Effects of sleeping with reduced carbohydrate availability on acute training responses

Abstract

We determined the effects of "periodized nutrition" on skeletal muscle and whole body responses to a bout of prolonged exercise the following morning. Seven cyclists completed two trials receiving isoenergetic diets differing in the timing of ingestion: they consumed either 8 g/kg body mass (BM) of carbohydrate (CHO) before undertaking an evening session of high-intensity training (HIT) and slept without eating (FASTED), or consumed 4 g/kg BM of CHO before HIT, then 4 g/kg BM of CHO before sleeping (FED). The next morning subjects completed 2 h of cycling (120SS) while overnight fasted. Muscle biopsies were taken on day 1 (D1) before and 2 h after HIT and on day 2 (D2) pre-, post-, and 4 h after 120SS. Muscle [glycogen] was higher in FED at all times post-HIT (P < 0.001). The cycling bouts increased PGC1α mRNA and PDK4 mRNA (P < 0.01) in both trials, with PDK4 mRNA being elevated to a greater extent in FASTED (P < 0.05). Resting phosphorylation of AMPK(Thr172), p38MAPK(Thr180/Tyr182), and p-ACC(Ser79) (D2) was greater in FASTED (P < 0.05). Fat oxidation during 120SS was higher in FASTED (P = 0.01), coinciding with increases in ACC(Ser79) and CPT1 as well as mRNA expression of CD36 and FABP3 (P < 0.05). Methylation on the gene promoter for COX4I1 and FABP3 increased 4 h after 120SS in both trials, whereas methylation of the PPARδ promoter increased only in FASTED. We provide evidence for shifts in DNA methylation that correspond with inverse changes in transcription for metabolically adaptive genes, although delaying postexercise feeding failed to augment markers of mitochondrial biogenesis.

New strategies in sport nutrition to increase exercise performance

“…At present, research studies examining the efficacy of train-low strategies have largely adopted fasted training protocols [60], protein only sessions [70], training twice per day models [62] reducing CHO intake in the post-exercise period [71] and most recently, both sleeping and training (i.e. sleep low-train low models) on the subsequent morning with reduced CHO intake [21,72]. Ultimately, the simplest advice at present may be to adopt the practical concept of "fuelling for the work required" in that completing pre-determined training workloads that can be readily performed with reduced muscle glycogen and without exogenous CHO feeding may represent a strategic approach for which to implement day-today nutrient-exercise periodization protocols.…”

Periodization of Carbohydrate Intake: Short-Term Effect on Performance

“…This has led to interest in a “periodized” approach to CHO availability in the training program, where sessions undertaken to promote adaptation are carefully integrated with others focused on high quality performance outcomes. The “sleep-low” (SL) strategy represents one such sequence of periodized CHO availability, which allows athletes to perform high intensity training sessions supported by high CHO availability while enhancing metabolic adaptation associated with low glycogen availability [14,15,16,17]. …”

“…Previous studies have reported that this strategy leads to increased activity of several proteins with putative roles in training adaptation (AMPK, p38 MAPK, p53) [9,14] and higher rates of fat oxidation during submaximal exercise [14]. However, the effects on endurance performance are equivocal.…”

Skeletal muscle cells possess a ‘memory’ of acute early life TNF-α exposure: role of epigenetic adaptation

“…Notably, a recent study in skeletal muscle, demonstrated acute metabolic stress (aerobic exercise) reduces DNA methylation of enhancer regions (hypomethlyation) of genes associated with mitochondrial biogenesis (PGC-1α, PDK4 and PPAR-δ) that presumably in turn allowed increased promoter activity (although not directly investigated) and thus increased corresponding transcript expression (Barres et al 2012). Similarly a more recent study suggests that acute nutritional manipulation (fasting) in combination with acute exercise also provides evidence of an inverse relationship with DNA methylation and gene expression of important metabolic genes involved in substrate utilization (Lane et al 2015). However, adaptation in the terms of stable methylation patters after chronic anabolic exercise stimuli or periods of catabolic injury/disuse remains unstudied, as do methylation of genes that control muscle mass.…”