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Assessments of individual fiber glycogen and mitochondrial volume percentages reveal a graded reduction in muscle oxidative power during prolonged exhaustive exercise.

Joachim NielsenRasmus JensenNiels Ørtenblad
Published in: Scandinavian journal of medicine & science in sports (2024)
During submaximal exercise, there is a heterogeneous recruitment of skeletal muscle fibers, with an ensuing heterogeneous depletion of muscle glycogen both within and between fiber types. Here, we show that the mean (95% CI) mitochondrial volume as a percentage of fiber volume of non-glycogen-depleted fibers was 2 (-10:6), 5 (-21:11), and 12 (-21:-2)% lower than all the sampled fibers after continuing exercise for 1, 2 h, and until task failure, respectively. Therefore, a glycogen-dependent fatigue of individual fibers during submaximal exercise may reduce the muscular oxidative power. These findings suggest a relationship between glycogen and mitochondrial content in individual muscle fibers, which is important for understanding fatigue during prolonged exercise.
Keyphrases
  • skeletal muscle
  • high intensity
  • resistance training
  • physical activity
  • oxidative stress
  • insulin resistance
  • type diabetes
  • sleep quality
  • metabolic syndrome
  • body composition
  • dna methylation
  • genome wide
  • single cell