Comparison of a 12-week exercise protocol of hiit vs. mict on cardiorespiratory fitness and glycosylated hemoglobin in type 2 diabetics

Resumen

INTRODUCTION: Cardiorespiratory fitness (CRF) is impaired in type 2 diabetes mellitus (T2DM). Moreover, the glycosylatedhaemoglobin (Hb1Ac) values have been considered an important marker in glucose control in T2DM (1). Aerobic exercisetraining improves both the CRF and values of Hb1A in T2DM (2), but it remains unclear if the type and intensity of the exercise may produce different benefits. Hence, the main aim of this study was to compared high intensity interval training(HIIT) vs. moderate intensity continuos training (MICT) on cardiorespiratory fitness and Hb1Ac. Indeed, a second aim was toanalyse the relationship between changes with each training in CRF with Hb1A levels in type 2 diabetics.METHODS: This preliminary analysis includes 46 type 2 diabetes participants (55.70 ± 6.97 years), who were randomizedinto 12 weeks of HIIT (n=15, 4 women), or MICT (n=20, 8 women) or control group (CG) (n=11, 5 women). Participants weretested on two consecutive days in fasting condition. On day 1, blood sampling was taken to determine the Hb1Ac. On thesecond day, body composition was evaluated by bioimpedance, and the maximum oxygen consumption (VO2max) wasdetermined through an incremental test on a cycle ergometer (15W/1´). All measurments were performed before and after12 weeks of intervention. Changes in study variables were tested for time (pre vs. post), group (HIIT, MICT, and CG), andtime-by-group interactions using a mixed factorial ANOVA with Bonferroni post hoc comparisons. The significance levelwas set at a p value < 0.05. Pearsons correlation was used to observe if changes in VO2max correlated with largerchanges in Hb1A.RESULTS: The VO2max significantly increased in both intervention groups after the intervention (HIIT 22.43 to 26.16ml/kg/min, p<0.001 / MICT 23.15 to 25.67 ml/kg/min, p<0.001), whereas CG remained unchanged (20.12 to 19.02ml/kg/min). In addition to this, a time-by-group effect was found between HIIT, and MICT with CG (p<0.002). The Hb1Acimproved significantly in both intervention groups (HIIT 7.25% to 6.59%, p=0.003 / MICT 6.70% to 6.42%, p<0.001), but nodifferences were found in the GC group (7.04% to 6.97%).No significant correlation was found between the changes inrelative VO2max and changes in Hb1Ac.CONCLUSION: Both exercise interventions increases cardiorespiratory fitness and decreases glycosylated hemoglobinlevels. The HIIT seems to be an time-efficient intervention compared to MICT that achieve similar results.