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Aim: The aim of this observational study was to determine the immune status and function in young adults with cerebral palsy (CP) in comparison to typically developing individuals. Method: Blood samples from 12 individuals with CP (five males, seven females; mean age: 25 years 1 month (5 years 9 months); age range: 19–38 years) and 17 typically developing individuals (eight males, nine females; mean age: 31 years 4 months (6 years 2 months); age range: 20–40 years) were collected before, immediately after, and 1 hour after 45 minutes of frame running or running respectively. Independent t‐tests were used to compare heart rate, level of exertion, and baseline cell proportions between groups. Mixed model analysis of variance was utilized to investigate immune cell responses to exercise across groups. Results: Baseline levels of gamma delta (TCRγδ+) T‐cells were significantly higher (absolute percentage: +2.65, p = 0.028) in the individuals with CP. Several cell populations showed similar significant changes after exercise in both CP and typically developing groups. Cytotoxic (CD8+) T‐cells were only significantly elevated immediately after exercise in the typically developing participants (p < 0.01). Individuals with CP exhibited significantly lower heart rates (−11.1%, p < 0.01), despite similar ratings of perceived exertion. Interpretation: Elevated baseline TCRγδ+ T‐cells may indicate low‐grade inflammation in adults with CP. Although most of the cell populations showed typical responses to endurance exercise, the absence of response in CD8+ T‐cells in individuals with CP may indicate the need for higher intensity during exercise. What this paper adds: TCRγδ+ T‐cell baseline levels are elevated in adults with cerebral palsy (CP).The CD8+ T‐cell response to exercise was blunted in adults with CP.Exercise intensity is decisive for CD8+ T‐cell responses in individuals with CP. [ABSTRACT FROM AUTHOR]

Background: Flywheel resistance training has become more integrated within resistance training programs in a variety of sports due to the neuromuscular, strength, and task-specific enhancements reported with this training. Objective: This paper aimed to present the consensus reached by internationally recognized experts during a meeting on current definitions and guidelines for the implementation of flywheel resistance training technology in sports. Methods: Nineteen experts from different countries took part in the consensus process; 16 of them were present at the consensus meeting (18 May 2023) while three submitted their recommendations by e-mail. Prior to the meeting, evidence summaries were developed relating to areas of priority. This paper discusses the available evidence and consensus process from which recommendations were made regarding the appropriate use of flywheel resistance training technology in sports. The process to gain consensus had five steps: (1) performing a systematic review of systematic reviews, (2) updating the most recent umbrella review published on this topic, (3) first round discussion among a sample of the research group included in this consensus statement, (4) selection of research group members—process of the consensus meeting and formulation of the recommendations, and (5) the consensus process. The systematic analysis of the literature was performed to select the most up-to-date review papers available on the topic, which resulted in nine articles; their methodological quality was assessed according to AMSTAR 2 (Assessing the Methodological Quality of Systematic Review 2) and GRADE (Grading Recommendations Assessment Development and Evaluation). Statements and recommendations scoring 7–9 were considered appropriate. Results: The recommendations were based on the evidence summary and researchers' expertise; the consensus statement included three statements and seven recommendations for the use of flywheel resistance training technology. These statements and recommendations were anonymously voted on and qualitatively analyzed. The three statements reported a score ranging from 8.1 to 8.8, and therefore, all statements included in this consensus were considered appropriate. The recommendations (1–7) had a score ranging from 7.7 to 8.6, and therefore, all recommendations were considered appropriate. Conclusions: Because of the consensus achieved among the experts in this project, it is suggested that practitioners and researchers should adopt the guidelines reported in this consensus statement regarding the use of flywheel resistance technology in sports. [ABSTRACT FROM AUTHOR]

Background: The primary aim of this study was to examine the relationship between maximal oxygen update (V̇O2max) and within-set fatigue and between-set recovery during resistance exercise in men and women. Methods: We examined the relationship between V̇O2max and various indices of fatigue and recovery during parallel squats (3 sets, 90 s rest, 70% of 1RM to failure) and isokinetic knee extensions (3 × 10 maximal repetitions at 60 deg/s, 45 s rest) in 28 (age 27.0 ± 3.6 years) resistance-trained subjects (14 men and 14 women). We also examined whether there were sex differences in within-set fatigue and between-set recovery. Results: V̇O2max was weakly related to recovery and fatigue in both men and women (range of P-values for V̇O2max as a covariate; 0.312–0.998, range of R-values, 0.005–0.604). There were no differences between the sexes in fatigue within a set for the squat, but men showed less within-set fatigue than women in the first set of the isokinetic knee extension exercise (~ 8% torque loss difference, main effect of sex P = 0.034). Regarding recovery between sets, men showed greater relative peak power (P = 0.016) and peak torque (P = 0.034) loss between sets in both exercises, respectively, compared to women. Women also tended to complete more repetitions than men (main effect of sex, P = 0.057). Loss of peak torque between sets in knee extension was evident in both absolute and relative (%) values in men but not in women. Conclusions: Our study suggests that aerobic capacity is weakly associated with within-set fatigue and between-set recovery in resistance training in both men and women. Women and men show comparable levels of within-set fatigue in the multi-joint squat, but women show more within-set fatigue during the single-joint isokinetic knee extension compared with men. In contrast, women recover better than men between sets in both exercises. [ABSTRACT FROM AUTHOR]

A recent study published in Experimental Physiology details the first Canadian study to investigate the physiological, psychological, and cognitive responses to 14 days of bed rest and the benefits of exercise during bed rest. The study involved 23 older male and female participants who completed 14 days of bed rest, followed by supervised rehabilitation. Half of the participants performed aerobic and resistance exercise during bed rest to test its effectiveness as a countermeasure. The study provides important insights into the physiological responses to inactivity and may help inform future countermeasure development. Bed rest studies are also relevant for understanding periods of hospitalization and testing countermeasures for microgravity and severe inactivity. [Extracted from the article]

The skeletal muscle and the immune system are heavily affected by the space environment. The crosstalk between these organs, although established, is not fully understood. This study determined the nature of immune cell changes in the murine skeletal muscle following (hindlimb) unloading combined with an acute session of irradiation (HLUR). Our findings show that 14 days of HLUR induces a significant increase of myeloid immune cell infiltration in skeletal muscle. [ABSTRACT FROM AUTHOR]

Based on the European Space Agency (ESA) Science in Space Environment (SciSpacE) community White Paper "Human Physiology – Musculoskeletal system", this perspective highlights unmet needs and suggests new avenues for future studies in musculoskeletal research to enable crewed exploration missions. The musculoskeletal system is essential for sustaining physical function and energy metabolism, and the maintenance of health during exploration missions, and consequently mission success, will be tightly linked to musculoskeletal function. Data collection from current space missions from pre-, during-, and post-flight periods would provide important information to understand and ultimately offset musculoskeletal alterations during long-term spaceflight. In addition, understanding the kinetics of the different components of the musculoskeletal system in parallel with a detailed description of the molecular mechanisms driving these alterations appears to be the best approach to address potential musculoskeletal problems that future exploratory-mission crew will face. These research efforts should be accompanied by technical advances in molecular and phenotypic monitoring tools to provide in-flight real-time feedback. [ABSTRACT FROM AUTHOR]

In this study, the properties of circulating extracellular vesicles (EVs) were examined in cerebral palsy (CP) and typically developed (TD) individuals at rest and after aerobic exercise, focusing on the size, concentration, and microRNA cargo of EVs. Nine adult individuals with CP performed a single exercise bout consisting of 45 min of Frame Running, and TD participants completed either 45min of cycling (n = 10; TD EX) or were enrolled as controls with no exercise (n = 10; TD CON). Blood was drawn before and 30min after exercise and analyzed for EV concentration, size, and microRNA content. The size of EVs was similar in CP vs. TD, and exercise had no effect. Individuals with CP had an overall lower concentration (~25%, p < 0.05) of EVs. At baseline, let-7a, let-7b and let-7e were downregulated in individuals with CP compared to TD (p < 0.05), while miR-100 expression was higher, and miR-877 and miR-4433 lower in CP compared to TD after exercise (p < 0.05). Interestingly, miR-486 was upregulated ~2-fold in the EVs of CP vs. TD both at baseline and after exercise. We then performed an in silico analysis of miR-486 targets and identified the satellite cell stemness factor Pax7 as a target of miR-486. C2C12 myoblasts were cultured with amiR-486 mimetic and RNA-sequencing was performed. Gene enrichment analysis revealed that several genes involved in sarcomerogenesis and extracellular matrix (ECM) were downregulated. Our data suggest that circulating miR-486 transported by EVs is elevated in individuals with CP and that miR-486 alters the transcriptome of myoblasts affecting both ECM- and sarcomerogenesis-related genes, providing a link to the skeletal muscle alterations observed in individuals with CP. [ABSTRACT FROM AUTHOR]

Maintenance of skeletal muscle mass and function is critical to health and wellbeing throughout the lifespan. However, disuse through reduced physical activity (e.g., sedentarism), immobilisation, bed rest or microgravity has significant adverse effects on skeletal muscle health. Conversely, resistance exercise training (RET) induces positive muscle mass and strength adaptations. Several studies have employed microarray technology to understand the transcriptional basis of muscle atrophy and hypertrophy after disuse and RET, respectively, to devise fully effective therapeutic interventions. More recently, rapidly falling costs have seen RNA-sequencing (RNA-seq) increasingly applied in exploring muscle adaptations to RET and disuse. The aim of this review is to summarise the transcriptional responses to RET or disuse measured via RNA-seq in young and older adults. We also highlight analytical considerations to maximise the utility of RNA-seq in the context of skeletal muscle research. The limited number of muscle transcriptional signatures obtained thus far with RNA-seq are generally consistent with those obtained with microarrays. However, RNA-seq may provide additional molecular insight, particularly when combined with data-driven approaches such as correlation network analyses. In this context, it is essential to consider the most appropriate study design parameters as well as bioinformatic and statistical approaches. This will facilitate the use of RNA-seq to better understand the transcriptional regulators of skeletal muscle plasticity in response to increased or decreased use. [ABSTRACT FROM AUTHOR]

Skeletal muscle adaptations to exercise have been associated with a range of health-related benefits, but cell type-specific adaptations within the muscle are incompletely understood. Here we use single-cell sequencing to determine the effects of exercise on cellular composition and cell type-specific processes in human skeletal muscle before and after intense exercise. Fifteen clusters originating from six different cell populations were identified. Most cell populations remained quantitatively stable after exercise, but a large transcriptional response was observed in mesenchymal, endothelial, and myogenic cells, suggesting that these cells are specifically involved in skeletal muscle remodeling. We found three subpopulations of myogenic cells characterized by different maturation stages based on the expression of markers such as PAX7, MYOD1, TNNI1, and TNNI2. Exercise accelerated the trajectory of myogenic progenitor cells towards maturation by increasing the transcriptional features of fast- and slow-twitch muscle fibers. The transcriptional regulation of these contractile elements upon differentiation was validated in vitro on primary myoblast cells. The cell type-specific adaptive mechanisms induced by exercise presented here contribute to the understanding of the skeletal muscle adaptations triggered by physical activity and may ultimately have implications for physiological and pathological processes affecting skeletal muscle, such as sarcopenia, cachexia, and glucose homeostasis. Single-cell RNA-sequencing of human skeletal muscle before and after exercise highlights how physical activity changes the composition and transcriptomic profile of muscle tissue. [ABSTRACT FROM AUTHOR]

Skeletal muscle in individuals with CP also contains lower amounts of mtDNA, potentially indicating fewer mitochondria in CP skeletal muscle compared with typically developing muscle. We compared skeletal muscle samples from children with cerebral palsy (CP) and typically developing children and observed evidence of reduced mtDNA and OXPHOS protein content in CP skeletal muscle, indicating reduced mitochondrial abundance. Cerebral palsy (CP) muscle contains fewer energy-generating organelles than typically developing muscle. [Extracted from the article]

Mitochondrial-derived peptides (MDPs) humanin (HN) and mitochondrial open reading frame of the 12S rRNA-c (MOTS-c) are involved in cell survival, suppression of apoptosis, and metabolism. Circulating levels of MDPs are altered in chronic diseases such as diabetes type 2 and chronic kidney disease. Whether acute resistance (RE) or endurance (EE) exercise modulates circulating levels of HN and MOTS-c in humans is unknown. Following familiarization, subjects were randomized to EE (n = 10, 45 min cycling at 70% of estimated VO2max), RE (n = 10, 4 sets x 7RM, leg press and knee extension), or control (CON, n = 10). Skeletal muscle biopsies and blood samples were collected before and at 30 min and 3 h following exercise. Plasma concentration of HN and MOTS-c, skeletal muscle MOTS-c as well as gene expression of exercise-related genes were analyzed. Acute EE and RE promoted changes in skeletal muscle gene expression typically seen in response to each exercise modality (c-Myc, 45S prerRNA, PGC-1a-total, and PGC-1a-ex1b). At rest, circulating levels of HN were positively correlated to MOTS-c levels and age. Plasma levels of MDPs were not correlated to fitness outcomes [VO2max, leg strength, or muscle mitochondrial (mt) DNA copy number]. Circulating levels of HN were significantly elevated by acute EE but not RE. MOTS-C levels showed a trend to increase after EE. These results indicate that plasma MDP levels are not related to fitness status but that acute EE increases circulating levels of MDPs, in particular HN. [ABSTRACT FROM AUTHOR]

To evaluate the individual responses in skeletal muscle outcomes following bed rest, data from three studies (21-day PlanHab; 10-day FemHab and LunHab) were combined. Subjects (n = 35) participated in three cross-over campaigns within each study: normoxic (NBR) and hypoxic bed rest (HBR), and hypoxic ambulation (HAMB; used as control). Individual variability (SDIR) was investigated as √(SD Exp 2 –SD Con 2), where SDExp and SDCon are the standard deviations of the change score (i.e., post – pre) in the experimental (NBR and HBR) and the control (HAMB) groups, respectively. Repeatability and moderators of the individual variability were explored. Significant SDIR was detected for knee extension torque, and thigh and calf muscle area, which translated into an individual response ranging from 3 to −17% for knee extension torque, −2 to −12% for calf muscle area, and −1 to −8% for thigh muscle area. Strong correlations were found for changes in NBR vs. HBR (i.e., repeatability) in thigh and calf muscle area (r = 0.65–0.75, P < 0.0001). Change-scores in knee extension torque, and thigh and calf muscle area strongly correlated with baseline values (P < 0.001; r between −0.5 and −0.9). Orthogonal partial least squares regression analysis explored if changes in the investigated variables could predict calf muscle area alterations. This analysis indicated that 43% of the variance in calf muscle area could be attributed to changes in all of the other variables. This is the first study using a validated methodology to report clinically relevant individual variability after bed rest in knee extension torque, calf muscle area, and (to a lower extent) thigh muscle area. Baseline values emerged as a moderator of the individual response, and a global bed rest signature served as a moderately strong predictor of the individual variation in calf muscle area alterations. [ABSTRACT FROM AUTHOR]

Key points: Ribosome biogenesis and MYC transcription are associated with acute resistance exercise (RE) and are distinct from endurance exercise in human skeletal muscle throughout a 24 h time course of recovery.A PCR‐based method for relative ribosomal DNA (rDNA) copy number estimation was validated by whole genome sequencing and revealed that rDNA dosage is positively correlated with ribosome biogenesis in response to RE.Acute RE modifies rDNA methylation patterns in enhancer, intergenic spacer and non‐canonical MYC‐associated regions, but not the promoter.Myonuclear‐specific rDNA methylation patterns with acute mechanical overload in mice corroborate and expand on rDNA findings with RE in humans.A genetic predisposition for hypertrophic responsiveness may exist based on rDNA gene dosage. Ribosomes are the macromolecular engines of protein synthesis. Skeletal muscle ribosome biogenesis is stimulated by exercise, although the contribution of ribosomal DNA (rDNA) copy number and methylation to exercise‐induced rDNA transcription is unclear. To investigate the genetic and epigenetic regulation of ribosome biogenesis with exercise, a time course of skeletal muscle biopsies was obtained from 30 participants (18 men and 12 women; 31 ± 8 years, 25 ± 4 kg m–2) at rest and 30 min, 3 h, 8 h and 24 h after acute endurance (n = 10, 45 min cycling, 70% V̇O2max) or resistance exercise (n = 10, 4 × 7 × 2 exercises); 10 control participants underwent biopsies without exercise. rDNA transcription and dosage were assessed using quantitative PCR and whole genome sequencing. rDNA promoter methylation was investigated using massARRAY EpiTYPER and global rDNA CpG methylation was assessed using reduced‐representation bisulphite sequencing. Ribosome biogenesis and MYC transcription were associated primarily with resistance but not endurance exercise, indicating preferential up‐regulation during hypertrophic processes. With resistance exercise, ribosome biogenesis was associated with rDNA gene dosage, as well as epigenetic changes in enhancer and non‐canonical MYC‐associated areas in rDNA, but not the promoter. A mouse model of in vivo metabolic RNA labelling and genetic myonuclear fluorescence labelling validated the effects of an acute hypertrophic stimulus on ribosome biogenesis and Myc transcription, and also corroborated rDNA enhancer and Myc‐associated methylation alterations specifically in myonuclei. The present study provides the first information on skeletal muscle genetic and rDNA gene‐wide epigenetic regulation of ribosome biogenesis in response to exercise, revealing novel roles for rDNA dosage and CpG methylation. Key points: Ribosome biogenesis and MYC transcription are associated with acute resistance exercise (RE) and are distinct from endurance exercise in human skeletal muscle throughout a 24 h time course of recovery.A PCR‐based method for relative ribosomal DNA (rDNA) copy number estimation was validated by whole genome sequencing and revealed that rDNA dosage is positively correlated with ribosome biogenesis in response to RE.Acute RE modifies rDNA methylation patterns in enhancer, intergenic spacer and non‐canonical MYC‐associated regions, but not the promoter.Myonuclear‐specific rDNA methylation patterns with acute mechanical overload in mice corroborate and expand on rDNA findings with RE in humans.A genetic predisposition for hypertrophic responsiveness may exist based on rDNA gene dosage. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Role of Toll-like receptor 2 and 4 signaling pathways on the inflammatory response to resistance training in elderly subjects" published in the journal GeroScience in 2014. The correction involves the legend for Figure 2, which has been updated to clarify that the images were merged for representative purposes. The document also mentions that the raw material for panel 2A has been added to the article, indicating which samples are representative of the present findings and which are representative of other forms of exercise not included in the article. The publisher, Springer Nature, notes that it remains neutral regarding jurisdictional claims and institutional affiliations. [Extracted from the article]

The current study explored whether the marked hypertrophic response noted with a short-term unilateral concurrent exercise paradigm was associated with more prominent changes in myonuclei accretion, ribosome biogenesis, and capillarization compared with resistance exercise alone (RE). Ten men (age 25 ± 4 yr) performed aerobic and resistance exercise (AE + RE) for one leg while the other leg did RE. Muscle biopsies were obtained before and after 5 wk of training and subjected to fiber-type specific immunohistochemical analysis, and quantification of total RNA content and mRNA/rRNA transcript abundance. Type II fiber cross-sectional area (CSA) increased with both AE + RE (22%) and RE (16%), while type I fiber CSA increased mainly with AE + RE (16%). The change score tended to differ between legs for type I CSA (P = 0.099), and the increase in smallest fiber diameter was greater in AE + RE than RE (P = 0.029). The number of nuclei per fiber increased after AE + RE in both fiber types, and this increase was greater (P = 0.027) than after RE. A strong correlation was observed between changes in number of nuclei per fiber and fiber CSA in both fiber types, for both AE + RE and RE (r > 0.8, P < 0.004). RNA content increased after AE + RE (24%, P = 0.019), but the change-scores did not differ across legs. The capillary variables generally increased in both fiber types, with no difference across legs. In conclusion, the accentuated hypertrophic response to AE + RE was associated with more pronounced myonuclear accretion, which was strongly correlated with the degree of fiber hypertrophy. This suggests that myonuclear accretion could play a role in facilitating muscle hypertrophy also during very short training periods. [ABSTRACT FROM AUTHOR]

Background: Multiple circulatory factors are increased in heart failure (HF). Many have been linked to cardiac and/or skeletal muscle tissue processes, which in turn might influence physical activity and/or capacity during HF. This study aimed to provide a better understanding of the mechanisms linking HF with the loss of peripheral function. Methods and results: Physical capacity measured by maximum oxygen uptake, myocardial function (measured by echocardiography), physical activity (measured by accelerometry), and mortality data was collected for patients with severe symptomatic heart failure an ejection fraction < 35% (n = 66) and controls (n = 28). Plasma circulatory factors were quantified using a multiplex immunoassay. Multivariate (orthogonal projections to latent structures discriminant analysis) and univariate analyses identified many factors that differed significantly between HF and control subjects, mainly involving biological functions related to cell growth and cell adhesion, extracellular matrix organization, angiogenesis, and inflammation. Then, using principal component analysis, links between circulatory factors and physical capacity, daily physical activity, and myocardial function were identified. A subset of ten biomarkers differentially expressed in patients with HF vs controls covaried with physical capacity, daily physical activity, and myocardial function; eight of these also carried prognostic value. These included established plasma biomarkers of HF, such as NT-proBNP and ST2 along with recently identified factors such as GDF15, IGFBP7, and TfR, as well as a new factor, galectin-4. Conclusions: These findings reinforce the importance of systemic circulatory factors linked to hemodynamic stress responses and inflammation in the pathogenesis and progress of HF disease. They also support established biomarkers for HF and suggest new plausible markers. [ABSTRACT FROM AUTHOR]

Background: Individuals with cerebral palsy (CP) are less physically active, spend more time sedentary and have lower cardiorespiratory endurance as compared to typically developed individuals. RaceRunning enables high-intensity exercise in individuals with CP with limited or no walking ability, using a three-wheeled running bike with a saddle and a chest plate for support, but no pedals. Training adaptations using this type of exercise are unknown.Methods: Fifteen adolescents/young adults (mean age 16, range 9-29, 7 females/8 males) with CP completed 12 weeks, two sessions/week, of RaceRunning training. Measurements of cardiorespiratory endurance (6-min RaceRunning test (6-MRT), average and maximum heart rate, rate of perceived exertion using the Borg scale (Borg-RPE)), skeletal muscle thickness (ultrasound) of the thigh (vastus lateralis and intermedius muscles) and lower leg (medial gastrocnemius muscle) and passive range of motion (pROM) of hip, knee and ankle were collected before and after the training period.Results: Cardiorespiratory endurance increased on average 34% (6-MRT distance; pre 576 ± 320 m vs. post 723 ± 368 m, p < 0.001). Average and maximum heart rate and Borg-RPE during the 6-MRT did not differ pre vs. post training. Thickness of the medial gastrocnemius muscle increased 9% in response to training (p < 0.05) on the more-affected side. Passive hip flexion increased (p < 0.05) on the less-affected side and ankle dorsiflexion decreased (p < 0.05) on the more affected side after 12 weeks of RaceRunning training.Conclusions: These results support the efficacy of RaceRunning as a powerful and effective training modality in individuals with CP, promoting both cardiorespiratory and peripheral adaptations. [ABSTRACT FROM AUTHOR]

Because manual immunohistochemical analysis of features such as skeletal muscle fiber typing, capillaries, myonuclei, and fiber size-related parameters is time consuming and prone to user subjectivity, automatic computational methods could allow for faster and more objective evaluation. Here, we developed Muscle2View, a free CellProfiler-based pipeline that integrates all key fiber-morphological variables, including the novel quantification of the capillary-to-fiber interface, in one single tool. Provided that the images are of sufficient quality and the settings are configured for the specific study, the pipeline allows for automatic and unsupervised analysis of fiber borders, myonuclei, capillaries, and morphometric parameters in a fiber type-specific manner from large batches of images in <10 min/tissue sample. The novel identification of the capillary-to-fiber interface allowed for the calculation of microvascular factors such as capillary contacts (CC), individual capillary-to-fiber ratio (C/Fi), and capillary-to-fiber perimeter exchange (CFPE) index. When comparing the Muscle2View pipeline to manual or semiautomatic analysis, overall the results revealed strong correlations. For several variables, however, there were differences (5-15%) between values computed by manual counting and Muscle2View, suggesting that the methods should not necessarily be used interchangeably. Collectively, we demonstrate that the Muscle2View pipeline can provide unbiased and high-content analysis of muscle cross-sectional immunohistochemistry images. In addition to the classical morphological measurements, the Muscle2View can identify the complex capillary-to-fiber network and myonuclear density in a fiber type-specific manner. This robust analysis is done in one single run within a user-friendly and flexible environment based on the free and widely used image software CellProfiler. [ABSTRACT FROM AUTHOR]

This study aimed to analyse whether increasing the eccentric overload (EO) during resistance training, in terms of range of motion and/or velocity using an electric-motor device, would induce different muscle adaptations than conventional flywheel-EO resistance training. Forty physically active university students (21.7 ± 3.4 years) were randomly placed into one of the three training groups (EX1, EX2, FW) and a control group without training (n = 10 per group). Participants in the training groups completed 12 sessions (4 sets of 7 repetitions) of iso-inertial single-leg squat training over 6 weeks for the dominant leg. Resistance was generated either by an electric-motor device at two different velocities for the eccentric phase; 100% (EX1) or 150% (EX2) of concentric speed, or by a conventional flywheel device (FW). Thigh lean tissue mass, unilateral leg press one-repetition maximum (1-RM), unilateral muscle power at different percentages of the 1-RM and bilateral/unilateral vertical jump were assessed before and after the 6-week training. There were significant (p < 0.05–0.001) main effects of time in the 3 training groups, indicating increased thigh lean tissue mass (2.5–5.8%), 1-RM load (22.4–30.2%), vertical jump performance (9.1–32.9%) and muscle power (8.8–21.7%), without differences across experimental groups. Participants in the control group did not improve any of the variables measured. In addition, EX2 showed greater gains in eccentric average peak power during training than EX1 and FW (p < 0.001). Despite the different EO offered, 6 weeks of resistance training using flywheel or electric-motor devices induced similar significant gains in muscle mass, strength, muscle power and vertical jump. [ABSTRACT FROM AUTHOR]

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The current study examined the effects of a preceding bout of aerobic exercise (AE) on subsequent molecular signaling to resistance exercise (RE) of the elbow extensors. Eleven men performed unilateral elbow-extensor AE (~45 min at 70% peak workload) followed by unilateral RE (4 × 7 maximal repetitions) for both arms. Thus, one arm performed AE+RE interspersed with 15 min recovery, whereas the other arm conducted RE alone. Muscle biopsies were taken from the triceps brachii of each arm immediately before (PRE) and 15 min (POST1) and 3 h (POST2) after RE. Molecular markers involved in translation initiation, protein breakdown, mechanosignaling, and ribosome biogenesis were analyzed. Peak power during RE was reduced by 24% (±19%) when preceded by AE (P < 0.05). Increases in PGC1a and MuRF1 expression were greater from PRE to POST2 in AE+RE compared with RE (18-vs. 3.5- and 4- vs. 2-fold, respectively, interaction, P < 0.05). Myostatin mRNA decreased in both arms (P < 0.05). Phosphorylation of AMPK (Thr172) increased (2.5-fold), and 4E-BP1 (Thr37/46) decreased (2.0-fold), after AE (interactions, P < 0.05). p70 S6K, yesassociated protein, and c-Jun NH2-terminal kinase phosphorylation were unaltered, whereas focal adhesion kinase decreased ~1.5-fold, and β1- integrin increased ~1.3- to 1.5-fold, (time effect, P < 0.05). Abundance of 45S pre-ribosomal (r)RNA (internally transcribed spacer, ITS) decreased (~30%) after AE (interaction, P < 0.05), whereas CMYC mRNA was greater in AE+RE compared with RE (12-fold, P < 0.05). POLR1B abundance increased after both AE+RE and RE. All together, our results suggest that a single bout of AE leads to an immediate decrease in signaling for translation initiation and ribosome biogenesis. Yet, this did not translate into altered RE-induced signaling during the 3-h postexercise recovery period. [ABSTRACT FROM AUTHOR]

Our understanding of skeletal muscle structural and functional alterations during unloading has increased in recent decades, yet the molecular mechanisms underpinning these changes have only started to be unraveled. The purpose of the current investigation was to assess changes in skeletal muscle gene expression after 21 days of bed rest, with a particular focus on predicting upstream regulators of muscle disuse. Additionally, the association between differential microRNA expression and the transcriptome signature of bed rest were investigated. mRNAs from musculus vastus lateralis biopsies obtained from 12 men before and after the bed rest were analyzed using a microarray. There were 54 significantly upregulated probesets after bed rest, whereas 103 probesets were downregulated (false discovery rate 10%; fold-change cutoff ≥1.5). Among the upregulated genes, transcripts related to denervation-induced alterations in skeletal muscle were identified, e.g., acetylcholine receptor subunit delta and perinatal myosin. The most downregulated transcripts were functionally enriched for mitochondrial genes and genes involved in mitochondrial biogenesis, followed by a large number of contractile fiber components. Upstream regulator analysis identified a robust inhibition of the myocyte enhancer factor-2 (MEF2) family, in particular MEF2C, which was suggested to act upstream of several key downregulated genes, most notably peroxisome proliferator-activated receptor ɣ coactivator 1- (PGC-1α)/peroxisome proliferator-activated receptors (PPARs) and CRSP3. Only a few microRNAs were identified as playing a role in the overall transcriptome picture induced by sustained bed rest. Our results suggest that the MEF2 family is a key regulator underlying the transcriptional signature of bed rest and, hence, ultimately also skeletal muscle alterations induced by systemic unloading in humans. [ABSTRACT FROM AUTHOR]

Although immune dysfunction by space conditions has been reported postflight, as well as during ground-based experiments, the cause(s) and nature of the immunological changes are not completely understood. Microgravity has been suggested as one of the factors responsible for the observed immune dysregulation. The goal of this study was to assess immune changes in simulated microgravity (s-μG) using an in vitro cytokine release assay. The effect of s-μG provided by the desktop random positioning machine on cell-mediated immunity was examined by analyzing interleukin 2 (IL-2), interferon-γ (IFN-γ), tumor necrosis factor alpha (TNF-α), and interleukin 10 (IL-10), in response to immune cell stimulation in whole blood samples ( n = 10). Stimuli used were bacterial recall antigens, pokeweed mitogen (PWM), lipopolysaccharide (LPS), or heat-killed Listeria monocytogenes (HKLM). S-μG caused an overall inhibition of the IL-2 and IFN-γ responses to recall antigen and mitogen stimulation. More specifically, s-μG most strongly influenced the levels of all four cytokines elicited by bacterial recall antigen stimulation. In contrast, HKLM-induced TNF-α secretion was elevated. The average concentrations of TNF-α in response to PWM and LPS and IL-10 release stimulated by PWM, LPS, and HKLM were not significantly altered by s-μG. However, a variable response between individual subjects could be observed. In conclusion, our results demonstrate that the in vitro cytokine release assay can detect gravity-related immune alterations. Furthermore, the use of multiple stimuli and the associated changes in cytokine secretion has the potential to reveal information on the underlying mechanisms affected by s-μG. [ABSTRACT FROM AUTHOR]

Exercise load is a key component in determining end-point adaptations to resistance exercise. Yet, there is no information regarding the use of different inertia (i.e., loads) during isoinertial flywheel resistance exercise, a very popular high-intensity training model. Thus, this study examined power, work, force, and eccentric overload produced during flywheel resistance exercise with different inertial settings in men and women. Twenty-two women (n = 11) and men (n = 11) performed unilateral (in both legs) isolated concentric (CON) and coupled CON and eccentric (ECC) exercise in a flywheel knee extension device employing 6 inertias (0.0125, 0.025, 0.0375, 0.05, 0.075, 0.1 kg⋅m-2). Power decreased as higher inertias were used, with men showing greater (p ≤ 0.05) decrements than women (-36 vs. -29% from lowest to highest inertia). In contrast, work increased as higher inertias were employed, independent of sex (p ≤ 0.05; ~48% from lowest to highest inertia). Women increased CON and ECC mean force (46-55%, respectively) more (p ≤ 0.05) than men (34-50%, respectively) from the lowest to the highest inertia evaluated, although the opposite was found for peak force data (i.e., peak force increased more in men than in women as inertia was increased). Men, but not women, increased ECC overload from inertia 0.0125 to 0.0375 kg⋅m². Although estimated stretch-shorting cycle use during flywheel exercise was higher (p ≤ 0.05) in men (6.6%) than women (4.9%), values were greater for both sexes when using low-to-medium inertias. The information gained in this study could help athletes and sport and health professionals to better understand the impact of different inertial settings on skeletal muscle responses to flywheel resistance exercise. [ABSTRACT FROM AUTHOR]

In the quest for a viable non-gravity dependent method to "lift weights" in space, our laboratory introduced iso-inertial resistance (YoYo™) exercise using spinning flywheel(s), more than 25 years ago. After being thoroughly tested in individuals subjected to various established spaceflight analogs, a multi-mode YoYo™ exercise apparatus was eventually installed on the International Space Station in 2009. The method, applicable to any muscle group, provides accommodated resistance and optimal muscle loading through the full range of motion of concentric actions, and brief episodes of eccentric overload. This exercise intervention has found terrestrial applications and shown success in enhancing sports performance and preventing injury and aiding neurological or orthopedic rehabilitation. Research has proven that this technique offers unique physiological responses not possible with other exercise hardware solutions. This paper provides a brief overview of research that has made use, and explored the efficacy, of this method in healthy sedentary or physically active individuals and populations suffering from muscle wasting, disease or injury. While the collective evidence to date suggests YoYo™ offers a potent stimulus to optimize the benefits of resistance exercise, systematic research to support clinical use of this method has only begun to emerge. Thus, we also offer perspectives on unresolved issues, unexplored applications for clinical conditions, and how this particular exercise paradigm could be implemented in future clinical research and eventually being prescribed. Fields of particular interest are those aimed at promoting muscle health by preventing injury or combating muscle wasting and neurological or metabolic dysfunction due to aging or illness, or those serving in rehabilitation following trauma and/or surgery. [ABSTRACT FROM AUTHOR]

Despite the generalized use of photon-based radiation (i.e., gamma rays and X-rays) to treat different cancer types, particle radiotherapy (i.e., protons and carbon ions) is becoming a popular, and more effective tool to treat specific tumors due to the improved physical properties and biological effectiveness. Current scientific evidence indicates that conventional radiation therapy affects the tumor immunological profile in a particular manner, which in turn, might induce beneficial effects both at local and systemic (i.e., abscopal effects) levels. The interaction between radiotherapy and the immune system is being explored to combine immune and radiation (including particles) treatments, which in many cases have a greater clinical effect than any of the therapies alone. Contrary to localized, clinical irradiation, astronauts are exposed to whole body, chronic cosmic radiation, where protons and heavy ions are an important component. The effects of this extreme environment during long periods of time, e.g., a potential mission to Mars, will have an impact on the immune system that could jeopardize the health of the astronauts, hence the success of the mission. To this background, the purpose of this mini review is to briefly present the current knowledge in local and systemic immune alterations triggered by particle irradiation and to propose new lines of future research. Immune effects induced by particle radiation relevant to clinical applications will be covered, together with examples of combined radiotherapy and immunotherapy. Then, the focus will move to outer space, where the immune system alterations induced by cosmic radiation during spaceflight will be discussed. [ABSTRACT FROM AUTHOR]

As metabolic changes in human skeletal muscle after long-term (simulated) spaceflight are not well understood, this study examined the effects of long-term microgravity, with and without concurrent resistance exercise, on skeletal muscle oxidative and glycolytic capacity. Twenty-one men were subjected to 84 days head-down tilt bed rest with (BRE; n = 9) or without (BR; n = 12) concurrent flywheel resistance exercise. Activity and gene expression of glycogen synthase, glycogen phosphorylase (GPh), hexokinase, phosphofructokinase- 1 (PFK-1), and citrate synthase (CS), as well as gene expression of succinate dehydrogenase (SDH), vascular endothelial growth factor (VEFG), peroxisome proliferator-activated receptor gamma coactivator- 1 (PGC-1α), and myostatin, were analyzed in samples from m. vastus lateralis collected before and after bed rest. Activity and gene expression of enzymes controlling oxidative metabolism (CS, SDH) decreased in BR but were partially maintained in BRE. Activity of enzymes regulating anaerobic glycolysis (GPh, PFK-1) was unchanged in BR. Resistance exercise increased the activity of GPh. PGC-1α and VEGF expression decreased in both BR and BRE. Myostatin increased in BR but decreased in BRE after bed rest. The analyses of these unique samples indicate that long-term microgravity induces marked alterations in the oxidative, but not the glycolytic, energy system. The proposed flywheel resistance exercise was effective in counteracting some of the metabolic alterations triggered by 84-day bed rest. Given the disparity between gene expression vs. enzyme activity in several key metabolic markers, posttranscriptional mechanisms should be explored to fully evaluate metabolic adaptations to long-term microgravity with/without exercise countermeasures in human skeletal muscle. [ABSTRACT FROM AUTHOR]

The present study examined site-specific hamstring muscles use with functional magnetic resonance imaging (MRI) in elite soccer players during strength training. Thirty-six players were randomized into four groups, each performing either Nordic hamstring, flywheel leg-curl, Russian belt or the hip-extension conic-pulley exercise. The transverse relaxation time (T2) shift from pre- to post-MRI were calculated for the biceps femoris long (BFl) and short (BFs) heads, semitendinosus (ST) and semimembranosus (SM) muscles at proximal, middle and distal areas of the muscle length. T2 values increased substantially after flywheel leg-curl in all regions of the BFl (from 9±8 to 16±8%), BFs (41±6–71±11%), and ST (60±1–69±7%). Nordic hamstring induced a substantial T2 increase in all regions of the BFs (13±8–16±5%) and ST (15±7–17±5%). T2 values after the Russian belt deadlift substantially increased in all regions of the BFl (6±4–7±5%), ST (8±3–11±2%), SM (6±4–10±4%), and proximal and distal regions of BFs (6±6–8±5%). T2 values substantially increased after hip-extension conic-pulley only in proximal and middle regions of BFl (11±5–7±5%) and ST (7±3–12±4%). The relevance of such MRI-based inter- and intra-muscle use in designing more effective resistance training for improving hamstring function and preventing hamstring injuries in elite soccer players should be explored with more mechanistic studies. [ABSTRACT FROM AUTHOR]

Recent reports suggest that aerobic exercise may boost the hypertrophic response to short-term resistance training. This study explored the effects of an acute aerobic exercise bout on the transcriptional response to subsequent resistance exercise. Ten moderately trained men performed ~45 min cycling on one leg followed by 4 x 7 maximal knee extensions for each leg, 15 min later. Thus, one limb performed aerobic and resistance exercise (AE + RE) while the opposing leg did resistance exercise only (RE). Biopsies were obtained from the vastus lateralis muscle of each leg 3 h after the resistance exercise bout. Using DNA microarray, we analyzed differences [≥1.5-fold, false discovery rate (FDR) ≤10%] in gene expression profiles for the two modes of exercise. There were 176 genes up (127)- or downregulated (49) by AE + RE compared with RE. Among the most significant differentially expressed genes were established markers for muscle growth and oxidative capacity, novel cytokines, transcription factors, and micro-RNAs (miRNAs). The most enriched functional categories were those linked to carbohydrate metabolism and transcriptional regulation. Upstream analysis revealed that vascular endothelial growth factor, cAMP-response element-binding protein, Tet methylcytosine dioxygenase, and mammalian target of rapamycin were regulators highly activated by AE + RE, whereas JnK, NF-κβ, MAPK, and several miRNAs were inhibited. Thus, aerobic exercise alters the skeletal muscle transcriptional signature of resistance exercise to initiate important gene programs promoting both myofiber growth and improved oxidative capacity. These results provide novel insight into human muscle adaptations to diverse exercise modes and offer the very first genomic basis explaining how aerobic exercise may augment, rather than compromise, muscle growth induced by resistance exercise. [ABSTRACT FROM AUTHOR]

The unilateral lower limb suspension (ULLS) method was developed, introduced, and validated in the quest for a simple, effective, and highly reliable human analog to study the consequences of spaceflight on muscle size and function. Because withdrawal of weight bearing for no more than 2-3 days is sufficient to inflict disturbances in protein metabolism of postural muscles, it is imperative ULLS serves as a very powerful method to manifest skeletal muscle adaptations similar to those experienced in 0 g. Thus the rate of global muscle loss appears rather constant over the first 2 mo, amounting to about 2-3% per week. At the microscopic level, these changes are accompanied by a corresponding decrease in individual muscle fiber size. ULLS alters metabolism favoring more carbohydrate over fat substrate utilization. Altogether, these changes result in impaired work and endurance capacity of muscles being subjected to ULLS. Maximal voluntary force decreases out of proportion to the muscle loss, suggesting motor control is modified. Past reviews offer near exhaustive information on ULLS-induced responses with regard to the above changes. Hence, the current brief review describes more broadly the evolution of the ULLS model, from issues of subject recruitment and compliance control, to recent advances unraveling molecular mechanisms facilitating unloading-induced muscle wasting. Such knowledge is critical in designing future studies aimed at exploring and developing exercise countermeasures or other means to combat the debilitating effects on muscle experienced by astronauts during longhaul missions in Orbit. [ABSTRACT FROM AUTHOR]

Background: Resistance exercise (RE) improves neuromuscular function and physical performance after stroke. Yet, the effects of RE emphasizing eccentric (ECC; lengthening) actions on muscle hypertrophy and cognitive function in stroke patients are currently unknown. Thus, this study explored the effects of ECC-overload RE training on skeletal muscle size and function, and cognitive performance in individuals with stroke. Methods: Thirty-two individuals with chronic stroke (≥6 months post-stroke) were randomly assigned into a training group (TG; n = 16) performing ECC-overload flywheel RE of the more-affected lower limb (12 weeks, 2 times/week; 4 sets of 7 maximal closed-chain knee extensions; <2 min of contractile activity per session) or a control group (CG; n = 16), maintaining daily routines. Before and after the intervention, quadriceps femoris volume, maximal force and power for each leg were assessed, and functional and dual task performance, and cognitive functions were measured. Results: Quadriceps femoris volume of the more-affected leg increased by 9.4 % in TG. Muscle power of the more-affected, trained (48.2 %), and the less-affected, untrained limb (28.1 %) increased after training. TG showed enhanced balance (8.9 %), gait performance (10.6 %), dual-task performance, executive functions (working memory, verbal fluency tasks), attention, and speed of information processing. CG showed no changes. Conclusion: ECC-overload flywheel resistance exercise comprising 4 min of contractile activity per week offers a powerful aid to regain muscle mass and function, and functional performance in individuals with stroke. While the current intervention improved cognitive functions, the cause-effect relationship, if any, with the concomitant neuromuscular adaptations remains to be explored. Trial Registration: Clinical Trials NCT02120846. [ABSTRACT FROM AUTHOR]

Autophagy is a molecular process essential for the maintenance of cellular homeostasis, which appears to (i) decline with age and (ii) respond to physical exercise. In addition, recent evidence suggests a crosstalk between autophagy and toll-like receptor (TLR)-associated inflammatory responses. This study assessed the effects of aerobic exercise training on autophagy and TLR signaling in older subjects. Twenty-nine healthy women and men (age, 69.7 ± 1.0 year) were randomized to a training (TG) or a control (CG) group. TG performed an 8-week aerobic training program, while CG followed their daily routines. Peripheral blood mononuclear cells were isolated from blood samples obtained before and after the intervention, and protein levels of protein 1 light chain 3 (LC3), sequestosome 1 (p62/SQSTM1), beclin-1, phosphorylated unc-51-like kinase (ULK-1), ubiquitin-like autophagy-related (Atg)12, Atg16, and lysosome-associated membrane protein (LAMP)-2 were measured. TLR2 and TLR4 signaling pathways were also analyzed. Peak oxygen uptake increased in TG after the intervention. Protein expression of beclin-1, Atg12, Atg16, and the LC3II/I ratio increased following the training program (p < 0.05), while expression of p62/SQSTM1 and phosphorylation of ULK-1 at Ser757 were lower (p < 0.05). Protein content of TLR2, TLR4, myeloid differentiation primary response gen 88 (MyD88), and TIR domain-containing adaptor-inducing interferon (TRIF) were not significantly modified by exercise. The current data indicate that aerobic exercise training induces alterations in multiple markers of autophagy, which seem to be unrelated to changes in TLR2 and TLR4 signaling pathways. These results expand knowledge on exercise-induced autophagy adaptations in humans and suggest that the exercise type employed may be a key factor explaining the potential relationship between autophagy and TLR pathways. [ABSTRACT FROM AUTHOR]

This study assessed the effects of a resistance exercise training program on the inflammatory response associated with Toll-like receptor (TLR) 2 and TLR4 signaling pathways in senior participants. Twenty-six healthy subjects (age, 69.5 ± 1.3) were randomized to a training (TG; n = 16) or a control (CG; n = 10) group. TG performed an 8-week resistance training program, while CG followed their daily routines. Peripheral blood mononuclear cells were isolated from blood samples obtained before and after the intervention, and levels of proteins involved in the TLR2, TLR4, and myeloid differentiation primary response gene 88 (MyD88)-dependent and MyD88-independent pathways were analyzed. The inflammatory status was evaluated through messenger RNA (mRNA) and protein content of interleukin (IL)-10 and tumor necrosis factor alpha (TNF-α) and plasma levels of C-reactive protein (CRP). After the 8-week resistance training, TLR2 and TLR4 protein expression was reduced in TG. MyD88, p65, phospho-p38, TIR domain-containing adaptor inducing interferon (TRIF), IKKi/IKKε, phospho-interferon regulatory factor (IRF) 3, and phosho-IRF7 were also downregulated in TG after the intervention. The training program induced an increase of phospho-extracellular signal-regulated kinases 1 and 2 (ERK1/2) and Hsp70 and a reduction of Hsp60. While TNF-α mRNA and protein values remained unchanged in both TG and CG, IL-10 mRNA and protein content were upregulated in TG after the intervention. CRP values decreased in TG only. The increase in Hsp70 negatively correlated with TLR2 and TLR4 downregulation. These data suggest that resistance exercise may represent an effective tool to ameliorate the pro-inflammatory status of old participants through an attenuation of MyD88-dependent and MyD88-independent TLR2 and TLR4 signaling pathways. [ABSTRACT FROM AUTHOR]

Purpose: This study assessed markers of muscle damage and training adaptations to eccentric-overload flywheel resistance exercise (RE) in men and women. Methods: Dynamic strength (1 RM), jump performance, maximal power at different percentages of 1 RM, and muscle mass in three different portions of the thigh were assessed in 16 men and 16 women before and after 6 weeks (15 sessions) of flywheel supine squat RE training. Plasma creatine kinase (CK) and lactate dehydrogenase (LDH) concentrations were measured before, 24, 48 and 72 h after the first and the last training session. Results: After training, increases in 1 RM were somewhat greater (interaction P < 0.001) in men (25 %) than in women (20 %). Squat and drop jump height and power performance at 50, 60, 70 and 80 % of 1 RM increased after training in both sexes ( P < 0.05). Power improvement at 80 % of 1 RM was greater (interaction P < 0.02) in men than women. Muscle mass increased ~5 % in both groups ( P < 0.05). CK increased in men after the first training session ( P < 0.001), whereas the response in women was unaltered. In both sexes, LDH concentration was greater after the first training session compared with basal values ( P < 0.05). After the last session, CK and LDH remained at baseline in both groups. Conclusions: These results suggest that although improvements in maximal strength and power at high loads may be slightly greater for men, eccentric-overload RE training induces comparable and favorable gains in strength, power, and muscle mass in both men and women. Equally important, it appears muscle damage does not interfere with the adaptations triggered by this training paradigm. [ABSTRACT FROM AUTHOR]

As aerobic exercise (AE) may interfere with adaptations to resistance exercise (RE), this study explored acute and chronic responses to consecutive AE (∼45 min cycling) and RE (4 × 7 maximal knee extensions) vs. RE only. Ten men performed acute unilateral AE + RE interspersed by 15 min recovery. The contralateral leg was subjected to RE. This exercise paradigm was then implemented in a 5-wk training program. Protein phosphorylation, gene expression, and glycogen content were assessed in biopsies obtained from the vastus lateralis muscle of both legs immediately before and 3 h after acute RE. Quadriceps muscle size and in vivo torque were measured, and muscle samples were analyzed for citrate synthase activity and glycogen concentration, before and after training. Acute AE reduced glycogen content (32%; P < 0.05) and increased (P < 0.05) phosphorylation of AMPK (1.5-fold) and rpS6 (1.3-fold). Phosphorylation of p70S6K and 4E-BP1 remained unchanged. Myostatin gene expression was downregulated after acute AE + RE but not RE. Muscle size showed greater (P < 0.05) increase after AE + RE (6%) than RE (3%) training. Citrate synthase activity (18%) and endurance performance (22%) increased (P < 0.05) after AE + RE but not RE. While training increased (P < 0.05) in vivo muscle strength in both legs, normalized and concentric torque increased after RE only. Thus AE activates AMPK, reduces glycogen stores, and impairs the progression of concentric force, yet muscle hypertrophic responses to chronic RE training appear not to be compromised. [ABSTRACT FROM AUTHOR]

BACKGROUND: Although resistance training adaptations in multiple sclerosis (MS) patients have been described, the detraining response in this population is largely unknown. OBJETIVE: This study was designed to evaluate the effects of a 12-week detraining period on muscle strength (isometric and endurance) and muscle power of multiple sclerosis (MS) patients that had previously carried out a 12-week resistance training program (RTP). METHODS: Forty-two MS patients were randomly assigned into two groups: an exercise group (EG) that performed a 12-week RTP for the knee extensors muscles; and a control group (CG), that did not perform any specific training. Knee extension maximal voluntary isometric contraction (MVIC), muscle power and muscle endurance were evaluated before and after the RTP, as well as 12 weeks after training completion. A strain gauge was used to measure the maximal voluntary isometric contraction and muscle power was assessed with a linear encoder. Muscle endurance was interpreted as the number of repetitions that a patient could perform in a single set of knee extension exercise. RESULTS: The EG increased MVIC and muscle power after the training period, although the training did not affect muscle endurance. After 12 weeks of detraining, MVIC returned to pre-training values but muscle power was still greater than pre-training values in the EG. The CG did not present any change in the variables measured during the intervention. CONCLUSIONS: A 12-week RTP improved MVIC and muscle power in MS patients. Additionally, 12 weeks of detraining blunted strength training adaptations in MS patients, although muscle power training adaptations were still evident after the detraining period. [ABSTRACT FROM AUTHOR]

This study assessed the inflammatory response mediated by the toll-like receptor 4 (TLR4) signaling pathway after acute eccentric exercise before and after an eccentric training program in women. Twenty women performed two acute eccentric bouts using a squat machine over a ∼9 week interval. The training group (TG) carried out an eccentric training program during 6 weeks, while the control group (CG) did not follow any training. Protein content of markers involved in the TLR4-mediated activation of several nuclear transcription factors, such as nuclear factor βB (NF-βB), and interferon regulatory transcription factor 3 (IRF3), was analyzed. The inflammatory response after the first acute bout was similar between TG and CG, showing an upregulation of all the markers analyzed, with the exception of IRF3. After the second bout, the upregulation of TLR4 signaling pathway was blunted in TG, but not in CG, through both the myeloid differentiation factor 88- and toll/interleukin-1 receptor domain containing adapter inducing interferon-β-dependent pathways. These results highlight the role of the TLR4 in controlling the exercise-induced inflammatory response in young women. More importantly, these data suggest eccentric training may help to prevent TLR4 activation principally through NF-βB, and perhaps IRF3, downstream signaling in this population. [ABSTRACT FROM AUTHOR]

The article presents the results of a study on how the physiological and technical performance of prepubescent male soccer players evolve. Factors contributing to success in soccer are considered. The assessment of technical skills, maximum voluntary isometric contraction of lower limbs, jumping ability and endurance is discussed. Results suggest that most physical capacities are enhanced during the first stages of puberty.

Background: Resistance exercise comprising eccentric (ECC) muscle actions enhances muscle strength and function to aid stroke patients in conducting daily tasks. The purpose of this study was to assess the efficacy of a novel ECC-overload flywheel resistance exercise paradigm to induce muscle and functional performance adaptations in chronic stroke patients. Methods: Twelve patients (~8 years after stroke onset) performed 4 sets of 7 coupled concentric (CON) and ECC actions using the affected limb on a flywheel leg press (LP) device twice weekly for 8 weeks. Maximal CON and ECC isokinetic torque at 30, 60 and 90°/s, isometric knee extension and LP force, and CON and ECC peak power in LP were measured before and after training. Balance (Berg Balance Scale, BBS), gait (6-Min Walk test, 6MWT; Timed-Up-and-Go, TUG), functional performance (30-s Chair-Stand Test, 30CST), spasticity (Modified Ashworth Scale) and perceived participation (Stroke Impact Scale, SIS) were also determined. Results: CON and ECC peak power increased in both the trained affected (34 and 44%; P < 0.01), and the untrained, non-affected leg (25 and 34%; P < 0.02). Power gains were greater (P = 0.008) for ECC than CON actions. ECC isokinetic torque at 60 and 90°/s increased in the affected leg (P < 0.04). The increase in isometric LP force for the trained, affected leg across tests ranged 10-20% (P < 0.05). BBS (P = 0.004), TUG (P = 0.018), 30CST (P = 0.024) and SIS (P = 0.058) scores improved after training. 6MWT and spasticity remained unchanged. Conclusions: This novel, short-term ECC-overload flywheel RE training regime emerges as a valid, safe and viable method to improve muscle function, balance, gait and functional performance in men and women suffering from chronic stroke. [ABSTRACT FROM AUTHOR]