Protein and Performance (PROPER) in Endurance Athletes

Diet, Healthy Clinical Trial

— PROPER  

Official title:

Reduced Dietary Protein, Performance and Health

Clinical Trial Details — Status: Active, not recruiting

Administrative data

• NCT number: NCT05426447
• Other study ID #: PROPER
• Status: Active, not recruiting
• Phase: N/A
• Start date: February 23, 2021
• Est. completion date: December 31, 2025

Study information

• Verified date: May 2024
• Source: University of Copenhagen
• Contact: n/a
• Is FDA regulated: No
• Study type: Interventional

Clinical Trial 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.

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.

Recruitment information / eligibility

• Status: Active, not recruiting
• Enrollment: 20
• Est. completion date: December 31, 2025
• Est. primary completion date: December 31, 2024
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Male
• Age group: 20 Years to 50 Years

Eligibility

Inclusion Criteria:

• Endurance athlete

• Exercising at least 10hrs per week

• Habitual dietary protein intake ~2g/kg body mass

• BMI<25

Exclusion Criteria:

• Food allergies that exclude the controlled diet

• Inconsistent endurance training load

Related Conditions & MeSH terms

• Diet, Healthy
• Protein Deficiency

Intervention

Other:
• Dietary intervention of reduced protein intake
6-wk dietary intervention of reduced protein intake
• Dietary intervention of normal protein intake
6-wk dietary intervention of normal protein intake

Locations

Country	Name	City	State
Denmark	University of Copenhagen	Copenhagen

Sponsors (2)

Lead Sponsor	Collaborator
University of Copenhagen	Maastricht University Medical Center

Country where clinical trial is conducted

Denmark, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Endurance performance on a bike	Endurance performance defined as maximal aerobic power (Wmax) during incremental test to exhaustion on a bike measured as 1-minute mean power output (W)	From Pre (week0) to post (week6)
Primary	Microbiome	Diversity of bacterial strains in gut microbiome measured in feces samples	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary	Resting metabolic rate	Measured in an over-night fasted state via indirect calorimetry expressed in MJ/day	Pre (week0) to mid (week3)
Secondary	Resting metabolic rate	Measured in an over-night fasted state via indirect calorimetry expressed in MJ/day	Pre (week0) to Post (week6)
Secondary	Lean body mass	Measured by dual-energy x-ray (DXA)-scanningg expressed in kg	Run-in (week-3) to Pre (week0)
Secondary	Lean body mass	Measured by dual-energy x-ray (DXA)-scanning expressed in kg	Pre (week0) to Post (week6)
Secondary	Total fat mass	Measured by dual-energy x-ray (DXA)-scanning expressed in kg	Pre (week0) to Post (week6)
Secondary	Total fat mass	Measured by dual-energy x-ray (DXA)-scanning expressed in kg	Pre (week0) to mid (week3)
Secondary	Total fat mass	Measured by dual-energy x-ray (DXA)-scanning expressed in kg	Run-in (week-3) to Pre (week0)
Secondary	Power output at 4mmol/L blood lactate	Alterations in Power output at 4mmol/L blood lactate in response to diet	Pre (week0) to mid (week3)
Secondary	Power output at 4mmol/L blood lactate	Alterations in Power output at 4mmol/L blood lactate in response to diet	Pre (week0) to Post (week6)
Secondary	Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate	Alterations in Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate in response to diet	Pre (week0) to mid (week3)
Secondary	Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate	Alterations in Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate in response to diet	Pre (week0) to Post (week6)
Secondary	Maximal oxygen uptake VO2peak	Alterations in Maximal oxygen uptake VO2peak measured by an online VO2 apparatus	Pre (week0) to mid (week3)
Secondary	Maximal oxygen uptake VO2peak	Alterations in Maximal oxygen uptake VO2peak measured by an online VO2 apparatus	Pre (week0) to Post (week6)
Secondary	Peak power output on a 10-seconds sprint	Alterations in peak power output on a 10-seconds sprint in response to diet	Pre (week0) to mid (week3)
Secondary	Peak power output on a 10-seconds sprint	Alterations in peak power output on a 10-seconds sprint in response to diet	Pre (week0) to Post (week6)
Secondary	Mean power output on a 10-seconds sprint	Alterations in mean power output on a 10-seconds sprint in response to diet	Pre (week0) to mid (week3)
Secondary	Mean power output on a 10-seconds sprint	Alterations in mean power output on a 10-seconds sprint in response to diet	Pre (week0) to Post (week6)
Secondary	Gross efficiency on a bike	Gross efficiency expressed as % of external power compared to internal (metabolic) power	Pre (week0) to mid (week3)
Secondary	Gross work efficiency on a bike	Gross efficiency expressed as % of external power compared to internal (metabolic) power	Pre (week0) to Post (week6)
Secondary	15-minute time-trial power output on a bike	Alterations in 15-minute time-trial mean power output	Pre (week0) to mid (week3)
Secondary	15-minute time-trial power output on a bike	Alterations in 15-minute time-trial mean power output	Pre (week0) to Post (week6)
Secondary	Fractional utilisation of maximal oxygen uptake during 15-minute time-trial	Alterations in Fractional utilisation of maximal oxygen uptake during 15-minute time-trial	Pre (week0) to mid (week3)
Secondary	Fractional utilisation of maximal oxygen uptake during 15-minute time-trial	Alterations in Fractional utilisation of maximal oxygen uptake during 15-minute time-trial	Pre (week0) to Post (week6)
Secondary	Respiratory exchange ratio	respiratory exchange ratio (RER) during rest and exercise using indirect calorimetry	Pre (week0) to Post (week6)
Secondary	Respiratory exchange ratio	respiratory exchange ratio (RER) during rest and exercise using indirect calorimetry	Pre (week0) to Mid (week3)
Secondary	Training load	Training load as quantified by Edward's Training Impulse based on heart rate zones	Run-in (week-3) vs dietary intervention (week0 to week6)
Secondary	Energy intake	Habitual energy intake registered by food diaries expressed in Mega Joules	Run-in (week-3) vs dietary intervention (week0 to week6)
Secondary	Energy expenditure	Energy expenditure is measured by combining resting metabolic rate and daily activity recording from accelerometer data and heart rate monitor	Run-in (week-3) vs dietary intervention (week0 to week6)
Secondary	Blood lactate concentration	Glucose lactate measured in fasted state on an ABL800	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary	Blood glucose concentration	Glucose concentration measured in fasted state on an ABL800	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary	Blood amino acid concentration	Amino acid concentration measured by ELISA	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary	Plasma metabolomics	Plasma metabolomics by chromatography-mass spectrometry	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary	Skeletal muscle protein expression	Alterations in Skeletal muscle protein expression	Pre (week0) to mid (week3)
Secondary	Skeletal muscle protein expression	Alterations in Skeletal muscle protein expression	Pre (week0) to Post (week6)
Secondary	Haemoglobin mass expressed in grams	Haemoglobin mass measured via inhalation of carbon monoxide (CO) using the modified CO-rebreathing method	Pre (week0) to mid (week3)
Secondary	Haemoglobin mass expressed in grams	Haemoglobin mass measured via inhalation of carbon monoxide (CO) using the modified CO-rebreathing method	Pre (week0) to Post (week6)
Secondary	Blood volume in ml	Blood volume measured via inhalation of carbon monoxide (CO) using the modified CO-rebreathing method	Pre (week0) to Post (week6)
Secondary	Blood volume in ml	Blood volume measured via inhalation of carbon monoxide (CO) using the modified CO-rebreathing method	Pre (week0) to Mid (week3)
Secondary	Energy expenditure measured as energy intake to maintain body weight	Daily energy intake during intervention measured in Mega Joules	Run-in (week-3 to week0) vs dietary intervention (week0 to week6)