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 l 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 regimens 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 less than 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 less than 0.05). The time to fatigue in the six bout was also significantly increased; I, 74.7 s; II, 111.0 s; III, 106.0 p (P less than 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.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of Sodium Bicarbonate Ingestion on Anaerobic Performance: A Meta-Analytic Review

“…McKenzie et al (46) confused the issues with a 1986 study using an interval protocol similar to those of Wijnen et al (65) and Costill et al (7). They compared dosages of 150 and 300 mgfkg and, like the others, found incremental increases in resting blood pH and HC03-levels, but unexpectedly found that the lower dosage actually resulted in slightly superior performance enhancement (49% vs. 42%).…”

“…Most of the performance outcomes (17 of 35) looked at time to exhaustion, that is, the duration that exercise at a specific intensity could be sustained. These studies ranged from a single trial at 80% V0,max lasting 30 minutes (12), to near maximal intensities (90-95% V02max) of 5 to 7 minutes following 20 to 40 minutes of submaximal (3346% V0,max) work (27,53,62,63), to single trials at 100% V0,max (25,35,37), to single trials at 125% V0,max (3,4,28), to interval protocols consisting of four to five 1-min trials followed by a trial to exhaustion, all at 125% V0,max (7,46,65). Eight studies measured changes in power over a given time period, three of which were Wingate tests of 30 seconds (24,44,48), one a 10-s interval protocol (33), another a single 2-min trial (30), and two measured the power over a trial to exhaustion after four l-min intervals (65).…”

“…The type of protocol employed plays a role in the extent of anaerobiosis achieved. Studies that employed interval protocols with the final bout carried to exhaustion (7,11,33,46,65) showed the greatest increase in blood lactate levels, with a mean increase of 14.3 mmolpiter. They were also associated with larger decreases in blood pH (mean decrease = 0.27) and HCO3-(mean decrease = 15.4 mmol/L,).…”

“…While this result supported Costill's hypothesis that a lower dose was sufficient when intracellular acidosis was increased by interval work, it contradicted the dose response relationship. McKenzie et al (46) hypothesized that there may be a threshold of increase in extracellular pH above which there would be no additional benefit. This hypothesis was not supported by our meta-analytic data.…”

“…Some ingestions took place all at once (3,4,7,11,21,24,28,30,35,37,46,48,51) while others occurred over 15 to 30 minutes (53,65), over an hour (12,15,33), 2 hours (5,25,29,66), or even 3 hours (27, 31,44,53,62,63). But even at the same dosage and ingestion criteria there was considerable variability in the degree of induced alkalosis achieved.…”