Effects of sodium bicarbonate on cardiorespiratory measurements and exercise capacity in Thoroughbred horses

Abstract

Summary We examined the effects of sodium bicarbonate in 6 Thoroughbred horses during submaximal and maximal treadmill exercise. Cardiorespiratory function was assessed together with the effect on exercise capacity by determining the run time to fatigue at maximal intensities. To discriminate between sodium bicarbonate's alkalinising effects and the fluid shifts that could result from the high osmotic load, we administered an equimolar solution of sodium chloride as a control. The horses were given sodium bicarbonate (1 g/kg bwt) or an equivalent number of moles of sodium chloride by nasogastric tube. Arterial blood samples were collected before exercise and 5 h after treatment, resulting in mean standard bicarbonate values of 39.6 mmol/l in horses treated with sodium bicarbonate compared with 24.2 mmol/l in horses that received saline. The horses were exercised on a treadmill at 40, 60 and 80% of their VO2max for 4, 2 and 2 mins respectively. The horses were walked for 3 mins and accelerated rapidly to a speed approximately equivalent to 110% VO2max and run until fatigued. The horses ran for 170 ± 20 secs (mean ± sem) after administration of sodium bicarbonate compared with 128 ± 13 secs after receiving sodium chloride (P<0.02). At rest and throughout submaximal and maximal exercise, the bicarbonate‐treated horses had significantly lower arterial oxygen tensions and higher arterial carbon dioxide tensions. There were no differences in cardiac output, heart rate, oxygen uptake or carbon dioxide production between the saline and bicarbonate treatments. A second experiment was carried out in which the control group received no treatment. The horses that were given sodium bicarbonate ran for 142 ± 21 secs compared with 182 ± 24 secs for the controls (P=0.05). We conclude that metabolic alkalosis can affect ventilation during exercise and that sodium bicarbonate at an oral dose rate of 1 g/kg bwt significantly affects performance.

A Review of Recent Research on Nutrition and Metabolism in the Athletic Horse

“…Blood pH, [HCO,-], and standardized base excess (BE) were higher in NaHC0,-dosed horses at rest (Corn et al 1991;Greenhaff et al 1991;Jahn et al 1991;Roberts et al 1991;Hanson et al 1993;Lloyd et al 1993;Frey et al 1995). However, in a subsequent study using Miniature Horses Corn et al (1995) did not observe a significant increase in pH, HC0,-or BE 3 h after dosing with 400 mg/kg.…”

The effect of sodium bicarbonate and validation of beckman coulterAU680 analyzers for measuring total carbon dioxide (TCO2) concentrations in horse serum

“…Sodium bicarbonate given by nasogastric tube has been used by some trainers as the key ingredient in a ‘milkshake’ (Lloyd et al . ; Frey et al . ; Manohar et al .…”

“…Sodium bicarbonate given by nasogastric tube has been used by some trainers as the key ingredient in a 'milkshake' (Lloyd et al 1993;Frey et al 1995;Manohar et al 2004). It has been suggested that such treatment given 3-5 h prior to racing may enhance a horse's racing performance by increasing the blood buffering capacity and enhancing lactate clearance from skeletal muscle, thereby delaying the onset of fatigue (Sutton et al 2014).…”

Effect of sodium bicarbonate administration on metabolic responses to maximal exercise

“…However, results regarding the influence of sodium bicarbonate loading on performance, both in human athletes and in horses, are conflicting. Most studies on horses performing intensive track or treadmill exercise have failed to show any effect of sodium bicarbonate administration on performance (Kelso et al 1987;Lawrence et al 1990;Greenhaff et al 1991a;Harkins and Kamerling 1992;Lloyd et al 1993;Lloyd and Rose 1995). Two of these studies, however, indicated a tendency towards a shorter running time after intake of sodium bicarbonate (Kelso et al 1987;Lawrence et al 1990).…”