Trained athletes performing repeated sprints show a measurable reduction in performance when following low-carbohydrate or ketogenic diets, linked to lower muscle glycogen levels that limit ATP...
Mechanism
Synthesis from 1 study
When muscle sugar runs low, the body can't make enough quick energy for repeated all-out efforts, and the signals that trigger strong muscle contractions weaken. This combination causes performance to drop during repeated sprints, even though single sprints may still be powerful.
Most probable mechanism
When muscle sugar stores run low, the body cannot make enough quick energy for repeated all-out efforts, and the signals that tell muscles to contract strongly become less effective, causing performance to drop.
Dietary carbohydrate restriction reduces plasma glucose and insulin, suppressing glycogen synthesis and promoting continuous glycogen breakdown during training.
Intramuscular glycogen stores decline in inter- and intra-myofibrillar compartments of fast-twitch muscle fibers, limiting substrate availability for anaerobic glycolysis.
Reduced glycogen availability limits phosphofructokinase and pyruvate kinase activity, attenuating glycolytic flux and decreasing ATP production rate during high-intensity efforts.
Diminished glycolytic ATP production fails to meet the energy demands of repeated maximal contractions, reducing mean power output and sprint speed.
Low glycogen in subcellular compartments reduces calcium release from the sarcoplasmic reticulum during action potential propagation, impairing cross-bridge cycling and force generation.
Reduced pyruvate production from glycolysis decreases lactate dehydrogenase activity, lowering lactate accumulation during high-intensity exercise.
Less supported by current evidence, but not ruled out
After prolonged low-carb adaptation, the body becomes better at using fat for energy during rest periods between sprints, helping restore the quick-energy system used for each sprint.
Chronic carbohydrate restriction upregulates mitochondrial fat oxidation enzymes and increases mitochondrial density.
Enhanced fat oxidation increases ATP production via oxidative phosphorylation during recovery phases between high-intensity efforts.
Increased ATP from fat oxidation accelerates phosphocreatine resynthesis via creatine kinase, restoring phosphagen capacity for subsequent maximal efforts.
Evidence from Studies
Supporting (1)
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Effects of Low-Carbohydrate and Ketogenic Diets on Anaerobic Performance in Competitive Athletes: A Systematic Review and Meta-Analysis
Contradicting (0)
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