Effects of acute aerobic, resistance and combined exercises on 24-h glucose variability and skeletal muscle signalling responses in type 1 diabetics

Purpose To compare the effect of high-intensity aerobic (AER), resistance (RES), and combined (COMB: RES + AER) exercise, on interstitial glucose (IG) variability and skeletal muscle signalling pathways in type 1 diabetes (T1D). Methods T1D participants (6 M/6F) wore a flash glucose monitoring system in four randomized sessions: one control (CONT), and one AER, RES and COMB (40 min each). Mean amplitude of glycemic excursions (MAGE), standard deviation (SD) and coefficient variation (CV) of IG were used to compare the 24 h post-exercise IG variability. Blood and muscle samples were collected to compare exercise-induced systemic and muscle signalling responses related to metabolic, growth and inflammatory adaptations. Results Both RES and COMB decreased the 24 h MAGE compared to CONT; additionally, COMB decreased the 24 h SD and CV. In the 6-12 h post-exercise, all exercise modalities reduced the IG CV while SD decreased only after COMB. Both AER and COMB stimulated thePGC-1 alpha mRNA expression and promoted the splicing ofIGF-1Eavariant, while Akt and p38MAPK phosphorylation increased only after RES and COMB. Additionally, COMB enhanced eEF2 activation and RES increasedmyogeninandMRF4mRNA expression. Blood lactate and glycerol levels and muscleIL-6,TNF-alpha, andMCP-1mRNAs increased after all exercise sessions, while serum CK and LDH level did not change. Conclusion COMB is more effective in reducing IG fluctuations compared to single-mode AER or RES exercise. Moreover, COMB simultaneously activates muscle signalling pathways involved in substrate metabolism and anabolic adaptations, which can help to improve glycaemic control and maintain muscle health in T1D.