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

Joachim Nielsen*, Rasmus Jensen, Niels Ørtenblad

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review

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Abstract

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.
Original languageEnglish
Article numbere14571
JournalScandinavian Journal of Medicine & Science in Sports
Volume34
Issue number2
Number of pages6
ISSN0905-7188
DOIs
Publication statusPublished - Feb 2024

Bibliographical note

Publisher Copyright:
© 2024 The Authors. Scandinavian Journal of Medicine & Science In Sports published by John Wiley & Sons Ltd.

Keywords

  • exercise
  • fatigue
  • glycogen
  • mitochondria
  • muscle fiber
  • transmission electron microscopy

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