The Impact of Type 2 Diabetes on Exercise Capacity of Adolescents

Abstract

Aerobic capacity is reduced in type 2 diabetic adults due to impaired cardiac output and arterio-venous O difference (a-vO). However, it is not known whether adolescents, who have been recently diagnosed with type 2 diabetes, have a similarly impaired hemodynamic exercise response. PURPOSE: This preliminary investigation aimed to determine whether adolescents with type 2 diabetes have reduced aerobic capacity compared to matched non-diabetic adolescents and whether stroke volume, heart rate, and a-vO response to exercise are impaired in type 2 diabetic adolescents. METHODS: Five type 2 diabetic and 6 age- Tanner stage- and body composition-matched non-diabetic adolescents were recruited for this study. Baseline data included blood analysis, maximal aerobic capacity (cycle ergometer) and a DEXA scan. On a separate day, cardiac output and a-vO were determined at rest and during exercise eliciting 100 (± 5) and 120 (± 5) beats per minute (bpm) using a CO2 rebreathing technique. RESULTS: Maximal O2 consumption (1.8 ± 0.1 vs 2.4 ± 0.5 L/min p <0.05) and workload (121 ± 13 vs 175 ± 29 W p <0.05) were lower in the diabetic vs. non-diabetic group. Resting (81 ± 18 vs 72 ± 11) and maximal (168 ± 20 vs. 180± 15) heart rate were similar between groups (p >0.05). There were no group differences in resting cardiac output or stroke volume (p >0.05); however, cardiac output and stroke volume were lower in the diabetic group at 100 and 120 bpm (see Table). Arterio-venous O difference was similar between groups at rest and during both exercise conditions (p >0.05).TableCONCLUSION: These preliminary data suggest that aerobic capacity is reduced in type 2 diabetic adolescents due to a blunted exercise stroke volume response. Hemodynamic characteristics: