2.8. Sample Size

A sample size estimation for the primary analysis (urine HCO₃⁻) indicated that approximately 6 participants for each group were needed to produce an 80% chance of obtaining statistical significance at the 0.05 level (G Power 3.1). This required sample size was calculated based on a previous study that a minimum significant change of urine HCO₃⁻ between sea level and high altitude >3000 m is ~5 mmol L⁻¹ [29]. Eight participants for each group completed the experimental protocol to account for potential missing data.