Skin autofluorescence is associated with arterial stiffness and insulin level in endurance runners and healthy controls - Effects of aging and endurance exercise

Background Life-long regular endurance exercise yields positive effects on cardiovascular and metabolic function, disease and mortality rate. Glycation may be a major mechanism behind age-related diseases. However, it remains unknown if skin autofluorescence (SAF), which reflects glycation, is related to arterial and metabolic function in life-long endurance runners and sedentary controls. Methods Healthy elderly men: 15 life-long endurance runners (OT) (64 ± 4 years) and 12 old untrained (OU) (66 ± 4 years), and healthy young men; ten young athletes (YT) (26 ± 4 years) matched to OT for running distance, and 12 young untrained (YU) (24 ± 3 years) were recruited. Endothelial function (reactive hyperemia index, RHI) and arterial stiffness (augmentation index, AI@75 and AI) were measured by an operator-independent PAT 2000. SAF was non-invasively determined using an autofluorescence spectrometer. Results For AI@75 there was an effect of age (p < 0.0001), but not training (p = 0.71). There was an interaction for endothelial function (p < 0.05): YT had higher RHI than YU (p < 0.05) and OU (p < 0.01). SAF was associated with arterial stiffness (r² = 0.57, p < 0.001), insulin and HOMA-index levels after age correction (both r² = 0.19, p < 0.05). Conclusions To our knowledge, these are the first data to show that skin autofluorescence (SAF) is linked to human arterial stiffness and insulin resistance in well-trained elderly and young men as well as sedentary controls. SAF may in the future be a helpful tool to predict vascular and metabolic dysfunction (early signs of aging and pathology). Surprisingly, endurance running only had modest effects on cardiovascular function compared to lean healthy controls.