Functional high-intensity exercise training ameliorates insulin resistance and cardiometabolic risk factors in type 2 diabetes.

NEW FINDINGS: What is the central question of this study? Does short-duration, high-intensity exercise training that combines functional aerobic and resistance exercises into training sessions lasting 8-20 min benefit individuals with type 2 diabetes? What is the main finding and its importance? Functional high-intensity training improves insulin sensitivity and reduces cardiometabolic risk in individuals with type 2 diabetes. This type of exercise training may be an effective exercise mode for managing type 2 diabetes. The increase in insulin sensitivity addresses a key defect in type 2 diabetes. ABSTRACT: Functional high-intensity training (F-HIT) is a novel fitness paradigm that integrates simultaneous aerobic and resistance training in sets of constantly varied movements, based on real-world situational exercises, performed at high-intensity in workouts that range from ∼8 to 20 min per session. We hypothesized that F-HIT would be an effective exercise mode for reducing insulin resistance in type 2 diabetes (T2D). We recruited 13 overweight/obese adults (5 males, 8 females; 53 ± 7 years; BMI 34.5 ± 3.6 kg m-2 , means ± SD) with T2D to participate in a 6-week (3 days week-1 ) supervised F-HIT programme. An oral glucose tolerance test was used to derive measures of insulin sensitivity. F-HIT significantly reduced fat mass (43.8 ± 83.8 vs. 41.6 ± 7.9 kg; P < 0.01), diastolic blood pressure (80.2 ± 7.1 vs. 74.5 ± 5.8; P < 0.01), blood lipids (triglyceride and VLDL, both P < 0.05) and metabolic syndrome z-score (6.4 ± 4.5 vs. -0.2 ± 5.2 AU; P < 0.001), and increased basal fat oxidation (0.08 ± 0.03 vs. 0.10 ± 0.04 g min-1 ; P = 0.05), and high molecular mass adiponectin (214.4 ± 88.9 vs. 288.8 ± 127.4 ng mL-1 ; P < 0.01). Importantly, F-HIT also increased insulin sensitivity (0.037 ± 0.010 vs. 0.042 ± 0.010 AU; P < 0.05). Increases in high molecular mass adiponectin and basal fat oxidation correlated with the change in insulin sensitivity (ρ, 0.75, P < 0.05 and ρ, 0.81, P < 0.01, respectively). Compliance with the training programme was >95% and no injuries or adverse events were reported. These data suggest that F-HIT may be an effective exercise mode for managing T2D. The increase in insulin sensitivity addresses a key defect in T2D and is consistent with improvements observed after more traditional aerobic exercise programmes in overweight/obese adults with T2D.

Functional high-intensity training improves pancreatic ß-cell function in adults with type 2 diabetes.

Type 2 diabetes (T2D) is characterized by reductions in ß-cell function and insulin secretion on the background of elevated insulin resistance. Aerobic exercise has been shown to improve ß-cell function, despite a subset of T2D patients displaying "exercise resistance." Further investigations into the effectiveness of alternate forms of exercise on ß-cell function in the T2D patient population are needed. We examined the effect of a novel, 6-wk CrossFit functional high-intensity training (F-HIT) intervention on ß-cell function in 12 sedentary adults with clinically diagnosed T2D (54 ± 2 yr, 166 ± 16 mg/dl fasting glucose). Supervised training was completed 3 days/wk, comprising functional movements performed at a high intensity in a variety of 10- to 20-min sessions. All subjects completed an oral glucose tolerance test and anthropometric measures at baseline and following the intervention. The mean disposition index, a validated measure of ß-cell function, was significantly increased (PRE: 8.4 ± 3.1, POST: 11.5 ± 3.5, P = 0.02) after the intervention. Insulin processing inefficiency in the ß-cell, expressed as the fasting proinsulin-to-insulin ratio, was also reduced (PRE: 2.40 ± 0.37, POST: 1.78 ± 0.30, P = 0.04). Increased ß-cell function during the early-phase response to glucose correlated significantly with reductions in abdominal body fat (R2 = 0.56, P = 0.005) and fasting plasma alkaline phosphatase (R2 = 0.55, P = 0.006). Mean total body-fat percentage decreased significantly (Δ: -1.17 0.30%, P = 0.003), whereas lean body mass was preserved (Δ: +0.05 ± 0.68 kg, P = 0.94). We conclude that F-HIT is an effective exercise strategy for improving ß-cell function in adults with T2D.

Hemodynamic design requirements for in-series thoracic artificial lung attachment in a model of pulmonary hypertension.

Recent thoracic artificial lung (TAL) prototypes have impedances lower than the natural lung. With these devices, proximal pulmonary artery (PA) to distal PA TAL attachment may be possible in patients without right ventricular dysfunction. This study examined the relationship between pulmonary system impedance and cardiac output (CO) to create TAL design constraints. A circuit with adjustable resistance and compliance (C) was attached in a PA-PA fashion with the pulmonary circulation of seven sheep with chronic pulmonary hypertension. The pulmonary system zeroth harmonic impedance modulus (Z(0)) was increased by 1, 2.5, and 4 mmHg/(L/min) above baseline. At each Z(0), C was set to 0, 0.34, and 2.1 ml/mmHg. The change in pulmonary system zeroth and first harmonic impedance moduli (ΔZ(0) and ΔZ(1)), the percent change in CO (%ΔCO), and the inlet and outlet anastomoses resistances were calculated for each situation. Results indicate that ΔZ(0) (p < 0.001) but not ΔZ(1) (p = 0.5) had a significant effect on %ΔCO and that %ΔCO = -7.45*ΔZ(0) (R(2) = 0.57). Inlet and outlet anastomoses resistances averaged 0.77 ± 0.16 and 0.10 ± 0.19 mmHg/(L/min), respectively, and the relationship between %ΔCO and TAL resistance, R(T), in mmHg/(L/min) was determined to be %ΔCO = -(7.45f)×(R(T) + 0.87), in which f = the fraction of CO through the TAL. Thus, newer TAL designs can limit %ΔCO to less than 10% if f < 0.75.