HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS		QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Free Full Text (PDF) Free All Versions of this Article: 103/5/1604    most recent 00309.2007v1 Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via Google Scholar Google Scholar Articles by Henderson, G. C. Articles by Brooks, G. A. Search for Related Content PubMed PubMed Citation Articles by Henderson, G. C. Articles by Brooks, G. A.

Retention of intravenously infused [¹³C]bicarbonate is transiently increased during recovery from hard exercise

Exercise Physiology Laboratory, Department of Integrative Biology, University of California, Berkeley, California

Submitted 19 March 2007 ; accepted in final form 13 August 2007

The effects of exercise on energy substrate metabolism persist into the postexercise recovery period. We sought to derive bicarbonate retention factors (k) to correct for carbon tracer oxidized, but retained from pulmonary excretion before, during, and after exercise. Ten men and nine women received a primed-continuous infusion of [¹³C]bicarbonate (sodium salt) under three different conditions: 1) before, during, and 3 h after 90 min of exercise at 45% peak oxygen consumption (O_2peak); 2) before, during, and 3 h after 60 min of exercise at 65% O_2peak; and 3) during a time-matched resting control trial, with breath samples collected for determination of ¹³CO₂ excretion rates. Throughout the resting control trial, k was stable and averaged 0.83 in men and women. During exercise, average k in men was 0.93 at 45% O_2peak and 0.94 at 65% O_2peak, and in women k was 0.91 at 45% O_2peak and 0.92 at 65% O_2peak, with no significant differences between intensities or sexes. After exercise at 45% O_2peak, k returned rapidly to control values in men and women, but following exercise at 65% O_2peak, k was significantly less than control at 30 and 60 min postexercise in men (0.74 and 0.72, respectively, P < 0.05) and women (0.75 and 0.76, respectively, P < 0.05) with no significant postexercise differences between men and women. We conclude that bicarbonate/CO₂ retention is transiently increased in men and women for the first hour of postexercise recovery following endurance exercise bouts of hard but not moderate intensity.

prior exercise; postexercise; exertion; physical activity; NaHCO₃; correction factor; glucose oxidation; fatty acid oxidation; leucine oxidation