Effect of Differential Exercise Intensities on Interleukin-22 in Metabolic Syndrome

Elevated serum interleukin-22 (IL-22) concentration is independently associated with the incidence of type 2 diabetes and coronary artery disease. Individuals with metabolic syndrome (MetS) are at increased risk of developing both conditions.Paradoxically, evidence also exists demonstrating that IL-22 may have a role in the alleviation of MetS.

PURPOSE: We investigated the impact of moderate-intensity continuous training (MICT) and different volumes of high-intensity interval training (HIIT) on IL-22.

METHODS: This was a sub-study of the ‘Exercise in prevention of Metabolic Syndrome’ (EX-MET) multi-center randomized trial, based on data collected at the Brisbane site. Thirty-nine MetS individuals were randomized to one of three 16-wk interventions: i)MICT(n=10,30min at 60-70%HRpeak,5x/wk);ii)4HIIT(n=13, 4x4min at 85-95%HRpeak,interspersed with 3min of recovery at 50-70%HRpeak,3x/wk);or iii)1HIIT(n=16,1x4min at 85-95%HRpeak, 3x/wk).Serum IL-22 concentration was measured following a 12-hr fast via enzyme linked immunosorbent assays, before/after the intervention.MetS severity, cardiorespiratory fitness (CRF), insulin resistance(IR), and visceral adipose tissue(VAT) were also measured via MetS z-score,HOMA-IR,dual-energy x-ray absorptiometry, and indirect calorimetry, respectively.

RESULTS: The median (IQR) IL-22 percent changes from pre- to post-intervention in the MICT, 4HIIT, and 1HIIT groups were -17%(-43.0%;31.3%),+16.5%(-18.9%;154.9%), and +15.9%(-28.7%;46.1%) respectively. Although there was no significant between-group difference in IL-22 change, there was a medium-to-large group x time interaction effect on this cytokine[F(2,35)=2.08, p=0.14,η2=0.14].There were similar reductions in MetS severity(MICT,-0.5±1.8; 4HIIT,-0.5±0.9;1HIIT,-1.3±1.8), IR(MICT,-2.1±2.7;4HIIT,-0.8±1.4;1HIIT,-1.0±2.0), and VAT(MICT,-47.2±152.6g; 4HIIT,-68.2±106.0g; 1HIIT,-44.9±102.7g) following all interventions. 4HIIT(+5.7±4.7ml/kg/min) significantly improved CRF more than MICT (+2.7±1.9ml/kg/min) and 1HIIT (+2.9±2.2ml/kg/min).

CONCLUSION: Although there was no significant between-group difference in IL-22 change, the study suggests that different exercise intensities may have different effects on IL-22 in MetS individuals.