The aim of this study was to examine the effect of short-term protein supplementation (aiming to consume 1.2 g protein/kg body weight per day) combined with moderate resistance training on 3 days of the week on tryptophan-kynurenine metabolism in 40 older patients with hip fracture. Secondary outcomes for physical recovery were hand-grip strength and chair-rise score. Older patients with hip fracture exhibited higher degrees of immune activation, detected by increased neopterin and kynurenine to tryptophan levels compared with reference values for healthy elderly with no significant differences between those who received the exercise-protein intervention compared to the control. Increasing dietary protein intake during hospitalization did not alleviate the Th1-type immune response in the elderly patient. On the other hand, muscularity per se may affect immune activation responses following injury, as improvements in maximum hand-grip strength with the intervention were related to decreases in neopterin levels.
Keywords: Aging; Dietary protein; Exercise; Muscle disuse; Tryptophan–kynurenine metabolism.