Clinical trial NCT05426447: Protein and Performance (PROPER) in Endurance Athletes
Official title: Reduced Dietary Protein, Performance and Health
Study type: INTERVENTIONAL
Overall status: ACTIVE_NOT_RECRUITING
Phase: NA
Conditions: Diet, Healthy
Protein Deficiency
Keywords: Diet intervention
Endurance athletes
Endurance performance
Skeletal muscle protein synthesis
Protein intake
Health markers
Microbiome
Lead sponsor: University of Copenhagen
Sponsor class: OTHER
Collaborators: name: Maastricht University Medical Center
First posted: 2022-06-22
Enrollment: 20
Sex: MALE
Minimum age (years): 20
Maximum age (years): 50
Standard ages: ADULT
Accepts healthy volunteers: yes
Allocation: RANDOMIZED
Intervention model: PARALLEL
Intervention model description: A pair-matched group, parallel design within each sex
Primary purpose: BASIC_SCIENCE

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.

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

Primary outcomes:
measure: Endurance performance on a bike
timeFrame: From Pre (week0) to post (week6)
measure: Microbiome
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Secondary outcomes:
measure: Resting metabolic rate
timeFrame: Pre (week0) to mid (week3)
measure: Resting metabolic rate
timeFrame: Pre (week0) to Post (week6)
measure: Lean body mass
timeFrame: Run-in (week-3) to Pre (week0)
measure: Lean body mass
timeFrame: Pre (week0) to Post (week6)
measure: Total fat mass
timeFrame: Pre (week0) to Post (week6)
measure: Total fat mass
timeFrame: Pre (week0) to mid (week3)
measure: Total fat mass
timeFrame: Run-in (week-3) to Pre (week0)
measure: Power output at 4mmol/L blood lactate
timeFrame: Pre (week0) to mid (week3)
measure: Power output at 4mmol/L blood lactate
timeFrame: Pre (week0) to Post (week6)
measure: Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate
timeFrame: Pre (week0) to mid (week3)
measure: Fractional utilisation of maximal oxygen uptake at 4mmol/L blood lactate
timeFrame: Pre (week0) to Post (week6)
measure: Maximal oxygen uptake VO2peak
timeFrame: Pre (week0) to mid (week3)
measure: Maximal oxygen uptake VO2peak
timeFrame: Pre (week0) to Post (week6)
measure: Peak power output on a 10-seconds sprint
timeFrame: Pre (week0) to mid (week3)
measure: Peak power output on a 10-seconds sprint
timeFrame: Pre (week0) to Post (week6)
measure: Mean power output on a 10-seconds sprint
timeFrame: Pre (week0) to mid (week3)
measure: Mean power output on a 10-seconds sprint
timeFrame: Pre (week0) to Post (week6)
measure: Gross efficiency on a bike
timeFrame: Pre (week0) to mid (week3)
measure: Gross work efficiency on a bike
timeFrame: Pre (week0) to Post (week6)
measure: 15-minute time-trial power output on a bike
timeFrame: Pre (week0) to mid (week3)
measure: 15-minute time-trial power output on a bike
timeFrame: Pre (week0) to Post (week6)
measure: Fractional utilisation of maximal oxygen uptake during 15-minute time-trial
timeFrame: Pre (week0) to mid (week3)
measure: Fractional utilisation of maximal oxygen uptake during 15-minute time-trial
timeFrame: Pre (week0) to Post (week6)
measure: Respiratory exchange ratio
timeFrame: Pre (week0) to Post (week6)
measure: Respiratory exchange ratio
timeFrame: Pre (week0) to Mid (week3)
measure: Training load
timeFrame: Run-in (week-3) vs dietary intervention (week0 to week6)
measure: Energy intake
timeFrame: Run-in (week-3) vs dietary intervention (week0 to week6)
measure: Energy expenditure
timeFrame: Run-in (week-3) vs dietary intervention (week0 to week6)
measure: Blood lactate concentration
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
measure: Blood glucose concentration
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
measure: Blood amino acid concentration
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
measure: Plasma metabolomics
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
measure: Skeletal muscle protein expression
timeFrame: Pre (week0) to mid (week3)
measure: Skeletal muscle protein expression
timeFrame: Pre (week0) to Post (week6)
measure: Haemoglobin mass expressed in grams
timeFrame: Pre (week0) to mid (week3)
measure: Haemoglobin mass expressed in grams
timeFrame: Pre (week0) to Post (week6)
measure: Blood volume in ml
timeFrame: Pre (week0) to Post (week6)
measure: Blood volume in ml
timeFrame: Pre (week0) to Mid (week3)
measure: Energy expenditure measured as energy intake to maintain body weight
timeFrame: Run-in (week-3 to week0) vs dietary intervention (week0 to week6)
Other outcomes:
Locations:
city: Copenhagen
country: Denmark
facility: University of Copenhagen
Study officials:
affiliation: University of Copenhagen
name: Nicki W Almquist, Post Doc
role: STUDY_DIRECTOR
affiliation: University of Copenhagen
name: Bente Kiens, Professor
role: PRINCIPAL_INVESTIGATOR
References: