In muscle cells upon heavy exertion, oxygen can be lacking and aerobic metabolism leads to conversion of [Select) to [Select] The importance of this reaction to continued glycolysis in muscle is evidenced by the effects on the exercise capacity of individuals with (Select) deficiency. This reaction is vital to regenerate [Select] required for [ Select] a critical enzyme in glycolysis. [ Select] aldolase glyceraldehyde-3-phosphate dehydrogenase