Intracellular pH and bicarbonate concentration in human muscle during recovery from exercise

Abstract

Eight subjects exercised on an ergometer until exhaustion. Femoral venous blood was analyzed for lactate, pyruvate, protein, electrolytes, and acid-base parameters. Muscle samples taken during the recovery period from m. quadriceps femoris were analyzed for water, electrolytes, lactate, and acid-labile CO2. Water content in the muscle biopsy sample was increased after exercise to 78.7 +/- 0.5% compared with the normal 76.7 +/- 0.8% at rest. The distribution of water between the extra- and intracellular space was calculated by the chloride method. In spite of elevated PCO2 in femoral venous blood the content of acid-labile CO2 was decreased in muscle after exercise. One minute after termination of exercise muscle CO2 was about half of the normal content at rest. During the recovery period muscle CO2 increased but was 20 min after termination of exercise still significantly below the value at rest. Intracellular pH (pHi) and bicarbonate concentration ([HCO3-]i) in muscle have been calculated. The validity of the assumptions underlying the calculations are thoroughly discussed. pHi decreased from the normal value at rest, 7.00 +/- 0.06 (mean +/- SD), to about 6.4 after exercise. [HCO3-] decreased from 10.2 +/- 1.2 mmol/l at rest to about 3 mmol/l after exercise. The changes are the greatest so far reported for an in vivo situation. After 20 min recovery pHi was almost the same as at rest, whereas bicarbonate was still well below.

Acid-base status of arterial and femoral-venous blood during and after intense cycle exercise

“…During exercise there was no respiratory compensation in femoral-venous blood but in fact a doubling of the pCO 2 near the end of the exercise and in the early recovery, thus adding a respiratory acidosis to the metabolic one. That observation is in line with that of Sahlin and coworkers [37]. Finally, the observed changes in plasma chloride concentration are in line with a recent study [3].…”

“…Venous blood may act as a closed compartment unable to reduce its pCO 2 and thereby buffer acids by bicarbonate. A raised pCO 2 will expectedly reduce the pH of venous blood considerably below that of arterial blood [16]; femoral-venous pCO 2 may double during strenuous exercise, reducing pH further by 0.2 below that of arterial blood [37].Further differences in the acid-base status between venous and arterial blood have apparently not been studied.…”

Lactic Acidosis as a Result of Iron Deficiency

“…This is not to say that severe acidosis created by lactate excess is without effect. Certainly there is ample evidence of its ability to impair cardiac function (24), to impair vasomotor regulation (28), and to impair the catabolism of lactate itself -in the liver (29). Our observation, however, differs from the usual descriptions of lactic acidosis in that it occurs in the face of increased physical activity, and focuses rather on striate muscle performance.…”

Effect of different recovery modalities on anaerobic power in off-road cyclists

“…The elevated metabolic rate during active recovery serves to promote lactate clearance via an accelerated rate of lactate oxidation [5,9]. The changes in lactate concrentation after exercises are parallel to the changes in pH values [4,24]. Despite the findings of Bogdanis et al [2] about nonsignificant correlation between intramuscular pH and peak power restoration there is certain support from literature that decline in maximal voluntary contraction correlate with muscular pH decrease and that recovery of power output during repeated sprint exercise is enhanced when low-intensity exercise is performed between sprints [3,8,13,25].…”