Acute potassium phosphate intake after exercise has no effect on subsequent exercise-induced performance time, substrate oxidation, and food intake in men

Background: Phosphorus availability during exercise is believed to positively affect adenosine triphosphate availability, increase glycogen synthesis, and enhance exercise performance. Aim: The aim of the present study was to examine the effect of potassium phosphate intake after exercise on physiological responses during subsequent running at anaerobic threshold and on appetite and food intake postexercise in men. Settings and Design: Nine moderately active young men (age, 22 ± 3 years; body mass index, 22.3 ± 3.0 kg/m2; and peak oxygen uptake (VO2peak) 48.5 ± 6.3 ml/kg/min) underwent two experimental conditions. Each condition consisted of two time-to-exhaustion treadmill running tests (time to exhaustion [TTE]) (bout 1 and 2), separated by 3 h recovery. During the recovery, either 500 mg phosphorus in the form of potassium phosphate or placebo was consumed with a glucose solution (1.2 g glucose/10 ml water × body weight) over 3 h. Methods: Expired gas was collected during the running. Appetite using visual analog scale and food intake from access to an ad libitum meal were measured after the second TTE run. Exercise intensity, VO2,and running speed were 67 ± 3% VO2peak, 32.3 ± 4.5 ml/kg/min, and at 10.1 ± 1.1 km/h, respectively. Statistical Analysis Used: Data were checked for normality, and Kolmogorov–Smirnov test was performed. Physiological variables, duration of exercise tests, and postexercise food intake and appetite sensations were analyzed using univariate ANOVA with interaction of exercise order and conditions. Results: There was no group effect in running time of the 2nd TTE although running time was reduced by ~ 5% in the placebo condition and by ~ 37% in the potassium phosphate condition in comparison to running time of the 1st TTE. A group × time interaction was present for the 1st exercise bout (P = 0.03). There were no interactions of condition (placebo and potassium phosphate) and running bouts (1st and 2nd) on respiratory exchange ratio, whole-body fat oxidation, and carbohydrate oxidation, but the interaction effect on VO2trended toward significance (F = 3.97, P = 0.06). There were no differences between conditions for appetite sensations and food intake. Conclusions: An acute dose of potassium phosphate after exercise did not affect subsequent exercise performance, exercise-induced substrate oxidation, and food intake. Potassium phosphate did not seem to affect metabolic responses and appetite in an ecological setting with repeated exercise and access to food during recovery.