Perspective Review: Advancing toward the diagnosis of sarcopenia in the pediatric population.

Sarcopenia is a muscle disorder characterized by the progressive loss of muscle mass and strength, leading to diminished physical performance. Although primarily associated with aging and chronic diseases, it is increasingly recognized in younger populations, particularly among those with chronic illnesses. Recent evidence suggests that muscle mass and strength deficits can manifest as early as childhood and adolescence, affecting three out of ten adolescents. Pediatric sarcopenia, while challenging to define due to the lack of standardized diagnostic criteria, presents significant health risks, including increased susceptibility to metabolic syndrome and chronic non-communicable diseases. Recent studies have attempted to establish normative values for muscle health in pediatric populations, yet many rely only on assessment of either muscle mass or strength, thus limiting the understanding of overall muscle health. In this context, the interaction between muscle mass, strength, and functionality, herein referred to as the muscle mass-strength-functionality triad (MSFt), is crucial for understanding the onset and progression of pediatric sarcopenia. The present review provides a perspective on concepts and operators defining pediatric sarcopenia and advocates for incorporating novel diagnostic criteria encompassing the MSFt. Furthermore, the importance of physical literacy and the acquisition of fundamental movement skills during childhood is highlighted, as these factors significantly influence long-term muscle health and physical activity levels. IMPACT: This perspective review provides an insightful view of muscle health in children and adolescents centered around the definition of pediatric sarcopenia. We discussed how to understand and describe sarcopenic-like deficits in pediatric populations. We propose the muscle mass-strength-functionality triad as an attribute that describes physical competence and is key to defining pediatric sarcopenia. We suggest the addition of physical literacy and movement competence assessment to the current diagnostic criteria of pediatric sarcopenia.