Carnitine status in fit and pre-frail/frail elderly compared to healthy young individuals

Ageing is associated with increasing physical disabilities and prevalence of frailty, which negatively affects quality of life. In addition, ageing is also associated with a decrease in intramuscular carnitine levels. Simultaneously, intramuscular mitochondrial content and function decline. There are three studies describing the decline in intramuscular carnitine levels during ageing, but none of these studies did measure if
frailty status is associated with the degree of decline in carnitine status and mitochondrial function. In this study we are going to test the hypothesize that declined intramuscular carnitine levels are associated to declined mitochondrial function and, subsequently, to the frailty score.
Therefore the main objective is to compare the intramuscular carnitine status of prefrail/
frail elderly with fit elderly and young individuals. The secondary objectives are; 1)
determine if intramuscular carnitine status is associated with carnitine levels in PBMCs;
2) compare lean mass, physical function, muscle function/strength, cognitive function
and mitochondrial function in skeletal muscle and PBMCs between fit and pre-frail/frail
elderly, by using the healthy young individuals as a reference group.

We hypothesize that declined intramuscular carnitine levels are associated to declined
mitochondrial function and, subsequently, to the frailty score. We suspect that prefrail/
frail elderly will have the lowest intramuscular carnitine levels and mitochondrial
function compared to the fit elderly and healthy young individuals, whereas fit elderly will have higher intramuscular carnitine status and mitochondrial function compared to pre-frail/
frail elderly, but lower compared to healthy young individuals.

All parameters will be measured within two weeks.

A blood sample and muscle biopsy. In addition, participants will perform several physical and cognitive tests and fill in questionnaires.