Serum Electrolyte, Fluid and Acid-Base Balance after Prolonged Heavy Exercise at Low Environmental Temperature

Abstract

To acquire a broad picture of the consequences of heavy muscular exercise of prolonged duration at low environmental temperature, 41 men, aged 33.2 years (21–54) were studied before and after a 90-km cross-country ski race, at 0 °C, with snow-fall and a contrary wind, with mean finishing time 8.09 hours. An estimate, based on the mean intake of fluid and sugar (2.37 and 0.29 kg), weight loss (1.93 kg), and other data on the metabolic cost of skiing, suggested a well-maintained free water balance. Serum creatinine, urea and phosphorus, whole blood lactate and β-hydroxy-butyric acid rose significantly (P < 0.001), whereas serum Mg and Ca, plasma HCO₃, and whole blood pH, P_CO2 and Hb fell significantly (P < 0.001), and serum Na, K, Cl, total cation, and protein remained unchanged (P > 0.05). With the exception that the pre-exercise serum creatinine and urea were higher in subjects above 35 years (mean 44.9) than in those below (mean 25.7) (P < 0.001), and the increase in serum creatinine was clearly higher in the older men (P < 0.005), there were no marked differences between the observations in the older and younger participants. It is concluded that strenuous exercise of long duration under the present circumstances led to remarkably small disturbances in fluid, electrolyte and acid-base balance, also in the relatively older subjects.

Key Words:

• Acid-base
• β-hydroxy-butyrate
• creatinine
• electrolytes
• exercise
• haptoglobin
• hemoglobin
• lactate
• serum
• temperature
• urea
• water