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

Abstract

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.

Keywords: CrossFit™; diabetes; insulin resistance; insulin sensitivity; obesity.

Figure 1

Relative heart rates for 5 individuals during the “deck of cards” workout (Session 12). During this workout participants performed a set of exercises determined by deck of cards. In this example, ♣ = Kettlebell Swings; ♠ = Squats; ♥ = Push Ups; ◆ = Sit Ups; Joker = 10 Burpees, and the number of reps performed was determined by the value of the card, ie. 8◆ = 8 Sit Ups. Participants alternated between flipping a card and performing the exercise with a partner until the deck was finished.

Figure 2

A) ISI_OGTT was significantly increased and B) metabolic syndrome severity was reduced following the 6-week intervention. Data are Mean±SD. *P<0.05

Figure 3

A) Fat oxidation and B) HMW adiponectin are significantly increased following the intervention. Data are Mean±SD. *P<0.05

Figure 4

Correlation between pre- to post-intervention changes in ISI_OGTT and A. plasma HMW adiponectin (rho = 0.70; P<0.05) and, B. whole body fat oxidation (rho = 0.86; P<0.05). Data were analysed using a Spearman’s rank correlation.