Strength training improves heart function, collagen and strength in rats with heart failure

BACKGROUND/OBJECTIVES

Myocardial infarction (MI) frequently leads to cardiac remodeling and failure with impaired life quality, playing an important role in cardiovascular deaths. Although physical exercise is a well-recognized effective non-pharmacological therapy for cardiovascular diseases, the effects of strength training (ST) on the structural and functional aspects of cardiac remodeling need to be further documented. In this study, we aimed to investigate the role of a linear block ST protocol in the rat model of MI.

METHODS AND RESULTS

After 6 weeks of MI induction or sham surgery, male adult rats performed ST for the following 12 weeks. The ladder-based ST program was organized in three mesocycles of 4 weeks, with one load increment for each block according to the maximal carrying load test. After 12 weeks, the infarcted-trained rats exhibited an increase in performance, associated with reduced cardiac hypertrophy and pulmonary congestion compared with the untrained group. Despite not changing MI size, the ST program partially prevented cardiac dilatation and ventricular dysfunction assessed by echocardiography and hemodynamics, and interstitial fibrosis evaluated by histology. In addition, isolated cardiac muscles from infarcted-trained rats had improved contractility parameters in a steady state, and in response to calcium or stimuli pauses.

CONCLUSIONS

The ST in infarcted rats increased the capacity to carry mass, associated with attenuation of cardiac remodeling and pulmonary congestion with improving cardiac function that could be attributed, at least in part, to the improvement of myocardial contractility.

Exercise-Induced Muscle Damage after a High-Intensity Interval Exercise Session: Systematic Review

High-intensity interval training (HIIT) is considered an effective method to improve fitness and health indicators, but its high-intensity exercises and the mechanical and metabolic stress generated during the session can lead to the occurrence of exercise-induced muscle damage. Therefore, this study aimed to describe, by means of a systematic review, the effects of a single HIIT session on exercise-induced muscle damage. A total of 43 studies were found in the Medline/PubMed Science Direct/Embase/Scielo/CINAHL/LILACS databases; however, after applying the exclusion criteria, only 15 articles were considered eligible for this review. The total sample was 315 participants. Among them, 77.2% were men, 13.3% were women and 9.5 uninformed. Their age ranged from 20.1 ± 2 to 47.8 ± 7.5 years. HIIT protocols included running with ergometers (n = 6), CrossFit-specific exercises (n = 2), running without ergometers (n = 3), swimming (n = 1), the Wingate test on stationary bicycles (n = 2), and cycling (n = 1). The most applied intensity controls were %vVO2max, "all out", MV, MAV, Vmax, and HRreserve%. The most used markers to evaluate muscle damage were creatine kinase, myoglobin, and lactate dehydrogenase. The time for muscle damage assessment ranged from immediately post exercise to seven days. HIIT protocols were able to promote changes in markers of exercise-induced muscle damage, evidenced by increases in CK, Mb, LDH, AST, ALT, pain, and muscle circumference observed mainly immediately and 24 h after the HIIT session.

Effect of Supervised and Unsupervised Exercise Training in Outdoor Gym on the Lifestyle of Elderly People

The aim of this study was to investigate the effectiveness of supervised and unsupervised physical training programs using outdoor gym equipment on the lifestyles of elderly people.

METHODS

physically independent elderly people were randomly distributed into three groups: supervised training (n: 20; ST), unsupervised training (n: 20; UT) and control (n: 20; C). The ST and UT groups completed a 12-week program, with exercises performed three times a week. The ST group underwent weekly 30 min sessions consisting of a 5 min warm-up (walking at 60% of HRmax), followed by 20 sets of 30, "monitored by a metronome with 30" of passive recovery between sets and a five-minute cool-down. The following equipment was used: elliptical, rowing, surfing and leg press. The UT group was instructed to freely attend the gym and train spontaneously using the same equipment used by ST. Lifestyle changes were evaluated using a questionnaire containing specific domains.

RESULTS

no significant differences were identified in the domains for family, physical activity, nutrition, smoking, sleep, behavior, introspection, work and overall score; however, the values corresponding to the alcohol domain for the ST and UT groups were lower (p < 0.05) than the C group, remaining even lower after the 12 weeks of intervention. Time effect (p < 0.05) was found only in the ST group for the physical domains, sleep, behavior and overall score.

CONCLUSION

elderly people submitted to supervised and unsupervised physical exercise programs using outdoor gym equipment present positive changes in lifestyle parameters compared to physical inactive elderly people.

Skeletal Muscle Discomfort and Lifestyle of Brazilian Military Police Officers of Administrative and Tactical Force

Our aim was to evaluate musculoskeletal discomfort and the lifestyle of military police officers of administrative and tactical force departments. Military police officers were distributed into two groups: administrative (Adm, n = 15) and tactical force (TF, n = 16) departments. Their lifestyle was assessed using the Fantastic Lifestyle questionnaire. Moreover, physical activity quantification was assessed using the International Physical Activity questionnaire, and musculoskeletal discomfort was quantified using the Corlett diagram. The mean total time of physical activity was 546 ± 276 min per week. No differences (p = 0.0832) were found between the Adm (454 ± 217 min) and TF (623 ± 301 min) groups. Concerning lifestyle, in general the sample presented very good (42%) and good (42%) style classification. For this parameter, no significant differences were found, but only a tendency was discovered (x2: 7.437; p = 0.0592); indeed, the TF presented a better classification (63%) of very good, compared to the Adm (53%) of good. No differences (p > 0.05) were found in musculoskeletal perception of discomfort between the right and left sides (p > 0.05) for all police officers and between the Adm and FT groups (p > 0.05). Military police officers showed high and moderate risk for waist circumference and waist-to-hip ratio, respectively; however, lifestyle and total time of physical activity were considered adequate without differences between military administrative and tactical force sectors.

Psychophysiological Responses of Exercise Distribution During High Intensity Interval Training Using Whole Body Exercise

The time-efficient nature of HIIT using bodyweight exercises can facilitate the application of exercise programs at home by encouraging more people to perform regular physical exercise. However, there are no studies investigating the influence of the distribution/order of exercises during HIIT training sessions using this method. The aim of the present study was to evaluate the effects of different exercise orders on training load indicators during HIIT sessions using body weight. Twenty male participants performed three 20-min sessions of HIIT using whole body exercise, consisting of 20 sets with 30 s of activity performed at maximal intensity, followed by 30 s of passive recovery. Three designs of exercise protocols were randomly performed according to the following exercise distribution: A: jumping jack, burpee, mountain climb and squat jump); B: jumping jack, mountain climb, burpee, and squat jump) and C: burpee, squat jump, jumping jack and mountain climb. No differences were found between protocols for relative heart rate, perceived exertion, and lactate concentrations. Significant differences (p &lt; 0.001) were found for the number of movements (A:712 ± 59, B:524 ± 49, C:452 ± 65). No differences were observed for the area under curve when examining perceived exertion between protocols. However, the values for perceived recovery significantly differed (p &lt; 0.001) between protocols (A:64 ± 19; B:52 ± 11; C:17 ± 13). Interestingly, protocol B and C induced a displeasure perception compared to protocol A. Our findings suggest that exercise distribution/order using HIIT whole body exercise promotes alterations in psychophysiological responses in HIIT using whole body exercises.

Effects of music on psychophysiological responses during high intensity interval training using body weight exercises

The use of music in exercise sessions is considered an interesting strategy as it facilitates, through motivation, an improvement in physical performance, as well as a reduction in the subjective perception of effort and an improvement in mood. Such factors are important for the maintenance of physical exercise programs, however, considering high intensity interval training, the effects of music remain inconclusive. Thus, the objective of this study was to evaluate the influence of music during high intensity interval training sessions using body weight (HIIT-B) on the physiological parameters and mood state of adults.

METHODS

11 CrossFit male practitioners were randomly submitted to three sessions of HIIT-C under the following experimental conditions: preference music (PM), non-preference music (nPM) and without music (WM). The HIIT-B protocol consisted of 20 sets of 30 seconds of stimulus using maximal intensities followed by 30 seconds of passive recovery. The following exercises were used: jumping jacks, burpee, mountain climbing and squat jumping. The following parameters were analyzed: heart rate (HR), lactate (La), total amount of movements (TAM), affective response (AR), rating of perceived exertion (RPE) and recovery (RPR) and mood states.

RESULTS

although an increase (p< 0.05) of HR, RPE and La reduction of RPR was found after performing the HIIT session, no differences were found between the three conditions to these parameters. The nPM condition promoted lower (p< 0.001) TAM compared to the WM and PM conditions, which also differed from each other. However, for AR, a music effect was found among the protocols (p< 0.0001), indicating that the PM session promoted an increase in pleasure, unlike WM and nPM session which provided pleasure reduction and displeasure respectively. The WM session did not promote any changes. There were no main effects on time for depression and anger, which were different for vigor, fatigue, mental confusion, tension and mood disturbance. Additionally, differences were found after session to tension (p= 0.0229), vigor (p= 0.0424) and fatigue (p= 0.0400) for PM condition, vigor (p= 0.0424), fatigue (p= 0.0400) mental confusion (p= 0.0302) and mood disturbance (p= 0.0129) and vigor (p= 0.0363) and fatigue (p= 0.0468) to WM conditions.

CONCLUSION

Listening to preferred music during an 'all out' HIIT-B session increases exercise performance and elicits more positive affective responses in recreationally active adult males, despite similar HR, blood lactate, RPE and fatigue compared to nonpreferred music or no-music.

Effect of Sodium Bicarbonate Supplementation on Muscle Performance and Muscle Damage: A Double Blind, Randomized Crossover Study

Sodium bicarbonate (NaHCO3) has been used as an ergogenic substance during high-intensity exercises. Therefore, the aim of the present study was to investigate the effects of NaHCO3 supplementation on external and internal load parameters during isokinetic exercise in trained subjects. Ten subjects were tested on two occasions: after ingesting 0.3 g.kg-1 of body mass of NaHCO3 or placebo. Maximum voluntary isometric contraction was performed before and after a dynamic protocol consisting of 10 series of 10 movements of flexion/extension of the knee extensors at 120° s-1 at an interval of 60 s between series. Outcomes considered were: peak torque (isokinetic dynamometry), blood lactate and creatine concentration (CK), analysis of perceptions of effort (OMNI scale), pain (visual analog scale) and recovery (scale raging 6 to 20). Performance was assessed using peak torque values. Muscle damage was assessed prior and 24 h post exercise. The subjective perceptions of effort, pain and recovery were assessed at different times and the internal load of the session was assessed 30 min post-effort. Although significant reductions in peak torque were noted both in isometric (NaHCO3:-29.11 ± 22.95%, Placebo: -23.51 ± 15.23%; p = 0.38) and isokinetic strength (NaHCO3:-23.0 ± 13.9%, Placebo:-19.6 ± 9.1%; p = 0.09), there was no effect of supplementation on performance (p > 0.05). The blood CK concentrations (NaHCO3: pre:225.3 ± 135.9 U/L, post: 418.4 ± 318.4 U/L; Placebo: pre:238 ± 94.03 U/L, post:486 ± 336.6 U/L) increased after protocol (p = 0.005), however, without differences between conditions. In conclusion, the NaHCO3 did not attribute benefits in performance or in parameters related to the internal load of exercise.

Physical exercise attenuates stress-induced hypertension in rats but not the impairments on the myocardial mechanics

BACKGROUND

Acute and chronic stresses have become a health problem in the contemporary society, and prolonged exposure to stressful events are related to the pathogenesis of cardiovascular diseases. Physical exercise is a well-recognized effective nonpharmacological therapy for cardiovascular diseases and stress-induced injuries. Thus, this study evaluated the effect of exercise on the cardiac remodelling of chronically stressed rats.

METHODS AND RESULTS

Wistar adult rats were used (n = 10 each group) and chronic stress protocol consisted of restricting movement in individual rodent restrainers (60 min, 5 days/week, 12 weeks); and exercise consisted of swimming sessions in a pool (60 min, 5 days/week, 12 weeks). During protocol, blood pressure was measured in conscious rats, and at the end cardiac morphology/function was assessed. Animals exposed to stress exhibited continuous rise in blood pressure from the sixth week, but exercise attenuated it. Similarly, restrained rats increased serum corticosterone compared with nonstressed rats, but exercise also prevented it. No changes were found in cardiac mass, but chronic stress not only impaired the steady state contractions of the cardiac muscle, but also reduced inotropic responses to stretching, increasing calcium and beta-adrenergic receptor stimulation. Despite this, exercise was unable to prevent these functional impairments induced by stress, and instead, the association of stress and physical exercise worsened myocardial compliance.

CONCLUSION

Despite the known benefits to the cardiovascular system, our results indicate that aerobic swimming exercise for 12 weeks reduced blood pressure but did not impede the chronic stress-induced myocardial damages in rats.

Acute Behavior of Oxygen Consumption, Lactate Concentrations, and Energy Expenditure During Resistance Training: Comparisons Among Three Intensities

Purpose: This study aimed to compare the oxygen consumption, lactate concentrations, and energy expenditure using three different intensities during the resistance training sessions.

Methods: A total of 15 men (22.9 ± 2.61 years) experienced in resistance training underwent 3 sessions composed of 8 exercises (chest press, pec deck, squat, lat pull-down, biceps curl, triceps extension, hamstring curl, and crunch machine), which were applied in the same order. The weight lifted differed among the sessions [high session: 6 sets of 5 repetitions at 90% of 1-repetition maximum (1-RM); intermediary session: 3 sets of 10 repetitions at 75% of 1-RM; and low session: 2 sets of 15 repetitions at 60% of 1-RM]. The oxygen consumption (VO₂)—during and after (excess post-exercise oxygen consumption (EPOC)) the session, blood lactate concentration, and energy expenditure (i.e., the sum of aerobic and anaerobic contributions, respectively) were assessed.

Results: The VO2 significantly decreased in the function of the weight lifting (F_(2.28) = 17.02; p < 0.01; ηG2 = 0.32). However, the aerobic contributions significantly increase in the function of the weight lifting (F_(2.28) = 79.18; p < 0.01; ηG2 = 0.75). The anaerobic contributions were not different among the sessions (p > 0.05; ηG2 < 0.01). Thus, the total energy expenditure during the session (kcal) significantly increased in the function of the weight lifting (F_(2.28) = 86.68; p < 0.01; ηG2 = 0.75). The energy expenditure expressed in time unit (kcal·min⁻¹) was higher in low session than in high session (F_(2.28) = 6.20; p < 0.01; ηG2 = 0.15).

Conclusion: The weight lifted during resistance training-induced different physiological responses, which induced higher energy expenditure per unit of time during the low session.

Effect of a short-term whole-body high-intensity interval training on fitness, morphological, and functional parameters in untrained individuals

BACKGROUND

High-intensity interval training protocols using the body weight (WBHIIT) as resistance could be an interesting and inexpensive alternative due to the absence of equipment required (low cost) and the possibility to be performed in a wide range of locations. Therefore, the purpose of the present study was to analyze the effects of a short-term WBHIIT protocol on muscle thickness (MT), muscular endurance (ME), one maximum repetition test (1RM), and maximum oxygen uptake (VO2max) of untrained individuals.

METHODS

Fifty healthy men (28.2 ± 6.7 years, 77.5 ± 26.2 kg, 171 ± 10 cm, 23.2 ± 8.2 % Fat) were randomized into WB-HIIT (n = 25) or control (CON, n = 25) group. The WB-HIIT performed 9 exercises (40-second stimulus in all out intensity/ 20-second of passive recovery) divided into 3 blocks with 2 sets each for 6 weeks (three times a week).

RESULTS

Only WB-HIIT resulted in a significant increase in MT, ME, 1RM, and VO2max (all p < 0.05) outcomes and were significantly greater compared to CON (all p < 0.05).

CONCLUSIONS

Our results demonstrate that a WB-HIIT program can be a time-efficient strategy to promote changes on fitness, morphological and functional parameters in previously untrained sedentary individuals.

THE DOSE-RESPONSE PHENOMENON ASSOCIATED WITH STRENGTH TRAINING IS INDEPENDENT OF THE VOLUME OF SETS AND REPETITIONS PER SESSION

ABSTRACT Introduction There are few studies on the effectiveness of training models with high volume sets per session in particular muscle groups. Objective The aim of the study was to investigate the effects of different resistance training (RT) repetitions with equalized volumes on muscle adaptations. Methods This study used an experimental design in which forty-seven volunteers underwent 8 weeks of RT after having been distributed randomly into three groups: ten sets of three maximum repetitions (10x3), three sets of ten maximum repetitions (3x10) and five sets of six maximum repetitions (5x6) for each muscular group per training session. Maximum strength (1RM test) and muscle thickness (MT) were evaluated as outcomes. Results A significant main effect (p=0.001) of time on maximum strength was observed for the three groups, but no significance was observed (p>0.05) in time x group interactions. A significant main effect (p=0.001) of time was observed on MT for biceps, triceps and vastus lateralis, without significant differences for time x group interactions. Significant correlations were found between maximum strength and muscle thickness after general statistical analyses for all protocols. Conclusion Improvements in maximum strength and muscle thickness are similar when repetition volumes are equalized through the number of series and repetitions. Level of evidence I; Therapeutic studies, investigation of treatment results.

Effects of a Kinect-based physical training program on body composition, functional fitness and depression in institutionalized older adults

Exergames have already been used as therapeutic tools to enhance both physical and cognitive functions in older adults.

AIM

To evaluate the effects of a Kinect-based physical activity program on the quality of life, depression, functional fitness and body composition in institutionalized older adults.

METHODS

A total of 50 older adults aged >60 years were selected and randomized to a control and video game group. Body composition was determined by means of anthropometric measurements. Quality of life was assessed using the WHOQOL-BREF questionnaire, and depression was classified using the Beck Depression inventory. Functional fitness was assessed using the Arm Curl, Chair Stand, 8-foot up-and-go, sit and reach, and the aerobic endurance test.

RESULTS

After 12 weeks of protocol, we observed a significant improvement in all functional fitness parameters.

CONCLUSIONS

Our findings suggest that a Kinect-based physical activity program seems to positively impact the three domains related to quality of life and directly associated with age (physical, social and psychological domains), and to promote a more active lifestyle in institutions housing older individuals. Geriatr Gerontol Int 2020; ••: ••-••.

Delayed Reperfusion-Coronary Artery Reperfusion Close to Complete Myocardial Necrosis Benefits Remote Myocardium and Is Enhanced by Exercise

The present study aimed to analyze the effects of reperfusion of a distant coronary artery on cardiac function, the ultrastructure, and the molecular environment of the remote myocardium immediately after the completion of myocardial regional necrosis: delayed reperfusion (DR). Additionally, the effects of prior exercise on the outcomes of DR were investigated. Female rats with permanent occlusion or delayed reperfusion were randomly assigned to an exercise (swimming, 1 h/day, 5 days/week for 8 weeks) or sedentary protocol. Thus, the study included the following four groups: sedentary permanent occlusion, exercise permanent occlusion, sedentary delayed reperfusion, and exercise delayed reperfusion. The descending coronary artery was occluded for 1 h. Reperfusion was confirmed by contrast echocardiography, and the rats were observed for 4 weeks. Permanent occlusion and DR caused similar myocardial infarction sizes among the four groups. Interestingly, exercise significantly decreased the mortality rate. Delayed reperfusion resulted in significant benefits, including enhanced hemodynamics and papillary muscle contraction, as well as reduced apoptosis and collagen content. Protein calcium kinetics did not change. Meanwhile, developed tension and the Frank–Starling mechanism were enhanced, suggesting that calcium sensitivity was intensified in myofilaments. Remarkable remote myocardial benefits occurred after distant DR, and prior exercise intensified cardiac recovery. Our findings provide valuable information about DR. Our data might explain the better clinical outcomes in recent studies showing that late reperfusion could improve heart failure in patients with myocardial infarction. In conclusion, DR has remote myocardial benefits, including inotropism enhancement, pulmonary congestion reduction, and collagen and apoptosis attenuation, which are enhanced by prior exercise.

Body-image and -size perception after a single session of HIIT body work in healthy adult men

It was our objective to analyze the effects of a single session of whole body HIIT on body-image and -scheme parameters of healthy adult men. Twenty-one active, healthy adults performed high-intensity intermittent training based on full body exercise. The training session involved 20 sets of 30 second all-out exercise and 30 seconds of passive recovery between sets. All subjects underwent blood lactate measurement, rate of perceived exertion, feeling scale and body image assessment and perception of body size measurements. Significant differences (p<0.001) were found on blood lactate but not in feeling scale. The values of current and adequate silhouette did not differ between each other and the real silhouette. Significant differences were found on Image Marking Procedure (IMP) (p< 0.003). Additionally, significant differences (p= 0.009) were found on prevalence of adequate, hypoeschematic and hypeschematic. Although alteration was not found on self-perception of body image, a single session of HIIT body work promoted alteration on body size perception in healthy adult men.

Description of training loads using whole-body exercise during high-intensity interval training

OBJECTIVES

To describe external training load and internal training load through sets of a single session of high-intensity interval training (HIIT) body work.

METHODS

Twenty male individuals (24±3 years) performed a HIIT body work protocol consisting of a single bout of exercise with 1:1 stimuli. The exercises used were 30 min in duration with "all-out" intensity. The exercises included jumping jacks, mountain climbers, burpees and squat jumps, totaling 20 min of exercise. During exercise, total movement capacity, blood lactate measurement, ratings of perceived exertion and recovery, training load and intensity were monitored.

RESULTS

The single bout examined showed a total of 382±89 movements. Differences (p<0.01) in the total amount of movement for each exercise were noted, reflecting the difficulty of maintaining exercise over time. Increases in lactate concentrations (before: 0.98±0.16, after: 14.10±1.66; mmol/L) were found postexercise. Significant differences (p<0.01) were found after the fifth set, and the values for movement capacity remained higher than the values of the first set, demonstrating high load in a single session. No differences in ratings of perceived exertion (RPE) during the sets were found. However, the ratings of perceived recuperation from the second set were significantly (p<0.01) lower than those from the first set.

CONCLUSIONS

The exercise protocol used in this study was of high intensity and produced large values for stress during performance, with increases recorded for the internal load indicators.

Metabolic and hormonal responses to different resistance training systems in elderly men

OBJECTIVE

To compare acute and sub-acute responses in hormonal profile and metabolic parameters in elderly people who participated in two methods of strength training (ST) with equalized loads.

METHODS AND MATERIALS

A total of 12 elder individuals (65 ± 3 years) were randomly assigned to two training methods: constant intensity (CI, 3 sets of 10 repetitions with 75% of 1RM) and variable intensity (VI, 1st set: 12 repetitions at 67% of 1RM > 2nd set: 10 repetitions at 75% of 1RM and 3rd set: 8 repetitions at 80% of 1RM). Both methods included the following exercises: leg press, knee extension, and squat with 1 min rest intervals between sets. Free speed of execution and maximum range of movement were encouraged throughout each set for both protocols. Blood samples were analyzed included glucose, testosterone (T), cortisol (C), T/C rate, growth hormone (GH), and lactate at 2 and 24 h post intervention.

RESULTS

There were no observed differences in glucose, testosterone, GH, and lactate concentrations both at 2 and 24 h after the execution of the two training methods. However, significant increases in the levels of T/C rate and decrease on cortisol were observed immediately post exercise for both protocols.

CONCLUSIONS

Although no significant differences were observed between the two interventions in relation to the hormonal and metabolic parameters analyzed, both training methods promoted a favorable response, with a slight superiority noted for the CI method relative to the hormonal profile.

Cardiac morphofunctional characteristics of transgenic rats with overexpression of the bradykinin B1 receptor in the endothelium

Our aim was to evaluate whether endothelial overexpressing of the bradykinin B1 receptor could be associated with altered left ventricular and myocardial performance. Echocardiography and hemodynamic were employed to assess left ventricular morphology and function in Sprague Dawley transgenic rats overexpressing the endothelial bradykinin B1 receptor (Tie2B1 rats). The myocardial inotropism was evaluated on papillary muscles contracting in vitro. In Tie2B1 animals, an enlarged left ventricular cavity and lower fractional shortening coupled with a lower rate of pressure change values indicated depressed left ventricular performance. Papillary muscle mechanics revealed that both Tie2B1 and wild-type rat groups had the same contractile capacities under basal conditions; however, in transgenic animals, there was accentuated inotropism due to post-pause potentiation. Following treatment with the Arg(9)-BK agonist, Tie2B1 papillary muscles displayed a reduction in myocardial inotropism. Endothelial B1 receptor overexpression has expanded the LV cavity and worsened its function. There was an exacerbated response of papillary muscle in vitro to a prolonged resting pause, and the use of a B1 receptor agonist impairs myocardial inotropism.

Low-Level Laser Application in the Early Myocardial Infarction Stage Has No Beneficial Role in Heart Failure

Low-level laser therapy (LLLT) has been targeted as a promising approach that can mitigate post-infarction cardiac remodeling. There is some interesting evidence showing that the beneficial role of the LLLT could persist long-term even after the end of the application, but it remains to be systematically evaluated. Therefore, the present study aimed to test the hypothesis that LLLT beneficial effects in the early post-infarction cardiac remodeling could remain in overt heart failure even with the disruption of irradiations. Female Wistar rats were subjected to the coronary occlusion to induce myocardial infarction or Sham operation. A single LLLT application was carried out after 60 s and 3 days post-coronary occlusion, respectively. Echocardiography was performed 3 days and at the end of the experiment (5 weeks) to evaluate cardiac function. After the last echocardiographic examination, LV hemodynamic evaluation was performed at baseline and on sudden afterload increases. Compared with the Sham group, infarcted rats showed increased systolic and diastolic internal diameter as well as a depressed shortening fraction of LV. The only benefit of the LLLT was a higher shortening fraction after 3 days of infarction. However, treated-LLLT rats show a lower shortening fraction in the 5th week of study when compared with Sham and non-irradiated rats. A worsening of cardiac function was confirmed in the hemodynamic analysis as evidenced by the higher LV end-diastolic pressure and lower +dP/dt and −dP/dt with five weeks of study. Cardiac functional reserve was also impaired by infarction as evidenced by an attenuated response of stroke work index and cardiac output to a sudden afterload stress, without LLLT repercussions. No significant differences were found in the myocardial expression of Akt₁/VEGF pathway. Collectively, these findings illustrate that LLLT improves LV systolic function in the early post-infarction cardiac remodeling. However, this beneficial effect may be dependent on the maintenance of phototherapy. Long-term studies with LLLT application are needed to establish whether these effects ultimately translate into improved cardiac remodeling.

Effects of vitamin D supplementation on pulmonary function in postmenopausal women following an aquatic exercise program

OBJECTIVE

This study sought to investigate the effects of vitamin D supplementation and aquatic exercise on pulmonary function in postmenopausal women.

MATERIALS AND METHODS

This prospective and controlled study included 104 women (62 ± 6.5 years) divided into three groups: a control group lacking vitamin D and calcium supplementation which remained sedentary (CG; n = 17); a control group receiving vitamin D and calcium supplementation which remained sedentary (CDG, n = 33); and a group that completed aquatic exercises three times a week and received vitamin D and calcium supplementation (DTG, n = 54). Data before and after 6 months of the study were analyzed, including serum 25-hydroxyvitamin D (25(OH)D) and calcium concentrations, peak expiratory flow (PEF), forced vital capacity (FVC), and cirtometry.

RESULTS

We observed significant increases in 25(OH)D concentrations in CDG (52.9 ± 2.4 to 69.1 ± 2.2; nmol/L; p < 0.0001) and DTG groups (55.5 ± 3 to 71.5 ± 3 nmol/L; p < 0.0001). PEF increased by 7 ± 2% (p = 0.0080) in CDG group and 11 ± 2% (p < 0.0001) in DTG group, whereas FVC increased by 7 ± 2% (p = 0.0016) in the CDG group and 10 ± 2% (p < 0.0001) in the DTG group, whereas CG had no changes in any of these parameters. The increment value of cirtometry in DTG group (+43 ± 3%) were significantly (p < 0.0001) higher than those in CG (-4 ± 8%) and CDG (+4 ± 9%) groups.

CONCLUSION

Our data suggest that vitamin D supplementation improves pulmonary function parameters in postmenopausal women.

To be or not to be physically active: Insights for a real chance to have an appropriate body mass in a sample of teachers

BACKGROUND

Studies on the relationship between physical activity (PA) and being overweight/obese are inconclusive.

OBJECTIVE

The purpose of this study was to examine the prevalence of excess body weight (EBW) and its association with daily PA level in a sample of 1506 Brazilian teachers.

METHODS

The PA level was analyzed with the International Physical Activity Questionnaire and EBW was categorized as a body mass index (BMI) ≥25 kg/m2 and called 'overweight'. Chi-squared test and odds ratios (OR) were applied in the analysis.

RESULTS

The prevalence of persons who were overweight was lower as a function of higher PA levels and higher PA levels resulted in a lower prevalence of overweight for men and women, respectively. The authors found that for men, moderate (OR: 1.69; P = 0.03) and high (OR: 2.57; P = 0.002) PA levels were predictive for being in the normal body mass index (BMI) range. In women, a greater association of being in the normal BMI range was reported only for a moderate PA level (OR: 1.43; P = 0.004).

CONCLUSIONS

Higher daily PA levels are associated with being in the normal BMI range. To date, these findings will have important public health implications for an effective plan for the prevention of weight gain in Brazilian teachers.

Does Stroke Volume Increase During an Incremental Exercise? A Systematic Review

INTRODUCTION

Cardiac output increases during incremental-load exercise to meet metabolic skeletal muscle demand. This response requires a fast adjustment in heart rate and stroke volume. The heart rate is well known to increase linearly with exercise load; however, data for stroke volume during incremental-load exercise are unclear. Our objectives were to (a) review studies that have investigated stroke volume on incremental load exercise and (b) summarize the findings for stroke volume, primarily at maximal-exercise load.

METHODS

A comprehensive review of the Cochrane Library's, Embase, Medline, SportDiscus, PubMed, and Web of Sci-ence databases was carried out for the years 1985 to the present. The search was performed between February and June 2014 to find studies evaluating changes in stroke volume during incremental-load exercise. Controlled and uncontrolled trials were evaluated for a quality score.

RESULTS

The stroke volume data in maximal-exercise load are inconsistent. There is evidence to hypothesis that stroke volume increases during maximal-exercise load, but other lines of evidence indicate that stroke volume reaches a plateau under these circumstances, or even decreases.

CONCLUSION

The stroke volume are unclear, include contradictory evidence. Additional studies with standardized reporting for subjects (e.g., age, gender, physical fitness, and body position), exercise test protocols, and left ventricular function are required to clarify the characteristics of stroke volume during incremental maximal-exercise load.

Effects of exercise intensity on postexercise hypotension after resistance training session in overweight hypertensive patients

Among all nonpharmacological treatments, aerobic or resistance training (RT) has been indicated as a significantly important strategy to control hypertension. However, postexercise hypotension responses after intensity alterations in RT are not yet fully understood. The purpose of this study was to compare the outcomes of differing intensities of RT on hypertensive older women. Twenty hypertensive older women participated voluntarily in this study. After a maximum voluntary contraction test (one repetition maximum) and determination of 40% and 80% experimental loads, the protocol (3 sets/90″ interset rest) was performed in a single session with the following exercises: leg press, leg extension, leg curl, chest press, elbow flexion, elbow extension, upper back row, and abdominal flexion. Systolic and diastolic blood pressures were evaluated at rest, during exercise peak, and after 5, 10, 15, 30, 45, and 60 minutes of exercise and compared to the control. Both experimental loads were effective (P<0.01) in promoting postexercise systolic hypotension (mmHg) compared to controls, after 30, 45, and 60 minutes, respectively, at 40% (113±2, 112±4, and 110±3 mmHg) and 80% (111±3, 111±4, and 110±4 mmHg). Both procedures promoted hypotension with similar systolic blood pressures (40%: -11%±1.0% and 80%: -13%±0.5%), mean arterial blood pressures (40%: -12%±5.5% and 80%: -12%±3.4%), and rate-pressure products (40%: -15%±2.1% and 80%: -17%±2.4%) compared to control measures (systolic blood pressure: 1%±1%, mean arterial blood pressure:\ 0.6%±1.5%, rate-pressure product: 0.33%±1.1%). No differences were found in diastolic blood pressure and heart rate measures. In conclusion, hypertensive older women exhibit postexercise hypotension independently of exercise intensity without expressed cardiovascular overload during the session.

Treadmill exercise training prevents myocardial mechanical dysfunction induced by androgenic-anabolic steroid treatment in rats

Elevated concentrations of testosterone and its synthetic analogs may induce changes in cardiovascular function. However, the effects of the combination of anabolic/androgenic steroid (AAS) treatment and exercise training on systolic and diastolic cardiac function are poorly understood. In the present study, we aimed to investigate the effects of low-dose steroid treatment (stanozolol) on cardiac contractile parameters when this steroid treatment was combined with exercise training in rats and the effects of chronic steroid treatment on the Frank-Starling (length-tension curves) relationship. Male Wistar rats were randomly assigned to one of four groups: U (untrained), US (untrained and treated with stanozolol 5 mg/kg/week), T (trained, 16 m/min/1 h) and TS (trained and treated with stanozolol 5 mg/kg/week). Continuous exercise training was conducted 5 days/week for 8 consecutive weeks. The speed of the treadmill was gradually increased to a final setting of 16 m/min/1 h. Experiments were divided into two independent series: 1) central hemodynamic analysis for mean arterial blood pressure (MAP) and cardiac output (CO) measurements and 2) isolated papillary muscle preparation in Krebs solution. Stanozolol treatment significantly increased the MAP and the heart size in untrained and trained rats (U 113±2; T 106±2; US 138±8 and TS 130±7 mmHg). Furthermore, stanozolol significantly decreased developed tension and dT/dt (maximal and minimal) in U rats. However, the developed tension was completely restored by training. The Frank/Starling relationship was impaired in rats treated with stanozolol; however, again, training completely restored diastolic function. Taken together, the present data suggest that AAS treatment is able to decrease cardiac performance (systolic and diastolic functions). The combination of stanozolol and physical training improved cardiac performance, including diastolic and systolic functions, independent of changes in central hemodynamic parameters. Therefore, changes in ventricular myocyte calcium transients may play a cardioprotective role.

Prior exercise training does not prevent acute cardiac alterations after myocardial infarction in female rats

OBJECTIVE

This study aimed to investigate whether previous exercise training could prevent or attenuate acute cardiac alterations after myocardial infarction.

METHODS

Female rats were submitted to swim training (1 h/day; 5 days/week) or allowed to remain sedentary for 8 weeks. Afterwards, they were randomly assigned to left coronary artery occlusion or sham surgery. After this procedure, the rats remained sedentary for one week until euthanasia. Cardiac structural and functional analyses were performed using Doppler echocardiography. The rats that had a moderate or large infarct size were included in the evaluations. The data (mean ± SEM) were analyzed using a two-way ANOVA model followed by Tukey's post-hoc test.

RESULTS

After the surgery, no significant difference between the exercise and sedentary groups was observed in the left ventricular infarct sizes (34.58 ± 3.04 vs. 37.59 ± 3.07). In another group of rats evaluated with Evans blue 1 h after myocardial infarction, no siginificant difference in the area at risk was observed between the exercised and sedentary rats (49.73 ± 1.52 vs. 45.48 ± 3.49). The changes in the left ventricular fractional areas for the exercised and sedentary myocardial infarction groups (36 ± 2% and 39 ± 3%, respectively) were smaller than those for the exercise sham surgery (ES, 67 ± 1%) and sedentary sham surgery (SS, 69 ± 2%) groups. The E/A was higher in the sedentary myocardial infarction (4.4 ± 0.3) and exercised myocardial infarction (5.5 ± 0.3) rats than in the SS (2.4 ± 0.1) and ES (2.2 ± 0.1) rats.

CONCLUSION

Previous swim training of female rats does not attenuate systolic and diastolic function alterations after myocardial infarction induced by left coronary artery occlusion, suggesting that cardioprotection cannot be provided by exercise training in this experimental model.

Exercise training inhibits inflammatory cytokines and more than prevents myocardial dysfunction in rats with sustained beta-adrenergic hyperactivity

Myocardial hypertrophy and dysfunction occur in response to excessive catecholaminergic drive. Adverse cardiac remodelling is associated with activation of proinflammatory cytokines in the myocardium. To test the hypothesis that exercise training can prevent myocardial dysfunction and production of proinflammatory cytokines induced by beta-adrenergic hyperactivity, male Wistar rats were assigned to one of the following four groups: sedentary non-treated (Con); sedentary isoprenaline treated (Iso); exercised non-treated (Ex); and exercised plus isoprenaline (Iso+Ex). Echocardiography, haemodynamic measurements and isolated papillary muscle were used for functional evaluations. Real-time RT-PCR and Western blot were used to quantify tumour necrosis factor alpha, interleukin-6, interleukin-10 and transforming growth factor beta(1) (TGF-beta(1)) in the tissue. NF-B expression in the nucleus was evaluated by immunohistochemical staining. The Iso rats showed a concentric hypertrophy of the left ventricle (LV). These animals exhibited marked increases in LV end-diastolic pressure and impaired myocardial performance in vitro, with a reduction in the developed tension and maximal rate of tension increase and decrease, as well as worsened recruitment of the Frank-Starling mechanism. Both gene and protein levels of tumour necrosis factor alpha and interleukin-6, as well as TGF-beta(1) mRNA, were increased. In addition, the NF-B expression in the Iso group was significantly raised. In the Iso+Ex group, the exercise training had the following effects: (1) it prevented LV hypertrophy; (ii) it improved myocardial contractility; (3) it avoided the increase of proinflammatory cytokines and improved interleukin-10 levels; and (4) it attenuated the increase of TGF-beta(1) mRNA. Thus, exercise training in a model of beta-adrenergic hyperactivity can avoid the adverse remodelling of the LV and inhibit inflammatory cytokines. Moreover, the cardioprotection is related to beneficial effects on myocardial performance.

Left ventricle radio-frequency ablation in the rat: a new model of heart failure due to myocardial infarction homogeneous in size and low in mortality

BACKGROUND

The purpose of the current study was to create a model of myocardial infarction (MI) that is homogeneous in size with a low immediate (24 hours) mortality.

METHODS AND RESULTS

Male and female rats (n = 256) underwent left ventricle (LV) ablation (Ab) by a radiofrequency current (1000 kHz; 12 watts for 12 seconds) to promote a MI. A transmural MI occurred in all rats. Post-Ab complex arrhythmias were frequent (atrioventricular block, ventricular tachycardia, and fibrillation), which rapidly and spontaneously reverted to sinus rhythm. Among 66 male rats, immediate mortality occurred in 7.5%. Small MI size dispersion was characterized by smaller variability following Ab (x +/- SD: 45 +/- 8%) when compared with coronary occlusion (Oc; 40 +/- 19%). The histopathologic evaluations identified lesions similar to those which occurred following Oc, with scarring complete at 4 weeks. The hemodynamic and Doppler echocardiograms showed comparable increases in LV dimension, end-diastolic pressure, and pulmonary water content 1 and 4 weeks post-MI. Papillary muscle mechanics 6 weeks post-MI had matched inotropic and lusitropic dysfunction.

CONCLUSIONS

LV Ab gave rise to a MI within a narrow size limit and with a low immediate mortality. LV Ab resulted in histopathologic evolution, ventricular dilation, and dysfunction, impairment in myocardial mechanics, and congestive outcome that reproduced a MI from Oc.