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Ultra-Endurance Athletes Push Energy Limits, Risk Muscle Breakdown

10/25/2025

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Summary

Story summary

A study published in Cell Biology found ultra-endurance athletes sustain energy expenditure at about 2.5x BMR.
They can temporarily exceed this limit, reaching up to seven times BMR during intense periods.
Prolonged expenditure beyond 2.5x BMR risks muscle breakdown.
The study tracked 14 athletes for one year using a new isotopic method to measure metabolic limits.

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Story summary

A study published in Cell Biology found ultra-endurance athletes sustain energy expenditure at about 2.5x BMR.
They can temporarily exceed this limit, reaching up to seven times BMR during intense periods.
Prolonged expenditure beyond 2.5x BMR risks muscle breakdown.
The study tracked 14 athletes for one year using a new isotopic method to measure metabolic limits.