title: Influence of muscle glycogen depletion on the rate of resynthesis.
abstract: In an effort to determine what effect the degree of muscle glycogen depletion has on the rate of resynthesis, six male cyclists completed an exercise protocol that involved both one- and two-legged cycling. One leg completed 30 min of single-leg cycling, ten one-min sprints, and 30 min cycling with both legs. This resulted in a large degree of depletion (LD). The contralateral leg completed only 30 min of double-leg cycling and experienced a small amount of depletion (SD). Following the exercise, the subjects rested quietly for 6 h and were fed a 24% carbohydrate (CHO) solution every 20 min in order to achieve a CHO intake of 0.7 g.kg-1.h-1. Biopsies taken from the vastus lateralis muscle immediately after exercise revealed that the glycogen content of the LD leg decreased 93.9 (+/- 11.6) mmol.kg-1 w.w., whereas the SD leg used 49.3 (+/- 5.7) mmol.kg-1 w.w. (P less than 0.01). Subsequent biopsies taken at 2 and 6 h of recovery demonstrated that the rate of muscle glycogen resynthesis was significantly greater in the LD leg, averaging 8.8 (+/- 2.4) mmol.kg-1.h1 w.w, while the SD leg restored glycogen at a rate of 3.0 (+/- 1.0) mmol.kg-1.h-1 w.w. (P less than 0.05). Glycogen synthase activity, expressed as its activity ratio (I/D), was also greater (P less than 0.01) in the LD leg both immediately after exercise (0.45 +/- 0.05 vs 0.24 +/- 0.04) and at 2 h of recovery (0.54 +/- 0.06 vs 0.27 +/- 0.06).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Human Performance Laboratory, Ball State University, Muncie, IN 47306.
authors.forename: J J
authors.initials: JJ
authors.lastname: Zachwieja
authors.forename: D L
authors.initials: DL
authors.lastname: Costill
authors.forename: D D
authors.initials: DD
authors.lastname: Pascoe
authors.forename: R A
authors.initials: RA
authors.lastname: Robergs
authors.forename: W J
authors.initials: WJ
authors.lastname: Fink
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D001786:Blood Glucose / Q000378:metabolism; D015444:Exercise / Q000502:physiology*; D006006:Glycogen Synthase / Q000096:biosynthesis* / Q000378:metabolism; D006801:Humans; D007773:Lactates / Q000097:blood; D019344:Lactic Acid; D007866:Leg; D008297:Male; D009132:Muscles / Q000378:metabolism*; D010766:Phosphorylation
chemical_list: D001786:Blood Glucose; D007773:Lactates; D019344:Lactic Acid; D006006:Glycogen Synthase