High-Intensity Interval Training: Safe and Beneficial Physical Activity Strategy in Adolescents with Type 1 Diabetes

INTRODUCTION: Cardiovascular risk factors and depressive symptoms are common in adolescents and young adults with type 1 diabetes (T1D). While exercise improves cardiovascular health and metabolic control, its mental health benefits remain unclear. High-intensity interval training (HIIT) has shown an improvement in aerobic capacity without a detrimental decline in blood glucose and home-based HIIT has reduced barriers towards exercise in adults with T1D. There is scant evidence in children with T1D.

AIMS: Metabolic effects of HIIT (time in range [TIR], glycemic variability, HbA1c, lipid profile, blood pressure, and body composition) were evaluated. Secondary outcomes included assessing aerobic capacity, strength endurance, depressive symptoms, and barriers toward physical activity.

METHODS: A prospective, longitudinal, multicenter study involving adolescents (aged 12 and 19) with T1D diagnosed for ≥1 year, at least Tanner stage III, HbA1c between 7 and 11.5%, and a total daily insulin dose ≥0.7 units/kg/day was conducted. Outcomes were assessed at baseline, 1, 3 months of intervention, and 3 months after intervention.

RESULTS: Twenty-two participants completed intervention (mean age: 14.32 ± 1.62 years) showing no changes in HbA1c or TIR. Mean blood glucose significantly declined during sessions (191.61 ± 13.69 to 159.95 ± 13.04 mg/dL, p < 0.001), with no increase in time in hypoglycemia. Body lean mass increase and fat mass decline after 3 months of training (40.84 ± 8.53 to 42.35 ± 8.34, p < 0.001, and 29.94 ± 8.99 to 28.85 ± 9.20, p = 0.010, respectively). Maximal oxygen consumption improved once the intervention was completed (33.86 ± 4.00 to 36.43 ± 3.64, p < 0.001). Lack of motivation and concerns regarding weather decreased after training (73% vs. 59% and 27% vs. 14%, respectively).

CONCLUSIONS: HIIT improved physical fitness and body composition maintaining glycemic stability, being a safe regimen to encourage physical activity in adolescents with TD1.