What question did this study set out to answer?

To determine whether extreme endurance training alters muscle fiber profiles, mitochondrial content, and metabolic enzyme activities similarly between the arm and leg muscles of elite cross-country skiers.

August 2, 2018Frontiers in PhysiologyOpen Access

The Muscle Fiber Profiles, Mitochondrial Content, and Enzyme Activities of the Exceptionally Well-Trained Arm and Leg Muscles of Elite Cross-Country Skiers

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To determine whether extreme endurance training alters muscle fiber profiles, mitochondrial content, and metabolic enzyme activities similarly between the arm and leg muscles of elite cross-country skiers.
Analyzed muscle tissue from the upper and lower extremities of elite cross-country skiers.
Measured fiber capillarization, mitochondrial volume, myosin heavy chain (MHC) profiles, and metabolic enzyme activities including citrate synthase (CS) and 3-hydroxyacyl-CoA dehydrogenase (HAD).
Capillarization and mitochondrial volume in type 2 fibers were equal to or exceeded those in type 1 fibers, demonstrating a divergence between traditional fiber type classification and aerobic metabolic capacity.
Differences in HAD enzyme activity between arm and leg muscles persisted despite equivalent training status and MHC distribution, indicating intrinsic metabolic divergence between the upper and lower body.
Trained type 1 and type 2A muscle fibers displayed comparable aerobic capacities regardless of whether they originated from arm or leg musculature.

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Implication

Cross-sectional study uncovers limb-specific metabolic divergence in elite skiers, indicating that intense training elevates fast-twitch muscle aerobic capacity to match slow-twitch fibers.

Cite This Study

Ørtenblad et al. (2018) studied this question.

synapsesocial.com/papers/69ff73abef8139f8ff775e09 https://doi.org/10.3389/fphys.2018.01031

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Implication

Cross-sectional study uncovers limb-specific metabolic divergence in elite skiers, indicating that intense training elevates fast-twitch muscle aerobic capacity to match slow-twitch fibers.

The Muscle Fiber Profiles, Mitochondrial Content, and Enzyme Activities of the Exceptionally Well-Trained Arm and Leg Muscles of Elite Cross-Country Skiers

Key Points

Discussion

Implication

Cite This Study

The Muscle Fiber Profiles, Mitochondrial Content, and Enzyme Activities of the Exceptionally Well-Trained Arm and Leg Muscles of Elite Cross-Country Skiers

Key Points

Discussion

Implication

Cite This Study

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