Potassium kinetics and its relationship with ventilation during repeated bouts of exercise in women

The purpose of this study was to determine the electrolyte concentration changes in arterial plasma from high-intensity repeated bouts of cycling exercise in well-trained females and to determine the relationships between arterial plasma lactate, potassium (K⁺), bicarbonate (HCO₃^-), and pH with minute ventilation. Fourteen female subjects (mean age = 27 ± 4 years; mean height = 170 ± 7 cm; mean weight = 62 ± 7 kg; maximal oxygen uptake = 50 ± 6 ml/kg/min) were recruited to perform 3 × 5 min bouts of exercise at 236 ± 27 W with 10 min recovery between each set. Minute ventilation, arterial plasma lactate, potassium, calcium, chloride, and sodium ion concentrations were measured a minute 0, 1, 2, 3, 4, 5 of each set and midway through recovery (21 sampling points total per subject). The results showed that the strongest relationship was between arterial plasma K⁺ concentration and minute ventilation (r² = 0.91), and, that arterial plasma lactate mirrored both arterial plasma HCO₃^- and pH. In conclusion, this study demonstrates that women exhibit similar electrolyte responses as reported elsewhere in men, and support the idea that K⁺ may partly contribute to controlling ventilation during high-intensity exercise and recovery.