NCT05426447

Protein and Performance (PROPER) in Endurance Athletes

Reduced Dietary Protein, Performance and Health

• Status: Active Not Recruiting
• Phase: N/A
• Study type: Interventional
• Enrollment: 20 (actual)
• Sponsor: University of Copenhagen · Academic / Other
• Sex: Male
• Age: 20 Years – 50 Years
• Healthy volunteers: Accepted

Summary

The present study is a parallel group design with randomised allocation to either a 1) reduced protein diet (RP) or a 2) normal protein diet (NP). The two groups will be pair-matched based on habitual dietary protein intake, endurance training, endurance performance, and sex. The aim of the study is to investigate the effects of reducing dietary protein (\~1g protein/kg body mass) compared to an eucaloric normal protein diet (\~2g protein/kg body mass) for 6 weeks in well-trained endurance athletes on endurance performance, body composition, skeletal muscle protein synthesis, and health-related outcomes. The hypothesis is that endurance performance will maintain or even be improved in well-trained endurance athletes after a 6-week dietary intervention of an eucaloric, protein reduced diet compared to a normal protein rich diet.

Detailed description

Design: The present study will include two phases: a 3-week run-in period, and a 6-week intervention of controlled diets containing either a reduced dietary protein (RP) or normal (habitual) protein (NP). The run-in period serves as a period for obtaining general activity data and habitual dietary and training habits in order to match the groups before entering the dietary intervention period. Subjects and dietary goals: The study is aiming at including 20 male endurance athletes exercising \~15hrs+/week. The 20 males will be pair-matched based on habitual endurance training, habitual dietary protein intake, and endurance performance, and allocated in a randomised order to: 1) a reduced-protein diet (RP) or 2) a normal-protein diet (NP). 3-weeks run-in period: After a minimum of 7 days after written consent has been obtained, the run-in period will begin. Habitual endurance training volumes will be registered in an online platform (TrainingPeaks) and daily activity level will be monitored using an accelerometer (SENS) throughout the run-in and diet intervention period. "Heavy water" (D2O) will be ingested in a large bolus (3.5ml/kg LBM) upon beginning of the run-in period and plasma enrichments will be maintained throughout the study period by ingesting small daily boluses. This serves to determine skeletal muscle protein synthesis throughout the study. 6-weeks dietary intervention: The diets will be eucaloric and the estimated energy percentages for macronutrients will be as follows: RP - Protein \~7E%, Carbohydrate \~63E%, Fat \~29E%. NP - Protein \~16E%, Carbohydrate \~53E%, Fat \~30E%. Weekly urine and faeces samples will be collected during the run-in period and dietary intervention and the controlled diets will be supplied weekly for the participants. Testing: Extensive endurance performance and metabolic testing will be performed prior to-, and during the intervention on weeks -1, 0 (Pre), 3 (Mid), and 6 (Post). The tests include: Body composition by DXA-scanning, resting metabolic rate by online respirometry using a Vyntus (Jaeger, PCX), venous blood-, and skeletal muscle biopsy sampling from m. Vastus Lateralis, a standardised breakfasts, endurance cycling on an electro-magnetically braked bike (Lode Excalibur) or running on a motorised treadmill (Woodway), and haemoglobin mass measuring using a modified version of the CO-rebreathing method. The body mass will be kept unchanged during the 6-weeks dietary intervention.

Conditions

• Diet, Healthy
• Protein Deficiency

Interventions

Type	Name	Description
OTHER	Dietary intervention of reduced protein intake	6-wk dietary intervention of reduced protein intake
OTHER	Dietary intervention of normal protein intake	6-wk dietary intervention of normal protein intake

Timeline

• Start date: 2021-02-23
• Primary completion: 2024-12-31
• Completion: 2025-12-31
• First posted: 2022-06-22
• Last updated: 2024-05-07

Locations

1 site across 1 country: Denmark