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Pro‐ and macroglycogenolysis in skeletal muscle during maximal treadmill exercise
Author(s) -
BRÖJER J.,
JONASSON R.,
SCHUBACK K.,
ESSÉNGUSTAVSSON B.
Publication year - 2002
Publication title -
equine veterinary journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.82
H-Index - 87
eISSN - 2042-3306
pISSN - 0425-1644
DOI - 10.1111/j.2042-3306.2002.tb05419.x
Subject(s) - anaerobic exercise , glycogenolysis , medicine , creatine , glycogen , skeletal muscle , endocrinology , treadmill , physical exercise , chemistry , physical therapy
Summary The purpose was to investigate the degradation of proglycogen and macroglycogen in skeletal muscle during intense exercise. Ten Standardbred trotters performed a maximal treadmill exercise test comprising a warm‐up period, an exercise period, starting at 7 m/s with increments of 1 m/s every 60 s until the onset of fatigue (mean ± s.d. 246 ± 32 s) and a walking recovery period. Muscle biopsies were taken at rest, immediately after exercise and 15 min postexercise. The exercise caused a marked anaerobic metabolism as shown by the decrease in both muscle ATP and creatine phosphate and increase in muscle lactate. Free muscle glucose increased immediately postexercise and a further increase was noted 15 min later. There was a significant decrease (P<0.05) in proglycogen (57.1 ± 22.2 mmol/kg dw) and macroglycogen (63.0 ± 65.5 mmol/kg dw) during exercise. The proglycogen concentration tended to increase 15 min after exercise (19.9 ± 27.3 mmol/kg dw; P= 0.06). The results from this study demonstrate that both proglycogen and macroglycogen contribute equally to glycogenolysis during intense exercise and suggest that glycogen resynthesis starts in the proglycogen pool.