Effects of exercise and alkalosis on serum insulin-like growth factor I and IGF-binding protein-3

This investigation examines the effects of orally induced alkalosis on serum IGF-I and IGFBP3 concentrations in response to an acute 90-s bout of high intensity cycle exercise. Ten healthy, active men, ages 24.60 +/- 4.90 years, participated in a randomized, double-blind, counterbalanced trial order with a cross-over design. Subjects ingested an experimental bicarbonate solution or a placebo solution. Blood was sampled at baseline; pre-exercise; and 0, 5, 10, and 30 min postexercise. The pH between groups for pre-exercise and postexercise time points differed significantly (p < or = .05) in the experimental condition (from 7.42 +/- 0.01 to 7.35 +/- 0.02) versus the placebo condition (from 7.36 +/- 0.01 to 7.25 +/- 0.03). Increases in IGF-I over resting conditions occurred with placebo conditions at 5 and 10 min postexercise and in the experimental condition at 5 min postexercise. Concentrations of IGFBP3 were elevated above baseline at IP in both experimental and placebo conditions.