Distinct Sources of Supplementary Protein in the Resistance Exercise Training-induced Adaptations

University of Sao Paulo General Hospital40 enrolled

Overview

This is a randomized controlled trial aimed to investigate the effects of different supplementary protein sources on muscle adaptations to resistance exercise. Young, healthy, recreationally active participants consuming an omnivorous diet with protein intake within recommended dietary allowance (RDA) (i.e.; 0.8-1.0 g.kg-1. d-1) will be recruited to undergo a 12-wk supervised resistance training program in combination with the intake of three 15-g daily doses (45g. d-1 total) of either a mixed plant- (i.e.; soy and pea protein) or animal-based (i.e.; whey protein) protein in drink form as a supplementary source of protein to their main meals of the day (i.e.; breakfast, lunch, and dinner). Before (PRE) and after (POST) the 12-wk intervention, participants will be assessed for body composition by dual-energy X-ray absorptiometry (DXA), muscle cross-sectional area (ultrasound) and fiber cross-sectional area (muscle biopsy), and maximal isotonic strength (1RM). Training consists of a resistance training (RT) program individually supervised by a researcher blinded to treatment in a laboratorial setting. Assessments will also be conducted in a blinded fashion.

Study Type

INTERVENTIONAL

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

TRIPLE

Enrollment

Conditions

Dietary Supplements Muscle Strength

Interventions

Animal proteinDIETARY_SUPPLEMENT

Patients allocated to this arm will be submitted a supervised resistance training program in combination with the intake of three 15-g daily doses (45g. d- 1 total) animal-based protein (i.e.; whey protein) in drink form as a supplementary source of protein in their main meals of the day.

Plant ProteinDIETARY_SUPPLEMENT

Patients allocated to this arm will be submitted a supervised resistance training program in combination with the intake of three 15-g daily doses (45g. d- 1 total) mixed plant protein (i.e.; soy and pea) in drink form as a supplementary source of protein in their main meals of the day.

Eligibility

Sex: MALEMin age: 18 YearsMax age: 35 YearsHealthy volunteers:

Medical Language ↔ Plain English

Inclusion Criteria: * Physically active (according to the International Physical Activity Questionnaire (IPAQ) * Absence of any chronic condition that could preclude participation in a RT program or physical testing * Habitual protein consumption within RDA ≥ 0.8 ≤1.0 g.kg-1. d-1 Exclusion Criteria: * Prior history of anabolic steroids use, current or previous (≤ 3 m) * Use of ergogenic or protein-based supplements, current or previous (\< 1 y) * Engagement in energy-restricted diets

Outcomes

Primary Outcomes

vastus lateralis muscle cross sectional area

the investigators used ultrasound measures of the vastus lateralis cross sectional area as the primary outcome

Time frame: Ultrasound images will be obtained both at baseline (before the comencement of the study) and immediately after the 12-week intervention period

Secondary Outcomes

lean mass

total body and lower limb lean mass assessed by DXA

Time frame: DXA scans will be taken both at baseline (before the comencement of the study) and immediately after the 12-week intervention period

fiber cross sectional area

vastus lateralis fiber cross sectional area from muscle biopsy samples

Time frame: Fiber cross sectional areas will be measured both at baseline (before the comencement of the study) and immediately after the 12-week intervention period

maximal isotonic strength

lower-limb maximal isotonic strength will be assessed in the leg-press exercise by means of the one-repetition-maximum test (1-RM test)

Time frame: 1-RM tests will be taken both at baseline (before the comencement of the study) and immediately after the 12-week intervention period