on June 23, 2026
Muscular autophagy
The process necessary to eliminate damaged muscle cells, which, if excessively activated, promotes atrophy.
What are the causes of sarcopenia
Sarcopenia is a multifactorial condition.
Biological aging
With age, the following are observed:
- reduction of anabolic hormones;
- reduced sensitivity to amino acids;
- reduced activity of muscle satellite cells;
- increased oxidative stress.
Between the ages of 40 and 70, muscle mass can decrease by an average of 8% per decade; over the age of 70, the rate of loss accelerates.
Immobilization and sedentary lifestyle
Even a few days of reduced physical activity can decrease protein synthesis and accelerate catabolism.
This phenomenon is particularly evident:
- after surgery;
- during hospital stays;
- after fractures;
- during long periods of convalescence.
Reduced protein intake
With age, the following decrease:
- appetite;
- perception of taste;
- digestive absorption.
This results in an insufficient intake of essential amino acids.
Chronic inflammation
Many chronic conditions promote a state known as inflammaging.
These include:
- obesity;
- diabetes;
- heart failure;
- neoplasms;
- respiratory diseases.
Inflammatory cytokines increase muscle catabolism.
How widespread is it
The prevalence varies depending on the diagnostic criteria used.
International estimates indicate:
- about 10–20% in older adults under 70;
- over 30–40% in very elderly people;
- higher prevalence in hospitalized and frail individuals.
With increasing life expectancy, sarcopenia represents one of the main challenges of preventive medicine.
Signs and symptoms: when to suspect it
Muscle mass loss is not always immediately visible.
The most frequent signs include:
- difficulty getting up from a chair;
- reduced walking speed;
- early fatigue;
- decreased grip strength;
- unintentional weight loss;
- instability and falls.
There may also be:
- reduced cold tolerance;
- reduced basal metabolism;
- poorer glycemic control;
- increased visceral adipose tissue.
Consequences of sarcopenia
Sarcopenia does not exclusively affect muscle.
Reduced autonomy
They worsen:
- walking;
- balance;
- the ability to perform daily activities.
Osteosarcopenia
Muscle loss is often associated with reduced bone density, increasing the risk of:
- osteoporosis;
- fractures;
- hospitalizations.
Increased metabolic risk
Reduced muscle mass worsens:
- insulin sensitivity;
- glucose utilization;
- cardiovascular health.
Worsening clinical prognosis
Numerous studies show associations with:
- longer hospital stays;
- increased complications;
- reduced survival.
How sarcopenia is assessed
The diagnosis integrates multiple elements.
Strength assessment
- hand dynamometry;
- chair stand test.
Muscle mass assessment
- DEXA;
- bioelectrical impedance analysis;
- CT or MRI in a specialist setting.
Physical performance
- walking speed;
- SPPB test;
- walking test.
Diet and sarcopenia: the central role of protein
Protein intake is one of the pillars of prevention.
Main food sources include:
- fish;
- eggs;
- meat;
- dairy;
- legumes;
- dairy products.
For older adults, many experts recommend a higher protein intake than for young adults, when clinically appropriate.
Particular attention is paid to essential amino acids and especially leucine, a powerful activator of protein synthesis.
Protein supplementation: the biological rationale
When diet and requirements are not adequately balanced, nutritional supplementation can be a supportive tool.
Numerous studies have shown that protein supplementation combined with exercise can promote:
- maintenance of lean mass;
- improvement of strength;
- functional recovery.
The effects appear greater when:
- total protein intake is insufficient;
- frailty is present;
- nutritional support is associated with physical activity.
Why vitamin D may be relevant
Traditionally known for bone metabolism, vitamin D also plays a role in the musculoskeletal system.
Vitamin D receptors are present in muscle cells.
Vitamin D contributes to:
- normal muscle function;
- regulation of intracellular calcium;
- control of muscle contraction;
- maintenance of balance.
Vitamin D deficiency has been associated with:
- muscle weakness;
- increased risk of falls;
- reduced physical performance.
Therefore, in selected individuals and following a professional assessment, nutritional support that also includes vitamin D can contribute to a more comprehensive strategy.
Physical activity: the treatment with the strongest evidence
Among all available interventions, physical exercise is the one with the strongest scientific support.
Particularly effective are:
- resistance exercises;
- balance exercises;
- progressive training;
- regular walking.
Physical activity directly stimulates protein synthesis by activating mTOR and improves insulin sensitivity and neuromuscular function.
Conclusions
Sarcopenia is not an inevitable part of aging but a condition that can be identified and addressed early.
Preserving lean mass means maintaining strength, autonomy, metabolism, and quality of life.
An integrated strategy based on adequate nutrition, proper protein intake, maintenance of nutritional status, regular physical activity, and vitamin D status assessment is today the most rational approach and supported by the evidence.
Bibliography
Cruz-Jentoft AJ et al. Sarcopenia: revised European consensus on definition and diagnosis (EWGSOP2). Age Ageing. 2019.
Cruz-Jentoft AJ, Sayer AA. Sarcopenia. Lancet. 2019.
Deutz NEP et al. Protein intake and exercise for optimal muscle function with aging. Clin Nutr. 2014.
Bauer J et al. Evidence-based recommendations for optimal dietary protein intake in older people. JAMDA. 2013.
Beaudart C et al. Health outcomes of sarcopenia. PLoS One. 2017.
Dent E et al. International Clinical Practice Guidelines for Sarcopenia. J Nutr Health Aging. 2018.
Houston DK et al. Dietary protein intake and lean mass change. Am J Clin Nutr. 2008.
Ceglia L. Vitamin D and skeletal muscle tissue. Mol Aspects Med. 2008.
Bischoff-Ferrari HA et al. Vitamin D and muscle function. BMJ. 2004.
Morley JE et al. Nutritional recommendations for sarcopenia. J Am Med Dir Assoc. 2010.
