Effect of induced alkalosis on performance during a field-simulated BMX cycling competition

Objectives

The aim of the present study was to test the effect of sodium bicarbonate (NaHCO₃^?) ingestion on performance during a simulated competition on a Bicycle Motocross (BMX) track.

Design

Double-blind cross-over study.

Methods

Twelve elite male BMX cyclists (age: 19.2 ± 3.4 years; height: 174.2 ± 5.3 cm; body mass: 72.4 ± 8.4 kg) ingested either NaHCO3- (0.3 g.kg^?1 body weight) or placebo 90 min prior to exercise. The cyclists completed three races in a BMX Olympic track interspersed with 15 min of recovery. Blood samples were collected to assess the blood acid-base status. Performance, cardiorespiratory, heart rate variability (HRV) as well as subjective variables were assessed.

Results

The main effect of condition (NaHCO₃^? vs. placebo) was observed in pH, bicarbonate concentration and base excess (p < 0.05), with a significant blood alkalosis. No changes were found in time, peak velocity and time to peak velocity for condition (p > 0.05). The HRV analysis showed a significant effect of NaHCO₃^? ingestion, expressed by the rMSSD30 (root mean square of the successive differences) (p < 0.001). There was no effect of condition on oxygen uptake, carbon dioxide production, or pulmonary ventilation (p > 0.05). Finally, there was no effect of condition for any subjective scale (p > 0.05).

Conclusions

We present here the first field condition study to investigate the effect of bicarbonate ingestion over performance in BMX discipline. The results showed that NaHCO₃^?-induced alkalosis did not improve performance in a simulated BMX competition in elite BMX cyclists, although future studies should consider the effects of NaHCO3- on autonomic function as a component of recovery.