Sodium bicarbonate ingestion augments the increase in PGC-1α mRNA expression during recovery from intense interval exercise in human skeletal muscle

Abstract

We investigated the hypothesis that ingestion of sodium bicarbonate prior to an acute session of high-intensity intense interval training (HIIT) would augment signalling cascades and gene expression linked to mitochondrial biogenesis in human skeletal muscle. On two occasions separated by ~1 wk, nine active men (22 ± 2 y; 78 ± 13 kg, VO2peak = 48 ± 8 mL/kg/min; mean ± SD) performed a HIIT protocol that involved 10 x 60 s cycling efforts at an intensity eliciting ~90% of maximal heart rate (263 ± 40 W), interspersed by 60 s of recovery. In a double-blind, crossover manner, participants ingested either 0.2 g kg-1 b.w. sodium bicarbonate (BICARB) or an equimolar dose of a placebo, sodium chloride (PLAC), 90 and 60 min prior to exercise. Blood samples confirmed that bicarbonate concentration, as well as pH and lactate, were all elevated during and following exercise after BICARB vs. PLAC (p < 0.05). Needle biopsies from the vastus lateralis obtained immediately post HIIT revealed that glycogen utilization was greater after BICARB (27%) vs. PLAC (11%). Phosphorylation of acetyl-CoA carboxylase, a downstream marker of AMPK activity, and p38 MAPK were increased immediately after exercise compared to rest with no differences between treatments (p > 0.05). However, compared to rest, PGC-1α mRNA expression was increased after 3 h of recovery to a greater extent in BICARB vs. PLAC (~7- vs. 5-fold, p < 0.05). We conclude that NaHCO3 ingestion altered skeletal muscle metabolism during HIIT and augmented the expression of PGC-1α mRNA during recovery. These results provide novel insights into potential mechanisms responsible for enhanced adaptations after chronic supplementation.