Moderate Intensity Exercise and Phenylketonuria

The Effects of an Acute Bout of Moderate Intensity Exercise on Plasma Amino Acids in Subjects With Phenylketonuria

Phenylketonuria (PKU), an inherited genetic disorder, can cause irreversible brain damage, declined executive function, and autistic tendencies unless a phenylalanine (Phe) restricted diet is consistently maintained throughout life. Promoting anabolism, the uptake of free amino acids from the extracellular space, is a key component to maintaining plasma phenylalanine concentrations within treatment range among patients with PKU. Exercise promotes muscle protein synthesis and anabolism, but the effect on blood phenylalanine concentrations in patients with PKU has not been reported.

Our objective is to assess the impact of an acute bout of moderate intensity exercise on protein oxidation and plasma amino acid concentrations, as a potential adjunctive therapy for patients with PKU.

The investigators hypothesize that moderate intensity exercise decreases amino acid oxidation, increases muscle protein synthesis, and promotes tissue uptake of essential amino acids, thereby lowering plasma phenylalanine concentrations in patients with Phenylketonuria.

Study Overview

• Status: Terminated
• Conditions: Phenylketonuria; PKU
• Intervention / Treatment: Other: Acute Moderate Intensity Exercise

Detailed Description

The indicator amino acid oxidation technique utilizes a carbon labeled isotope (L-[13C]) tracer that is ingested orally and is measured in expired breath. This method is based on the theory that if one essential amino acid is deficient, all other amino acids will be oxidized until a break-point is reached and at that time all amino acids will be incorporated into muscle protein synthesis. Using a randomized crossover design the investigators plan to investigate the effects of an acute bout of moderate intensity treadmill exercise versus sedentary activities on plasma amino acids in four subjects with PKU. The long-term goal of this novel research is to determine if exercise could be used as an adjunctive therapy to improve the management of plasma phenylalanine levels and promote a normal, healthy quality of life among patients with PKU.

Patient Recruitment: Four post-pubertal participants ranging from 14-17 years of age with classical phenylketonuria (PKU), treated at Oregon Health & Science University, will participate in this pilot study. Participants will be recruited during their routine clinic visit at Doernbecher Children's Hospital Metabolic clinic.

Study Design: This randomized crossover clinical trial will compare the effects of moderate intensity exercise and sedentary activities on amino acid oxidation and plasma amino acid pools using the indicator amino acid oxidation technique. Each participant will be studied on two separate occasions over a one-month period.

• Study Type: Interventional
• Enrollment (Actual): 2
• Phase: Not Applicable

Contacts and Locations

Study Locations

• United States
  • Oregon
    • Portland, Oregon, United States, 97239
      • Oregon Health and Science University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 14 years to 17 years (Child)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: Male

Description

Inclusion Criteria:

• plasma phenylalanine concentration of >1200 micromols at diagnosis
• treated by dietary phenylalanine restriction from early infancy
• willing to participate in this study
• stable BMI of 20-25 for the past 3 months
• currently in average to good physical fitness condition
• physically active 3-4 days per week

Exclusion Criteria:

• previously or are currently taking approved or experimental pharmacologic treatments (i.e.: Biopterin (BH4), sapropterin dihydrochloride (Kuvan), Large Neutral Amino Acids (LNAA), pegylated phenylalanine ammonia lyase (PEG-PAL))
• recent history of weight loss
• endocrine disorder
• pregnant
• anemic
• involved in any other study or research protocol
• participation in a current strength training or performance training regimen

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Sedentary Visit; Subjects will do quiet, sedentary activities for 8 hours. Hourly blood draws and breath sampling will be collected. Bolus C13-Lysine will be given at hour 4.
Active Comparator: Exercise Visit; Subjects will do quiet, sedentary activities until hour 5. Blood and breath samples will be collected. At hour 4, subject will consume a bolus of C13-Lysine and immediately walk on a treadmill at a moderate intensity (exercise at 75% of max heart rate) for 45 minutes.	Other: Acute Moderate Intensity Exercise; Moderate intensity exercise by walking on a treadmill at 75% of max heart rate.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Compare plasma phenylalanine concentration of final blood draw during exercise versus sedentary visits.	Compare the final blood sample for phenylalanine concentration from each arm of the study.	up to 8 hours

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Breath Enrichment of C13-Lysine during sedentary and exercise	Compare the AUC total breath enrichment of C13-Lysine during the sedentary and exercise arms.	Hours 1-8 of the study day from each arm.

Collaborators and Investigators

• Sponsor: Oregon Health and Science University
• Investigators: Principal Investigator: Melanie Gillingham, PhD, RD, Oregon Health and Science University

Study record dates

Study Major Dates

• Study Start: May 1, 2013
• Primary Completion (Actual): June 1, 2014
• Study Completion (Actual): June 1, 2014

Study Registration Dates

• First Submitted: May 31, 2013
• First Submitted That Met QC Criteria: July 19, 2013
• First Posted (Estimate): July 22, 2013

Study Record Updates

• Last Update Posted (Estimate): October 16, 2014
• Last Update Submitted That Met QC Criteria: October 15, 2014
• Last Verified: October 1, 2014

More Information

Terms related to this study

• Keywords: Exercise; Phenylketonuria; PKU; Muscle Protein Synthesis; Plasma Phenylalanine concentration
• Additional Relevant MeSH Terms: Metabolic Diseases; Brain Diseases; Central Nervous System Diseases; Nervous System Diseases; Genetic Diseases, Inborn; Metabolism, Inborn Errors; Brain Diseases, Metabolic; Brain Diseases, Metabolic, Inborn; Amino Acid Metabolism, Inborn Errors; Phenylketonurias
• Other Study ID Numbers: 9202