Showing papers on "Interval training published in 2012"

Physiological adaptations to low-volume, high-intensity interval training in health and disease

Abstract: Exercise training is a clinically proven, cost-effective, primary intervention that delays and in many cases prevents the health burdens associated with many chronic diseases. However, the precise type and dose of exercise needed to accrue health benefits is a contentious issue with no clear consensus recommendations for the prevention of inactivity-related disorders and chronic diseases. A growing body of evidence demonstrates that high-intensity interval training (HIT)canserveasaneffectivealternatetotraditionalendurance-basedtraining,inducingsimilar or even superior physiological adaptations in healthy individuals and diseased populations, at least when compared on a matched-work basis. While less well studied, low-volume HIT can also stimulate physiological remodelling comparable to moderate-intensity continuous training despite a substantially lower time commitment and reduced total exercise volume. Such findings areimportantgiventhat'lackoftime'remainsthemostcommonlycitedbarriertoregularexercise participation. Here we review some of the mechanisms responsible for improved skeletal muscle metabolic control and changes in cardiovascular function in response to low-volume HIT. We also consider the limited evidence regarding the potential application of HIT to people with, or at risk for, cardiometabolic disorders including type 2 diabetes. Finally, we provide insight on the utility of low-volume HIT for improving performance in athletes and highlight suggestions for future research.

The Potential for High-Intensity Interval Training to Reduce Cardiometabolic Disease Risk

Abstract: In the US, 34% of adults currently meet the criteria for the metabolic syndrome defined by elevated waist circumference, plasma triglycerides (TG), fasting glucose and/or blood pressure, and decreased high-density lipoprotein cholesterol (HDL-C). While these cardiometabolic risk factors can be treated with medication, lifestyle modification is strongly recommended as a first-line approach. The purpose of this review is to focus on the effect of physical activity interventions and, specifically, on the potential benefits of incorporating higher intensity exercise. Several recent studies have suggested that compared with continuous moderate exercise (CME), high-intensity interval training (HIT) may result in a superior or equal improvement in fitness and cardiovascular health. HIT is comprised of brief periods of high-intensity exercise interposed with recovery periods at a lower intensity. The premise of using HIT in both healthy and clinical populations is that the vigorous activity segments promote greater adaptations via increased cellular stress, yet their short length, and the ensuing recovery intervals, allow even untrained individuals to work harder than would otherwise be possible at steady-state intensity. In this review, we examine the impact of HIT on cardiometabolic risk factors, anthropometric measures of obesity and cardiovascular fitness in both healthy and clinical populations with cardiovascular and metabolic disease. The effects of HIT versus CME on health outcomes were compared in 14 of the 24 studies featuring HIT. Exercise programmes ranged from 2 weeks to 6 months. All 17 studies that measured aerobic fitness and all seven studies that measured insulin sensitivity showed significant improvement in response to HIT, although these changes did not always exceed responses to CME comparison groups. A minimum duration of 12 weeks was necessary to demonstrate improvement in fasting glucose in four of seven studies (57%). A minimum duration of 8 weeks of HIT was necessary to demonstrate improvement in HDL-C in three of ten studies (30%). No studies reported that HIT resulted in improvement of total cholesterol, low-density lipoprotein cholesterol (LDL-C), or TG. At least 12 weeks of HIT was required for reduction in blood pressure to emerge in five studies of participants not already being treated for hypertension. A minimum duration of 12 weeks was necessary to see consistent improvement in the six studies that examined anthropometric measures of obesity in overweight/obese individuals. In the 13 studies with a matched-exercise-volume CME group, improvement in aerobic fitness in response to HIT was equal to (5 studies), or greater than (8 studies) in response to CME. Additionally, HIT has been shown to be safe and effective in patients with a range of cardiac and metabolic dysfunction. In conclusion, HIT appears to promote superior improvements in aerobic fitness and similar improvements in some cardiometabolic risk factors in comparison to CME, when performed by healthy subjects or clinical patients for at least 8–12 weeks. Future studies need to address compliance and efficacy of HIT in the real world with a variety of populations.

Aerobic interval training reduces blood pressure and improves myocardial function in hypertensive patients

Abstract: Aims: Exercise is recommended as prevention, management, and control of all stages of hypertension. There are still controversies about the optimal training dose, frequency, and intensity. We aimed...

High-Intensity Interval Training in Cardiac Rehabilitation

Abstract: High-intensity interval training (HIIT) is frequently used in sports training. The effects on cardiorespiratory and muscle systems have led scientists to consider its application in the field of cardiovascular diseases. The objective of this review is to report the effects and interest of HIIT in patients with coronary artery disease (CAD) and heart failure (HF), as well as in persons with high cardiovascular risk. A non-systematic review of the literature in the MEDLINE database using keywords 'exercise', 'high-intensity interval training', 'interval training', 'coronary artery disease', 'coronary heart disease', 'chronic heart failure' and 'metabolic syndrome' was performed. We selected articles concerning basic science research, physiological research, and randomized or non-randomized interventional clinical trials published in English. To summarize, HIIT appears safe and better tolerated by patients than moderate-intensity continuous exercise (MICE). HIIT gives rise to many short- and long-term central and peripheral adaptations in these populations. In stable and selected patients, it induces substantial clinical improvements, superior to those achieved by MICE, including beneficial effects on several important prognostic factors (peak oxygen uptake, ventricular function, endothelial function), as well as improving quality of life. HIIT appears to be a safe and effective alternative for the rehabilitation of patients with CAD and HF. It may also assist in improving adherence to exercise training. Larger randomized interventional studies are now necessary to improve the indications for this therapy in different populations.

Towards the minimal amount of exercise for improving metabolic health: Beneficial effects of reduced-exertion high-intensity interval training

Abstract: High-intensity interval training (HIT) has been proposed as a time-efficient alternative to traditional cardiorespiratory exercise training, but is very fatiguing. In this study, we investigated the effects of a reduced-exertion HIT (REHIT) exercise intervention on insulin sensitivity and aerobic capacity. Twenty-nine healthy but sedentary young men and women were randomly assigned to the REHIT intervention (men, n = 7; women, n = 8) or a control group (men, n = 6; women, n = 8). Subjects assigned to the control groups maintained their normal sedentary lifestyle, whilst subjects in the training groups completed three exercise sessions per week for 6 weeks. The 10-min exercise sessions consisted of low-intensity cycling (60 W) and one (first session) or two (all other sessions) brief ‘all-out’ sprints (10 s in week 1, 15 s in weeks 2–3 and 20 s in the final 3 weeks). Aerobic capacity (\( \dot{V}{\text{O}}{}_{ 2}{\text{peak}} \)) and the glucose and insulin response to a 75-g glucose load (OGTT) were determined before and 3 days after the exercise program. Despite relatively low ratings of perceived exertion (RPE 13 ± 1), insulin sensitivity significantly increased by 28% in the male training group following the REHIT intervention (P < 0.05). \( \dot{V}{\text{O}}{}_{ 2}{\text{peak}} \) increased in the male training (+15%) and female training (+12%) groups (P < 0.01). In conclusion we show that a novel, feasible exercise intervention can improve metabolic health and aerobic capacity. REHIT may offer a genuinely time-efficient alternative to HIT and conventional cardiorespiratory exercise training for improving risk factors of T2D.

Acute high-intensity interval exercise reduces the postprandial glucose response and prevalence of hyperglycaemia in patients with type 2 diabetes.

Abstract: High-volume endurance exercise (END) improves glycaemic control in type 2 diabetes (T2D) but many individuals cite 'lack of time' as a barrier to regular participation. High-intensity interval training (HIT) is a time-efficient method to induce physiological adaptations similar to END, but little is known regarding the effect of HIT in T2D. Using continuous glucose monitoring (CGM), we examined the 24-h blood glucose response to one session of HIT consisting of 10 × 60 s cycling efforts at ~90% maximal heart rate, interspersed with 60 s rest. Seven adults with T2D underwent CGM for 24-h on two occasions under standard dietary conditions: following acute HIT and on a non-exercise control day (CTL). HIT reduced hyperglycaemia measured as proportion of time spent above 10 mmol/l (HIT: 4.5 ± 4.4 vs. CTL: 15.2 ± 12.3%, p = 0.04). Postprandial hyperglycaemia, measured as the sum of post-meal areas under the glucose curve, was also lower after HIT vs. CTL (728 ± 331 vs. 1142 ± 556 mmol/l·9 h, p = 0.01). These findings highlight the potential for HIT to improve glycaemic control in T2D.

Aerobic interval training increases peak oxygen uptake more than usual care exercise training in myocardial infarction patients: a randomized controlled study:

Abstract: Objective: Exercise capacity strongly predicts survival and aerobic interval training (AIT) increases peak oxygen uptake effectively in cardiac patients. Usual care in Norway provides exercise training at the hospitals following myocardial infarction (MI), but the effect and actual intensity of these rehabilitation programmes are unknown.Design: Randomized controlled trial.Setting: Hospital cardiac rehabilitation.Subjects: One hundred and seven patients, recruited two to 12 weeks after MI, were randomized to usual care rehabilitation or treadmill AIT.Interventions: Usual care aerobic group exercise training or treadmill AIT as 4 × 4 minutes intervals at 85–95% of peak heart rate. Twice weekly exercise training for 12 weeks.Main measures: The primary outcome measure was peak oxygen uptake. Secondary outcome measures were endothelial function, blood markers of cardiovascular disease, quality of life, resting heart rate, and heart rate recovery.Results: Eighty-nine patients (74 men, 15 women, 57.4 ± 9.5 year...

Effect of High-Intensity Interval Training on Cardiovascular Function, V̇o2max, and Muscular Force

Abstract: The purpose of this study was to examine the effects of short-term high-intensity interval training (HIIT) on cardiovascular function, cardiorespiratory fitness, and muscular force. Active, young (age and body fat = 25.3 ± 4.5 years and 14.3 ± 6.4%) men and women (N = 20) of a similar age, physical activity, and maximal oxygen uptake (VO2max) completed 6 sessions of HIIT consisting of repeated Wingate tests over a 2- to 3-week period. Subjects completed 4 Wingate tests on days 1 and 2, 5 on days 3 and 4, and 6 on days 5 and 6. A control group of 9 men and women (age and body fat = 22.8 ± 2.8 years and 15.2 ± 6.9%) completed all testing but did not perform HIIT. Changes in resting blood pressure (BP) and heart rate (HR), VO2max, body composition, oxygen (O2) pulse, peak, mean, and minimum power output, fatigue index, and voluntary force production of the knee flexors and extensors were examined pretraining and posttraining. Results showed significant (p 0.05) in resting BP, HR, or force production was revealed. Data show that HIIT significantly enhanced VO2max and O2 pulse and power output in active men and women.

Heart rate monitoring in soccer: interest and limits during competitive match play and training, practical application.

Abstract: The identification of physiological loads imposed by soccer training or match play reveals essential information, which may help improve training and recovery strategies Until today, the use of heart rate (HR) monitoring is not standardized in soccer Thus, the aim of this review was to analyze, determine and compare the exercise intensity (EI) monitored by HR in professional, youth, and recreational soccer players during matches and training sessions using a meta-analysis Heart rate is one of the most common physiological variables used to determine exercise internal training load The mean EI recorded during competitive matches was described as 70-80% of VO2max or 80-90% of maximal heart rate (HRmax), independent of the playing level With respect to HR training zones, approximately 65% of the total match duration is spent at intensity of 70-90% HRmax and rarely below 65% HRmax However, although HRmax is mostly employed in the literature, monitoring EI should be expressed in relation to reserve heart rate, as it was described as a more reliable indicator of HR, allowing interindividual comparisons The HR response according to the playing position indicates that midfielders are characterized by the highest EI, followed by forwards and fullbacks Moreover, in the second half of the match, the EI is lower than that observed during the first half; this reduction could be correlated with the level of the player's physical conditioning Consequently, coaches may favor the use of interval training or small-sided training games because these are shown to improve both aerobic capacity and the ability to repeat high-intensity actions Small-sided games allow reaching similar HR responses to those found during interval training and match play but with greater heterogeneity values Future investigations should include a larger sample of players with special reference to playing position and the expression of EI in percentage of the reserve heart rate, analyzing the possible intergender differences in HR response

Similar Health Benefits of Endurance and High-Intensity Interval Training in Obese Children

Abstract: Purpose: To compare two modalities of exercise training (i.e., Endurance Training [ET] and High-Intensity Interval Training [HIT]) on health-related parameters in obese children aged between 8 and 12 years. Methods: Thirty obese children were randomly allocated into either the ET or HIT group. The ET group performed a 30 to 60-minute continuous exercise at 80% of the peak heart rate (HR). The HIT group training performed 3 to 6 sets of 60-s sprint at 100% of the peak velocity interspersed by a 3-min active recovery period at 50% of the exercise velocity. HIT sessions last ,70% less than ET sessions. At baseline and after 12 weeks of intervention, aerobic fitness, body composition and metabolic parameters were assessed. Results: Both the absolute (ET: 26.0%; HIT: 19.0%) and the relative VO2 peak (ET: 13.1%; HIT: 14.6%) were significantly increased in both groups after the intervention. Additionally, the total time of exercise (ET: 19.5%; HIT: 16.4%) and the peak velocity during the maximal graded cardiorespiratory test (ET: 16.9%; HIT: 13.4%) were significantly improved across interventions. Insulinemia (ET: 29.4%; HIT: 30.5%) and HOMA-index (ET: 42.8%; HIT: 37.0%) were significantly lower for both groups at POST when compared to PRE. Body mass was significantly reduced in the HIT (2.6%), but not in the ET group (1.2%). A significant reduction in BMI was observed for both groups after the intervention (ET: 3.0%; HIT: 5.0%). The responsiveness analysis revealed a very similar pattern of the most responsive variables among groups. Conclusion: HIT and ET were equally effective in improving important health related parameters in obese youth.

Small-sided games versus interval training in amateur soccer players: effects on the aerobic capacity and the ability to perform intermittent exercises with changes of direction.

Abstract: The purpose of this study was to compare the effects of small-sided games (SSGs) in soccer versus high-intensity intermittent training (HIT) on a continuous aerobic test (Vameval) and the performance in an intermittent test with changes of direction (CODs; 30-15 intermittent fitness test [30-15(IFT)]). Twenty-two amateur soccer players (mean age ± SD: 26.3 ± 4.7 years) were assigned to 3 different groups for 6 weeks: SSG group (n = 8), HIT group (n = 8), and control group (CG; n = 6). In addition to the usual technical and tactical sessions and competitive games, the SSG group performed 9 sessions of 2 versus 2 and 1 versus 1 SSGs, whereas the HIT group performed 9 sessions of intermittent runs in the form of 30 seconds of effort interspersed with 30 seconds of passive recovery (30s-30s), 15s-15s, and 10s-10s. The HIT and SSG groups showed performance improvements in the Vameval test (5.1 and 6.6%, respectively) and the 30-15(IFT) intermittent test with CODs (5.1 and 5.8%, respectively), whereas there was no change in the performance of the CG. Players from HIT and SSG groups showed similar increase in their performance in the 30-15(IFT) and the Vameval tests during the 6-week training period, especially with an increase significantly different to that in a traditional training as in the CG (p < 0.05). This investigation demonstrates that both SSG and HIT interventions are equally effective in developing the aerobic capacity and the ability to perform intermittent exercises with CODs in male amateur soccer players. Furthermore, these 2 methods of training applied during the 6 weeks induce similar effect on the recovery capacity and on the ability to repeat directional changes of 180°. Coaches will now be able to choose between these two methods according to the objective of the training and to optimize the training.

High-Intensity Interval Resistance Training (HIRT) influences resting energy expenditure and respiratory ratio in non-dieting individuals

Abstract: Background The benefits of exercise are well established but one major barrier for many is time. It has been proposed that short period resistance training (RT) could play a role in weight control by increasing resting energy expenditure (REE) but the effects of different kinds of RT has not been widely reported.

High-Intensity Interval Training: An Alternative for Older Adults

Abstract: High-intensity interval training (HIT) is characterized by intermittent periods of work and rest and may include work bouts lasting seconds to minutes. HIT has typically been applied to older, diseased, and at-risk populations using longer work intervals (2-4 minutes), whereas more recent definitions of HIT include work intervals of 30 to 60 s. Both traditional endurance training (TET) and HIT exert a peripheral affect increasing the capacity of muscle cells to oxidize substrate via signaling cascades that support the activation of transcription factors that orchestrate the coexpression of nuclear and mitochondrial genes, with HIT triggering these benefits following minutes of training. With 1 exception, reports of central adaptations (eg, increased stroke volume) have been based on longer work intervals (eg, 4 minutes). Recent investigations have tied HIT to increased lipolysis and enhanced insulin sensitivity. HIT favors the activation of oxidative as opposed to hypertrophic pathways. Although the lengt...

Review Article High-intensity interval training and hypertension: maximizing the benefits of exercise?

Abstract: Essential arterial hypertension is the most common risk factor for cardiovascular morbidity and mortality. Regular exercise is a well-established intervention for the prevention and treatment of hypertension. Continuous moderate-intensity exercise training (CMT) that can be sustained for 30 min or more has been traditionally recom- mended for hypertension prevention and treatment. On the other hand, several studies have shown that high- intensity interval training (HIT), which consists of several bouts of high-intensity exercise (~85% to 95% of HRMAX and/ or VO2MAX lasting 1 to 4 min interspersed with intervals of rest or active recovery, is superior to CMT for improving cardiorespiratory fitness, endothelial function and its markers, insulin sensitivity, markers of sympathetic activity and arterial stiffness in hypertensive and normotensive at high familial risk for hypertension subjects. This compelling evidence suggesting larger beneficial effects of HIT for several factors involved in the pathophysiology of hypertension raises the hypothesis that HIT may be more effective for preventing and controlling hypertension.

High-intensity interval training vs. repeated-sprint training in tennis.

Abstract: The aim of this study was to compare the effects of high-intensity interval training (HIIT) and repeated-sprint training (RST) on aerobic fitness, tennis-specific endurance, linear and repeated-sprint ability (RSA), and jumping ability. Thirty-one competitive male tennis players took part in a training intervention of 6 weeks. The players were matched into 3 groups, HIIT (n = 11), RST (n = 12), or control group (CON, n = 9). The results showed significant time × intervention interactions for VO(2)peak, with a significant increase in the VO(2)peak level of 6.0% in HIIT (p = 0.008) and 4.9% in RST (p = 0.010), whereas no changes occurred in CON. However, the following differences were found between the intervention groups: The HIIT-induced greater improvements in tennis-specific endurance (HIIT 28.9% vs. RST 14.5%; p < 0.05) and RST led to a significant improvement in RSA (i.e., reduction in the mean sprint time of 3.8%; p < 0.05). Neither training strategy induced any effects on jumping and sprinting abilities. Both training interventions showed similar improvements in general aerobic fitness. Also, the present results suggest that RST represents a time-efficient stimulus for a simultaneous improvement of general and tennis-specific aerobic fitness as well for RSA.

Long-term lifestyle intervention with optimized high-intensity interval training improves body composition, cardiometabolic risk, and exercise parameters in patients with abdominal obesity.

Abstract: ObjectiveThe aim of this study was to study the impact of a combined long-term lifestyle and high-intensity interval training intervention on body composition, cardiometabolic risk, and exercise tolerance in overweight and obese subjects.DesignSixty-two overweight and obese subjects (53.3 ±

High intensity interval exercise training in overweight young women

Abstract: The purpose of this study was intended to evaluate the effects of a high intensity interval training (HIIT) program on the body composition, cardiac function and aerobic capacity in overweight young women. Sixty female university students (aged 19-20, BMI≥25kg/m2 and percentage body fat ≥ 30%) were chosen and then randomly assigned to each of the HIIT group, the moderate intensity continuous training (MICT) group and the non-training control group. The subjects in both the HIIT and MICT groups underwent exercise training five times per week for 12 weeks. In each of the training sessions, the HIIT group performed interval exercises at the individualized heart rate (HR) of 85% of VO2max and separated by brief periods of low intensity activity (HR at 50% of VO2max), while the MICT group did continuous walking and/or jogging at the individualized HR of 50% of VO2max. Both of these exercise training programs produced significant improvements in the subjects' body composition, left ventricular ejection fraction, heart rate at rest, maximal oxygen uptake and ventilatory threshold. However, the HIIT group achieved better results than those in the MICT group, as it was evaluated by the amount of the effect size. The control group did not achieve any change in all of the measured variables. The tangible results achieved by our relatively large groups of homogeneous subjects have demonstrated that the HIIT program is an effective measure for the treatment of young women who are overweight.

Effect of exercise training on inflammation status among people with metabolic syndrome.

Abstract: Background: Metabolic syndrome is associated with chronic low-grade inflammation, a condition thought to play a key role in the pathogenesis of the syndrome. Among a number of proinflammatory cytokines, interleukin-18 (IL-18) seems to be the best marker for inflammation among people with metabolic syndrome. The aim of this study was to examine the effect of aerobic training versus strength training on circulating IL-18 and other proinflammatory markers in people with metabolic syndrome. Methods: Thirty-one inactive men and women with metabolic syndrome were randomized to either high-intensity aerobic interval training (AIT, n=11), strength training (ST, n=10), or a control group (n=10). Exercise training was carried out three times per week for 12 weeks. Serum insulin, high-sensitivity C-reactive protein (hsCRP), IL-18, IL-6, and tumor necrosis factor-α (TNF-α) were measured before and after the intervention. Results: Serum IL-18 was reduced by 43% after AIT (P<0.001). Although there was no chang...

Effects of high-intensity interval training on pulmonary function.

Abstract: To determine whether high-intensity interval training (HIT) would increase respiratory muscle strength and expiratory flow rates more than endurance training (ET), 15 physically active, healthy subjects (untrained) were randomly assigned to an ET group (n = 7) or a HIT group (n = 8). All subjects performed an incremental test to exhaustion (VO2max) on a cycle ergometer before and after training. Standard pulmonary function tests, maximum inspiratory pressure (PImax), maximum expiratory pressure (PEmax), and maximal flow volume loops were performed pre training and after each week of training. HIT subjects performed a 4-week training program, 3 days a week, on a cycle ergometer at 90% of their VO2max final workload, while the ET subjects performed exercise at 60-70% VO2max. The HIT group performed five 1-min bouts with 3-min recovery periods and the ET group cycled for 45 min continuously. A five-mile time trial (TT) was performed prior to, after 2 weeks, and after completion of training. Both groups showed improvements (P 0.05) between groups. Both groups increased (P 0.05) in expiratory flow rates with training in either group. These data suggest that both whole-body exercise training and HIT are effective in increasing inspiratory muscle strength with HIT offering a time-efficient alternative to ET in improving aerobic capacity and performance.

Two minutes of sprint-interval exercise elicits 24-hr oxygen consumption similar to that of 30 min of continuous endurance exercise.

Abstract: Six weeks (3 times/wk) of sprint-interval training (SIT) or continuous endurance training (CET) promote body-fat losses despite a substantially lower training volume with SIT. In an attempt to explain these findings, the authors quantified VO₂ during and after (24 h) sprint-interval exercise (SIE; 2 min exercise) vs. continuous endurance exercise (CEE; 30 min exercise). VO₂ was measured in male students (n = 8) 8 times over 24 hr under 3 treatments (SIE, CEE, and control [CTRL, no exercise]). Diet was controlled. VO₂ was 150% greater (p < .01) during CEE vs. SIE (87.6 ± 13.1 vs. 35.1 ± 4.4 L O₂; M ± SD). The observed small difference between average exercise heart rates with CEE (157 ± 10 beats/min) and SIE (149 ± 6 beats/min) approached significance (p = .06), as did the difference in peak heart rates during CEE (166 ± 10 beats/min) and SIE (173 ± 6 beats/min; p = .14). Total O₂ consumed over 8 hr with CEE (263.3 ± 30.2 L) was greater (p < .01) than both SIE (224.2 ± 15.3 L; p < .001) and CTRL (163.5 ± 16.1 L; p < .001). Total O₂ with SIE was also increased over CTRL (p < .001). At 24 hr, both exercise treatments were increased (p < .001) vs. CTRL (CEE = 500.2 ± 49.2; SIE = 498.0 ± 29.4; CTRL = 400.2 ± 44.6), but there was no difference between CEE and SIE (p = .99). Despite large differences in exercise VO₂, the protracted effects of SIE result in a similar total VO₂ over 24 hr vs. CEE, indicating that the significant body-fat losses observed previously with SIT are partially due to increases in metabolism postexercise.

Controlled study of myocardial recovery after interval training in heart failure : SMARTEX-HF : rationale and design

Abstract: Background: The large randomized controlled multicentre clinical trial, HF-ACTION, recently demonstrated that a programme of recommendation of regular exercise training at moderate intensity is safe, improves quality of life, and reduces the combined endpoint of all-cause death and hospitalization in patients with chronic heart failure. However, the size of beneficial effects was modest compared to results published in smaller single studies and meta-analyses.Objective: Based on results of a pilot study, the objective of the present investigation is to test the hypothesis that a programme comprising interval training at high relative intensity would yield significantly larger effects in terms of left ventricular remodelling compared to moderate continuous exercise training.Study design: In a three-armed randomized multicentre study of stable heart failure patients with left ventricular ejection fraction ≤35%, the effects of a 12-week programme of high-intensity interval training (HIT; 85–90% of peak oxyge...

High-intensity interval training and hypertension: maximizing the benefits of exercise?

Abstract: Essential arterial hypertension is the most common risk factor for cardiovascular morbidity and mortality. Regular exercise is a well-established intervention for the prevention and treatment of hypertension. Continuous moderate-intensity exercise training (CMT) that can be sustained for 30 min or more has been traditionally recommended for hypertension prevention and treatment. On the other hand, several studies have shown that high-intensity interval training (HIT), which consists of several bouts of high-intensity exercise (~85% to 95% of HRMAX and/or VO2MAX lasting 1 to 4 min interspersed with intervals of rest or active recovery, is superior to CMT for improving cardiorespiratory fitness, endothelial function and its markers, insulin sensitivity, markers of sympathetic activity and arterial stiffness in hypertensive and normotensive at high familial risk for hypertension subjects. This compelling evidence suggesting larger beneficial effects of HIT for several factors involved in the pathophysiology of hypertension raises the hypothesis that HIT may be more effective for preventing and controlling hypertension.

Metabolic response of different high-intensity aerobic interval exercise protocols.

Abstract: Although high-intensity sprint interval training (SIT) employing the Wingate protocol results in significant physiological adaptations, it is conducted at supramaximal intensity and is potentially unsafe for sedentary middle-aged adults. We therefore evaluated the metabolic and cardiovascular response in healthy young individuals performing 4 high-intensity (~90% VO2max) aerobic interval training (HIT) protocols with similar total work output but different work-to-rest ratio. Eight young physically active subjects participated in 5 different bouts of exercise over a 3-week period. Protocol 1 consisted of 20-minute continuous exercise at approximately 70% of VO2max, whereas protocols 2-5 were interval based with a work-active rest duration (in seconds) of 30/30, 60/30, 90/30, and 60/60, respectively. Each interval protocol resulted in approximately 10 minutes of exercise at a workload corresponding to approximately 90% VO2max, but differed in the total rest duration. The 90/30 HIT protocol resulted in the highest VO2, HR, rating of perceived exertion, and blood lactate, whereas the 30/30 protocol resulted in the lowest of these parameters. The total caloric energy expenditure was lowest in the 90/30 and 60/30 protocols (~150 kcal), whereas the other 3 protocols did not differ (~195 kcal) from one another. The immediate postexercise blood pressure response was similar across all the protocols. These finding indicate that HIT performed at approximately 90% of VO2max is no more physiologically taxing than is steady-state exercise conducted at 70% VO2max, but the response during HIT is influenced by the work-to-rest ratio. This interval protocol may be used as an alternative approach to steady-state exercise training but with less time commitment.

Short-Term Intensified Cycle Training Alters Acute and Chronic Responses of PGC1α and Cytochrome C Oxidase IV to Exercise in Human Skeletal Muscle

Abstract: Reduced activation of exercise responsive signalling pathways have been reported in response to acute exercise after training; however little is known about the adaptive responses of the mitochondria. Accordingly, we investigated changes in mitochondrial gene expression and protein abundance in response to the same acute exercise before and after 10-d of intensive cycle training. Nine untrained, healthy participants (mean±SD; VO2peak 44.1±17.6 ml/kg/min) performed a 60 min bout of cycling exercise at 164±18 W (72% of pre-training VO2peak). Muscle biopsies were obtained from the vastus lateralis muscle at rest, immediately and 3 h after exercise. The participants then underwent 10-d of cycle training which included four high-intensity interval training sessions (6×5 min; 90–100% VO2peak) and six prolonged moderate-intensity sessions (45–90 min; 75% VO2peak). Participants repeated the pre-training exercise trial at the same absolute work load (64% of pre-training VO2peak). Muscle PGC1-α mRNA expression was attenuated as it increased by 11- and 4- fold (P<0.001) after exercise pre- and post-training, respectively. PGC1-α protein expression increased 1.5 fold (P<0.05) in response to exercise pre-training with no further increases after the post-training exercise bout. RIP140 protein abundance was responsive to acute exercise only (P<0.01). COXIV mRNA (1.6 fold; P<0.01) and COXIV protein expression (1.5 fold; P<0.05) were increased by training but COXIV protein expression was decreased (20%; P<0.01) by acute exercise pre- and post-training. These findings demonstrate that short-term intensified training promotes increased mitochondrial gene expression and protein abundance. Furthermore, acute indicators of exercise-induced mitochondrial adaptation appear to be blunted in response to exercise at the same absolute intensity following short-term training.

Aerobic interval training compensates age related decline in cardiac function

Abstract: Objectives. To study the effect of aerobic interval training (AIT) on myocardial function in sedentary seniors compared to master athletes (MA) and young controls. Design. Sixteen seniors (72± 1 years, 10 men) performed AIT (4 × 4 minutes) at ∼90% of maximal heart rate three times per week for 12 weeks. Results were compared with 11 male MA (74± 2 years) and 10 young males (23±2 years). Results. Seniors had an impaired diastolic function compared to the young at rest. AIT improved resting diastolic parameters, increased E/A ratio (44%, p <0.01), early diastolic tissue Doppler velocity (e′) (11%, p <0.05) and e′ during exercise (11%, p <0.01), shortened isovolumic relaxation rate (IVRT) (13%, p <0.01). Left ventricle (LV) systolic function (S′) was unaffected at rest, whereas S′ during stress echo increased by 29% (p <0.01). Right ventricle (RV) S′ and RV fractional area change (RFAC) increased (9%, p <0.01, 12%, p =0.01, respectively), but not RV e′. MA had the highest end-diastolic volume, stroke volume,...

Sex differences in the effectiveness of treadmill training in enhancing axon regeneration in injured peripheral nerves.

Abstract: Exercise in the form of daily treadmill training results in significant enhancement of axon regeneration following peripheral nerve injury. Because androgens are also linked to enhanced axon regeneration, we wanted to investigate whether sex differences in the effect of treadmill training might exist. The common fibular nerves of thy-1-YFP-H mice were cut and repaired with a graft of the same nerve from a strain-matched wild-type donor mouse. Animals were treated with one of two daily treadmill training paradigms: slow continuous walking for 1 h or four higher intensity intervals of 2 min duration separated by 5-min rest periods. Training was begun on the third day following nerve injury and continued 5 days per week for 2 weeks. Effects on regeneration were evaluated by measuring regenerating axon profile lengths in optical sections through the repair sites and grafts at the end of the training period. No sex differences were found in untrained control mice. Continuous training resulted in significant enhancement of axon regeneration only in males. No effect was found in females or in castrated males. Interval training was effective in enhancing axon regeneration only in females and not in intact males or castrated males. Untrained females treated with the aromatase inhibitor, anastrozole, had significant enhancement of axon regeneration without increasing serum testosterone levels. Two different mechanisms exist to promote axon regeneration in a sex-dependent manner. In males treadmill training uses testicular androgens. In females, a different cellular mechanism for the effect of treadmill training must exist.

Prospective, randomized assessment of the acquisition, maintenance, and loss of laparoscopic skills.

Abstract: BACKGROUND: Laparoscopic skills are difficult to learn. We, therefore, assessed the factors involved in skill acquisition, maintenance, and loss in 2 prospective, randomized studies. METHODS: In study 1, 24 laparoscopic novices were randomly assigned to a control condition who performed the laparoscopic assessment task; Massed condition who trained on virtual reality (VR) simulation during 1 day or Interval condition who had the same amount of VR training distributed over 3 consecutive days. All groups also completed a novel laparoscopic box-trainer task on 5 consecutive days. In study 2, 16 laparoscopic novices were randomly assigned to a Practice or a No-practice condition. All subjects were required to train on a VR simulation curriculum for the same duration and skill attainment level. The week after completion of training, subjects in the Practice condition were allowed 1 complete practice trial on the simulator. Both groups completed the same tasks 2 weeks after completion of the training. RESULTS: In study 1, the Interval trained group showed the fastest rate of learning and on completion of training significantly outperformed both the Massed and Control groups (P < 0.0001). In study 2, both groups showed significant skills improvement from training trial T1 to T3 (P < 0.0001). The subjects in the Practice group maintained or improved their skills at 1 week but those in the No practice group showed significant decline of skills at 2 weeks after training completion (P < 0.0001). CONCLUSIONS: Laparoscopic skills are optimally acquired on an Interval training schedule. They significantly decline with 2 weeks of nonuse.