Explore the vast range of titles available.

Background Evidence for the efficacy of low-volume high-intensity interval training (HIIT) for the modulation of body composition is unclear. Objectives We examined the effect of low-volume HIIT versus a non-exercising control and moderate-intensity continuous training (MICT) on body composition and cardiorespiratory fitness in normal weight, overweight and obese adults. We evaluated the impact of low-volume HIIT (HIIT interventions where the total amount of exercise performed during training was ≤ 500 metabolic equivalent minutes per week [MET-min/week]) compared to a non-exercising control and MICT. Methods A database search was conducted in PubMed (MEDLINE), EMBASE, CINAHL, Web of Science, SPORTDiscus and Scopus from the earliest record to June 2019 for studies (randomised controlled trials and non-randomised controlled trials) with exercise training interventions with a minimum 4-week duration. Meta-analyses were conducted for between-group (low-volume HIIT vs. non-exercising control and low-volume HIIT vs. MICT) comparisons for change in total body fat mass (kg), body fat percentage (%), lean body mass (kg) and cardiorespiratory fitness. Results From 11,485 relevant records, 47 studies were included. No difference was found between low-volume HIIT and a non-exercising control on total body fat mass (kg) (effect size [ES]: − 0.129, 95% confidence interval [CI] − 0.468 to 0.210; p  = 0.455), body fat (%) (ES: − 0.063, 95% CI − 0.383 to 0.257; p  = 0.700) and lean body mass (kg) (ES: 0.050, 95% CI − 0.250 to 0.351; p  = 0.744), or between low-volume HIIT and MICT on total body fat mass (kg) (ES: − 0.021, 95% CI − 0.272 to 0.231; p  = 0.872), body fat (%) (ES: 0.005, 95% CI − 0.294 to 0.304; p  = 0.974) and lean body mass (kg) (ES: 0.030, 95% CI − 0.167 to 0.266; p  = 0.768). However, low-volume HIIT significantly improved cardiorespiratory fitness compared with a non-exercising control ( p  < 0.001) and MICT ( p  = 0.017). Conclusion These data suggest that low-volume HIIT is inefficient for the modulation of total body fat mass or total body fat percentage in comparison with a non-exercise control and MICT. A novel finding of our meta-analysis was that there appears to be no significant effect of low-volume HIIT on lean body mass when compared with a non-exercising control, and while most studies tended to favour improvement in lean body mass with low-volume HIIT versus MICT, this was not significant. However, despite its lower training volume, low-volume HIIT induces greater improvements in cardiorespiratory fitness than a non-exercising control and MICT in normal weight, overweight and obese adults. Low-volume HIIT, therefore, appears to be a time-efficient treatment for increasing fitness, but not for the improvement of body composition.

Background Exercise-induced improvements in cardiorespiratory fitness (CRF) often coincide with improvements in insulin sensitivity and reductions in liver fat content. However, there are limited data concerning the relationship between CRF and liver fat content in adults with varying degrees of metabolic dysfunction. Methods The aim of this study was to examine the association between CRF, liver fat content, and insulin resistance in inactive adults with obesity and with or without type 2 diabetes (T2D), via cross-sectional analysis. CRF was determined via a graded exercise test. Liver fat content was assessed via proton magnetic resonance spectroscopy and insulin resistance was assessed via homeostatic model of insulin resistance (HOMA-IR). A partial correlation analysis, controlling for age and gender, was performed to determine the association between CRF, demographic, cardiometabolic, and anthropometric variables. Independent t tests were performed to compare cardiometabolic outcomes between participants with T2D and participants without T2D. Results Seventy-two adults (46% male) with a mean age of 49.28 ± 10.8 years, BMI of 34.69 ± 4.87 kg/m 2 , liver fat content of 8.37 ± 6.90%, HOMA-IR of 3.07 ± 2.33 and CRF of 21.52 ± 3.77 mL/kg/min participated in this study. CRF was inversely associated with liver fat content ( r  = − 0.28, p  = 0.019) and HOMA-IR ( r  = − 0.40, p  < 0.001). Participants with T2D had significantly higher liver fat content (+ 3.66%, p  = 0.024) and HOMA-IR (+ 2.44, p  < 0.001) than participants without T2D. Participants with T2D tended to have lower CRF than participants without T2D (− 1.5 ml/kg/min, p  = 0.094). Conclusion CRF was inversely associated with liver fat content and insulin resistance. Participants with T2D had lower CRF than those without T2D, however, the difference was not statistically significant. Further longitudinal studies are required to elucidate the relationship between CRF and the progression of obesity-related diseases such as T2D. Registration: ACTRN12614001220651 (retrospectively registered on the 19th November 2014) and ACTRN12614000723684 (prospectively registered on the 8th July 2014).

ObjectivesGreater arterial stiffness and poor 24h blood pressure (BP) are recognized as indicators of poor cardiovascular health. Evidence has shown that high intensity interval training (HIIT) may be a superior alternative to moderate intensity continuous training (MICT) for improving cardiovascular disease risk factors such as cardiorespiratory fitness and vascular function. However, there are limited data comparing the effect of HIIT to MICT on central arterial stiffness and/or 24h BP response. The purpose of this study was to compare HIIT versus MICT on central arterial stiffness and 24h BP outcomes by systematic review and meta-analysis.DesignA systematic review and meta-analysis was conducted.MethodsEligible studies were exercise training interventions (≥4weeks) that included both HIIT and MICT and reported central arterial stiffness, as measured by pulse wave velocity and augmentation index and/or 24h BP outcome measures.ResultsHIIT was found to be superior to MICT for reducing night-time diastolic BP (ES: −0.456, 95% CI: −0.826 to −0.086mmHg; P=0.016). A near-significant greater reduction in daytime systolic (ES: −0.349, 95% CI: −0.740 to 0.041mmHg; p=0.079) and diastolic BP was observed with HIIT compared to MICT (ES: −0.349, 95% CI: −0.717 to 0.020mmHg; p=0.063). No significant difference was found for other BP responses or arterial stiffness outcomes.ConclusionsHIIT leads to a superior reduction in night-time diastolic BP compared to MICT. Furthermore, a near-significant greater reduction in daytime BP was found with HIIT compared to MICT. No significant difference was observed for changes to central arterial stiffness between HIIT and MICT.

This Position Statement examines the evidence for physical activity in weight and adiposity loss, prevention of weight and adiposity gain, and in weight regain in adults, and provides guidance on implications for exercise practitioners. Research evidence indicates that >150 min but preferably 300 min per week of aerobic activity of at least moderate intensity is required to prevent weight and adiposity gain, and at least the upper end of this range of activity to prevent weight regain after weight loss. For meaningful weight and total adiposity loss, a minimum of 300–420 min per week of aerobic activity of at least moderate intensity is required. The evidence around the volume of aerobic physical activity required to reduce central adiposity is emerging, and research suggests that it may be substantially less than that required for weight loss. The impact of high-intensity physical activity and resistance exercise for weight management is uncertain. During consultations for weight management, exercise practitioners should advise that metabolic and cardiovascular health benefits can be achieved with physical activity at any weight, and irrespective of weight change.

Greater arterial stiffness and poor 24h blood pressure (BP) are recognized as indicators of poor cardiovascular health. Evidence has shown that high intensity interval training (HIIT) may be a superior alternative to moderate intensity continuous training (MICT) for improving cardiovascular disease risk factors such as cardiorespiratory fitness and vascular function. However, there are limited data comparing the effect of HIIT to MICT on central arterial stiffness and/or 24h BP response. The purpose of this study was to compare HIIT versus MICT on central arterial stiffness and 24h BP outcomes by systematic review and meta-analysis. A systematic review and meta-analysis was conducted. Eligible studies were exercise training interventions (≥4weeks) that included both HIIT and MICT and reported central arterial stiffness, as measured by pulse wave velocity and augmentation index and/or 24h BP outcome measures. HIIT was found to be superior to MICT for reducing night-time diastolic BP (ES: −0.456, 95% CI: −0.826 to −0.086mmHg; P=0.016). A near-significant greater reduction in daytime systolic (ES: −0.349, 95% CI: −0.740 to 0.041mmHg; p=0.079) and diastolic BP was observed with HIIT compared to MICT (ES: −0.349, 95% CI: −0.717 to 0.020mmHg; p=0.063). No significant difference was found for other BP responses or arterial stiffness outcomes. HIIT leads to a superior reduction in night-time diastolic BP compared to MICT. Furthermore, a near-significant greater reduction in daytime BP was found with HIIT compared to MICT. No significant difference was observed for changes to central arterial stiffness between HIIT and MICT.

Females with type 2 diabetes (T2D) have a 25–50% greater risk of developing cardiovascular disease compared with males. While aerobic exercise training is effective for improving cardiometabolic health outcomes, there is limited sex-segregated evidence on the feasibility of aerobic training in adults with T2D. A secondary analysis of a 12-week randomized controlled trial examining aerobic training in inactive adults with T2D was conducted. Feasibility outcomes were recruitment, retention, treatment fidelity, and safety. Sex differences and intervention effects were assessed using two-way analyses of variances. Thirty-five participants (14 females) were recruited. The recruitment rate was significantly lower among females (9% versus 18%; p = 0.022). Females in the intervention were less adherent (50% versus 93%; p = 0.016), and experienced minor adverse events more frequently (0.08% versus 0.03%; p = 0.003). Aerobically trained females experienced clinically meaningful reductions in pulse wave velocity (−1.25 m/s, 95%CI [−2.54, 0.04]; p = 0.648), and significantly greater reductions in brachial systolic pressure (−9 mmHg, 95%CI (3, 15); p = 0.011) and waist circumference (−3.8 cm, 95%CI (1.6, 6.1); p < 0.001) than males. To enhance the feasibility of future trials, targeted strategies to improve female recruitment and adherence are needed. Females with T2D may experience greater cardiometabolic health improvements from aerobic training than males.

It is unclear if cutaneous microvascular dysfunction associated with diabetes and obesity can be ameliorated with exercise. We investigated the effect of 12-weeks of exercise training on cutaneous microvascular reactivity in the foot. Thirty-three inactive adults with type 2 diabetes and obesity (55% male, 56.1 ± 7.9 years, BMI: 35.8 ± 5, diabetes duration: 7.9 ± 6.3 years) were randomly allocated to 12-weeks of either (i) moderate-intensity continuous training [50–60% peak oxygen consumption (VO2peak), 30–45 min, 3 d/week], (ii) low-volume high-intensity interval training (90% VO2peak, 1–4 min, 3 d/week) or (iii) sham exercise placebo. Post-occlusive reactive hyperaemia at the hallux was determined by laser-Doppler fluxmetry. Though time to peak flux post-occlusion almost halved following moderate intensity exercise, no outcome measure reached statistical significance (p > 0.05). These secondary findings from a randomised controlled trial are the first data reporting the effect of exercise interventions on cutaneous microvascular reactivity in the foot in people with diabetes. A period of 12 weeks of moderate-intensity or low-volume high-intensity exercise may not be enough to elicit functional improvements in foot microvascular reactivity in adults with type 2 diabetes and obesity. Larger, sufficiently powered, prospective studies are necessary to determine if additional weight loss and/or higher exercise volume is required.