AEROBİK VE DİRENÇ EGZERSİZLERİ UYGULANAN KLASİK FENİLKETONÜRİ HASTALARINDA EGZERSİZ ÖNCESİ VERİLEN FARKLI ÖĞÜN TÜRLERİNİN PLAZMA AMİNO ASİT DÜZEYLERİ VE METABOLİK KONTROL PARAMETRELERİ ÜZERİNE ETKİSİ

Abstract

Kalkan D. Effect of Different Meal Types Given Before Exercise on Plasma Amino Acid Levels and Metabolic Control Parameters in Classical Phenylketonuria Patients Undergoing Aerobic and Resistance Exercises. Hacettepe University, Graduate School of Health Sciences, Program of Nutrition and Dietetics, PhD Thesis, Ankara, 2026. In this single-center, randomised cross-over designed study, the nutritional status and physical activity levels of adult phenylketonuria (PKU) patients were evaluated in the first phase, and 10 adult classic PKU patients (50% male, 50% female) with a mean age of 27.7±5.0 years who agreed to participate in the intervention study were included. 10 adult classic PKU patients (50% male, 50% female) with an average age of 27.7±5.0 years were included. Patients received three different test meals (water, carbohydrate, and carbohydrate+protein) before aerobic and resistance exercises, and these meals were evaluated in a randomised crossover design to assess their acute effects on plasma amino acid levels (phenylalanine, tyrosine, branched-chain amino acids) as well as serum glucose, insulin, blood urea nitrogen (BUN), and creatinine levels. Each participant performed aerobic and resistance exercises on a total of six different days with three different test meals, with a seven-day wash-out period between the sessions. The test meals were given 10 minutes before the exercise. Plasma amino acid levels, as well as serum glucose, insulin, BUN, and creatinine levels, were evaluated before the standard breakfast (-120 min), at the 0th minute of exercise, and at 30, 60, 90, and 120 minutes post-exercise. The test meals administered before exercise significantly affected the time-dependent changes of some amino acids. It was determined that the levels of tyrosine and branched-chain amino acids were higher after the meal containing carbohydrates and protein, while plasma phenylalanine levels were not affected by the type of meal, type of exercise, or their interactions (p>0.05). While serum glucose and insulin levels varied depending on the meal content, exercise-related physiological changes were observed in BUN and creatinine levels. However, the type of exercise (aerobic or resistance) did not have an independent significant effect on plasma amino acid levels and metabolic control parameters (p>0.05). While the changes observed in the biochemical parameters evaluated in the study largely occurred over time, significant differences related to meal type were determined in some amino acids. In conclusion, short-term moderate-intensity aerobic and resistance exercises did not negatively affect metabolic control in patients with classic phenylketonuria. The combined application of carbohydrates and a phenylalanine-free amino acid mixture before exercise contributed to the preservation of certain amino acid responses without causing an increase in phenylalanine levels. These findings suggest that in planning pre-exercise nutrition strategies for individuals with phenylketonuria, the composition of the meal may be more decisive than the type of exercise.