Age-related loss of skeletal muscle is characterised by a progressive and generalised loss of muscle mass, function and strength and is the main cause of disability and weakness in older people with reduced quality of life. The diagnosis of sarcopenia is difficult due to its multifactorial component. The identification of biomarkers through rapid, non-invasive and stress-free saliva sampling specifically related to skeletal muscle mass and strength could help in the early detection of sarcopenia and support the success of prevention. One hundred female and male volunteers with an average age of 64.0 ± 5.7 years were initially recruited for the study and took part in a physical training programme for one year. After six months half of them received a dietary supplement containing 100 mg/d of oleuropein from olive leaf extract, a bioactive compound with antioxidant properties. Sestrin 1, sestrin 2 and interleukin 6 were detected in the saliva of volunteers at baseline (T0), after 6 months (T6) and at the end of the study, after 12 months(T12), and muscle strength and functional capacity were recorded. The concentration of sestrin 1 decreased in women and men from T6 to T12 regardless of the intake of oleuropein, while sestrin 2 and, in men, interleukin 6 increased at T12 after the intake of oleuropein. Muscle functionality was also significantly improved in both sexes at T12. These preliminary results are promising and pave the way for further studies to assess muscle functionality, also in the context of natural product intake.
