm skeletal muscle volume, but did not show a significant difference in skeletal muscle hypertrophy or strength with resistance training.

Biomarkers of muscle quality: N‐terminal propeptide of type III procollagen and C‐terminal agrin fragment responses to resistance exercise training in older adults

BackgroundN-terminal peptide of procollagen type III (P3NP) and C-terminal agrin fragment (CAF) are circulating biomarkers that are related to lean body mass in older adults. P3NP is a circulating marker reflective of muscular structural remodeling while CAF is a circulating marker of neuromuscular remodeling. As resistance exercise is an established intervention that can effectively improve muscle quality, we sought to evaluate circulating biomarker changes corresponding to a resistance exercise intervention in older adults.MethodsTwenty-three older adults (aged 61 to 85 years) were randomized into an intervention (6-week resistance training) or control group. Resting circulating P3NP, CAF, lean body mass (LBM), muscle cross-sectional area (CSA), muscle strength, and muscle quality were determined at baseline and after the intervention or control period by enzyme-linked immunosorbent assay, dual-energy X-ray absorptiometry, ultrasound, leg extension, and relative strength, respectively. Changes in circulating biomarkers and measures of muscle mass and quality were evaluated with repeated-measures analysis of variance; clinical interpretations were made with magnitude-based inferences, and relationships between variables were evaluated with bivariate correlations.ResultsThe short-term resistance exercise intervention was effective at improving muscle quality by 28 % (p < 0.001) despite no significant changes in lean body mass. Baseline circulating P3NP was somewhat lower in older women (4.15 ± 1.9 ng/mL) compared with older men (4.81 ± 2.1 ng/mL). The exercise intervention tended to increase circulating P3NP (baseline = 4.53 ± 1.80 to post = 4.88 ± 1.86) and was significantly correlated with changes in LBM (r = 0.422, p = 0.045). At baseline, women (3.91 ± 1.12 pg/mL) had somewhat higher circulating CAF than men (3.47 ± 1.37 pg/mL). Circulating CAF increased by 10.4 % (3.59 to 4.00 pg/ml) in older adults following 6 weeks of resistance exercise training. Changes in circulating CAF were significantly related to changes in CSA of the vastus lateralis (r = 0.542, p = 0.008).ConclusionsAssessment of P3NP and CAF from blood samples may provide minimally invasive and clinically informative measures of skeletal muscle status in older adults. Circulating CAF appears to increase in response to short-term resistance exercise training in older adults to a clinically meaningful magnitude. Changes in circulating P3NP in response to the intervention were less clear but appear to reflect muscle hypertrophy. Further research is needed to elucidate whether P3NP, CAF, or other biomarkers can reflect muscle qualitative adaptations with larger and longer studies.

Effects of short-term isokinetic training with reciprocal knee extensors agonist and antagonist muscle actions: A controlled and randomized trial

Previous studies have shown that preloading an antagonist muscle may increase the acute agonist neuromuscular performance. In addition, studies have suggested that very short-term resistance exercise (RE) programs may also be useful to increase strength and muscular performance. To evaluate the effects of three days of RE using a reciprocal action method on the muscular performance of healthy men and to compare these effects with those of a traditional RE group. Thirty-three men (21.1 ± 2.3 years) were randomly assigned to one of three groups: 1) reciprocal (REC; knee flexion immediately followed by a knee extension exercise); 2) traditional (TRA; non-preload; a concentric knee extension exercise); and 3) control (CON; no exercise). The REC and TRA subjects performed four sets of 10 repetitions at 60º/s with one minute of rest. The pre- and post-RE tests included two sets of four maximal concentric repetitions at 60º/s and 180º/s. A 3x2 ANOVA with Tukey post-hoc was used to analyze the differences in peak torque (PT), rating of acceleration development (RAD) and time to peak torque (TIMEtorque). A significant PT increase was found for REC and TRA (p<0.05) at 60º/s and for REC at 180º/s (p<0.05). There was a decrease in the RAD for REC and TRA (p<0.05), and TIMEtorque showed a significant decrease for REC. The inter-group analysis revealed that REC is more effective than TRA for PT gains at both velocities (p<0.05). It is recommended that REC offers benefits for the clinical practice of professionals involved in neuromuscular rehabilitation.

Proliferation of myogenic stem cells in human skeletal muscle in response to low‐load resistance training with blood flow restriction

Low-load resistance training with blood flow restriction has been shown to elicit substantial increases in muscle mass and muscle strength; however, the effect on myogenic stem cells (MSCs) and myonuclei number remains unexplored. Ten male subjects (22.8 ± 2.3 years)performed four sets of knee extensor exercise (20% 1RM) to concentric failure during bloodflow restriction (BFR) of the proximal thigh (100 mmHg), while eight work-matched controls(21.9 ± 3.0 years) trained without BFR (control, CON). Twenty-three training sessions were performed within 19 days. Maximal isometric knee extensor strength (MVC) was examined pre- and post-training, while muscle biopsies were obtained at baseline (Pre), after 8 days intervention(Mid8) and 3 (Post3) and 10 days (Post10) post training to examine changes in myofibre area (MFA), MSC and myonuclei number. MVC increased by 7.1% (Post5) and 10.6% (Post12)(P <0.001) with BFR training, while type I and II MFA increased by 38% (Mid8), 35 – 37%(Post3) and 31 – 32% (Post10) (P <0.001). MSCs per myofibre increased with BFR training from 0.10 ± 0.01 (Pre) to 0.38 ± 0.02 (Mid8), 0.36 ± 0.04 (Post3) and 0.25 ± 0.02 (Post10) (P <0.001). Likewise, myonuclei per myofibre increased from 2.49 ± 0.07 (Pre) to 3.30 ± 0.22(Mid8), 3.20 ± 0.16 (Post3) and 3.11 ± 0.11 (Post10), (P<0.01). Although MFA increased in CON at Mid8, it returned to baseline at Post3. No changes in MSC or myonuclei number were observed in CON. This study is the first to show that short-term low-load resistance exercise performed with partial blood flow restriction leads to marked proliferation of myogenic stem cells and resulting myonuclei addition in human skeletal muscle, which is accompanied by substantial myofibre hypertrophy.

Quadriceps short-term resistance exercise in subjects with resistant hypertension

INTRODUCTION: Resistant arterial hypertension may lead to muscle disuse and reduced functional capacity due to arterial and target-organs lesions. The main objective of this work is to evaluate the quadriceps strength and fatigue tolerance after a program of resistance exercise in subjects with resistant primary hypertension. METHODS: Six patients under pharmacological treatment were submitted to a four-week resistance exercise training program for the quadriceps (8-14 repetitions, 3 sets, 3 days per week). Strength was evaluated by isometric dynamometry, as the percentage change in maximum voluntary contraction over the four week program. Fatigue was analyzed by surface electromyography, as the change in both root mean square value and intercept of median frequency slope of vastus medialis and vastus lateralis. RESULTS: Significant increase in the maximum voluntary contraction was observed (p = 0.04). Fatigue tolerance was not improved as seen by root mean square as well as in the intercept of median frequency (p &gt; 0.05). Additionally, no significant changes were observed in resting arterial blood pressure and heart rate throughout the training period. CONCLUSION: The prescribed protocol seemed to successfully increase localized muscle strength without negatively affecting the monitored cardiovascular variables in patients with resistant hypertension under pharmacological treatment.

Increase in calf post-occlusive blood flow and strength following short-term resistance exercise training with blood flow restriction in young women

The response of calf muscle strength, resting (R (bf)) and post-occlusive (PO(bf)) blood flow were investigated following 4 weeks resistance training with and without blood flow restriction in a matched leg design. Sixteen untrained females performed unilateral plantar-flexion low-load resistance training (LLRT) at either 25% (n = 8) or 50% (n = 8) one-repetition maximum (1 RM). One limb was trained with unrestricted blood flow whilst in the other limb blood flow was restricted with the use of a pressure applied cuff above the knee (110 mmHg). Regardless of the training load, peak PO(bf), measured using venous occlusion plethysmography increased when LLRT was performed with blood flow restriction compared to no change following LLRT with unrestricted blood flow. A significant increase (P < 0.05) in the area under the blood time-flow curve was also observed following LLRT with blood flow restriction when compared LLRT with unrestricted blood flow. No changes were observed in R (bf) between groups following training. Maximal dynamic strength (1 RM), maximal voluntary contraction and isokinetic strength at 0.52 and 1.05 rad s(-1) also increased (P < 0.05) by a greater extent following resistance training with blood flow restriction. Moreover, 1 RM increased to a greater extent following training at 50% 1 RM compared to 25% 1 RM. These results suggest that 4 weeks LLRT with blood flow restriction provides a greater stimulus to increase peak PO(bf) as well as strength parameters than LLRT with unrestricted blood flow.