The exercising patient with phenylketonuria: Considerations and research recommendations

While exercise is widely recognised for its physical and psychological benefits, its integration into PKU management is underexplored. This manuscript reviews the interplay between exercise, metabolic control, and dietary management in PKU, addressing key considerations such as protein intake, energy availability, bone health, and nutritional timing. The manuscript highlights PKU challenges, including reliance on phenylalanine-free protein substitutes, altered energy metabolism, and psychosocial barriers. While speculative and yet to be explored, regular exercise, when supported by tailored dietary strategies, may mitigate risks such as poor bone health, obesity, and mental health challenges often associated with PKU. These knowledge gaps are important to close, and exploring topics such as substrate utilisation during exercise, effective recovery strategies, and the long-term impact of structured exercise on metabolic control and overall health. Practical recommendations include upskilling metabolic dietitians in sport and exercise nutrition, developing exercise-compatible protein substitutes, and integrating exercise guidance into PKU management plans. This manuscript calls for a multidisciplinary approach to improve support for exercising PKU patients, including dietitians, exercise physiologists (if accessible), performance nutritionists and metabolic specialists, especially in view of professional sport persons with PKU. It also identifies research priorities, such as understanding phenylalanine kinetics during exercise, optimising protein substitute formulations for recovery and learning the impact of novel treatments and nutrients and their potential role is supporting exercising patients. By addressing these gaps, healthcare practitioners, researchers, and industry stakeholders can better enable safe and effective exercise participation, enhancing the health and quality of life for individuals with PKU.