Intramuscular short-chain acylcarnitines in elderly people are decreased in (pre-)frail females, but not in males

Hoek, Marjanne D. van der; Nieuwenhuizen, Arie G.; Kuda, Ondřej; Bos, Paul; Paluchová, Veronika; Verschuren, Lars; Hoek, Anita M. van den; Kleemann, Robert; Veeger, Nic J.G.M.; Leij, Feike R. van der; Keijer, Jaap


This study tested the hypothesis that in human aging, a decreased intramuscular acylcarnitine status is associated with (pre-)frailty, reduced physical performance, and altered mitochondrial function. We used a cross-sectional study design with well-matched fit and (pre-)frail old males and females, using young males and females as healthy controls. Frailty was assessed according to the Fried criteria and physical performance was determined by 400 m walk test, short physical performance battery and handgrip strength. Muscle and plasma acylcarnitine status, and muscle mitochondrial gene expression was analyzed. Results showed that intramuscular total carnitine levels and short-chain acylcarnitine levels were lower in (pre-)frail old females compared to fit old females and young females, whereas no differences were observed in males. The low intramuscular short-chain acylcarnitine levels in females correlated with low physical performance, even after correction for muscle mass (%), and were accompanied with lowered expression of genes involved in mitochondrial energy production and functionality. It is, therefore, concluded that in (pre-)frail old females, intramuscular total carnitine levels and short-chain acylcarnitine levels are decreased, and this decrease is associated with reduced physical performance and low expression of a wide range of genes critical for mitochondrial function. The results stress the importance of taking sex differences into account in aging research.