Differential effects of high-intensity interval training (HIIT) on choriocapillaris perfusion in healthy adults and patients with type 1 diabetes mellitus (T1DM)

Alten F, Eter N, Schmitz B

Abstract

PURPOSE To investigate the effects of a four-week high-intensity interval training (HIIT) on choriocapillaris (CC) perfusion in young healthy adults and type 1 diabetes mellitus (T1DM) patients. METHODS Data of two HIIT studies with baseline to follow-up comparison were retrospectively analysed. Twenty healthy participants and twenty T1DM patients without clinical signs of diabetic retinopathy were included. All participants had performed a four-week all-out HIIT protocol with a total of 8 training sessions. Changes in physical fitness were assessed using power output at the individual aerobic lactate threshold (IANT). Optical coherence tomography angiography (OCTA) imaging was performed at baseline and follow-up. CC images were analysed for number, size and total area of flow deficits (FD), mean signal intensity, signal intensity standard deviation and kurtosis of signal intensity distribution. RESULTS At baseline, CC OCTA revealed a lower and more heterogeneous intensity signal in T1DM eyes (mean intensity signal and standard deviation of signal intensity, p~{\textless}~0.001). Percent of CC FD area was greater in T1DM eyes (p~{\textless}~0.001). While T1DM patients showed greater improvement of exercise capacity at IANT than healthy controls (group$\times$time p~=~0.0403), CC FD area and standard deviation of intensity increased in healthy controls but not in T1DM patients (group$\times$time p~$\leq$~0.029). Moreover, linear regression slopes of FD region distribution differed significantly at baseline and follow-up (p~=~0.0002) in healthy individuals but not in T1DM patients. CONCLUSIONS Effects of regular physical exercise performed as HIIT on CC perfusion were only seen in healthy participants, not in T1DM patients suggesting impaired CC adaptation in T1DM.