The Effect of Exercise Intensity and Volume on Metabolic Phenotype in Patients with Metabolic Syndrome: A Randomized Controlled Trial

Background: Moderate intensity continuous training (MICT) ameliorates dysmetabolism in patients with metabolic syndrome (MetS). The impact of low- (1HIIT) versus high-volume high-intensity interval training (4HIIT) versus MICT on central adiposity, insulin resistance, and atherogenic dyslipidemia in patients with MetS has not yet been reported. Methods: Twenty-nine patients with MetS according to International Diabetes Federation criteria (nine females, age 61 +/- 5 years, body mass index 31.1 +/- 3.7 kg/m(2), waist circumference (WC) female 102.2 +/- 10.6 cm, male 108.5 +/- 8.6 cm) were randomized (1:1:1) to 16 weeks of (1) MICT (5 x 30 min/week, 35%-50% heart rate reserve (HRR), (2) 1HIIT (3 x 17 min/week incl. 4 min @80%-90% HRR), and (3) 4HIIT (3 x 38 min/week incl. 4 x 4 min @80%-90% HRR). Peak oxygen uptake (V?O-2peak), WC and anthropometric/metabolic indices indicative of MetS, fasting glucose/insulin, Homeostatic Model Assessment for Insulin Resistance (HOMA-IR), dyslipidemia, and respiratory exchange ratio (RER) at warm-up were quantified at baseline and study completion. Analysis of variance and paired t tests were used for statistical analysis. Analyses were performed after checking for parametric distribution. Results: There were no significant differences between groups in waist-to-height ratio (female: Delta -0.10 +/- -0.05, male: Delta -0.08 +/- -0.06, P = 0.916), WC (female: Delta -1.4 +/- -0.1 cm, male: Delta 0.1 +/- 0.9 cm, P = 0.590), fasting glucose (Delta -1.18 +/- 16.7 mu U/mL, P = 0.773), fasting insulin (Delta 0.76 +/- 13.4 mu U/mL, P = 0.509), HOMA-IR (Delta 0.55 +/- 4.1, P = 0.158), atherogenic dyslipidemia [triglycerides (TAG) Delta -10.1 +/- 46.9 mg/dL, P = 0.468, high-density lipoprotein cholesterol (HDL-C) Delta 1.5 +/- 5.4, P = 0.665, TAG/HDL-C -0.19 +/- 1.3, P = 0.502], V?O-2peak (P = 0.999), or RER (P = 0.842). In the entire group, waist-to-height-ratio and V?O-2peak significantly improved by a clinically meaningful amount (Delta 2.7 +/- 0.9 mL/min/kg; P < 0.001) and RER at warm-up significantly decreased (Delta -0.03 +/- 0.06, P = 0.039). Conclusion: In patients with MetS, there was no significant difference between HIIT, irrespective of volume, to MICT for improving exercise capacity or metabolic health.

Automated summary

In patients with metabolic syndrome, there was no significant difference between low- or high-intensity interval training and moderate intensity continuous training in improving exercise capacity or metabolic health.