Increase in Serum Ionized Calcium during Exercise

Abstract

1. Normal subjects showed an average increase in serum ionized calcium (Ca2+) concentration of 0·11 mmol/l in peripheral venous blood 10 min after onset of bicycle exercise at 70% of maximum aerobic capacity. The corresponding mean rise in serum total calcium concentration was 0·21 mmol/l. 2. The change in serum Ca2+ as result of acidification was studied in 20 normal subjects by carbon dioxide equilibration in vitro followed by measurement of serum Ca2+. The log serum Ca2+ was inversely proportional to serum pH. 3. The Δlog serum Ca2+/ΔpH in vitro was similar to the Δlog serum Caa+/ΔpH in vivo during exercise, this ratio, however, being somewhat greater during the first minute of exercise. 4. Serum Ca2+ returned to normal values about 20 min after stopping exercise as the pH returned to normal, but the fall immediately after stopping exercise was more pronounced than that due to the change in pH, as predicted from the studies in vitro. 5. Blood lactate concentration rose from 0·86 to 8·41 mmol/l after 10 min exercise, but the rise in blood lactate during exercise was slower than the rise in serum Ca2+. Also the fall during the recovery period was delayed compared with the fall in serum Ca2+. 6. It is suggested that the rise in serum Ca2+ during severe muscular exercise might be important for the physiological adaptations during work, and for bone metabolism.

Effect of NaCI and NaHCO3 on serum ionised calcium and blood gas status during sprinting

“…The current study examined a smaller number of horses, all of whom were clinically normal, but over a much wider range of blood pH. The inverse relationship between iCa and pH is similar to that observed in man during intense exercise (Nielsen et al 1977).…”

Adjusted calcium conflict resolved? Differing effects on plasma total calcium of changes in plasma albumin after venous stasis or myocardial infarction.

“…Finally, clenching the fist for as short a period as 1 minute during venous occlusion has been shown to cause an increase in lactate of 3 0-3 5 mmol/l and a decrease in venous pH to 7-10-7-15 (van Leeuwen et al, 1961), and intermittent fist-clenching once a second for 3 minutes during occlusion increases blood lactate by a mean of 4-5 mmol/l (Braybrooke et al, 1975). Direct measurement has shown that serum ionised calcium increases during exercise on a bicycle ergometer (Nielsen et al, 1977). Variation in forearm exercise, which causes hypoxia and dissociation of calcium bound to protein due to a fall in pH and to an increase in undissociated calcium lactate, might cause a variable decrease in the change of total calcium as albumin increases.…”

Acid:base and serum biochemistry changes in horses competing at a modified 1 Star 3‐day‐event

“…Ionised calcium concentrations of horses completing Phase D of the Endurance Test have previously been reported to be lower than values before the event (Geiser et al 1995). Serum ionised calcium concentrations of human individuals increase during exercise at 70% of maximal aerobic capacity, and the increase is related, at least in part, to a decrease in blood pH (Nielsen et al 1977). Three-day-event horses perform Phase D with heart rates approximately 75% of their estimated maximal heart rate .…”