Intradialytic protein ingestion and exercise study

Chronic hemodialysis patients suffer from poor physical functioning due to progressive loss of skeletal muscle mass and function. Few studies in chronic hemodialysis patients suggest that oral protein ingestion during hemodialysis is able to prevent this decline and associated muscle protein breakdown. However, the amount of protein required to achieve this effect (±60 g) is not feasible for clinical practice. Nonetheless, a feasible amount of protein combined with an additional anabolic stimulus, such as exercise, might be able to prevent the hemodialysis-induced decline in plasma amino acid concentrations. In healthy adults, exercise before protein ingestion enhances the net protein balance of skeletal muscle and improves postprandial glycemia. However, the effect of intradialytic exercise on plasma and dialysate amino acid concentrations throughout hemodialysis is unclear. In addition, it is not known if this effect differs between fed and fasted patients. Knowledge about the acute metabolic response after protein ingestion and exercise during hemodialysis is important for the development of intradialytic anabolic strategies in chronic hemodialysis patients. Therefore, the present study assess the effects of intradialytic exercise and protein ingestion on amino acid loss into the dialysate and plasma total amino acid concentrations.

- Intradialytic protein ingestion increases plasma total amino acid concentrations throughout hemodialysis compared to placebo.

- Intradialytic exercise increases amino acid loss into the dialysate in fasted patients and decreases amino acid loss when performed before protein ingestion.

Following initiation of the hemodialysis session, arterial plasma samples will be obtained with 30-min intervals during a 4-h period for analysis of plasma amino acid, glucose, and insulin concentrations. In addition, spent dialysate will be collected and glucose monitoring will be applied continuously throughout the hemodialysis session.

During four hemodialysis sessions, patients will (A) ingest a placebo drink, (B) ingest a placebo drink and perform aerobic exercise, (C) ingest a protein supplement, and (D) ingest a protein supplement and perform aerobic exercise.