Resistance Exercise Sessions Comprising Multijoint vs. Single-Joint Exercises Result in Similar Metabolic and Hormonal Responses, But Distinct Levels of Muscle Damage in Trained Men.

ABSTRACT: Barbosa, PH, Bueno de Camargo, JB, Jonas de Oliveira, J, Reis Barbosa, CG, Santos da Silva, A, Dos-Santos, JW, Verlengia, R, Barreira, J, Braz, TV, and Lopes, CR. Resistance exercise sessions comprising multijoint vs. single-joint exercises result in similar metabolic and hormonal responses, but distinct levels of muscle damage in trained men. J Strength Cond Res 38(5): 842-847, 2024-Resistance-type exercise (RE) elicits distinct acute metabolic and hormonal responses, which can be modulated by the manipulation of training variables. The purpose of this study was to compare the metabolic (blood lactate and estimated lactic anaerobic system energy expenditure) and hormonal (growth hormone [GH]) responses to RE sessions composed exclusively of multijoint (MULTI) or single-joint (SINGLE) exercises. Assessments of creatine kinase (CK) levels were also performed. In a crossover design, 10 recreationally resistance-trained men (age: 26.9 ± 3.0 years, total body mass: 83.2 ± 13.8 kg; height: 176 ± 7.0 cm; training experience: 5.5 ± 2.4 years) were randomly submitted to both protocols. Blood collections were made pre, 3 minutes after, and 36 hours after each experimental session. No significant difference between MULTI vs. SINGLE was observed for the rises in blood lactate (p = 0.057) and GH (p = 0.285) levels. For CK, a significant difference between the protocols was noted, in which MULTI resulted in significant rises after 3 minutes (p = 0.017) and 36 hours (p = 0.043) compared with SINGLE. In conclusion, the findings of this study suggest that resistance-trained individuals display similar metabolic and hormonal responses when performing MULTI and SINGLE exercise protocols. Also, RE sessions comprising MULTI exercises induce a higher magnitude of muscle damage, which may require a longer recovery period compared with SINGLE.

Muscle Hypertrophy Responses to Changes in Training Volume: A Retrospective Analysis.

This study assessed associations between changes in the weekly number of sets performed and the percentage change in muscle thickness of the biceps (MTBB) and triceps (MTTB) brachii muscles. Through a retrospective analysis, sixty-eight resistance-trained subjects that participated in previous studies had their previous training volumes analyzed and compared to the volume imposed during each individual study. The relationship between variables was determined through Spearman correlation and a k-cluster analysis was performed to subdivide the participants into three groups and classified as:<0%; 0-50%, and >50% increase in the number of sets for both muscle groups. Moderate and weak correlations were observed between the alterations in training volume and changes in MTBB (rs=0.44, p=0.001) and MTTB (rs=0.35, p=0.002), respectively. A significant difference was noted between<0% to >50% for MTBB and MTTB (p=0.017; p=0.042, respectively), while no significant difference was observed between<0% to 0-50% and 0-50% to >50% (both p >0.05) for both muscle groups. In conclusion, muscle hypertrophy of the upper limbs is only weakly to moderately associated with changes in training volume of trained subjects.

Resistance-Trained Individuals Can Underestimate the Intensity of the Resistance Training Session: An Analysis Among Sexes, Training Experience, and Exercises.

ABSTRACT: Dos Santos, WM, Tavares Junior, AC, Braz, TV, Lopes, CR, Brigatto, FA, and Dos Santos, JW. Resistance-trained individuals can underestimate the intensity of the resistance training session: An analysis among genders, training experience, and exercises. J Strength Cond Res 36(6): 1506-1510, 2022-Resistance training (RT) promotes improvements in healthy parameters for young to elderly adults and athletes' performance. Strength and muscle mass improvements are dependent on exercise intensity. This study verifies whether 53 healthy young adults underestimate exercise intensity in 3 different exercises, such as bench press (BP), biceps curl (BC), and leg press 45° (LP). Researchers asked the subjects "How much load do you use to perform 10 repetitions in this exercise usually in workout routines?" in each exercise. Individuals warmed up and then performed as many repetitions as possible until they reached the concentric failure. Deviations from data normality were found by using Levene's test; the number of repetitions per exercise within sex was tested by using Friedman's test and Conover's post hoc and Kruskal-Wallis tests to compare the number of repetitions between sex and RT experience. We correlated the number of repetitions and training experience using the Spearman test. The number of repetitions for both groups (male and female) is greater than 8-12 repetitions for BC and LP and BP of the female group, except for men who perform around 8-12 repetitions on BP. Frequency of maximal repetitions reached for 8-12 repetitions for women was 12% for BP, 28% for BC, and 28% for LP. The frequency men reached was 46.5% for BP, 14.3% for BC, and 14.3% for LP. Training experience did not influence the number of repetitions reached. Resistance training practitioners underestimate exercise load (56% of total sample) to be independent of experience. Women underestimate exercise load more than men. Based on the present results, it is possible to state that RT should not be prescribed considering a predefined number of repetitions and a linked percentage of loads, without the guidance for frequent adjustments of loads, according to the exercise performed.

Dissociated Time Course of Indirect Markers of Muscle Damage Recovery Between Single-Joint and Multi-joint Exercises in Resistance-Trained Men.

ABSTRACT: de Camargo, JBB, Braz, TV, Batista, DR, Germano, MD, Brigatto, FA, and Lopes, CR. Dissociated time course of indirect markers of muscle damage recovery between single-joint and multi-joint exercises in resistance-trained men. J Strength Cond Res 36(8): 2089-2093, 2022-This study compared the time course of indirect markers of muscle damage after multi-joint and single-joint exercises. Ten resistance-trained men (years: 26.9 ± 3.0; total body mass: 83.2 ± 13.8 kg; height: 176 ± 7.0 cm; resistance training [RT] experience: 5.5 ± 2.4 years; RT frequency: 5.3 ± 0.7 sessions; relative squat 1 repetition maximum: 1.4 ± 0.3) performed, in a random order, 5 sets of 8 repetition maximum of the back squat (BS) and knee extension (KE) exercises. Rectus femoris muscle thickness (MT RF ), leg circumference (LC), and muscle soreness (MS) were recorded at baseline (pre), 0, 12, 24, and 36 hours after each exercise protocol. There was a significant increase ( p < 0.05) in dependent variables at every time point after both the multi-joint and single-joint exercise sessions. However, MT RF and LC were greater at 0 and 36 hours, and MS was greater at 24 and 36 hours after BS when compared with KE (all p < 0.05). This study shows that resistance-trained individuals can experience significant higher levels of indirect markers of muscle damage when performing a multi-joint lower-limb exercise compared with a single one.

ARF6 protects sister chromatid cohesion to ensure the formation of stable kinetochore-microtubule attachments.

Sister chromatid cohesion, facilitated by the cohesin protein complex, is crucial for the establishment of stable bipolar attachments of chromosomes to the spindle microtubules and their faithful segregation. Here, we demonstrate that the GTPase ARF6 prevents the premature loss of sister chromatid cohesion. During mitosis, ARF6-depleted cells normally completed chromosome congression. However, at the metaphase plate, chromosomes failed to establish stable kinetochore-microtubule attachments because of the impaired cohesion at centromeres. As a result, the spindle assembly checkpoint (SAC) was active and cyclin B ubiquitylation and degradation were blocked. Chromosomes and/or chromatids in these cells scattered gradually from the metaphase plate to the two poles of the cell or remained blocked at the metaphase plate for hours. Our study demonstrates that the small GTP-binding protein ARF6 is essential for maintaining centromeric cohesion between sister chromatids, which is necessary for the establishment of stable k-fibres, SAC satisfaction and the onset of anaphase.

ß-Arrestin-mediated Angiotensin II Signaling Controls the Activation of ARF6 Protein and Endocytosis in Migration of Vascular Smooth Muscle Cells.

Angiotensin II (Ang II) is a vasopressive hormone but is also a potent activator of cellular migration. We have previously shown that it can promote the activation of the GTPase ARF6 in a heterologous overexpressing system. The molecular mechanisms by which receptors control the activation of this small G protein remain, however, largely unknown. Furthermore, how ARF6 coordinates the activation of complex cellular responses needs to be further elucidated. In this study, we demonstrate that Ang II receptors engage ß-arrestin, but not Gq, to mediate ARF6 activation in HEK 293 cells. To further confirm the key role of ß-arrestin proteins, we overexpressed ß-arrestin2-(1-320), a dominant negative mutant known to block receptor endocytosis. We show that expression of this truncated construct does not support the activation of the GTPase nor cell migration. Interestingly, ß-arrestin2 can interact with the ARF guanine nucleotide exchange factor ARNO, although the C-terminally lacking mutant does not. We finally examined whether receptor endocytosis controlled ARF6 activation and cell migration. Although the clathrin inhibitor PitStop2 did not impact the ability of Ang II to activate ARF6, cell migration was markedly impaired. To further show that ARF activation regulates key signaling events leading to migration, we also examined MAPK activation. We demonstrate that this signaling axis is relevant in smooth muscle cells of the vasculature. Altogether, our findings show for the first time that Ang II receptor signaling to ß-arrestin regulates ARF6 activation. These proteins together control receptor endocytosis and ultimately cell migration.

Comparison Between Pre-Exhaustion and Traditional Exercise Order on Muscle Activation and Performance in Trained Men.

The purpose of this study was to measure the acute effects of pre-exhaustion vs. traditional exercise order on neuromuscular performance and sEMG in trained men. Fourteen young, healthy, resistance trained men (age: 25.5 ± 4.0 years, height: 174.9 ± 4.1 cm, and total body mass: 80.0 ± 11.1 kg) took part of this study. All tests were randomized and counterbalanced for all subjects and experimental conditions. Volunteers attended one session in the laboratory. First, they performed ten repetition maximum (10RM) tests for each exercise (bench press and triceps pushdown) separately. Secondly, they performed all three conditions at 10RM: pre-test (bench press and triceps pushdown, separately), pre-exhaustion (triceps pushdown+bench press, PE) and traditional (bench press+triceps pushdown, TR), and rested 30 minutes between conditions. Results showed that pre-test was significantly greater than PE (p = 0.031) but not different than TR, for total volume load lifted. There was a significant difference between the pre-test and the time-course of lactate measures (p = 0.07). For bench press muscle activity of the pectoralis major, the last repetition was significantly greater than the first repetition (pre-test: p = 0.006, PE: p = 0.016, and TR: p = 0.005). Also, for muscle activity of the triceps brachii, the last repetition was significantly greater than the first repetition (pre-test: p = 0.001, PE: p = 0.005, and TR: p = 0.006). For triceps pushdown, muscle activity of the triceps brachii, the last repetition was significantly greater than the first repetition (pre-test: p = 0.006, PE: p = 0.016, and TR: p = 0.005). For RPE, there were no significant differences between PE and TR (p = 0.15). Our results suggest that exercise order decreases repetitions performed, however, neuromuscular fatigue, lactate, and RPE are not impacted. The lack of difference in total volume load lifted between PE and TR might explain, at least in part, the similar metabolic and perceptual responses. Key pointsThe effects of different exercise order schemes (e.g. PE and TR) on muscle activity and strength performance indicated that similar responses were observed when comparing these schemes.Strength and conditioning coaches should consider these results when prescribing resistance training programs.The primary target (e.g. muscle group) of the training session should trained first, when fatigue level low, in order to maximize training outcomes.

Unilateral plantar flexors static-stretching effects on ipsilateral and contralateral jump measures.

The aim of this study was to evaluate the acute effects of unilateral ankle plantar flexors static-stretching (SS) on the passive range of movement (ROM) of the stretched limb, surface electromyography (sEMG) and single-leg bounce drop jump (SBDJ) performance measures of the ipsilateral stretched and contralateral non-stretched lower limbs. Seventeen young men (24 ± 5 years) performed SBDJ before and after (stretched limb: immediately post-stretch, 10 and 20 minutes and non-stretched limb: immediately post-stretch) unilateral ankle plantar flexor SS (6 sets of 45s/15s, 70-90% point of discomfort). SBDJ performance measures included jump height, impulse, time to reach peak force, contact time as well as the sEMG integral (IEMG) and pre-activation (IEMGpre-activation) of the gastrocnemius lateralis. Ankle dorsiflexion passive ROM increased in the stretched limb after the SS (pre-test: 21 ± 4° and post-test: 26.5 ± 5°, p < 0.001). Post-stretching decreases were observed with peak force (p = 0.029), IEMG (P<0.001), and IEMGpre-activation (p = 0.015) in the stretched limb; as well as impulse (p = 0.03), and jump height (p = 0.032) in the non-stretched limb. In conclusion, SS effectively increased passive ankle ROM of the stretched limb, and transiently (less than 10 minutes) decreased muscle peak force and pre-activation. The decrease of jump height and impulse for the non-stretched limb suggests a SS-induced central nervous system inhibitory effect. Key pointsWhen considering whether or not to SS prior to athletic activities, one must consider the potential positive effects of increased ankle dorsiflexion motion with the potential deleterious effects of power and muscle activity during a simple jumping task or as part of the rehabilitation process.Since decreased jump performance measures can persist for 10 minutes in the stretched leg, the timing of SS prior to performance must be taken into consideration.Athletes, fitness enthusiasts and therapists should also keep in mind that SS one limb has generalized effects upon contralateral limbs as well.

Chronic Effects of Inter-Set Static Stretching on Morphofunctional Outcomes in Recreationally Resistance-Trained Male and Female.

Purpose: The purpose of this study was to compare the effects of resistance training (RT) with inter-set static stretching (IS) versus traditional RT (TRT) on morphofunctional outcomes in recreationally resistance-trained male and female. Methods: Twenty-two recreationally-trained subjects were allocated to IS group (n = 12) or TRT (n = 10) and completed eight weeks of RT. The only difference between the groups was that IS group included static stretching between sets, while the TRT rested between the sets. Ultrasound images, dynamic and isometric strength tests for the elbow flexors and elbow extensors were evaluated pre- and post-intervention period. Results: Total training volume (TTV) was greater in TRT than IS (p = .031). TRT and IS caused similar increases in maximal dynamic and isometric strength. Fascicle length of the brachialis increased following TRT (p = .033); muscle thickness and the pennation angle of the distal portion of the triceps brachii increased following IS (p = .035 and p = .007, respectively). There were no significant changes in thickness and architecture for biceps brachii in either group. There were no significant differences between groups for any muscle strength and morphology outcome. Conclusion: IS negatively affects TTV but does not affect muscle strength and architecture of recreationally resistance-trained male and female.

An Examination of Two Resistance Training Frequency Techniques in Morphological and Functional Adaptations of the Patellar Tendon.

The aim of the present study was to investigate the effects of distinct resistance training frequencies with equated-volume conditions in morphological and functional adaptations of the patellar tendon. Twenty-seven recreationally resistance-trained subjects (men [n=17] and women [n=10]) (age: 20.8 ± 1.9 years [range 18 to 25 years]; height: 1.73 ± 9.8 cm; total body mass = 73.2 ± 11.7 kg; previous RT experience = 3.3 ± 1.6 years) volunteered to participate in this study. A total of 16 training sessions were performed during the study period. Each subject's leg was randomly allocated to one of the following training protocols: 2 training sessions/week (2x) or 4 training sessions/week (4x). Measurements of tendon cross sectional area (CSA) and length were performed through ultrasound imaging. One repetition maximum test was performed to assess patellar tendon force (PTF) unilaterally. For CSA (2x: Δ= -1.3%; 4x: Δ= -0.9%), and length (2x: Δ= -0.4%; 4x: Δ= 1.2%), no significant differences were observed within or between conditions (all p > 0.05). For PTF, a significant difference was observed between conditions (mean difference = 0.05 [-125 to 224] p= 0.001). In conclusion, the leg extension exercise performed 2 vs 4x/week induces similar patellar tendon morphological responses. However, the increase in force seems to be enhanced by a lower weekly training frequency associated with a longer intervention period.

Manipulating Resistance Training Variables to Induce Muscle Strength and Hypertrophy: A Brief Narrative Review.

The regular practice of resistance training (RT) has been shown to induce relevant increases in both muscle strength and size. In order to maximize these adaptations, the proper manipulation of RT variables is warranted. In this sense, the aim of the present study was to review the available literature that has examined the application of the acute training variables and their influence on strength and morphological adaptations of healthy young adults. The information presented in this study may represent a relevant approach to proper training design. Therefore, strength and conditioning coaches may acquire a fundamental understanding of RT-variables and the relevance of their practical application within exercise prescription.

Chronic Effects of Heavy Load Activity Performed Before Resistance Training Sessions on the Physical Performance of Youth Soccer Players.

The adoption of resistance training (RT) programs has been shown to positively influence sports performance-related parameters. However, the chronic effects of maximal strength protocols on the performance of soccer players are not completely investigated. The aim of this study was to evaluate the effects of performing two repetition maximum (2RM) before a resistance training session on the physical performance of youth soccer players. Seventeen players (under-20 category) were allocated in one of the following groups: 2RM + resistance training group (2RM + RT, n = 8) and resistance training group (RTG, n = 9). Both groups performed the same RT protocol during experimental weeks. However, the 2RM + RT performed 1 set of 2RM for 4 exercises, previously to RT protocol. Pre and post intervention period, one repetition maximum of the back squat exercise (1RMSQUAT), sprint time (15m-sprint test), countermovement jump (CMJ), repeated sprint ability (RSABEST and RSAMEAN), and yo-yo intermittent recovery test level-2 (YYIRT2) were assessed. Total load lifted (TLL) during the experimental weeks was also collected. Significant increases in 1RMSQUAT (2RM + RT: +45.1%, d = 4.40; RTG: +32.3%, d = 1.84), 15m sprint (2RM + RT: -9.0%, d = 7.9; RTG: -8.8%%, d = 3.2), CMJ (2RM + RT: +2.3%, d = 0.17; RTG: +0.8%, d = 0.07), RSABEST (2RM + RT: -2.4%, d = 0.6; RTG: -2.3%, d = 1.04), RSAMEAN (2RM + RT: -2.9%, d = 1.33; RTG: -3.4%, d = 1.78), YYIRT2 (2RM + RT: +12.0%, d = 0.82; RTG: +12.1%, d = 0.63) (all p < 0,05) were observed for both groups on pre to post-intervention periods, with no significant difference between groups. Therefore, the 2RM + RT protocol did not promote additional increase on performance of young soccer players.

Beta-alanine Supplementation for Four Weeks Increases Volume Index and Reduces Perceived Effort of Resistance-trained Men: A Pilot Study.

The aim of the present study was to assess the short-term effects of four weeks of beta-alanine supplementation (BA) (6.4 g/day) on the total volume performed and perceived effort of resistance-trained individuals. Sixteen trained men (age: 27.3 ± 5.0 years, height: 1.78 ± 0.1 cm, total body mass: 84.3 ± 8.4 kg, RT experience: 5.9 ± 3.3 years) were allocated in one of the following groups: BA or Placebo (PLA). In addition, during the same period, participants were submitted to a resistance training program. Volume index (VI) and the rate of perceived exertion (RPE) were collected during the experimental period for both groups. Significant increases from the first to the last intervention week in VI were observed only for BA (+6.5%, d = 0.61, p = 0.04). In addition, supplementation induced a lower mean RPE (BA: 8.8 ± 0.5 AU vs. PLA: 9.4 ± 0.3 AU, p = 0.02). In conclusion, four weeks of BA supplementation were able to increase resistance-training volume without affecting the perceived effort of trained men.

Order of Resistance Training Cycles to Develop Strength and Muscle Thickness in Resistance-Trained Men: A Pilot Study.

The aim of the present study was to assess the chronic effects of different order of resistance training cycles on strength and muscle thickness of recreationally resistance-trained men. The study sample was composed of 16 healthy men (age: 25.0 ± 3.8 years, height: 1.77 ± 7.6 cm, total body mass: 81.7 ± 10.4 kg, RT experience: 4.6 ± 0.7 years, relative bench press one repetition maximum: 1.2 ± 0.1, relative squat one-repetition maximum: 1.5 ± 0.2). According to baseline maximal strength, participants were allocated in one of the following groups: Maximal Strength-Strength Endurance (MS-SE) (six weeks of a maximal strength cycle followed by six weeks of a strength endurance cycle); Strength Endurance -Maximal Strength (MS-SE) (six weeks of a strength endurance cycle followed by six weeks of a maximal strength cycle). The following measurements were performed in the pre and post intervention periods: one-repetition maximum (1RM) on parallel back squat and bench press exercises, muscle thickness evaluation of biceps brachialis (MTBB), triceps brachialis (MTTB), and vastus lateralis (MTVL) by ultrasonography. Total load lifted (TLL) and Internal training load (ITL) were also assessed. Both groups presented significant increases in bench press (MS-SE p = 0.001, SE-MS p = 0.003) and half squat (MS-SE p = 0.004, SE-MS p = 0.001) 1RM, MTBB (MS-SE p = 0.020, SE-MS p = 0.005) and MTTB (MS-SE p = 0.001, SE-MS p = 0.001). For MTVL, a significant increase was observed only for MS-SE group (MS-SE p = 0.032, SE-MS p = 0.143). No significant difference between groups was observed for any strength or morphological outcomes. In conclusion, both MS-SE and SE-MS training cycles are effective strategies to enhance resistance training adaptations in trained men.

Acute Effects of Foam Rolling on Cycling Performance: A Randomized Cross-Over Study.

Acute foam rolling protocols may increase range of motion without a negative impact on muscle performance. The main purpose of the present study was to investigate the acute effects of foam rolling on cycling performance (mean power and maximal power), affect and perceived exertion. A secondary aim was to assess the effect of foam rolling on post-exercise muscle soreness. In a random order, ten recreationally trained cyclists (age: 26 ± 5 years; height 1.76 ± 0.06 m; total body mass 78.3 ± 19.8 kg; cycling experience: 5.6 ± 5.3 years; 4.1 ± 1.3 cycling sessions per week and 1.4 ± 1.4 strength sessions per week) were submitted to the following experimental conditions (separated by one week) before performing a three-minute, all-out cycling test: foam rolling or control. During foam rolling protocol, participants were instructed to roll back and forth on one leg and to place the opposite leg crossed over, from the proximal to the distal portion of the rectus femoris and vastus lateralis during one set of sixty seconds for each muscle group. Feeling scale (10 min pre and post-test), CR-10 scale of perceived exertion (ten-minute post-test), pressure pain threshold (pre and 24 h post-test) and mean/maximal power were assessed. No significant differences were observed between conditions for mean and maximal power, affect, perceived exertion, and pressure pain threshold (all p > 0.05). In conclusion, a pre-exercise acute session of self-myofascial release does not improve performance and post-exercise muscle soreness of recreationally trained cyclists.

Methods to Investigate the ß-Arrestin-Mediated Control of ARF6 Activation to Regulate Trafficking and Actin Cytoskeleton Remodeling.

ADP-ribosylation factors (ARF) are GTPases that act to control the activation of numerous signaling events and cellular responses. The ARF6 isoform, present at the plasma membrane, can be activated by the angiotensin II type 1 receptor (AT1R), a process dependent upon ß-arrestin recruitment to the activated receptor. Here, we describe classical methods used to assess ß-arrestin-dependent activation of ARF6 following agonist stimulation of cells. In addition, because ARF6 and ß-arrestin can form a complex, we describe the procedures used to detect the interaction of ß-arrestin with this GTPase.

Acute Effects of the New Method Sarcoplasma Stimulating Training Versus Traditional Resistance Training on Total Training Volume, Lactate and Muscle Thickness.

Background: Trained subjects have difficulty in achieving continued results following years of training, and the manipulation of training variables through advanced resistance training (RT) methods is widely recommended to break through plateaus. Objective: The purpose of the present study was to compare the acute effects of traditional RT (TRT) versus two types of sarcoplasma stimulating training (SST) methods on total training volume (TTV), lactate, and muscle thickness (MT). Methods: Twelve trained males (20.75 ± 2.3 years; 1.76 ± 0.14 meters; body mass = 79.41 ± 4.6 kg; RT experience = 4.1 ± 1.8 years) completed three RT protocols in a randomly sequenced order: TRT, SST contraction type (SST-CT), or SST rest interval variable (SST-RIV) with 7 days between trials in arm curl (elbow flexors) and triceps pulley extension (elbow extensors) performed on the same day. Results: The SST groups displayed greater acute biceps and triceps brachii (TB) MT versus the TRT session, with no difference in lactate levels between them. The SST-CT resulted in greater biceps and TB MT versus the SST-RIV session. The TTV was greater for the TRT session versus the SST sessions, except in the case of the elbow flexors (no difference was observed between TRT and SST-CT), and higher for the SST-CT versus the SST-RIV. Conclusion: Trained subjects may benefit from using the SST method as this method may offer a superior MT stimulus and reduced training time, even with a lower TTV.

ARF GTPases control phenotypic switching of vascular smooth muscle cells through the regulation of actin function and actin dependent gene expression.

Vascular smooth muscle cells (VSMC) can exhibit a contractile or a synthetic phenotype depending on the extracellular stimuli present and the composition of the extracellular matrix. Uncontrolled activation of the synthetic VSMC phenotype is however associated with the development of cardiovascular diseases. Here, we aimed to elucidate the role of the ARF GTPases in the regulation of VSMC dedifferentiation. First, we observed that the inhibition of the activation of ARF proteins with SecinH3, a blocker of the cytohesin ARF GEF family, reduced the ability of the cells to migrate and proliferate. In addition, this inhibitor also blocked expression of sm22α and αSMA, two contractile markers, at the transcription level impairing cell contractility. Specific knockdown of ARF1 and ARF6 showed that both isoforms were required for migration and proliferation, but ARF1 only regulated contractility through sm22α and αSMA expression. Expression of these VSMC markers was correlated with the degree of actin polymerization. VSMC treatment with SecinH3 as well as ARF1 depletion was both able to block the formation of stress fibres and focal adhesions, demonstrating the role of this GTPase in actin filament formation. Consequently, we observed that both treatments increased the ratio of G-actin to F-actin in these cells. The elevated amounts of cytoplasmic G-actin, acting as a signaling intermediate, blocked the recruitment of the Mkl1 (MRTF-A) transcription factor in the nucleus, demonstrating its involvement in the regulation of contractile protein expression. Altogether, these findings show for the first time that ARF GTPases are actively involved in VSMC phenotypic switching through the regulation of actin function in migration and proliferation, and the control of actin dependent gene regulation.

Water exercise in coronary artery disease patients, effects on heart rate variability, and body composition: A randomized controlled trial.

BACKGROUND AND PURPOSE: It is important to assess the effectiveness and efficiency of water-based training programs in order to prescribe it as an alternative in cardiac rehabilitation for patients who have coronary artery disease (CAD). In these patients, autonomic dysfunction is an important physiological change strongly associated with adverse outcomes, morbidity, and mortality. Given that the beneficial effects of physical training in CAD patients have been traditionally evidenced with programs involving land-based aerobic exercises, this study aims to evaluate the effects of water aerobic exercise training (WAET) on the autonomic modulation of heart rate (HR) and body composition, in the rehabilitation of CAD patients. METHODS: Twenty-six male subjects with CAD were randomly divided into a training group (n = 14), submitted to the WAET, and a control group (n = 12). The WAET consisted of 3 weekly sessions on alternate days, totalling 48 sessions. The analysis of HR variability was used to evaluate the autonomic modulation of HR, from the recording of R-R intervals for 15 min, at rest in the supine position, and the body composition was evaluated through the bioelectrical impedance analysis. RESULTS: Only the training group participants had improvement in the HR variability indices; patterns without variation decreased (0V, p = .005) and an increase of patterns of two different variations (p < .001), Shannon entropy (p = .02), and normalized conditional entropy (p = .03), whereas the control group had an increase of 0V (p = .04) and a decrease of normalized conditional entropy (p = .01). All body composition variables remained unchanged. CONCLUSIONS: The WAET protocol improved the cardiac autonomic modulation of patients with CAD and can be considered as exercise training strategy in cardiac rehabilitation programs.

Effects of resistance training on consecutive and non-consecutive days on hormonal, neuromuscular and morphological responses in recreationally trained men / Efeitos do treinamento de força em dias consecutivos e não consecutivos nas respostas hormonal, neuromuscular e morfológica em homens treinados recreacionalmente

abstract The purpose of the present study was to investigate the effect of two recovery periods between consecutive and non-consecutive days in strength training sessions on hormonal, neuromuscular and morphological variables in recreationally trained men. Nineteen young men completed the study and were randomly divided into two groups: 24R, 24-hour recovery group (n = nine) and 72R, 72-hour recovery group (n = ten). The strength training program (RT) lasted six weeks with two serial routines, with a weekly frequency of four times. The saliva sample was collected once a week in the morning to determine salivary testosterone. The 1RM, jump against movement and body composition tests were performed in the pre- and post-training periods. As for salivary testosterone, there was no significant effect with respect to time and between groups. Both groups improved maximal strength in terms of intervention time in the barbell bench press and in the leg press 45º, not differing between groups and body composition showed significant interaction in time to body fat percentage ∆% = -14.6 ± 10.0 (24R) and -17.2 ± 10.9 (72R); p = 0.00, fat mass ∆% = -13, 7 ± 9.2 (24R) and -18.2 ± 13.0 (72R); p = 0.00 and fat-free mass ∆% = 3.5 ± 2.7 (24R) and 2.5 ± 2 .8 (72R), p = 0.00. The recovery periods 24 and 72 hours between sessions induced similar responses in the parameters investigated in recreationally strength-trained men.

resumo O objetivo do presente estudo foi investigar o efeito de dois períodos de recuperação entre dias consecutivos e não consecutivos em sessões de treinamento de força sobre variáveis hormonais, neuromusculares e morfológicas em homens treinados recreacionalmente. Dezenove homens jovens completaram o estudo e foram divididos aleatoriamente em dois grupos: 24R, grupo de recuperação de 24 horas (n = nove) e 72R, grupo de recuperação de 72 horas (n = dez). O programa de treinamento de força (TF) durou seis semanas com duas rotinas seriadas, com frequência semanal de quatro vezes. A amostra de saliva foi coletada uma vez por semana no período da manhã para determinação da testosterona salivar. Os testes de 1RM, salto contra movimento e composição corporal foram realizados nos períodos pré e pós-treinamento. Quanto à testosterona salivar, não houve efeito significativo em relação ao tempo e entre os grupos. Ambos os grupos melhoraram a força máxima em termos de tempo de intervenção no supino reto com barra e no leg press 45º, não diferindo entre os grupos e composição corporal apresentaram interação significativa no tempo para percentual de gordura corporal ∆% = -14,6 ± 10,0 (24R) e -17,2 ± 10,9 (72R); p = 0,00, massa gorda ∆% = -13, 7 ± 9,2 (24R) e -18,2 ± 13,0 (72R); p = 0,00 e massa isenta de gordura ∆% = 3,5 ± 2,7 (24R) e 2,5 ± 2,8 (72R), p = 0,00. Os períodos de recuperação de 24 e 72 horas entre as sessões induziram respostas semelhantes nos parâmetros investigados em homens treinados de força recreacionalmente.