Skeletal muscle autophagy and mitophagy in endurance-trained runners before and after a high-fat meal

Abstract Objective We tested the hypothesis that skeletal muscle of endurance-trained male runners would exhibit elevated autophagy and mitophagy markers, which would be associated with greater metabolic flexibility following a high-fat meal (HFM). Methods Muscle biopsies were collected to determine differences in autophagy and mitophagy protein markers and metabolic flexibility under fasting conditions and 4 h following a HFM between endurance-trained male runners (n = 10) and sedentary, non-obese controls (n = 9). Results Maximal oxygen consumption (ml·kg·min −1 ) was approximately 50% higher (p   0.05), but increased in response to the HFM in endurance-trained athletes only (p  Thr257 and phospho-Parkin S65 (r = 0.64, p  Ser65 and phospho-Drp1 Ser616 (r = 0.70, p  Conclusion In summary, mitophagy may be enhanced in endurance-trained runners based on elevated markers of mitophagy and mitochondrial dynamics. The HFM did not alter autophagy or mitophagy in either group. The absence of a relationship between mitophagy markers and metabolic flexibility suggests that mitophagy is not a key determinant of metabolic flexibility in a healthy population, but further investigation is warranted.