Exercise-Derived Microvesicles: A Review of the Literature

Initially suggested as simple cell debris, cell-derived microvesicles (MVs) have now gained acceptance as recognized players in cellular communication and physiology. Shed by most, and perhaps all, human cells, these tiny lipid-membrane vesicles carry bioactive agents, such as proteins, lipids and microRNA from their cell source, and are produced under orchestrated events in response to a myriad of stimuli. Physical exercise introduces systemic physiological challenges capable of acutely disrupting cell homeostasis and stimulating the release of MVs into the circulation. The novel and promising field of exercise-derived MVs is expanding quickly, and the following work provides a review of the influence of exercise on circulating MVs, considering both acute and chronic aspects of exercise and training. Potential effects of the MV response to exercise are highlighted and future directions suggested as exercise and sports sciences extend the realm of extracellular vesicles

Procedimentos e aspectos necessários para a análise da relação força/EMG do músculo quadríceps femoral avaliado em condição isométrica e dinâmica

The electromyography (EMG) has been used as a resource related to clinical interventions, as well as control of the adjustments resulting from physical training, especially the muscular strength. The muscular electrical activity allows the investigation of which muscles are used in a motion, the level of muscle activation during the course of movement, intensity and duration of muscular demand. Due to the great usefulness of the study of muscle electrical signal and its complex relationship with the force production, both the relation to physiological and non physiological aspects as well as the procedures needed for the collection of EMG signal in isometric and dynamic activity took place this review. Therefore, the EMG signal presents relation with the strength production of the knee extensor muscles. This relationship has been better demonstrated in isometric assessments than in dynamic conditions, what stimulates further scientific production in this area to better understand and explain the relationship of the contraction dynamics, the production of force and changes in EMG signal and improve their applicability not only in the scientific scope, but in clinical tool, since the dynamic activities are similar to the sports gestures and activities of daily living

Whole-body heat stress and exercise stimulate the appearance of platelet microvesicles in plasma with limited influence of vascular shear stress

Intense, large muscle mass exercise increases circulating microvesicles, but our understanding of microvesicle dynamics and mechanisms inducing their release remains limited. However, increased vascular shear stress is generally thought to be involved. Here, we manipulated exercise-independent and exercise-dependent shear stress using systemic heat stress with localized single-leg cooling (low shear) followed by single-leg knee extensor exercise with the cooled or heated leg (Study 1, n = 8) and whole-body passive heat stress followed by cycling (Study 2, n = 8). We quantified femoral artery shear rates (SRs) and arterial and venous platelet microvesicles (PMV-CD41+) and endothelial microvesicles (EMV-CD62E+). In Study 1, mild passive heat stress while one leg remained cooled did not affect [microvesicle] (P ≥ 0.05). Single-leg knee extensor exercise increased active leg SRs by ~12-fold and increased arterial and venous [PMVs] by two- to threefold, even in the nonexercising contralateral leg (P < 0.05). In Study 2, moderate whole-body passive heat stress increased arterial [PMV] compared with baseline (mean±SE, from 19.9 ± 1.5 to 35.5 ± 5.4 PMV.μL-1.103, P < 0.05), and cycling with heat stress increased [PMV] further in the venous circulation (from 27.5 ± 2.2 at baseline to 57.5 ± 7.2 PMV.μL-1.103 during cycling with heat stress, P < 0.05), with a tendency for increased appearance of PMV across exercising limbs. Taken together, these findings demonstrate that whole-body heat stress may increase arterial [PMV], and intense exercise engaging either large or small muscle mass promote PMV formation locally and systemically, with no influence upon [EMV]. Local shear stress, however, does not appear to be the major stimulus modulating PMV formation in healthy humans

Características físicas e de desempenho de backs e forwards da seleção gaúcha de rugby

O objetivo desse estudo foi comparar características de desempenho de atletas regionais brasileiros de Rugby divididos entre posições. Foram investigados a massa corporal total, estatura, índice de massa corporal (IMC), desempenho no yo-yo intermittent recovery test level 1 (yo-yo test), altura dos saltos verticais e os valores de uma repetição máxima (1RM) de supino de 15 forwards e 16 backs que formaram a seleção gaúcha adulta de Rugby em 2010. A comparação dos resultados foi feita pelo teste T de Student para amostras independentes adotando α<0,05. Forwards eram mais pesados, mais fortes e apresentaram maior IMC do que atletas backs (p<0,05). Estes últimos, por outro lado, apresentaram melhor desempenho no yo-yo test (p<0,05). Estes resultados suportam a especificidade das diferentes posições estudadas em função de suas demandas de jogo, demonstrando que tais diferenças podem ser observadas em amadores competitivos. Os valores apresentados podem servir como referência preliminar para treinadores e atletas regionais

Strength Training Prior to Endurance Exercise: Impact on the Neuromuscular System, Endurance Performance and Cardiorespiratory Responses

This study aimed to investigate the acute effects of two strength-training protocols on the neuromuscular and cardiorespiratory responses during endurance exercise. Thirteen young males (23.2 ± 1.6 years old) participated in this study. The hypertrophic strength-training protocol was composed of 6 sets of 8 squats at 75% of maximal dynamic strength. The plyometric strength-training protocol was composed of 6 sets of 8 jumps performed with the body weight as the workload. Endurance exercise was performed on a cycle ergometer at a power corresponding to the second ventilatory threshold until exhaustion. Before and after each protocol, a maximal voluntary contraction was performed, and the rate of force development and electromyographic parameters were assessed. After the hypertrophic strength-training and plyometric strength-training protocol, significant decreases were observed in the maximal voluntary contraction and rate of force development, whereas no changes were observed in the electromyographic parameters. Oxygen uptake and a heart rate during endurance exercise were not significantly different among the protocols. However, the time-to-exhaustion was significantly higher during endurance exercise alone than when performed after hypertrophic strength-training or plyometric strength-training (p <0.05). These results suggest that endurance performance may be impaired when preceded by strength-training, with no oxygen uptake or heart rate changes during the exercise

The “Hypertension Approaches in the Elderly: a Lifestyle study” multicenter, randomized trial (HAEL Study): rationale and methodological protocol

Background: Hypertension is a clinical condition highly prevalent in the elderly, imposing great risks to cardiovascular diseases and loss of quality of life. Current guidelines emphasize the importance of nonpharmacological strategies as a first-line approach to lower blood pressure. Exercise is an efficient lifestyle tool that can benefit a myriad of health-related outcomes, including blood pressure control, in older adults. We herein report the protocol of the HAEL Study, which aims to evaluate the efficacy of a pragmatic combined exercise training compared with a health education program on ambulatory blood pressure and other health-related outcomes in older individuals. Methods: Randomized, single-blinded, multicenter, two-arm, parallel, superiority trial. A total of 184 subjects (92/center), ≥60 years of age, with no recent history of cardiovascular events, will be randomized on a 1:1 ratio to 12-week interventions consisting either of a combined exercise (aerobic and strength) training, three times per week, or an active-control group receiving health education intervention, once a week. Ambulatory (primary outcome) and office blood pressures, cardiorespiratory fitness and endothelial function, together with quality of life, functional fitness and autonomic control will be measured in before and after intervention. Discussion: Our conceptual hypothesis is that combined training intervention will reduce ambulatory blood pressure in comparison with health education group. Using a superiority framework, analysis plan prespecifies an intention-to-treat approach, per protocol criteria, subgroups analysis, and handling of missing data. The trial is recruiting since September 2017. Finally, this study was designed to adhere to data sharing practices. Trial registration: NCT03264443. Registered on 29 August, 2017

Recruitment methods and yield rates in a clinical trial of physical exercise for older adults with hypertension—HAEL Study: a study within a trial

Background: Although the prevalence of hypertension is high in older adults, clinical trial recruitment is a challenge. Our main aim was to describe the HAEL Study recruitment methods and yield rates. The secondary objectives were to explore the reasons for exclusion and to describe the characteristics of the enrolled participants. Methods: This is a descriptive study within a trial. The HAEL Study was a Brazilian randomized two-center, parallel trial with an estimated sample of 184 participants. The recruitment strategy was based on four methods: electronic health records, word of mouth, print and electronic flyer, and press media. The yield rate was the ratio of the number of participants who underwent randomization to the total number of volunteers screened, calculated for overall, per recruitment method, by study center and by age group and sex. Additionally, we described the reasons for exclusion in the screening phase, as well as the demographic characteristics of those enrolled. The data are presented in absolute/relative frequencies and mean ± standard deviation. Results: A total of 717 individuals were screened, and 168 were randomized over 32 months. The yield rate was higher for word of mouth (30.1%) in the overall sample. However, press media contributed the most (39.9%) to the absolute number of participants randomized in the trial. The coordinating center and participating center differed in methods with the highest yield ratios and absolute numbers of randomized participants. The main reason for exclusion in the screening phase was due to the physically active status in those intending to participate in the study (61.5%). Out of 220 participants included, 52 were excluded mainly because they did not meet the eligibility criteria (26.9%). Most of the screened volunteers were women (60.2%) age 60–69 years (59.5%), and most of the randomized participants were Caucasian/white (78.0%). Conclusions: Multiple recruitment methods constituted effective strategies. We observed that approximately one of every four individuals screened was allocated to an intervention group. Even so, there were limitations in obtaining a representative sample of older Brazilian adults with hypertension. Data show an underrepresentation of race and age groups

Water-based continuous and interval training in older women: Cardiorespiratory and neuromuscular outcomes (WATER study)

The purpose of this study was to investigate the effects of two water-based aerobic programs on cardiorespiratory and neuromuscular outcomes in older women. Forty-one women (60 to 75 years old) volunteered to participate in the study. Participants were randomized into a water-based continuous (CTG; n = 21; 63.9 ± 2.5 years) or an interval (ITG; n = 20; 64.8 ± 3.6 years) aerobic training group. Both training programs were performed for 12 weeks (45-min sessions twice a week), with exercise intensity based on rating of perceived exertion (Borg's RPE 6-20 Scale). Pre and post training assessments of cardiorespiratory and neuromuscular outcomes were performed. Data analyses were conducted using Generalized Estimating Equations and Bonferroni post-hoc test (α = 0.05). After the intervention, the CTG and the ITG displayed similar improvements in time to exhaustion (8% vs. 11%), peak oxygen uptake (9% vs. 7%), maximal dynamic knee extension strength (5% vs. 6%), dynamic muscular endurance of knee extensors (10% vs. 11%), maximal vastus lateralis electromyographic signal amplitude (13% vs. 35%), as well as an increase in muscle thickness (5% vs. 6%) and decrease in muscle echo intensity (-2% vs. -3%) of the quadriceps femoris. In conclusion, older women benefited from water-based exercise training prescribed based on participants' RPE, with both the interval and the continuous training programs resulting in similar increases in the cardiorespiratory and neuromuscular parameters

Maximal oxygen uptake is underestimated during incremental testing in hypertensive older adults: findings from the HAEL study

Purpose: The present cross-sectional study aimed to investigate whether a maximal oxygen uptake (VO2max) verification phase (VER) could improve the accuracy of a previous graded exercise test (GXT) to assess individual VO2max in hypertensive individuals. Methods: Thirtythree older adults with hypertension (24 women) taking part in the Hypertension Approaches in the Elderly Study (NCT03264443) were recruited. Briefly, after performing a treadmill GXT to exhaustion, participants rested for 10 min and underwent a multistage VER to confirm GXT results. Individual VO2max, respiratory exchange ratio (RER), maximal heart rate (HRmax), and rating of perceived exertion (RPE) were measured during both GXT and VER tests. Mean values were compared between bouts using paired sample t-tests and VO2max was also compared between GXT and VER on an individual basis. Results: Testing was well tolerated by all participants. Both absolute (p=0.011) and relative (p=0.014) VO2max values were higher in VER than in GXT. RER (p<0.001) and RPE (p=0.002) were lower in VER, whereas HRmax (p=0.286) was not different between the two trials. Individual VO2max comparisons revealed that 54.6% of the participants (18/33) achieved a VO2max value that was ≥3% during VER (mean: 13.5%, range: from +3% to +22.1%, ES=0.062), whereas 87.9% (29/33) of the tests would have been validated as a maximal effort if the classic criteria were employed (i.e. VO2 plateau or at least two secondary criteria). Conclusion: In sedentary older individuals with hypertension, GXT to exhaustion underestimated VO2max in more than half of tested participants, even when established but criticized criteria were used to confirm whether a maximal effort was attained. Employing VER after GXT is a quick approach to assist with the verification of an individual’s VO2max

Divergent isokinetic muscle strength deficits in street running athletes

Background: Running is a very popular activity and muscle strength imbalance has been treated with caution to prevent injuries. Aim: The present study aimed to compare and correlate knee flexion and extension strength imbalance based on peak torque (PT) and total work (TW) in running athletes. Methods: Thirty-eight male amateur running athletes (38 ± 6 years; 80.6 ± 8.3 kg; 177 ± 7 cm; 7.8 ± 8.4 years of training; 3.5 ± 0.9 training sessions a week; 33.5 ± 13.4 km of training per week) took part in the present study. Knee flexion eccentric and concentric PT and TW, as well as concentric knee extension PT and TW were assessed. PT- and TW-based hamstring-to-quadriceps ratios (H:Q), as well as PT and TW contralateral imbalance were quantified. Results: A significant correlation was observed between TW and PT concentric knee flexion contralateral deficits (r = 0.52, p 0.05). All mean comparisons of H:Q and contralateral imbalances using TW or PT were significantly different (p < 0.05). Conclusions: Our results showed that TW and PT muscle strength imbalance were unrelated, and the H:Q and contralateral imbalance profile of endurance runners may differ based on the isokinetic variable analyzed