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Glycogen depletion patterns in the muscle of Standardbred Trotters after exercise of varying intensities and durations
Author(s) -
VALBERG STEPHANIE
Publication year - 1986
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.2042-3306.1986.tb03697.x
Subject(s) - glycogen , horse , medicine , endocrinology , cardiology , biology , paleontology
Summary The glycogen depletion patterns in the gluteus muscle of Standardbred horses were studied under different trotting intensities. After racing significant glycogen depletion was found in all Type I and IIA fibres and in a varying percentage of Type IIB fibres, depending on the individual horse. When horses performed exercise over a short distance (5 to 8 km) at three different speeds, glycogen depletion was difficult to detect for the faster speeds (10 and 8 m/sec) but notably involved a major proportion of Type I fibres at the slowest speed (6 m/sec). When exercise was prolonged over a greater distance a larger proportion of Type IIA fibres were depleted at faster speeds (8 m/sec) than at slower speeds over the same distance. However, when slow trotting was continued over even greater distances, a gradual increase in the percentage of glycogen‐depleted Type IIA fibres was noticed. Very significant glycogen depletion in all three fibre types was seen in all horses where a near maximal exercise tolerance test was performed 3 h after the longest and slowest exercise run. In a further study of glycogen depletion, during a near maximal exercise tolerance test on a graded treadmill with consecutively increasing velocity, depletion was seen in a proportion of all three fibre types with the highest proportion being Type I and the lowest Type IIB.