A new scientific investigation from Italy sheds light on why skeletal muscles begin to decline far earlier than many people realise. Published in Nature Communications, the study suggests that ageing muscles are affected long before any visible loss of strength occurs, and that the origins lie deep within the delicate communication between two essential cellular organelles: peroxisomes and mitochondria.
Ageing Muscles Begin to Weaken from Within
Muscle tissue is far more than a structure for movement; it forms one of the body’s largest metabolic systems. According to the Italian research team, deterioration begins at a microscopic level, long before physical impairment becomes noticeable. Within muscle cells, peroxisomes and mitochondria cooperate to manage energy, break down lipids and control oxidative stress.
The study, conducted by scientists at the University of Padua and the Venetian Institute of Molecular Medicine (VIMM), reveals that the progressive loss of peroxisomes may act as a driver—rather than simply a marker—of muscular ageing.
Peroxisomes Decline with Age — and the Consequences Are Profound
The Italian researchers observed that healthy ageing is accompanied by a gradual reduction in the number of peroxisomes present in muscle tissue. For years, this phenomenon was assumed to be an incidental consequence of ageing. However, the group led by Dr Vanina Romanello has demonstrated that this decline may play an active role in accelerating muscular degeneration.
To distinguish cause from effect, the team engineered a highly specific mouse model in which the gene responsible for an essential peroxisomal transport protein—Pex5—was deleted exclusively in muscle cells. This protein functions like a “biological checkpoint”, allowing other proteins to enter peroxisomes and initiate key metabolic processes. When this gateway is disrupted, peroxisomes lose their functional capacity, becoming unable to regulate lipid metabolism or neutralise reactive oxygen species.
The animals lacking Pex5 developed early manifestations of accelerated muscular ageing, including increased oxidative stress, damaged cellular structures and altered fat processing. These alterations closely mirrored changes typically seen in naturally ageing mice, reinforcing the idea that peroxisomal decline contributes directly to the weakening of muscle tissue.
A Critical Link Between Peroxisomes and Mitochondria
One of the most important findings from the Italian study concerns the interdependence between peroxisomes and mitochondria. The deterioration of peroxisomes led to predictable mitochondrial abnormalities: structural damage, reduced numbers and diminished efficiency.
As a result, muscles showed early signs of energy shortfall, increased vulnerability to stress and progressive decline. In the affected mice, the researchers noted reduced strength, impaired neuromuscular junctions and signs of atrophy — features normally associated with much later stages of muscular ageing.
This work challenges long-standing assumptions that mitochondrial dysfunction alone is responsible for age-related muscular decline. Instead, the study highlights a far more intricate biological partnership, in which the health of peroxisomes is vital to maintaining mitochondrial stability and, ultimately, muscular longevity.
Implications for Understanding Sarcopenia
Although the findings are preliminary and based largely on animal models, they have clear relevance for the study of sarcopenia, a major contributor to loss of independence and reduced quality of life in older adults.
Understanding the molecular link between peroxisomes and mitochondria may open new scientific avenues aimed at preserving muscular function throughout life. Strategies that support metabolic health — such as controlling lipid disorders, preventing diabetes and managing body weight — may help to reduce the cellular stress that accelerates organelle decline.
Potential Pathways for Future Prevention
While the research does not yet translate into clinical treatments, it offers promising insights into how lifestyle factors might influence the cellular processes of ageing.
Regular physical activity, particularly strength-based exercise, is already known to improve mitochondrial performance. The Italian study suggests that these benefits might also extend to peroxisomes, potentially helping to maintain their number and function. This raises the possibility that established recommendations for muscular health—such as resistance training—may have a deeper molecular impact than previously understood.
A New Perspective on Healthy Ageing
The researchers emphasise that muscular strength is not dictated solely by visible mass or performance but by a finely balanced network of interactions within the cell. The decline of peroxisomes emerges as a previously overlooked factor that may shape the trajectory of muscular ageing long before symptoms appear.
By identifying the fragile collaboration between peroxisomes and mitochondria as a central determinant of muscular resilience, the study from Italy offers a renewed framework for understanding how muscles age — and how their decline might one day be slowed to preserve independence and quality of life in later years.