Longevity & AgingAging Muscles Preserve Mitochondrial Efficiency Despite Structural Remodeling
Researchers at UC Berkeley studied young (4-month) and older (24-month) C57BL/6JN mice to determine how aging affects the skeletal muscle mitochondrial reticulum. They found that mitochondrial coupling efficiency (ADP:O ratio) was fully preserved in older animals, challenging the narrative of widespread mitochondrial dysfunction in healthy aging. However, older mice showed reduced respiratory control ratios, lower expression of proteins involved in substrate uptake and fatty acid oxidation, significant muscle mass loss, and measurable changes in mitochondrial network architecture. Mitochondrial content per milligram of muscle tissue remained unchanged, but total mitochondrial mass fell due to sarcopenia. The findings suggest that performance declines in aging are driven primarily by muscle wasting and cardiovascular changes rather than intrinsic mitochondrial dysfunction.
