Showing papers on "Interval training published in 2014"

High-intensity interval training in patients with lifestyle-induced cardiometabolic disease: a systematic review and meta-analysis

Abstract: Background/Aim Cardiorespiratory fitness (CRF) is a strong determinant of morbidity and mortality. In athletes and the general population, it is established that high-intensity interval training (HIIT) is superior to moderate-intensity continuous training (MICT) in improving CRF. This is a systematic review and metaanalysis to quantify the efficacy and safety of HIIT compared to MICT in individuals with chronic cardiometabolic lifestyle diseases. Methods The included studies were required to have a population sample of chronic disease, where poor lifestyle is considered as a main contributor to the disease. The procedural quality of the studies was assessed by use of a modified Physiotherapy Evidence Base Database (PEDro) scale. A meta-analysis compared the mean difference (MD) of preintervention versus postintervention CRF (VO2peak) between HIIT and MICT. Results 10 studies with 273 patients were included in the meta-analysis. Participants had coronary artery disease, heart failure, hypertension, metabolic syndrome and obesity. There was a significantly higher increase in the VO2peak after HIIT compared to MICT (MD 3.03 mL/kg/ min, 95% CI 2.00 to 4.07), equivalent to 9.1%. Conclusions HIIT significantly increases CRF by almost double that of MICT in patients with lifestyle-induced chronic diseases.

Is high-intensity interval training a time-efficient exercise strategy to improve health and fitness?

Abstract: Growing research suggests that high-intensity interval training (HIIT) is a time-efficient exercise strategy to improve cardiorespiratory and metabolic health. “All out” HIIT models such as Wingate...

Effects of low-volume high-intensity interval training (HIT) on fitness in adults: a meta-analysis of controlled and non-controlled trials

Abstract: Low-volume high-intensity interval training (HIT) appears to be an efficient and practical way to develop physical fitness. Our objective was to estimate meta-analysed mean effects of HIT on aerobic power (maximum oxygen consumption [VO2max] in an incremental test) and sprint fitness (peak and mean power in a 30-s Wingate test). Five databases (PubMed, MEDLINE, Scopus, BIOSIS and Web of Science) were searched for original research articles published up to January 2014. Search terms included ‘high intensity’, ‘HIT’, ‘sprint’, ‘fitness’ and ‘VO2max’. Inclusion criteria were fitness assessed pre- and post-training; training period ≥2 weeks; repetition duration 30–60 s; work/rest ratio 18 years. The final data set consisted of 55 estimates from 32 trials for VO2max, 23 estimates from 16 trials for peak sprint power, and 19 estimates from 12 trials for mean sprint power. Effects on fitness were analysed as percentages via log transformation. Standard errors calculated from exact p values (where reported) or imputed from errors of measurement provided appropriate weightings. Fixed effects in the meta-regression model included type of study (controlled, uncontrolled), subject characteristics (sex, training status, baseline fitness) and training parameters (number of training sessions, repetition duration, work/rest ratio). Probabilistic magnitude-based inferences for meta-analysed effects were based on standardized thresholds for small, moderate and large changes (0.2, 0.6 and 1.2, respectively) derived from between-subject standard deviations (SDs) for baseline fitness. A mean low-volume HIT protocol (13 training sessions, 0.16 work/rest ratio) in a controlled trial produced a likely moderate improvement in the VO2max of active non-athletic males (6.2 %; 90 % confidence limits ±3.1 %), when compared with control. There were possibly moderate improvements in the VO2max of sedentary males (10.0 %; ±5.1 %) and active non-athletic females (3.6 %; ±4.3 %) and a likely small increase for sedentary females (7.3 %; ±4.8 %). The effect on the VO2max of athletic males was unclear (2.7 %; ±4.6 %). A possibly moderate additional increase was likely for subjects with a 10 mL·kg−1·min−1 lower baseline VO2max (3.8 %; ±2.5 %), whereas the modifying effects of sex and difference in exercise dose were unclear. The comparison of HIT with traditional endurance training was unclear (−1.6 %; ±4.3 %). Unexplained variation between studies was 2.0 % (SD). Meta-analysed effects of HIT on Wingate peak and mean power were unclear. Low-volume HIT produces moderate improvements in the aerobic power of active non-athletic and sedentary subjects. More studies are needed to resolve the unclear modifying effects of sex and HIT dose on aerobic power and the unclear effects on sprint fitness.

Continuous vs interval training on glycemic control and macro- and microvascular reactivity in type 2 diabetic patients.

Abstract: To determine the effects of continuous aerobic exercise training (CON) vs interval aerobic exercise training (INT) on glycemic control and endothelium-dependent vasodilatation, 43 participants with type 2 diabetes were randomly allocated to the sedentary, CON, and INT groups. The CON and INT exercise training programs were designed to yield the same energy expenditure/exercise session and included walking on treadmill for 30 and 40 min/day, 3 times/week for 12 weeks. Body fatness and heart rate at rest decreased and leg muscle strength increased (all P < 0.05) in both the CON and INT groups. Fasting blood glucose levels decreased (P < 0.05) in both exercise groups but glycosylated hemoglobin levels decreased (P < 0.05) only in the INT group. Maximal aerobic capacity, flow-mediated dilation, and cutaneous reactive hyperemia increased significantly in both exercise groups; however, the magnitude of improvements was greater in the INT group. Only the INT group experienced reductions in erythrocyte malondialdehyde and serum von Willebrand factor and increases in plasma glutathione peroxidase and nitric oxide (all P < 0.05). We concluded that both continuous and interval training were effective in improving glycemic control, aerobic fitness, and endothelium-dependent vasodilation, but the interval training program appears to confer greater improvements than the continuous training program.

Sprint Interval Training Effects on Aerobic Capacity: A Systematic Review and Meta-Analysis

Abstract: Sprint interval training (SIT) involving repeated 30-s “all out” efforts have resulted in significantly improved skeletal muscle oxidative capacity, maximal oxygen uptake, and endurance performance. The positive impact of SIT on cardiorespiratory fitness has far-reaching health implications. The objective of this study was to perform a systematic review of the literature and meta-analysis to determine the effects of SIT on aerobic capacity. A search of the literature was conducted using the key words ‘sprint interval training’, ‘high intensity intermittent training/exercise’, ‘aerobic capacity’, and ‘maximal oxygen uptake’. Seventeen effects were analyzed from 16 randomized controlled trials of 318 participants. The mean ± standard deviation number of participants was 18.7 ± 5.1. Participant age was 23.5 ± 4.3 years. The effect size calculated for all studies indicates that supramaximal-intensity SIT has a small-to-moderate effect (Cohen’s d = 0.32, 95 % CI 0.10–0.55; z = 2.79, P < 0.01) on aerobic capacity with an aggregate improvement of ~3.6 mL·kg−1·min−1 (~8 % increase). The effect is moderate to large in comparison with no-exercise control groups (Cohen’s d = 0.69, 95 % CI 0.46–0.93; z = 5.84, P < 0.01) and not different when compared with endurance training control groups (Cohen’s d = 0.04, 95 % CI −0.17 to 0.24; z = 0.36, P = 0.72). SIT improves aerobic capacity in healthy, young people. Relative to continuous endurance training of moderate intensity, SIT presents an equally effective alternative with a reduced volume of activity. This evaluation of effects and analysis of moderating variables consolidates the findings of small-sample studies and contributes to the practical application of SIT to improve cardiorespiratory fitness and health.

Where does HIT fit? An examination of the affective response to high-intensity intervals in comparison to continuous moderate- and continuous vigorous-intensity exercise in the exercise intensity-affect continuum.

Abstract: Affect experienced during an exercise session is purported to predict future exercise behaviour. Compared to continuous moderate-intensity exercise (CMI), the affective response to continuous vigorous-intensity exercise (CVI) has consistently been shown to be more aversive. The affective response, and overall tolerability to high-intensity interval training (HIT), is less studied. To date, there has yet to be a comparison between HIT, CVI, and CMI. The purpose of this study was to compare the tolerability and affective responses during HIT to CVI and CMI. This study utilized a repeated measures, randomized, counter-balanced design. Forty-four participants visited the laboratory on four occasions. Baseline fitness testing was conducted to establish peak power output in Watts (Wpeak). Three subsequent visits involved a single bout of a) HIT, corresponding to 1-minute at ∼100% Wpeak and 1-minute at ∼20% Wpeak for 20 minutes, b) CMI, corresponding to ∼40% Wpeak for 40 minutes, and c) CVI, corresponding to ∼80% Wpeak for 20 minutes. The order of the sessions was randomized. Affective responses were measured before, during and after each session. Task self-efficacy, intentions, enjoyment and preference were measured after sessions. Participants reported greater enjoyment of HIT as compared to CMI and CVI, with over 50% of participants reporting a preference to engage in HIT as opposed to either CMI or CVI. HIT was considered more pleasurable than CVI after exercise, but less pleasurable than CMI at these times. Despite this participants reported being just as confident to engage in HIT as they were CMI, but less confident to engage in CVI. This study highlights the utility of HIT in inactive individuals, and suggests that it may be a viable alternative to traditionally prescribed continuous modalities of exercise for promoting self-efficacy and enjoyment of exercise.

Polarized training has greater impact on key endurance variables than threshold, high intensity, or high volume training.

Abstract: Endurance athletes integrate four conditioning concepts in their training programs: high-volume training (HVT), “threshold-training” (THR), high-intensity interval training (HIIT) and a combination of these aforementioned concepts known as polarized training (POL). The purpose of this study was to explore which of these four training concepts provides the greatest response on key components of endurance performance in well-trained endurance athletes. Methods: Forty eight runners, cyclists, triathletes, and cross-country skiers (peak oxygen uptake: (VO2peak): 62.6 ± 7.1 mL·min−1·kg−1) were randomly assigned to one of four groups performing over 9 weeks. An incremental test, work economy and a VO2peak tests were performed. Training intensity was heart rate controlled. Results: POL demonstrated the greatest increase in VO2peak (+6.8 ml·min·kg−1 or 11.7%, P 0.05). Conclusion: POL resulted in the greatest improvements in most key variables of endurance performance in well-trained endurance athletes. THR or HVT did not lead to further improvements in performance related variables.

Phase I/II randomized trial of aerobic exercise in Parkinson disease in a community setting.

Abstract: Objectives: To (1) investigate effects of aerobic walking on motor function, cognition, and quality of life in Parkinson disease (PD), and (2) compare safety, tolerability, and fitness benefits of different forms of exercise intervention: continuous/moderate intensity vs interval/alternating between low and vigorous intensity, and individual/neighborhood vs group/facility setting. Methods: Initial design was a 6-month, 2 × 2 randomized trial of different exercise regimens in independently ambulatory patients with PD. All arms were required to exercise 3 times per week, 45 minutes per session. Results: Randomization to group/facility setting was not feasible because of logistical factors. Over the first 2 years, we randomized 43 participants to continuous or interval training. Because preliminary analyses suggested higher musculoskeletal adverse events in the interval group and lack of difference between training methods in improving fitness, the next 17 participants were allocated only to continuous training. Eighty-one percent of 60 participants completed the study with a mean attendance of 83.3% (95% confidence interval: 77.5%–89.0%), exercising at 46.8% (44.0%–49.7%) of their heart rate reserve. There were no serious adverse events. Across all completers, we observed improvements in maximum oxygen consumption, gait speed, Unified Parkinson9s Disease Rating Scale sections I and III scores (particularly axial functions and rigidity), fatigue, depression, quality of life (e.g., psychological outlook), and flanker task scores ( p p p Conclusions: Our preliminary study suggests that aerobic walking in a community setting is safe, well tolerated, and improves aerobic fitness, motor function, fatigue, mood, executive control, and quality of life in mild to moderate PD. Classification of evidence: This study provides Class IV evidence that in patients with PD, an aerobic exercise program improves aerobic fitness, motor function, fatigue, mood, and cognition.

Physiological and Health-Related Adaptations to Low-Volume Interval Training: Influences of Nutrition and Sex

Abstract: Interval training refers to the basic concept of alternating periods of relatively intense exercise with periods of lower-intensity effort or complete rest for recovery. Low-volume interval training refers to sessions that involve a relatively small total amount of exercise (i.e. ≤10 min of intense exercise), compared with traditional moderate-intensity continuous training (MICT) protocols that are generally reflected in public health guidelines. In an effort to standardize terminology, a classification scheme was recently proposed in which the term ‘high-intensity interval training’ (HIIT) be used to describe protocols in which the training stimulus is ‘near maximal’ or the target intensity is between 80 and 100 % of maximal heart rate, and ‘sprint interval training’ (SIT) be used for protocols that involve ‘all out’ or ‘supramaximal’ efforts, in which target intensities correspond to workloads greater than what is required to elicit 100 % of maximal oxygen uptake (VO2max). Both low-volume SIT and HIIT constitute relatively time-efficient training strategies to rapidly enhance the capacity for aerobic energy metabolism and elicit physiological remodeling that resembles changes normally associated with high-volume MICT. Short-term SIT and HIIT protocols have also been shown to improve health-related indices, including cardiorespiratory fitness and markers of glycemic control in both healthy individuals and those at risk for, or afflicted by, cardiometabolic diseases. Recent evidence from a limited number of studies has highlighted potential sex-based differences in the adaptive response to SIT in particular. It has also been suggested that specific nutritional interventions, in particular those that can augment muscle buffering capacity, such as sodium bicarbonate, may enhance the adaptive response to low-volume interval training.

Effects of high-intensity interval exercise versus continuous moderate-intensity exercise on postprandial glycemic control assessed by continuous glucose monitoring in obese adults

Abstract: The purpose of this study was to examine the impact of acute high-intensity interval training (HIIT) compared with continuous moderate-intensity (CMI) exercise on postprandial hyperglycemia in over...

Why sprint interval training is inappropriate for a largely sedentary population.

Abstract: Public health practitioners and researchers in behavioral medicine recognize the need to find effective physical activity interventions and prescriptions to curb the growth in inactivity and prevent chronic illness (Conn et al., 2009; Hagger, 2010; Hardcastle et al., 2012; Katzmarzyk and Lear, 2012). For example, researchers in exercise physiology have focused on the minimal dose of exercise needed to gain favorable physiological adaptations to cardiovascular and metabolic systems (Gibala et al., 2012). Efforts to identify a minimal dose of exercise are linked to the problem of exercise adherence with few people meeting current physical activity guidelines of 30 min per day of moderate intensity exercise. Given that time is the most commonly cited barrier to exercise (Trost et al., 2002; Sequeira et al., 2011), exercise professionals have focused attention on the development of time-efficient exercise interventions (Gibala, 2007). A recent development is the advocacy of Sprint Interval Training (SIT) as a means to attain substantial health benefits with a lower overall exercise volume. SIT is characterized by repeated, brief (4–6 × <30 s), intermittent bursts of all-out exercise, interspersed by periods (approximately 4.5 min) of active or passive recovery (Gibala et al., 2012). Research has consistently demonstrated that participation in SIT results in a host of physiological adaptations including improvements in health and fitness indicators (Burgomaster et al., 2006, 2008; Gibala et al., 2006, 2012; Rossow et al., 2010; Tong et al., 2011). In addition, these improvements have been reported to be equal or superior to traditional continuous aerobic training despite SIT involving a substantially lower total overall training volume (Rossow et al., 2010; Tong et al., 2011; Gibala et al., 2012; Cocks et al., 2013). Consequently, SIT is being advocated as a time-efficient alternative intervention for the achievement of fitness and health benefits through exercise (Gibala, 2007; Whyte et al., 2013).

Metabolic and hormonal responses to isoenergetic high-intensity interval exercise and continuous moderate-intensity exercise.

Abstract: This study investigated the effects of high-intensity interval training (HIIT) vs. work-matched moderate-intensity continuous exercise (MOD) on metabolism and counterregulatory stress hormones. In ...

Three minutes of all-out intermittent exercise per week increases skeletal muscle oxidative capacity and improves cardiometabolic health.

Abstract: We investigated whether a training protocol that involved 3 min of intense intermittent exercise per week — within a total training time commitment of 30 min including warm up and cool down — could increase skeletal muscle oxidative capacity and markers of health status. Overweight/obese but otherwise healthy men and women (n = 7 each; age = 29±9 y; BMI = 29.8±2.7 kg/m2) performed 18 training sessions over 6 wk on a cycle ergometer. Each session began with a 2 min warm-up at 50 W, followed by 3×20 s “all-out” sprints against 5.0% body mass (mean power output: ∼450–500 W) interspersed with 2 min of recovery at 50 W, followed by a 3 min cool-down at 50 W. Peak oxygen uptake increased by 12% after training (32.6±4.5 vs. 29.1±4.2 ml/kg/min) and resting mean arterial pressure decreased by 7% (78±10 vs. 83±10 mmHg), with no difference between groups (both p<0.01, main effects for time). Skeletal muscle biopsy samples obtained before and 72 h after training revealed increased maximal activity of citrate synthase and protein content of cytochrome oxidase 4 (p<0.01, main effect), while the maximal activity of β-hydroxy acyl CoA dehydrogenase increased in men only (p<0.05). Continuous glucose monitoring measured under standard dietary conditions before and 48–72 h following training revealed lower 24 h average blood glucose concentration in men following training (5.4±0.6 vs. 5.9±0.5 mmol/L, p<0.05), but not women (5.5±0.4 vs. 5.5±0.6 mmol/L). This was associated with a greater increase in GLUT4 protein content in men compared to women (138% vs. 23%, p<0.05). Short-term interval training using a 10 min protocol that involved only 1 min of hard exercise, 3x/wk, stimulated physiological changes linked to improved health in overweight adults. Despite the small sample size, potential sex-specific adaptations were apparent that warrant further investigation.

High intensity interval training in a real world setting: a randomized controlled feasibility study in overweight inactive adults, measuring change in maximal oxygen uptake.

Abstract: Background In research clinic settings, overweight adults undertaking HIIT (high intensity interval training) improve their fitness as effectively as those undertaking conventional walking programs but can do so within a shorter time spent exercising. We undertook a randomized controlled feasibility (pilot) study aimed at extending HIIT into a real world setting by recruiting overweight/obese, inactive adults into a group based activity program, held in a community park. Methods Participants were allocated into one of three groups. The two interventions, aerobic interval training and maximal volitional interval training, were compared with an active control group undertaking walking based exercise. Supervised group sessions (36 per intervention) were held outdoors. Cardiorespiratory fitness was measured using VO2max (maximal oxygen uptake, results expressed in ml/min/kg), before and after the 12 week interventions. Results On ITT (intention to treat) analyses, baseline (N = 49) and exit (N = 39) O2 was 25.3±4.5 and 25.3±3.9, respectively. Participant allocation and baseline/exit VO2max by group was as follows: Aerobic interval training N = 16, 24.2±4.8/25.6±4.8; maximal volitional interval training N = 16, 25.0±2.8/25.2±3.4; walking N = 17, 26.5±5.3/25.2±3.6. The post intervention change in VO2max was +1.01 in the aerobic interval training, −0.06 in the maximal volitional interval training and −1.03 in the walking subgroups. The aerobic interval training subgroup increased VO2max compared to walking (p = 0.03). The actual (observed, rather than prescribed) time spent exercising (minutes per week, ITT analysis) was 74 for aerobic interval training, 45 for maximal volitional interval training and 116 for walking (p = 0.001). On descriptive analysis, the walking subgroup had the fewest adverse events. Conclusions In contrast to earlier studies, the improvement in cardiorespiratory fitness in a cohort of overweight/obese participants undertaking aerobic interval training in a real world setting was modest. The most likely reason for this finding relates to reduced adherence to the exercise program, when moving beyond the research clinic setting. Trial Registration ACTR.org.au ACTRN12610000295044

Postexercise Cold Water Immersion Benefits Are Not Greater than the Placebo Effect.

Abstract: BROATCH, J. R., A. PETERSEN, and D. J. BISHOP. Postexercise Cold Water Immersion Benefits Are Not Greater than the PlaceboEffect. Med. Sci. Sports Exerc., Vol. 46, No. 11, pp. 2139–2147, 2014. Purpose: Despite a general lack of understanding of theunderlying mechanisms, cold water immersion (CWI) is widely used by athletes for recovery. This study examined the physiologicalmerit of CWI for recovery from high-intensity exercise by investigating if the placebo effect is responsible for any acute performance orpsychological benefits. Methods: Thirty males (mean T SD: age, 24 T 5 yr; V˙O 2peak , 51.1 T 7.0 mLIkg j1 Imin j1 ) performed an acutehigh-intensity interval training session, comprised of 4 30-s sprints, immediately followed by one of the following three 15-minrecovery conditions: CWI (10.3-C T 0.2-C), thermoneutral water immersion placebo (TWP) (34.7-C T 0.1-C), or thermoneutral waterimmersion control (TWI) (34.7-C T 0.1-C). An intramuscular thermistor was inserted during exercise and recovery to record muscletemperature. Swelling(thighgirth), painthreshold/tolerance, interleukin6 concentration, andtotal leukocyte, neutrophil,andlymphocytecounts were recorded at baseline, postexercise, postrecovery, and 1, 24, and 48 h postexercise. A maximal voluntary isometric con-traction (MVC) of the quadriceps was performed at the same time points, with the exception of postexercise. Self-assessments ofreadiness for exercise, fatigue, vigor, sleepiness, pain, and belief of recovery effectiveness were also completed. Results: Leg strengthafter the MVC and ratings of readiness for exercise, pain, and vigor were significantly impaired in TWI compared with those in CWI andTWP which were similar to each other. Conclusions: A recovery placebo administered after an acute high-intensity interval trainingsession is superior in the recovery of muscle strength over 48 h as compared with TWI and is as effective as CWI. This can be attributed toimproved ratings of readiness for exercise, pain, and vigor, suggesting that the commonly hypothesized physiological benefits surround-ing CWI are at least partly placebo related. Key Words: HYDROTHERAPY, RECOVERY, INFLAMMATION, HIGH-INTENSITYINTERVAL TRAINING, MUSCLE TEMPERATURE

The relationship between workloads, physical performance,injury and illness in adolescent male football players

Abstract: The expectation that training enhances performance is well explored in professional sport. However, the additional challenges of physical and cognitive maturation may require careful consideration when determining workloads to enhance performance in adolescents. The objective of this study was to determine the state of knowledge on the relationship between workloads, physical performance, injury and/or illness in adolescent male football players. A systematic review of workloads, physical performance, injury and illness in male adolescent football players was conducted. Studies for this review were identified through a systematic search of six electronic databases (Academic Search Complete, CINAHL, PsycINFO, PubMed, SPORTDiscus, and Web of Science). For the purpose of this review, load was defined as the cumulative amount of stress placed on an individual from multiple training sessions and games over a period of time, expressed in terms of either the external workloads performed (e.g., resistance lifted, kilometres run) or the internal response (e.g., heart rate, rating of perceived exertion) to that workload. A total of 2,081 studies were initially retrieved from the six databases, of which 892 were duplicates. After screening the titles, abstracts and full texts, we identified 23 articles meeting our criteria around adolescent football players, workloads, physical performance, injury and/or illness. Seventeen articles addressed the relationship between load and physical performance, four articles addressed the relationship between load and injury and two articles addressed both. A wide range of training modalities were employed to improve the physical performance of adolescent football players, with strength training, high-intensity interval training, dribbling and small-sided games training, and a combination of these modalities in addition to normal football training, resulting in improved performances on a wide range of physiological and skill assessments. Furthermore, there was some (limited) evidence that higher workloads may be associated with the development of better physical qualities, with one study demonstrating enhanced submaximal interval shuttle run performance with each additional hour of training or game play. Of the few studies examining negative consequences associated with workloads, increases in training load led to increases in injury rates, while longer training duration was associated with a greater incidence of illness. The combined capacity for adolescent males to grow, train and improve physical performance highlights and underscores an exciting responsiveness to training in the football environment. However, the capacity to train has some established barriers for adolescents experiencing high workloads, which could also result in negative consequences. Additional research on stage-appropriate training for adolescent male footballers is required in order to address the knowledge gaps and enhance safe and efficient training practices.

Fibre-Specific Responses to Endurance and Low Volume High Intensity Interval Training: Striking Similarities in Acute and Chronic Adaptation

Abstract: The current study involved the completion of two distinct experiments. Experiment 1 compared fibre specific and whole muscle responses to acute bouts of either low-volume high-intensity interval training (LV-HIT) or moderate-intensity continuous endurance exercise (END) in a randomized crossover design. Experiment 2 examined the impact of a six-week training intervention (END or LV-HIT; 4 days/week), on whole body and skeletal muscle fibre specific markers of aerobic and anaerobic capacity. Six recreationally active men (Age: 20.7 ± 3.8 yrs; VO2peak: 51.9 ± 5.1 mL/kg/min) reported to the lab on two separate occasions for experiment 1. Following a muscle biopsy taken in a fasted state, participants completed an acute bout of each exercise protocol (LV-HIT: 8, 20-second intervals at ∼ 170% of VO2peak separated by 10 seconds of rest; END: 30 minutes at ∼ 65% of VO2peak), immediately followed by a muscle biopsy. Glycogen content of type I and IIA fibres was significantly (p<0.05) reduced, while p-ACC was significantly increased (p<0.05) following both protocols. Nineteen recreationally active males (n = 16) and females (n = 3) were VO2peak-matched and assigned to either the LV-HIT (n = 10; 21 ± 2 yrs) or END (n = 9; 20.7 ± 3.8 yrs) group for experiment 2. After 6 weeks, both training protocols induced comparable increases in aerobic capacity (END: Pre: 48.3 ± 6.0, Mid: 51.8 ± 6.0, Post: 55.0 ± 6.3 mL/kg/min LV-HIT: Pre: 47.9 ± 8.1, Mid: 50.4 ± 7.4, Post: 54.7 ± 7.6 mL/kg/min), fibre-type specific oxidative and glycolytic capacity, glycogen and IMTG stores, and whole-muscle capillary density. Interestingly, only LV-HIT induced greater improvements in anaerobic performance and estimated whole-muscle glycolytic capacity. These results suggest that 30 minutes of END exercise at ∼ 65% VO2peak or 4 minutes of LV-HIT at ∼ 170% VO2peak induce comparable changes in the intra-myocellular environment (glycogen content and signaling activation); correspondingly, training-induced adaptations resulting for these protocols, and other HIT and END protocols are strikingly similar.

Aerobic Interval Training vs. Moderate Continuous Training in Coronary Artery Disease Patients: A Systematic Review and Meta-Analysis

Abstract: Exercise training improves exercise capacity (peakVO2), which is closely related to long-term survival in cardiac patients. However, it remains unclear which type and intensity of exercise is most effective for improving exercise tolerance and body weight. Individual studies suggest that aerobic interval training (AIT) might increase peakVO2 more in this population. We conducted a meta-analysis to summarize the effects of AIT compared with moderate continuous training (MCT) on peakVO2, submaximal exercise capacity, and body weight in patients with coronary artery disease (CAD) with preserved and/or reduced left ventricular ejection fraction (LVEF). A systematic search was conducted and we included randomized trials comparing AIT and MCT in CAD patients lasting at least 4 weeks, reporting peakVO2 results, and published in a peer-reviewed journal up to May 2013. The primary outcome measure was peakVO2. Secondary outcomes were submaximal exercise capacity parameters and body weight. Random- and fixed-effects models were used and data were reported as weighted means and 95 % confidence intervals (CIs). Nine study groups were included, involving 206 patients (100 AIT, 106 MCT). Overall, AIT resulted in a significantly larger increase in peakVO2 [+1.60 mL/kg/min (95 % CI 0.18–3.02; p = 0.03)] compared with MCT. MCT seemed to be more effective in reducing body weight (−0.78 kg; 95 % CI −0.01 to 1.58; p = 0.05). The small number of studies might have affected the power to reach significance for the secondary outcomes. In CAD patients with preserved and/or reduced LVEF, AIT is superior to MCT for improving peakVO2, while MCT seems to be more effective in reducing body weight. However, large, well-designed, randomized controlled trials are warranted to confirm these findings.

Influence of acute high-intensity aerobic interval exercise bout on selective attention and short-term memory tasks

Abstract: Acute moderate intensity continuous aerobic exercise can improve specific cognitive functions, such as short-term memory and selective attention. Moreover, high-intensity interval training (HIT) has been recently proposed as a time-efficient alternative to traditional cardiorespiratory exercise. However, considering previous speculations that the exercise intensity affects cognition in a U-shaped fashion, it was hypothesized that a HIT session may impair cognitive performance. Therefore, this study assessed the effects of an acute HIT session on selective attention and short-term memory tasks. 22 healthy middle-aged individuals (M age = 53.7 yr.) engaged in both (1) a HIT session, 10 1 min. cycling bouts at the intensity corresponding to 80% of the reserve heart rate interspersed by 1 min. active pauses cycling at 60% of the reserve heart rate and (2) a control session, consisting of an active condition with low-intensity active stretching exercise. Before and after each experimental session, cognitive performance was assessed by the Victoria Version of the Stroop test (a selective attention test) and the Digit Span test (a short-term memory test). Following the HIT session, the time to complete the Stroop "Color word" test was significantly lower when compared with that of the control session. The performances in the other subtasks of the Stroop test as well as in the Digit Span test were not significantly different. A HIT session can improve cognitive function.

Moderate-intensity interval training increases serum brain-derived neurotrophic factor level and decreases inflammation in Parkinson's disease patients.

Abstract: It has been demonstrated that physical training increases serum brain-derived neurotrophic factor (BDNF) in healthy people. The aim of this study was to establish the effect of physical training on the basal serum level of the BDNF in the Parkinson's disease patients (PD patients) in relation to their health status. Twelve PD patients (mean ± S.E.M: age 70 ± 3 years; body mass 70 ± 2 kg; height 163 ± 3 cm) performed a moderate-intensity interval training (three 1-hour training sessions weekly), lasting 8 weeks. Basal serum BDNF in the PD patients before training amounted to 10,977 ± 756 pg x mL(-1) and after 8 weeks of training it has increased to 14,206 ± 1256 pg x mL(-1) (i.e. by 34%, P=0.03). This was accompanied by an attenuation of total Unified Parkinson's Disease Rating Scale (UPDRS) (P=0.01). The training resulted also in a decrease of basal serum soluble vascular cell adhesion molecule 1 (sVCAM-1) (P=0.001) and serum tumor necrosis factor-α (TNF-α) (P=0.03) levels. We have concluded that the improvement of health status of the Parkinson's disease patients after training could be related to the increase of serum BDNF level caused by the attenuated inflammation in those patients.

Greater Improvement in Cardiorespiratory Fitness Using Higher-Intensity Interval Training in the Standard Cardiac Rehabilitation Setting.

Abstract: PURPOSE: We tested the hypothesis that higher-intensity interval training (HIIT) could be deployed into a standard cardiac rehabilitation (CR) setting and would result in a greater increase in cardiorespiratory fitness (ie, peak oxygen uptake, ) versus moderate-intensity continuous training (MCT). METHODS: Thirty-nine patients participating in a standard phase 2 CR program were randomized to HIIT or MCT; 15 patients and 13 patients in the HIIT and MCT groups, respectively, completed CR and baseline and followup cardiopulmonary exercise testing. RESULTS: No patients in either study group experienced an event that required hospitalization during or within 3 hours after exercise. The changes in resting heart rate and blood pressure at followup testing were similar for both HIIT and MCT. at ventilatory-derived anaerobic threshold increased more (P < .05) with HIIT (3.0 +/- 2.8 mL[middle dot]kg[middle dot]-1min-1) versus MCT (0.7 +/- 2.2 mL[middle dot]kg[middle dot]-1min-1). During followup testing, submaximal heart rate at the end of stage 2 of the exercise test was significantly lower within both the HIIT and MCT groups, with no difference noted between groups. Peak V[spacing dot above]o2 improved more after CR in patients in HIIT versus MCT (3.6 +/- 3.1 mL[middle dot]kg.-1[middle dot]min-1 vs 1.7 +/- 1.7 mL[middle dot]kg.-1[middle dot]min-1; P < .05). CONCLUSIONS: Among patients with stable coronary heart disease on evidence-based therapy, HIIT was successfully integrated into a standard CR setting and, when compared to MCT, resulted in greater improvement in peak exercise capacity and submaximal endurance.

Intermittent and continuous high-intensity exercise training induce similar acute but different chronic muscle adaptations

Abstract: New Findings What is the central question of this study? How important is the interval in high-intensity interval training (HIIT)? What is the main finding and its importance? The intermittent nature of HIIT is important for maximizing skeletal muscle adaptations to this type of exercise, at least when a relatively small total volume of work is performed in an ‘all-out’ manner. The protein signalling responses to an acute bout of HIIT were generally not predictive of training-induced outcomes. Nonetheless, a single session of exercise lasting <10 min including warm-up, performed three times per week for 6 weeks, was sufficient to improve maximal aerobic capacity. High-intensity interval training (HIIT) performed in an ‘all-out’ manner (e.g. repeated Wingate tests) is a time-efficient strategy to induce skeletal muscle remodelling towards a more oxidative phenotype. A fundamental question that remains unclear, however, is whether the intermittent or ‘pulsed’ nature of the stimulus is critical to the adaptive response. In study 1, we examined whether the activation of signalling cascades linked to mitochondrial biogenesis was dependent on the manner in which an acute high-intensity exercise stimulus was applied. Subjects performed either four 30 s Wingate tests interspersed with 4 min of rest (INT) or a bout of continuous exercise (CONT) that was matched for total work (67 ± 7 kJ) and which required ∼4 min to complete as fast as possible. Both protocols elicited similar increases in markers of adenosine monophosphate-activated protein kinase (AMPK) and p38 mitogen-activated protein kinase activation, as well as Peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) mRNA expression (main effects for time, P ≤ 0.05). In study 2, we determined whether 6 weeks of the CONT protocol (3 days per week) would increase skeletal muscle mitochondrial content to a similar extent to what we have previously reported after 6 weeks of INT. Despite similar acute signalling responses to the CONT and INT protocols, training with CONT did not increase the maximal activity or protein content of a range of mitochondrial markers. However, peak oxygen uptake was higher after CONT training (from 45.7 ± 5.4 to 48.3 ± 6.5 ml kg−1 min−1; P < 0.05) and 250 kJ time trial performance was improved (from 26:32 ± 4:48 to 23:55 ± 4:16 min:s; P < 0.001) in our recreationally active participants. We conclude that the intermittent nature of the stimulus is important for maximizing skeletal muscle adaptations to low-volume, all-out HIIT. Despite the lack of skeletal muscle mitochondrial adaptations, our data show that a training programme based on a brief bout of high-intensity exercise, which lasted <10 min per session including warm-up, and performed three times per week for 6 weeks, improved peak oxygen uptake in young healthy subjects.

High-intensity interval training induces a modest systemic inflammatory response in active, young men

Abstract: The purpose of this study was to determine: 1) the extent to which an acute session of high-intensity interval training (HIIT) increases systemic inflammatory cytokines and chemokines, and 2) whether 2 weeks of HIIT training alters the inflammatory response. Eight recreationally active males (aged 22±2 years) performed 2 weeks of HIIT on a cycle ergometer (six HIIT sessions at 8-12 intervals; 60-second intervals, 75-second active rest) at a power output equivalent to 100% of their predetermined peak oxygen uptake (VO 2 max). Serum samples were collected during the first and sixth HIIT sessions at rest and immediately, 15, 30, and 45 minutes post-exercise. An acute session of HIIT induced significant increases in interleukin (IL)-6, IL-8, IL-10, tumor necrosis factor-α, and monocyte chemotactic protein-1 compared with rest. The concentrations of interferon-γ, granulocyte macrophage-colony-stimulating factor, and IL-1β were unaltered with an acute session of HIIT. Two weeks of training did not alter the inflamma - tory response to an acute bout of HIIT exercise. Maximal power achieved during a VO 2 max test significantly increased 4.6%, despite no improvements in VO 2 max after 2 weeks of HIIT. These data suggest that HIIT exercise induces a small inflammatory response in young, recreationally active men; however, 2 weeks of HIIT does not alter this response.

High-intensity interval exercise induces 24-h energy expenditure similar to traditional endurance exercise despite reduced time commitment.

Abstract: Subjects performed high-intensity interval training (HIIT) and continuous moderate-intensity training (END) to evaluate 24-h oxygen consumption. Oxygen consumption during HIIT was lower versus END; however, total oxygen consumption over 24 h was similar. These data demonstrate that HIIT and END induce similar 24-h energy expenditure, which may explain the comparable changes in body composition reported despite lower total training volume and time commitment.

The talk test: a useful tool for prescribing and monitoring exercise intensity

Abstract: Purpose of reviewThis review focuses on recent literature examining the validity and reliability of the talk test for prescribing and monitoring exercise intensity. The utility of the talk test for high-intensity interval training and recently proposed exercise training guidelines for patients with

Running sprint interval training induces fat loss in women

Abstract: Data on whether sprint interval training (SIT) (repeated supermaximal intensity, short-duration exercise) affects body composition are limited, and the data that are available suggest that men resp...

High-intensity interval training on an aquatic treadmill in adults with osteoarthritis: effect on pain, balance, function, and mobility.

Abstract: Although aquatic exercise is considered a potentially effective treatment intervention for people with osteoarthritis (OA), previous research has focused primarily on calisthenics in a shallow pool with the inherent limitations on regulating exercise intensity. The purpose of this study was to quantify the efficacy of a 6-week aquatic treadmill exercise program on measures of pain, balance, function, and mobility. Eighteen participants (age = 64.5 ± 10.2 years) with knee OA completed a non-exercise control period followed by a 6-week exercise period. Outcome measures included visual analog scales for pain, posturography for balance, sit-to-stand test for function, and a 10-m walk test for mobility. The exercise protocol included balance training and high-intensity interval training (HIT) in an aquatic treadmill using water jets to destabilize while standing and achieve high ratings of perceived exertion (14-19) while walking. In comparison with pretests, participants displayed reduced joint pain (pre = 50.3 ± 24.8 mm vs. post = 15.8 ± 10.6 mm), improved balance (equilibrium pre = 66.6 ± 11.0 vs. post = 73.5 ± 7.1), function (rising index pre = 0.49 ± 0.19% vs. post = 0.33 ± 0.11%), and mobility (walk pre = 8.6 ± 1.4 s vs. post = 7.8 ± 1.1 s) after participating in the exercise protocol (p = 0.03-0.001). The same benefits were not observed after the non-exercise control period. Adherence to the exercise protocol was exceptional and no participants reported adverse effects, suggesting that aquatic treadmill exercise that incorporates balance and HIT training was well tolerated by patients with OA and may be effective at managing symptoms of OA.

Individual responses to completion of short-term and chronic interval training: a retrospective study.

Abstract: Alterations in maximal oxygen uptake (VO2max), heart rate (HR), and fat oxidation occur in response to chronic endurance training. However, many studies report frequent incidence of ‘‘non-responders’’ who do not adapt to continuous moderate exercise. Whether this is the case in response to high intensity interval training (HIT), which elicits similar adaptations as endurance training, is unknown. The aim of this retrospective study was to examine individual responses to two paradigms of interval training. In the first study (study 1), twenty active men and women (age and baseline VO2max=24.064.6 yr and 42.864.8 mL/kg/min) performed 6 d of sprint interval training (SIT) consisting of 4–6 Wingate tests per day, while in a separate study (study 2), 20 sedentary women (age and baseline VO2max=23.766.2 yr and 30.064.9 mL/kg/min) performed 12 wk of high-volume HIT at workloads ranging from 60–90% maximal workload. Individual changes in VO2max, HR, and fat oxidation were examined in each study, and multiple regression analysis was used to identify predictors of training adaptations to SIT and HIT. Data showed high frequency of increased VO2max (95%) and attenuated exercise HR (85%) in response to HIT, and low frequency of response for VO2max (65%) and exercise HR (55%) via SIT. Frequency of improved fat oxidation was similar (60–65%) across regimens. Only one participant across both interventions showed nonresponse for all variables. Baseline values of VO2max, exercise HR, respiratory exchange ratio, and body fat were significant predictors of adaptations to interval training. Frequency of positive responses to interval training seems to be greater in response to prolonged, higher volume interval training compared to similar durations of endurance training.

Time-course effects of aerobic interval training and detraining in patients with metabolic syndrome.

Abstract: Background and aims Exercise training can improve health of patients with metabolic syndrome (MetS). However, which MetS factors are most responsive to exercise training remains unclear. We studied the time-course of changes in MetS factors in response to training and detraining. Methods and results Forty eight MetS patients (52 ± 8.8 yrs old; 33 ± 4 BMI) underwent 4 months (3 days/week) of supervised aerobic interval training (AIT) program. After 1 month of training, there were progressive increases in high density lipoprotein cholesterol (HDL-c) and reductions in waist circumference and blood pressure (12 ± 3, −3.9 ± 0.4, and −12 ± 1%, respectively after 4 months; all P 2 peak) and exercise maximal fat oxidation (FO MAx ) also progressively improved with training (−17 ± 5; 21 ± 2 and 31 ± 8%, respectively, after 4 months; all P Vastus lateralis samples from seven subjects revealed that mitochondrial O 2 flux was markedly increased with training (71 ± 11%) due to increased mitochondrial content. After 1 month of detraining, the training-induced improvements in waist circumference and blood pressure were maintained. HDL-c and VO 2 peak returned to the values found after 1–2 months of training while HOMA and FO MAx returned to pre-training values. Conclusions The health related variables most responsive to aerobic interval training in MetS patients are waist circumference, blood pressure and the muscle and systemic adaptations to consume oxygen and fat. However, the latter reverse with detraining while blood pressure and waist circumference are persistent to one month of detraining.

Cardiac Autonomic Function and High-Intensity Interval Training in Middle-Age Men

Abstract: PurposeThe effects of short-term high-intensity interval training (HIT) on cardiac autonomic function are unclear. The present study assessed cardiac autonomic adaptations to short-term HIT in comparison with aerobic endurance training (AET).MethodsTwenty-six healthy middle-age sedentary men