The ASSIST trial: Acute effects of manipulating strength exercise volume on insulin sensitivity in obese adults: A protocol for a randomized controlled, crossover, clinical trial.

Type 2 diabetes mellitus is a disease in which insulin action is impaired, and an acute bout of strength exercise can improve insulin sensitivity. Current guidelines for strength exercise prescription suggest that 8 to 30 sets could be performed, although it is not known how variations in exercise volume impact insulin sensitivity. Additionally, this means an almost 4-fold difference in time commitment, which might directly impact an individual's motivation and perceived capacity to exercise. This study will assess the acute effects of high- and low-volume strength exercise sessions on insulin sensitivity. After being thoroughly familiarized, 14 obese individuals of both sexes (>40 year old) will undergo 3 random experimental sessions, with a minimum 4-day washout period between them: a high-volume session (7 exercises, 3 sets per exercise, 21 total sets); a low-volume session (7 exercises, 1 set per exercise, 7 total sets); and a control session, where no exercise will be performed. Psychological assessments (feeling, enjoyment, and self-efficacy) will be performed after the sessions. All sessions will be held at night, and the next morning, an oral glucose tolerance test will be performed in a local laboratory, from which indexes of insulin sensitivity will be derived. We believe this study will aid in strength exercise prescription for individuals who claim not to have time to exercise or who perceive high-volume strength exercise intimidating to adhere to. This trial was prospectively registered (ReBEC #RBR-3vj5dc5 https://ensaiosclinicos.gov.br/rg/RBR-3vj5dc5).

Randomized Controlled Trial to Study the Acute Effects of Strength Exercise on Insulin Sensitivity in Obese Adults.

An acute session of strength exercise (SE) ameliorates insulin sensitivity (IS) for several hours; however, the effects of SE volume (i.e., number of sets) have not been studied thoroughly. Although it is intuitive that some SE is better than none, and more is better than some for the improvement of IS, high-volume sessions might be challenging for diseased populations to complete, especially obese adults, for whom even a brisk walk can be challenging. This protocol details a randomized clinical trial to assess the acute effects of SE on IS in obese adults. The inclusion criteria are body mass index >30 kg/m2, central obesity (waist circumference >88 cm and >102 cm for women and men, respectively), and age >40 years. Participants will be familiarized with the SE (7 exercises targeting major muscle groups) and then will perform three sessions in a randomized order: session 1 - high-volume session (3 sets/exercise); session 2 - low-volume session (1 set/exercise); session 3 - control session (no exercise). Diet will be controlled the day before and on the day of the sessions. Sessions will be completed at night, and an oral glucose tolerance test will be performed the next morning, from which several indexes of IS will be derived, such as the area under the curve (AUC) of glucose and insulin, the Matsuda index, the Cederholm index, the muscle IS index, and the Gutt index. Based on pilot studies, we expect ~15% improvement in IS (insulin AUC, and Matsuda and Cederholm indexes) after the high-volume session, and ~8% improvement after the low-volume session compared to the control session. This study will benefit individuals who find high-volume SE sessions challenging but still aim to improve their IS by investing 1/3 of their time and effort.

Superior cardiometabolic and cellular adaptive responses to multiple versus single daily sessions of high-intensity interval training in Wistar rats.

This study aimed to compare in rats the cardiometabolic and cellular adaptative responses to 8 weeks of high-intensity interval training (HIIT) performed in a single (1xHIIT) or three shorter daily sessions (3xHIIT). Male Wistar rats were assigned to untrained (n = 10), 1xHIIT (n = 10), and 3xHIIT (n = 10) groups. Both HIIT groups performed 15 min of a treadmill run five times per week for 8 weeks. The 1xHIIT performed single daily sessions of 15 min, and the 3xHIIT performed three daily sessions of 5 min with an interval of 4 h between sessions. Resting VO2 and VO2max were measured using a metabolic chamber; blood pressure and heart rate were measured by plethysmography; body composition was estimated by DEXA; Glucose and insulin tolerance tests were performed; after euthanasia, hearts, gastrocnemius, and visceral fat were harvested for analysis of cardiac function, histology, and morphology. Mitochondrial densities of the gastrocnemius and left ventricle muscles were determined by electron microscopy. 3xHIIT induced similar positive adaptative responses to 1xHIIT on resting VO2 and VO2max, cardiac function, and mitochondria density. 3xHIIT was superior to 1xHIIT in reducing visceral fat weight and adipocyte size and improving insulin tolerance. Multiple short daily bouts of HIIT may be superior to single HIIT daily sessions in improving cardiometabolic and cellular adaptations in rats.

Effects of the association of different volumes of strength training with photobiomodulation therapy on insulin resistance: A protocol for a randomized, triple-blind, placebo-controlled trial.

Background: Insulin resistance (IR) is the main risk factor for developing type 2 diabetes. Both strength training (ST) and photobiomodulation therapy (PBMt) reduce IR, but the effect of combining different volumes of ST with PBMt is unknown. Methods: Overweight/obese individuals will be assigned to 4 groups (n = 12/group): ST with volume following international guidelines (3 sets per exercise - high volume) or one-third of this volume (1 set per exercise - low volume), combined with PBMt or placebo. ST will be performed for 20 sessions over 10 weeks and will consist of 7 exercises. The PBMt will be applied after training sessions using blankets with light emitters (LEDs) placed over the skin on the frontal and the posterior region of the body, following the parameters recommended by the literature. The placebo group will undergo an identical procedure, but blankets will emit insignificant light. To measure plasma glucose and insulin concentrations, oral glucose tolerance tests (OGTT) will be performed before and after the training period. Thereafter, IR, the area under the curve of glucose and insulin, and OGTT-derived indices of insulin sensitivity/resistance will be calculated. Expected impact on the field: This study will determine the effects of different ST volumes on IR and whether the addition of PBMt potentiates the effects of ST. Because previously sedentary, obese, insulin-resistant individuals might not comply with recommended volumes of exercise, the possibility that adding PBMt to low-volume ST enhances ST effects on IR bears practical significance.

A Real-World High-Intensity Interval Training Protocol for Cardiorespiratory Fitness Improvement.

High-Intensity Interval Training (HIIT) has emerged as an interesting time-efficient approach to increase exercise adherence and improve health. However, few studies have tested the efficiency of HIIT protocols in a "real world" setting, e.g., HIIT protocols designed for outdoor spaces without specialized equipment. This study presents a "real world" training protocol, named "beep training", and compares the efficiency of a HIIT regiment versus a traditional long-duration Moderate-Intensity Continuous Training (MICT) regiment using this beep training protocol on VO2 max of overweight untrained men. Twenty-two subjects performed outdoor running with MICT (n = 11) or HIIT (n = 11). Cardiorespiratory fitness was assessed before and after training protocols using a metabolic analyzer. Both training protocols were performed 3 days a week for 8 weeks using the Beep Test results. The MICT group performed the exercise program at 60%-75% of the maximum speed of the 20 m shuttle test (Vmax) and with a progression of the distance of 3,500-5,000 m. The HIIT group performed the interval exercise with 7-10 bouts of 200 m at 85%-100% of the maximum speed of the 20 m shuttle test (Vmax), interspersed with 1 min of passive recovery. Although the HIIT group presented a significantly lower training volume than the MICT group (p < 0.05) after 8 weeks of beep training, HIIT was superior to MICT in improving VO2 max (MICT: ~4.1%; HIIT: ~7.3%; p < 0.05). The "real world" HIIT regiment based on beep training protocol is a time-efficient, low-cost, and easy-to-implement protocol for overweight untrained men.

Accumulated High-intensity Interval Training Protocol: A New Approach to Study Health Markers in Wistar Rats.

High-Intensity Interval Training (HIIT) and accumulated exercises are two time-efficient programs to improve health in humans and animal models. However, to date, there are no studies on whether HIIT performed in an accumulated fashion is as effective as a traditional HIIT performed with single daily sessions in improving health markers. This paper presents the effects of a new HIIT protocol, called accumulated HIIT, on body weight gain, maximal oxygen consumption (VO2max), and cardiac hypertrophy in young Wistar rats. Sixty-day-old male Wistar rats were assigned to three groups: untrained (UN; n = 16), HIIT performed with single daily sessions (1-HIIT; n = 16), and HIIT performed with three daily sessions (3-HIIT; n = 16). Body weight and VO2max were recorded before and after the training period. The VO2max measurements were taken using a metabolic analyzer at the maximal running velocity (Vmax). The training was performed for both HIIT groups five days per week over eight weeks with the same weekly progression of the exercise intensity (85-100% Vmax). The 1-HIIT group performed single daily sessions (6 bouts of 1 min interspersed with 1 min of passive recovery). The 3-HIIT group performed three daily sessions (2 bouts of 1 min interspersed with 1 min of passive recovery with an interval of 4 h between bouts). After the last VO2max test, the rats were euthanized, and their hearts were harvested and weighed. The results showed that 3-HIIT had similar beneficial effects to 1-HIIT in preventing body weight gain, improving VO2max, and inducing cardiac hypertrophy. These findings reveal for the first time the efficacy of an accumulated HIIT protocol on the health markers of young Wistar rats. This new HIIT protocol may be more feasible than traditional HIIT protocols as exercise can be split into very short sessions throughout a day in this new approach.

Moderate-intensity continuous training and high-intensity interval training improve cognition, and BDNF levels of middle-aged overweight men.

The prevalence of overweight and obesity is increasing worldwide, which has been associated with poor cognitive outcomes. Participating in regular physical exercise may also improve cognition, and levels of brain-derived neurotrophic factor (BDNF), but the optimal exercise prescription remains to be elucidated. The purpose of the present study is to compare the effects of moderate intensity continuous training (MICT) and high intensity interval training (HIIT) on cognition, and serum BDNF levels in middle-aged and overweight men. Twenty-five sedentary, overweight men participated in the 8-week training intervention. Subjects were randomized into MICT (n = 12) or HIIT (n = 13) and performed exercise sessions 3x/week for 8-weeks. Cognitive function, and serum BDNF levels were assessed pre- and post-intervention. Statistical analysis was carried out using the Graph Pad Prism 7.0, and the level of significance was set at 5%. Significant improvements were observed in cognitive test scores, and BDNF levels in MICT and HIIT groups (p < 0.05). There were no significant differences in cognitive function between MICT and HIIT. The present study implicates that 8 weeks of MICT or HIIT may be a very useful non-pharmacological treatment option to improve cognitive function, and BDNF levels in middle-aged overweight men.

Endurance and high-intensity interval training improve the levels of anxiety and quality of life in overweight men.

OBJECTIVE: Body mass index (BMI) values of 25 kg/m2 or more have been associated with poor cognitive outcomes, reduced health-related quality of life (HRQoL), and mental health disorders. Participating in regular exercise may improve these negative outcomes. However, the optimal exercise prescription remains to be clarified. The purpose of the present study is to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on HRQoL, depression, and anxiety levels in middle-aged overweight men. METHODS: Twenty-five sedentary, overweight men participated in the 8-week training intervention. Subjects were randomized into MICT or HIIT and performed exercise sessions three times per week for 8 weeks. Participants answered the Physical Activity Readiness Questionnaire, the Short Form-36 survey, the Beck Depression Inventory-II, and the Beck Anxiety Inventory. Statistical analysis was carried out using the GraphPad Prism 7.0, and the level of significance was set at 5% to quantitative variables. RESULTS: HRQoL scores were enhanced to all domains of both the groups. MICT and HIIT did not significantly change the depression levels in middle-aged overweight men (p>0.05). Nevertheless, MICT was capable to reduce the anxiety levels in middle-aged overweight men (p<0.05). However, there was not a significant change in the anxiety levels at the HIIT group. CONCLUSIONS: HIIT may be a useful treatment to improve the HRQoL, but MICT alone can positively impact the anxiety levels in middle-aged overweight men.

Endurance and high-intensity interval training improve the levels of anxiety and quality of life in overweight men

SUMMARY OBJECTIVE Body mass index (BMI) values of 25 kg/m2 or more have been associated with poor cognitive outcomes, reduced health-related quality of life (HRQoL), and mental health disorders. Participating in regular exercise may improve these negative outcomes. However, the optimal exercise prescription remains to be clarified. The purpose of the present study is to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on HRQoL, depression, and anxiety levels in middle-aged overweight men. METHODS Twenty-five sedentary, overweight men participated in the 8-week training intervention. Subjects were randomized into MICT or HIIT and performed exercise sessions three times per week for 8 weeks. Participants answered the Physical Activity Readiness Questionnaire, the Short Form-36 survey, the Beck Depression Inventory-II, and the Beck Anxiety Inventory. Statistical analysis was carried out using the GraphPad Prism 7.0, and the level of significance was set at 5% to quantitative variables. RESULTS HRQoL scores were enhanced to all domains of both the groups. MICT and HIIT did not significantly change the depression levels in middle-aged overweight men (p>0.05). Nevertheless, MICT was capable to reduce the anxiety levels in middle-aged overweight men (p<0.05). However, there was not a significant change in the anxiety levels at the HIIT group. CONCLUSIONS HIIT may be a useful treatment to improve the HRQoL, but MICT alone can positively impact the anxiety levels in middle-aged overweight men.

HIIT is superior than MICT on cardiometabolic health during training and detraining.

PURPOSE: This study investigated the cardiometabolic health of overweight/obese untrained individuals in response to 8 weeks of HIIT and MICT using a field approach, and to 4 weeks of training cessation (TC). METHODS: Twenty-two subjects performed 8 weeks of moderate intensity continuous training (MICT-n = 11) or high-intensity interval training (HIIT-n = 11) (outdoor running), followed by 4 weeks of TC. Cardiorespiratory fitness, body composition, arterial blood pressure, glucose metabolism and blood lipids were measured pre-training (PRE), post-training (POST) and TC. RESULTS: HIIT improved eight indicators of cardiometabolic health ([Formula: see text], BMI, body fat, visceral fat, systolic blood pressure, total cholesterol, fasting glucose and triglycerides-p < 0.05) while MICT only three ([Formula: see text], BMI, and visceral fat-p < 0.05). After 4 weeks of TC, four positive adaptations from HIIT were negatively affected ( [Formula: see text], visceral fat, systolic blood pressure and total cholesterol-p < 0.05) and three in the MICT group ([Formula: see text], BMI and visceral fat, p < 0.05). CONCLUSION: Eight weeks of HIIT performed in a real-world setting promoted a greater number of positive adaptations in cardiometabolic health of individuals with overweight/obese compared to MICT. Most of the positive effects of the HIIT protocol were also found to be longer lasting and maintained after the suspension of high-intensity interval running for 4 weeks. Conversely, all positive effects of MICT protocols were reversed after TC.

Influence of the knee flexion on muscle activation and transmissibility during whole body vibration.

The influence of the knee flexion on muscle activation and transmissibility during whole body vibration is controversially discussed in the literature. In this study, 34 individuals had electromyography activity (EMG) of the vastus lateralis and the acceleration assessed while squatting with 60° and 90° of knee flexion either with or without whole-body vibration (WBV). The conditions were maintained for 10s with 1min of rest between each condition. The main findings were (1) the larger the angle of knee flexion (90° vs. 60°), the greater the EMG (p<0.001), with no difference on acceleration transmissibility; (2) for both angles of knee flexion, the addition of WBV produced no significant difference in EMG and higher acceleration compared to without WBV (p<0.001). These results suggest that the larger the knee flexion angle (60° vs. 90°), the greater the muscle activation without acceleration modification. However, the addition of WBV increases the transmissibility of acceleration in the lower limbs without modification in EMG of vastus lateralis.

Os exergames e a educação física escolar na cultura digital / Exergames and the school physical education in the digital culture / Exergames y la educación física escolar en la cultura digital

Os exergames são jogos eletrônicos que captam e virtualizam os movimentos reais dos usuários. Com o objetivo de discutir as perspectivas da utilização da virtualidade dos videogames na educação física escolar, participaram deste estudo 117 alunos de uma escola pública, com idade entre 13 e 14 anos. Os voluntários responderam a um questionário para identificar o nível de contato com as tecnologias digitais e, em seguida, relataram suas percepções sobre a vivência em dois jogos, o exergame e o real. Os resultados constataram a imersão dos estudantes na cultura digital e no processo de virtualização que lhe é típico, assim como apontaram algumas perspectivas de utilização crítica dessa nova linguagem, que pode ampliar e recriar as possibilidades das práticas e vivências corporais.

The exergames are electronic games that capture and virtualize the real movements of the users. With the aim of discussing the perspectives of using virtual videogames in school physical education, 117 students participated in this study at a public school aged 13 and 14. The subjects answered a questionnaire to identify the level of contact with digital technologies, and then reported their perceptions about the experience in two games, the exergame and the real. The results showed the students' immersion in the digital culture and in the process of virtualization which is typical, as pointed out some critical perspectives of using this new language that can expand and rebuild the possibilities of bodily practices and experiences.

Exergames son juegos electrónicos que capturan y virtualizan los movimientos reales de los usuarios. Con el objetivo de discutir las perspectivas de utilización de la virtualidad en la educación física escolar, 117 estudiantes entre 13 y 14 años de un colegio público participaron en este estudio. Los sujetos respondieron a un cuestionario para identificar el nivel de contacto con las tecnologías digitales, y informaron sus percepciones acerca de la experiencia en dos juegos, exergame y real. Los resultados mostraron la inmersión de los estudiantes en la cultura digital y el proceso de virtualización que le és típico, como se ha señalado algunas perspectivas críticas de la utilización de este lenguaje que puede ampliar y reconstruir las posibilidades de las prácticas corporales.

The effects of passive warm-up vs. whole-body vibration on high-intensity performance during sprint cycle exercise.

The purpose of this study was to compare the effects of passive warm-up (PW), whole-body vibration (WBV), and control (C) on high-intensity performance during sprint cycle exercise. Six recreationally trained men performed a 30-second sprint cycle test after the 3 aforementioned conditions; each test was carried out on a different day after balanced-order experimental tests. The WBV consisted of 5 minutes of squats associated with WBV (45 Hz, 2 mm). The PW consisted of 30 minutes of PW using a thermal blanket on the thighs and legs (35 W). The C consisted of 30 minutes of no warm-up with the subject lying down. Motor neuron excitability from the vastus lateralis muscle, evaluated by electromyography (EMG), was determined before exercise at rest and during sprint cycle exercise. Blood lactate levels (BLs), evaluated by spectroscopy, and muscle temperature (MT) of the thigh, estimated indirectly by measuring skin temperature, were determined at following time points: before exercise at rest (before and after experimental conditions), immediately, and 3 minutes after the 30-second sprint cycle test. Peak power, relative power, relative work, time of peak power, and pedaling cadence were significantly higher in the WBV compared with that for C (p < 0.05). Although MT was significantly greater in PW compared with that in WBV and C before exercise (p < 0.01), no significant differences were observed between the experimental conditions for BL immediately after sprint cycle exercise (p = 0.35) and in EMG during sprint cycle exercise (p = 0.16). Thus, it is plausible to suggest WBV as a method for an acute increase in high-intensity performance during sprint cycle exercise for athletes immediately before competition or training.

Paraquat (PQ)-induced pulmonary fibrosis increases exercise metabolic cost, reducing aerobic performance in rats.

Rats exposed to the quaternary herbicide paraquat (PQ) exhibit oxidative stress and lung injury. In the present study, we investigated the effect of multiple exposures to PQ on aerobic performance during progressive exercise on a treadmill in rats. PQ was dissolved in saline (SAL) (10 mg/ml) and administered intraperitoneally 7 mg/kg body wt to Wistar rats (n = 5) once a week for one month. Control rats received SAL (0.7 ml/kg body wt., intraperitoneally, n = 5) over the same time period. The animals were submitted to aerobic evaluation on a treadmill using a progressive protocol until fatigue prior to the administration of the first dose of PQ or SAL and repeated at 1 week and 40 days following the last dose of the herbicide. Twenty-four hours after the last performance tests, the animals were sacrificed, lungs removed and divided in two groups: PQ and SAL for histopathological analysis. The animals exposed to PQ exhibited decrease in aerobic performance and mechanical efficiency (ME) as well as increase in oxygen consumption during exercise in comparison to the controls forty days after the last dose of PQ. Lung histologic changes included atelectasis, interstitial edema, and inflammation cells in PQ group. The collagen system fibers, fraction area of alveolar collapse and influx of polymorphonuclear (PMN) cells in lung parenchyma were higher in PQ compared to SAL. In conclusion, multiple exposures to PQ induce pulmonary fibrosis, reduce the aerobic performance and mechanical efficiency and increase the metabolic cost of exercise in rats.

Carbohydrate ingestion during exercise does not delay the onset of fatigue during submaximal cycle exercise.

The objective of this study was to evaluate the effect of the ingestion of carbohydrate (CHO, in the form of maltodextrin) or placebo (PLAC, in the form of gelatin) on the physical performance of cyclists during submaximal exercise until fatigue on an ergometric cycle. Nine volunteers exercised on 2 separate occasions at least 2 days apart. On each occasion, after 48 hours of a balanced diet, they pedaled at approximately 66% Vo2peak until fatigue. Every 15 minutes, 150 mL of water and 18 capsules, containing either 0.5 g of CHO or PLAC (approximately 0.13 g x kg(-1) of body weight), were ingested in accordance with a double-blind, randomized protocol. The results show that after 40% of total exercise time, blood glucose levels in the CHO test returned to baseline levels. However, in the PLAC trial these levels failed to return to baseline levels, remaining lower than levels recorded in the CHO test after 60% of total exercise time. Despite these results, CHO ingestion failed to delay the onset of fatigue (CHO: 91.8 +/- 10.1 minutes vs. PLAC: 93.3 +/- 16.1 minutes; p = 0.87). In practical terms, coaches and trainers should consider that CHO ingestion in previously fed users does not delay the onset of fatigue during submaximal cycle exercise.

Sustained, prolonged exercise at stable heart rate defined by the deflection point identification method.

Gripp,The objectives of this study were to identify the heart rate deflection point (HRDP) assessed according to the Conconi test method, to evaluate the ability of trained cyclists to pedal for 90 minutes while remaining within a stable heart rate (HR) range determined by identifying the HRDP, and to discuss the motor and physiological parameters recorded during this long-duration exercise. Ten trained men cyclists (VO2max: 64.1 +/- 8.86 mlxkgxmin) had their HRDPs determined. One week later, they performed continuous exercise for 90 minutes on a cycle ergometer at a stable HR sustained within a range comprising the HRDP +/- 5 bpm. Subjects' HR and power output values were registered at each minute. Blood lactate, blood glucose, and body temperature were measured at rest and during exercise. All exercise was performed inside an environmental chamber (temperature of 22 degrees C, relative humidity of 60%). In the first 5 minutes, the participants increased power output to reach the HRDP, and adjustments were required in their physiological parameters to meet this exercise demand. Between the 5th and the 30th minutes, HRDP had already been reached by all participants; nevertheless, all the other physiological and motor parameters were adjusting to this exercise demand. After 30 minutes of exercise, the physiological and motor variables had already adjusted to the new demand and remained stable until the end of exercise (blood lactate was not significantly different from 4 mmolxL). These results suggest the efficacy of the HRDP as an auxiliary method for prescribing and controlling sport training: after the defined HRDP has been reached, the technique confirms maintenance of power output, as well as the other physiological parameters, at threshold levels until the end of exercise.

Acute heat exposure increases high-intensity performance during sprint cycle exercise.

The purpose of this study was to investigate the effects of acute heat exposure at thermal balance on high-intensity performance during sprint cycle exercise. Nine healthy male subjects were tested in three different, well-controlled environments in an environmental chamber: T (22 degrees C, 65% RH), H1 (30 degrees C, 55% RH) and H2 (35 degrees C, 62% RH), each test being carried out on a different day following a randomized sequence. After 30 min of exposure to the set environment, subjects performed the 30-s sprint cycle exercise. Heart rate, rectal and skin temperatures were measured prior to exercise, at rest, before and after environmental exposure, and after exercise. There were no differences in subjects' core temperature or heart rate prior to exercise. However, skin temperature was significantly higher in hot trials compared with the control throughout the experimental session (P < 0.05). Peak power was significantly higher in the hot environments compared with the control. Mean power was higher only in H2 compared with T (P < 0.05). This difference in power output was the consequence of a faster pedaling cadence in the hot trials (P < 0.05). Plasma ammonia was higher in the hot trials versus control at 4 min post-sprint. No differences in blood lactate levels at 3 min post-sprint were observed between tests. The results of this study suggest that the exposure to hot environment caused an improvement in power output for a single 30-s sprint. This increase in power output was associated with an elevation in plasma ammonia suggestive of an increase in adenine nucleotide loss.