Degree of adiposity and obesity severity is associated with cutaneous microvascular dysfunction in type 2 diabetes.

BACKGROUNDS AND AIMS: Obesity and diabetes independently contribute to cutaneous microvascular dysfunction via pathological processes that are not fully understood. We sought to determine if obesity severity is associated with cutaneous microvascular dysfunction and measures of peripheral arterial disease in adults with type 2 diabetes in cross-sectional observational study design. METHODS AND RESULTS: Primary outcomes were post-occlusive reactive hyperaemia as determined by laser-Doppler fluxmetry (peak flux post-occlusion, time to peak flux post-occlusion, peak as a percentage of baseline, and area under the curve [AuC] index post-occlusion to pre-occlusion). Secondary outcomes were ankle- and toe-brachial indices (ABI and TBI) and systolic toe pressure. Thirty-six participants (20 men, 16 women) with mean age 55 ± 8 years, BMI of 36 ± 5 kg/m2 and duration of diabetes 8 ± 6 years underwent measurements. After adjusting for age and duration of diabetes, SAT and total percentage body fat were able to explain 29% (p = 0.001) and 20% (p = 0.01) of variance of AuC index models, as well as 29% (p = 0.02) and 18% (p = 0.02) of peak as a percentage of baseline models, respectively. Though TBI demonstrated moderate, significant correlations with SAT (r:0.37, p = 0.04) and total percentage body fat (r:0.39, p = 0.03), these were not upheld by regression analyses. Neither ABI nor systolic toe pressure significantly correlated with any measure of adiposity or obesity. CONCLUSION: These findings demonstrate impairment in cutaneous microvascular function related to adiposity and obesity severity in adults with type 2 diabetes, suggesting that obesity may pathologically effect cutaneous microvascular function in the absence of overt macrovascular disease, warranting further investigation.

Physical activity in the management of obesity in adults: A position statement from Exercise and Sport Science Australia.

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.

The association between cardiorespiratory fitness, liver fat and insulin resistance in adults with or without type 2 diabetes: a cross-sectional analysis

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/m2, 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).

The effect of low-volume high-intensity interval training on cardiovascular health outcomes in type 2 diabetes: A randomised controlled trial.

BACKGROUND: Low-volume high-intensity interval training (HIIT) may be a time-efficient strategy that leads to similar or superior improvements in cardiorespiratory fitness (CRF) and cardiovascular disease (CVD) risk factors when compared with moderate-intensity continuous training (MICT). Our study investigated the effect of low-volume HIIT or MICT versus sham placebo-control (PLA) on central arterial stiffness, hemodynamic responses, and CVD risk factors in adults with obesity and type 2 diabetes (T2D). METHODS: Eligible participants were previously inactive adults with obesity and T2D. Individuals were randomly allocated to: i) HIIT (1 × 4 min cycling at 90% peak oxygen consumption [V̇O2peak]); ii) MICT (45 min of cycling at 60% VO2peak); or PLA. Training groups exercised thrice weekly for 12 weeks. Central arterial stiffness, hemodynamics and CVD risk factors were assessed at baseline and post-intervention. Analysis of covariance (ANCOVA) was used to examine changes following HIIT, MICT and PLA. RESULTS: Thirty-five participants (age: 55.1 ± 1.4 years, BMI: 36.1 ± 0.8 kg/m2) completed the study. A significant intervention effect was found for changes in pulse wave velocity (PWV) (p = .03), which reduced with HIIT (-0.3 ± 0.9 m/s) and MICT (-0.1 ± 1.1 m/s) but increased with PLA (0.8 ± 1.6 m/s). There was a significant intervention effect for changes in V̇O2peak (p < .01), glycosylated hemoglobin (p = .03), systolic blood pressure (p < .01), and waist circumference (p = .03), which all improved following MICT or HIIT but not PLA; there was no difference between MICT and HIIT. CONCLUSIONS: Twelve minutes of low-volume HIIT per week leads to improvements in central arterial stiffness and cardiovascular health in inactive individuals with obesity and T2D.

The Effect of a Novel Low-Volume Aerobic Exercise Intervention on Liver Fat in Type 2 Diabetes: A Randomized Controlled Trial.

OBJECTIVE: The aim of this study was to examine the effect of a novel low-volume high-intensity interval training (HIIT), moderate-intensity continuous training (MICT), or placebo (PLA) intervention on liver fat, glycemia, and cardiorespiratory fitness using a randomized placebo-controlled design. RESEARCH DESIGN AND METHODS: Thirty-five inactive adults (age 54.6 ± 1.4 years, 54% male; BMI 35.9 ± 0.9 kg/m2) with obesity and type 2 diabetes were randomized to 12 weeks of supervised MICT (n = 12) at 60% VO2peak for 45 min, 3 days/week; HIIT (n = 12) at 90% VO2peak for 4 min, 3 days/week; or PLA (n = 11). Liver fat percentage was quantified through proton MRS. RESULTS: Liver fat reduced in MICT (-0.9 ± 0.7%) and HIIT (-1.7 ± 1.1%) but increased in PLA (1.2 ± 0.5%) (P = 0.046). HbA1c improved in MICT (-0.3 ± 0.3%) and HIIT (-0.3 ± 0.3%) but not in PLA (0.5 ± 0.2%) (P = 0.014). Cardiorespiratory fitness improved in MICT (2.3 ± 1.2 mL/kg/min) and HIIT (1.1 ± 0.5 mL/kg/min) but not in PLA (-1.5 ± 0.9 mL/kg/min) (P = 0.006). CONCLUSIONS: MICT or a low-volume HIIT approach involving 12 min of weekly high-intensity aerobic exercise may improve liver fat, glycemia, and cardiorespiratory fitness in people with type 2 diabetes in the absence of weight loss. Further studies are required to elucidate the relationship between exercise-induced reductions in liver fat and improvements in glycemia.

The effect of high Intensity interval training versus moderate intensity continuous training on arterial stiffness and 24h blood pressure responses: A systematic review and meta-analysis.

OBJECTIVES: 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. DESIGN: A systematic review and meta-analysis was conducted. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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.

The Effect of Low-Volume High-Intensity Interval Training on Body Composition and Cardiorespiratory Fitness: A Systematic Review and Meta-Analysis.

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.

La actividad física en la gestión de la obesidad en adultos: una ponencia de Exercise and Sport Science Australia / Physical activity in the management of obesity in adults: A position statement from Exercise and Sport Science Australia / Atividade física no controle da obesidade em adultos: um documento da Exercise and Sport Science Australia

Resumen Esta ponencia examina las evidencias para la actividad física en la pérdida de peso y de adiposidad, la prevención del aumento de peso y la adiposidad, así como la recuperación de peso en adultos, y provee orientación sobre las implicaciones para los profesionales del ejercicio. La evidencia de la investigación indica que se requieren > 150 minutos, pero preferiblemente 300 minutos por semana de actividad aeróbica de intensidad al menos moderada para prevenir el aumento de peso y adiposidad, y al menos el extremo superior de esta gama de actividad para prevenir la recuperación de peso después de la pérdida de peso. Para que la pérdida de peso y adiposidad total sea significativa, se requiere un mínimo de 300 a 400 minutos por semana de actividad aeróbica de intensidad, al menos, moderada. La evidencia en torno al volumen de actividad física aeróbica requerida para reducir la adiposidad central está surgiendo, y las investigaciones apuntan a que puede ser sustancialmente menor que la que se requiere para la pérdida de peso. El impacto de la actividad física de alta intensidad y el ejercicio de resistencia para la gestión del peso es incierto. Durante las consultas para la gestión del peso, los profesionales en ejercicio deben aconsejar que se pueden lograr beneficios para la salud metabólica y cardiovascular por medio de la actividad física a cualquier peso, e independientemente del cambio de peso.

Abstract 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.

Resumo Este documento examina as evidências da atividade física na perda de peso e adiposidade, na prevenção do ganho de peso e adiposidade e na recuperação de peso em adultos, e fornece orientações sobre as implicações para os profissionais do exercício físico. As evidências da pesquisa indicam que são necessários mais de 150 minutos, mas preferencialmente 300 minutos por semana de atividade aeróbica de intensidade moderada para evitar o ganho de peso e adiposidade, e pelo menos o extremo superior dessa gama de atividade para evitar o ganho de peso após a perda de peso. É necessário um mínimo de 300 a 400 minutos por semana de atividade aeróbica de intensidade moderada para uma perda significativa de peso e adiposidade total. Estão surgindo evidências sobre a quantidade de atividade física aeróbica necessária para reduzir a adiposidade central, e pesquisas sugerem que ela pode ser substancialmente menor do que a necessária para a perda de peso. O impacto da atividade física de alta intensidade e dos exercícios de resistência no controle de peso é incerto. Durante as consultas de controle de peso, os profissionais do exercício físico devem informar que os benefícios metabólicos e cardiovasculares à saúde podem ser obtidos por meio da atividade física em qualquer peso, independentemente da mudança de peso.