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Muscle glycogen use in different muscle fiber types and locations during repeated intense bursts of exercise
Updated
Abstract
A higher glycogen breakdown rate in type 2 fibres compared to type 1 fibres was observed during high-intensity exercise.
- Utilisation of muscle glycogen varies by fibre type, with type 2 fibres showing greater breakdown in specific subcellular fractions during initial exercise.
- Intra and fractions exhibited significant depletion in type 2 fibres during the first exercise period.
- By the second and third exercise periods, glycogen utilisation in type 2 fibres decreased, leading to low glycogen levels across all subcellular fractions.
- Large variability in glycogen utilisation was noted at the single-fibre level, particularly with early depletion of Intra glycogen in type 2 fibres.
- These findings highlight the complexity of glycogen metabolism in muscle cells, showing localisation-specific and time-dependent differences during high-intensity exercise.
Simplified
Key numbers
490 ± 94 mmol kgDW to 76 ± 60 mmol kgDW
Whole-muscle glycogen content reduction
Measured pre-exercise and after exercise periods.
-59% (−72, −40%)
Type 2 fiber IMF glycogen utilization during EX1
Comparison of glycogen breakdown rates in type 2 vs. type 1 fibers.
-35% (−55, −5%)
Type 1 fiber IMF glycogen utilization during EX1
Comparison of glycogen breakdown rates in type 1 vs. type 2 fibers.