© Copyright 2019 YLMSportScience. Alle Rechte vorbehalten.

Repeated periodization of carbohydrate (CHO) intake using a diet-exercise strategy called the sleep-low model can potentially induce mitochondrial biogenesis and improve endurance performance in endurance-trained individuals. However, more studies are needed to confirm the performance-related effects and to investigate the sustained effects on maximal fat oxidation rate (MFO) and proteins involved in intramuscular lipid metabolism. Thirteen endurance-trained males (age 23-44 yr; VO2-max, 63.9±4.6 mL·kg-1·min-1) were randomized into two groups: Sleep-low (LOW-CHO) or high CHO availability (HIGH-CHO) in three weekly training blocks over four weeks. The acute metabolic response was investigated during 60 min of exercise within the last three weeks of the intervention. Pre and post intervention, 30-min time-trial performance was investigated after a 90-min pre-load, which as a novel approach included nine intense intervals (and measurement of MFO). Additionally, muscle biopsies (v. lateralis) were obtained to investigate expression of proteins involved in intramuscular lipid metabolism using Western Blotting. During acute exercise, average fat oxidation rate was ~36% higher in LOW-CHO compared to HIGH-CHO (p=0.03). This did not translate into sustained effects on MFO. Time-trial performance increased equally in both groups (overall time effect: p=0.005). We observed no effect on intramuscular proteins involved in lipolysis (ATGL, G0S2, CGI-58, HSL) or fatty acid transport and capacity (CD-36 and HAD, respectively). In conclusion, the sleep-low model did not induce sustained effects on MFO, endurance performance or proteins involved in intramuscular lipid metabolism when compared to HIGH-CHO. Our study therefore questions the transferability of acute effects of the sleep-low model to superior sustained adaptations.
© Copyright 2019 Scandinavian Journal of Medicine & Science in Sports. Wiley. Alle Rechte vorbehalten.