Sodium Bicarbonate Ingestion Improves Time-to-Exhaustion Cycling Performance and Alters Estimated Energy System Contribution: A Dose-Response Investigation
William H. Gurton, Lewis A. Gough, S. Andy Sparks, Mark A. Faghy, Katharine E. Reed
Abstract
This study investigated the effects of two sodium bicarbonate (NaHCO3) doses on estimated energy system contribution and performance during an intermittent high-intensity cycling test (HICT), and time-to-exhaustion (TTE) exercise. Twelve healthy males (stature: 1.75 ± 0.08 m; body mass: 67.5 ± 6.3 kg; age: 21.0 ± 1.4 years; maximal oxygen consumption: 45.1 ± 7.0 ml.kg.min-1) attended four separate laboratory visits. Maximal aerobic power (MAP) was identified from an incremental exercise test. During the three experimental visits, participants ingested either 0.2 g.kg-1 BM NaHCO3 (SBC2), 0.3 g.kg-1 BM NaHCO3 (SBC3), or 0.07 g.kg-1 BM sodium chloride (placebo; PLA), 60 minutes pre-exercise. The HICT involved 3 x 60 s cycling bouts (90%, 95%, 100% MAP) interspersed with 90 s recovery, followed by TTE cycling at 105% MAP. Blood lactate was sampled after each cycling bout to calculate estimates for glycolytic contribution to exercise. Gastrointestinal (GI) upset was quantified at baseline, 30 minutes and 60 minutes post-ingestion, and 5 minutes post-exercise. Cycling TTE increased for SBC2 (+20.2 s; p =0.045) and SBC3 (+31.9 s; p =0.004) compared to PLA. Glycolytic contribution increased during the TTE protocol for SBC2 (+7.77 kJ; p =0.10) and SBC3 (+7.95 kJ; p =0.07) compared to PLA. GI upset was exacerbated post-exercise after SBC3 for nausea compared to SBC2 and PLA (p 0.05). Both NaHCO3 doses enhanced cycling performance and glycolytic contribution, however, higher doses may maximise ergogenic benefits.