Effects of Non-periodized and Linear Periodized Combined Exercise Training on Insulin Resistance Indicators in Adults with Obesity: A Randomized Controlled Trial.

Background: The aim was to verify the effect of non-periodized and linear periodized combined (aerobic plus resistance) exercise training on insulin resistance markers in adults with obesity.

Methods: A blinded randomized control trial was conducted with three groups of individuals with obesity (BMI, 30-39.9 kg/m): control group (CG, n = 23), non-periodized group (NG, n = 23), and linear periodized group (PG, n = 23). The NG and PG performed aerobic and resistance exercises in the same session in aerobic-resistance order for 16 weeks. Both intervention groups trained three sessions weekly, with a total duration of 60 min each. The aerobic training of the NG had a duration of 30 min always between 50% and 59% of the reserve heart rate (HRres), while resistance exercise was comprised of 6 exercises, performed always in 2 × 10-12 maximum repetitions (MRs). The PG progressed the aerobic and resistance training from 40%-49% to 60%-69% (HRres) and from 2 × 12-14 to 2 × 8-10 RM, respectively, along the intervention period. The evaluated indicators of insulin resistance included fasting glucose, fasting insulin, and homeostasis model assessment-estimated insulin resistance (HOMA-IR) collected pre- and post-intervention. The analyses to verify the exercise training effect were performed using generalized estimating equations.

Results: After 16 weeks of training, per protocol analysis (n = 39) showed significant reductions in HOMA-IR only in the training groups (NG: Δ = - 1.6, PG: Δ = - 0.6; p = 0.094). Intention-to-treat analysis demonstrated significant reductions in fasting insulin levels (NG: Δ = - 1.4, PG: Δ = - 1.0; p = 0.004) and HOMA-IR (NG: Δ = - 5.5, PG: Δ = - 3.8; p = 0.002).

Conclusion: Periodized and non-periodized combined exercise training similarly reduces insulin resistance markers in adults with obesity.

Trial Registration: Brazilian Registry of Clinical Trials, RBR-3c7rt3. Registered 07 February 2019- https://ensaiosclinicos.gov.br/trial/5970/1 .