Protein and Performance (PROPER) in Endurance Athletes

Reduced Dietary Protein, Performance and Health

Sponsors

Lead Sponsor: University of Copenhagen

Collaborator: Maastricht University Medical Center

Source University of Copenhagen
Brief 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.

Overall Status Recruiting
Start Date 2021-02-23
Completion Date 2025-12-31
Primary Completion Date 2024-12-31
Phase N/A
Study Type Interventional
Primary Outcome
Measure Time Frame
Endurance performance on a bike From Pre (wk0) to post (wk6)
Microbiome Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Secondary Outcome
Measure Time Frame
Resting metabolic rate Pre (wk0) to mid (wk3)
Resting metabolic rate Pre (wk0) to Post (wk6)
Lean body mass Run-in (wk-3) to Pre (wk0)
Lean body mass Pre (wk0) to Post (wk6)
Total fat mass Pre (wk0) to Post (wk6)
Total fat mass Pre (wk0) to mid (wk3)
Total fat mass Run-in (wk-3) to Pre (wk0)
Power output at 4mmol/L blood lactate Pre (wk0) to mid (wk3)
Power output at 4mmol/L blood lactate Pre (wk0) to Post (wk6)
Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate Pre (wk0) to mid (wk3)
Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate Pre (wk0) to Post (wk6)
Maximal oxygen uptake VO2peak Pre (wk0) to mid (wk3)
Maximal oxygen uptake VO2peak Pre (wk0) to Post (wk6)
Peak power output on a 10-s sprint Pre (wk0) to mid (wk3)
Peak power output on a 10-s sprint Pre (wk0) to Post (wk6)
Mean power output on a 10-s sprint Pre (wk0) to mid (wk3)
Mean power output on a 10-s sprint Pre (wk0) to Post (wk6)
Gross efficiency on a bike Pre (wk0) to mid (wk3)
Gross work efficiency on a bike Pre (wk0) to Post (wk6)
15min TT power output on a bike Pre (wk0) to mid (wk3)
15min TT power output on a bike Pre (wk0) to Post (wk6)
Fractional utilisation of maximal oxygen uptake during 15min TT Pre (wk0) to mid (wk3)
Fractional utilisation of maximal oxygen uptake during 15min TT Pre (wk0) to Post (wk6)
Respiratory exchange ratio Pre (wk0) to Post (wk6)
Respiratory exchange ratio Pre (wk0) to Mid (wk3)
Training load Run-in (wk-3) vs dietary intervention (wk0 to wk6)
Energy intake Run-in (wk-3) vs dietary intervention (wk0 to wk6)
Energy expenditure Run-in (wk-3) vs dietary intervention (wk0 to wk6)
Blood lactate concentration Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Blood glucose concentration Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Blood amino acid concentration Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Plasma metabolomics Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Skeletal muscle protein expression Pre (wk0) to mid (wk3)
Skeletal muscle protein expression Pre (wk0) to Post (wk6)
Haemoglobin mass expressed in grams Pre (wk0) to mid (wk3)
Haemoglobin mass expressed in grams Pre (wk0) to Post (wk6)
Blood volume in ml Pre (wk0) to Post (wk6)
Blood volume in ml Pre (wk0) to Mid (wk3)
Energy expenditure measured as energy intake to maintain body weight Run-in (wk-3 to wk0) vs dietary intervention (wk0 to wk6)
Enrollment 20
Condition
Intervention

Intervention Type: Other

Intervention Name: Dietary intervention of reduced protein intake

Description: 6-wk dietary intervention of reduced protein intake

Arm Group Label: Reduced protein diet

Intervention Type: Other

Intervention Name: Dietary intervention of normal protein intake

Description: 6-wk dietary intervention of normal protein intake

Arm Group Label: Normal protein diet

Eligibility

Criteria:

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

Gender:

Male

Minimum Age:

20 Years

Maximum Age:

50 Years

Healthy Volunteers:

Accepts Healthy Volunteers

Overall Official
Overall Contact

Last Name: Bente Kiens, Professor

Phone: +4535321619

Email: [email protected]

Location
Facility: Status: Contact: Contact Backup: University of Copenhagen Nicki W Almquist, Post Doc +4593601842 [email protected]
Location Countries

Denmark

Verification Date

2022-06-01

Responsible Party

Type: Principal Investigator

Investigator Affiliation: University of Copenhagen

Investigator Full Name: Bente Kiens

Investigator Title: Professor of Exercise, Nutrition and Metabolism, D Sci, PhD, Principal Investigator

Keywords
Has Expanded Access No
Condition Browse
Number Of Arms 2
Arm Group

Label: Reduced protein diet

Type: Experimental

Description: A 6-week eucaloric dietary intervention of reduced protein intake (~1g protein/kg body mass). The diet will, hence, contain ~7E% protein, ~63E% carbohydrate, and ~29E% fat. Participants are free-living and receive all food pre-packed from the study kitchen. The energy provision will be set to match energy balance.

Label: Normal protein diet

Type: Active Comparator

Description: A 6-week eucaloric dietary intervention of normal protein intake (~2g protein/kg body mass). The diet will, hence, contain ~16E% protein, ~53E% carbohydrate, and ~30E% fat. Participants are free-living and receive all food pre-packed from the study kitchen. The energy provision will be set to match energy balance.

Acronym PROPER
Patient Data No
Study Design Info

Allocation: Randomized

Intervention Model: Parallel Assignment

Intervention Model Description: A pair-matched group, parallel design within each sex

Primary Purpose: Basic Science

Masking: None (Open Label)

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