Maximal work production following two levels of artificially induced metabolic alkalosis

Abstract

In order to determine the influence of two artificially induced alkalotic states on the ability to perform maximal exercise, six male subjects (mean age, 22.0 years; mean height, 176.8 cm; mean weight, 69.1 kg; mean VO₂ max, 3.83 1 min^‐1) were studied during three experimental trials. The subjects performed six 60‐s cycling bouts, at a work rate corresponding to 125% VO₂ max, with 60 s recovery between work bouts; these regimes were performed 1 h after the ingestion of a solution containing either: I, placebo; II, NaHCO₃ in a dosage of 0.15 g per kg body weight; or III, NaHCO₃ 0.30 g per kg body weight. The sixth work bout was continued until the pedal velocity dropped below 50 rev min^‐1. Total work done for the entire work period was calculated. Blood samples were taken from a forearm vein prior to the exercise bouts for analysis of pH and HCO₃. The results showed a significant pre‐exercise difference in pH and HCO₃ for all conditions (P<0.01). In conditions where artificial alkalosis had been achieved prior to exercise there was significant increase in the work produced: I, 121.6 kJ; II, 133.1 kJ; III, 133.5 kJ (P<0.05). The time to fatigue in the sixth bout was also significantly increased: I, 74.7 s; II, 111.0 s; III, 106.0 s (P<0.05). There were no significant differences between conditions II and III. Thus augmentation of the bicarbonate reserves has a significant positive effect on the energy metabolism in interval‐type exercise, leading to an increase in the work done and in the time to fatigue. However, an increasing level of alkalosis had no additional benefit, suggesting that maximum contribution to buffering capacity had been achieved at the lower dose.

Keywords:

• Fatigue
• acidosis
• bicarbonate
• pH