ANZCTR - Registration

Please note the ANZCTR will be unattended from Friday 20 December 2024 for the holidays. The Registry will re-open on Tuesday 7 January 2025. Submissions and updates will not be processed during that time.

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Trial registered on ANZCTR

Registration number

ACTRN12622000040763

Ethics application status

Approved

Date submitted

9/12/2021

Date registered

17/01/2022

Date last updated

17/01/2024

Date data sharing statement initially provided

17/01/2022

Type of registration

Prospectively registered

Titles & IDs

Public title

How the gut microbiome affects your ability to increase muscle size with weight training.

Scientific title

The influence of the gut microbiome on resistance training-based skeletal muscle hypertrophy in healthy individuals.

Secondary ID [1]

Nil known

Universal Trial Number (UTN)

U1111-1272-3680

Trial acronym

Linked study record

Health condition

Health condition(s) or problem(s) studied:

Whole-body lean mass

Gut microbiome composition

Gut microbiome diversity

Condition category

Condition code

Musculoskeletal

Normal musculoskeletal and cartilage development and function

Oral and Gastrointestinal

Normal oral and gastrointestinal development and function

Intervention/exposure

Study type

Interventional

Description of intervention(s) / exposure

This study will comprise two arms, a resistance training only arm (RT) and a resistance training with creatine supplementation arm (RT+CR). The RT intervention for both arms will be conducted face-to-face in the research and teaching gym at the Department of Exercise Physiology, School of Health Sciences, Faculty of Medicine and Health, Wallace Wurth Building, Kensington Campus, the University of New South Wales (UNSW), Sydney. Imtiaz Desai (ID) will be responsible for the programming and supervision of the exercise intervention. He is a qualified exercise scientist with significant experience in administering exercise programs and assessments. Exercise sessions will be conducted in the early mornings, lunch times, and after business hours to avoid clashes with business hours.

RT INTERVENTION
Both arms will follow the same RT intervention procedures. The program will be designed to elicit whole-body skeletal muscle hypertrophy, and will include the following variables:

1. Three one-hour RT sessions a week for 12 weeks, with at least one day of rest between sessions, to provide an adequate volume of training with sufficient recovery between sessions.

2. A training intensity that requires the participant to move the heaviest weight possible for 8, 10 or 12 repetitions (8-12 rep max) will be prescribed to provide an adequate training stimulus. A different rep max (8, 10 or 12) will be used on each session of the week. The rep max method will be used to ensure that the intensities (loads lifted) are relative to the individual's abilities, while standardising the intensity prescribed across all participants.

To adhere to the 8-12 rep max, an individual's rating of perceived exertion (RPE) on a Likert scale of 1-10 will be recorded during two warm-up and all working sets. RPE corresponds to the amount of repetitions an individual perceives they will be able to perform after the set is complete, where an RPE 5 equates to 5 reps more, RPE 6 is 4 reps more, RPE 7 is 3 reps more, and so on. An individual's loads will therefore be adjusted per set during each session using their RPE to adhere to the prescribed rep max for the session.

3. Three sets per exercise and five exercises per session (two lower and three upper body movements) will be prescribed to ensure an adequate volume of full body movements. Examples of lower body exercises to be prescribed include the leg press, curl and extension machines, lunges, and weighted squats. Upper body movements to be prescribed will include the chest press machine, shoulder press variations, seated row, lat pull down and dumbbell row. Movements for the elbow joint to be prescribed will include the bicep curl and cable triceps extensions.

4. To record adherence, the following information will be recorded at each session:
a. Sets and repetitions completed for each exercise
b. RPE for each set
c. Adverse reactions following the previous session
d. If a participant misses a session, and there are alternate times within that week to schedule a make-up session (based on room, participant and investigator availability), a make-up session will be scheduled. To adhere to the study’s timeline, make-up sessions will not roll over to following weeks. However, given that research indicates that at least two RT sessions a week are needed for muscular hypertrophy, three sessions have been selected to account for potential missed sessions. All missed sessions will be recorded for adherence reporting.

Intervention code [1]

Treatment: Other

Comparator / control treatment

The RT+CR group will be the comparator for this study. This group will undergo the same RT intervention as described above, and consume a creatine supplement for 13 weeks.

CREATINE SUPPLEMENT INTERVENTION
Following the first assessment, the participants will begin taking 5 grams of a creatine supplement daily for 13 weeks, commencing one week before their RT intervention begins. Creatine is asserted as the most effective supplement to augment RT-based hypertrophy, with a daily dose of 5 g proven to be sufficient. The enhanced gains in muscle strength and mass associated with creatine supplementation may be related to a greater intensity of training that can be achieved.

A creatine monohydrate supplement in powder form (True Protein Creatine Mono) has been procured from True Protein (Brookvale, NSW, Australia). True Protein have agreed to sponsor 132-250 g bags of creatine monohydrate for the study. Participants will be provided two 250 g bags each, with the first bag delivered at their first assessment. They will be instructed to mix one scoop (5 g) of the powder in water and to consume as soon as possible after an exercise bout with a meal. Post-workout ingestion is proposed to enhance the hypertrophy and strength benefits of creatine compared to pre-workout ingestion. On non-exercise days, they will be instructed to drink the water and creatine mixture at their first meal of the day. Participants will receive an online weekly creatine compliance calendar and will be instructed to record the days and time (pre or post workout) of ingestion on the compliance calendar which will signed and submitted digitally weekly.

Control group

Active

Outcomes

Primary outcome [1]

Whole-body lean mass measured by dual x-ray absorptiometry (DXA).

Timepoint [1]

1. Day 1 (week -1), 14 days prior to the RT intervention commencing for both arms.
2. Day 8 (week 0), 7 days prior to the RT intervention commencing for both arms.
3. Within 7 days post the end of the RT intervention (days 99-105).

Primary outcome [2]

Faith's phylogenetic diversity of the gut microbiota from stool stool samples collected using the OMNIgene GUT self collection kits (DNA Genotek Inc.).
Microbial DNA will be extracted from stool samples using the QIAamp PowerFecal Pro DNA Kit (QIAGEN Pty Ltd.), and genomics conducted with 16S V4 sequencing.

Timepoint [2]

1. Day 1 (week -1), 14 days prior to the RT intervention commencing for both arms.
2. Day 8 (week 0), 7 days prior to the RT intervention commencing for both arms.
3. Day 52 (week 6), at the midpoint of the RT intervention.
4. Within 7 days post the end of the RT intervention (days 99-105) (primary timepoint).

Primary outcome [3]

Serum short chain fatty acid (SCFA) content. Blood will be collected BD Vacutainer Safety-Lok blood collection set and 10 mL serum tubes. SCFA content will be determined using nuclear magnetic resonance (NMR) based metabolomics.

Timepoint [3]

Secondary outcome [1]

Total body fat percentage (BF%) will be recorded from the DXA scan.

Timepoint [1]

Secondary outcome [2]

Lower and upper body muscular strength will be measured using the Hammer Strength incline plate-loaded leg press and seated chest press machine, respectively. 10-repetition maximum (10RM) tests will be conducted to determine the heaviest load the participant is able to move for 10 repetitions. The 10RM will be determined in no fewer than two and no more than three attempts.

Timepoint [2]

1. Day 8 (week 0), 7 days prior to the RT intervention commencing for both arms.
3. Within 7 days post the end of the RT intervention (days 99-105).

Eligibility

Key inclusion criteria

1. Men and women aged 18-50
2. Body mass index (BMI) less than or equal to 25 (normal) because a BMI of greater than 25 has been shown to be associated with an altered gut microbiome.
3. Not meeting current physical activity guidelines of 150-300 minutes of moderate intensity (50-70% maximum heart rate) physical activity per week, measured with the IPAQ-S.
4. No resistance training for at least 12 months prior..
5. Able to commit to three 1-hour resistance exercise sessions per week for 12 weeks.

Minimum age

18 Years

Maximum age

50 Years

Sex

Both males and females

Can healthy volunteers participate?

Yes

Key exclusion criteria

1. Antibiotic use within the previous eight weeks.
2. Cardiovascular, gastrointestinal, metabolic, or neuromuscular diseases, and musculoskeletal disease or injury.
3. Creatine supplementation within the previous eight weeks.
4. Pregnancy.

Study design

Purpose of the study

Treatment

Allocation to intervention

Randomised controlled trial

Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)

Allocation will be concealed via placement of sequential group assignments into opaque sealed envelopes prepared by an independent researcher, which will be handed to the participant for opening by ID after the completion of assessment 1.

Methods used to generate the sequence in which subjects will be randomised (sequence generation)

A simple randomisation sequence will be conducted by an independent researcher using the website Randomization.com (http://randomization.com) will be used to generate a randomisation table.

Masking / blinding

Blinded (masking used)

Who is / are masked / blinded?

The people assessing the outcomes
The people analysing the results/data

Intervention assignment

Parallel

Other design features

Phase

Not Applicable

Type of endpoint/s

Efficacy

Statistical methods / analysis

SAMPLE SIZE

The total sample size for the project is 66, comprised of the following samples from each of the participant groups:
1. RT group, n=33
2. RT+CR group, n=33.

This is the first study to assess the effect of the gut microbiota on skeletal muscle hypertrophy. The effect size of the gut microbiota on hypertrophy is therefore unknown and an a priori power analysis was not conducted to calculate sample size. The sample size of 33 per group in this project includes a potential attrition rate of 10%, and is based on sample sizes of 28 to 32 used by previous studies conducting similar research about the gut microbiota and exercise. Given the individually supervised approach to conducting the exercise intervention in a private setting, a high rate of adherence is expected.

DATA ANALYSIS PLAN

1. Primary Outcomes
1.1. The primary outcomes for the randomised intervention will be to determine if Faith’s phylogenetic diversity or SCFA content at baseline predicts changes in whole-body lean mass following the intervention. This will be analysed using a regression analysis: Faith's diversity or SCFA content at baseline vs. change in whole-body lean mass (End of therapy - Baseline).

1.2. Additional Gut Microbiota Analysis

1.2.1. Changes in gut microbial Alpha diversity:
The alpha diversity metrics species richness, species evenness, Shannon's diversity and Faith's phylogenetic diversity will be calculated from taxonomic count data. Changes in alpha diversity across time and treatment will be assessed using a linear mixed model [Diversity ~ Time * TreatmentGroup + random(Patient.ID)].
If creatine supplementation shows no additive effect, the two treatment groups will be combined and changes in alpha diversity assessed through repeated measures ANOVA or a mixed-effects model where data is missing.

1.2.2. Differences in gut microbial Beta diversity:
Relative abundances of taxa will be square-root transformed and a Bray-Curtis dissimilarity resemblance matrix generated. The matrix will be ordinated using principal coordinate analysis (PCoA) and inter-group statistical differences calculated through permutational multivariate ANOVA (PERMANOVA) and validated using one-way analysis of similarities (ANOSIM).

1.2.3. Differentially abundant taxa:
Differentially abundant taxa will be identified using two statistical tests, linear discriminant analysis effect size (LEfSe) and DESeq2. Only taxa identified across both tests will be considered significantly differentially abundant.

1.3. Effects of creatine supplementation only on whole-body lean mass:
We will conduct an ANCOVA to determine the effect of creatine supplementation on whole-body lean mass between Assessment 1 (Week -1) and Assessment 2 (Week 0, Pre-RT Intervention). This will confirm a stable baseline for body composition.

1.4. Potential gut microbiota effect modifiers (i.e., dietary make-up and aerobic exercise participation) for all participants will be analysed via a paired t-test.

2. Secondary Outcomes
Changes in muscular strength and total body fat percentage across the intervention will be compared between groups using an ANCOVA.

Recruitment

Recruitment status

Completed

Date of first participant enrolment

Anticipated

7/02/2022

Actual

19/04/2022

Date of last participant enrolment

Anticipated

6/03/2023

Actual

24/02/2023

Date of last data collection

Anticipated

23/06/2023

Actual

8/06/2023

Sample size

Target

Accrual to date

Final

Recruitment in Australia

Recruitment state(s)

NSW

Recruitment postcode(s) [1]

2052 - Unsw Sydney

Recruitment postcode(s) [2]

2033 - Kensington

Recruitment postcode(s) [3]

2031 - Randwick

Recruitment postcode(s) [4]

2032 - Kingsford

Recruitment postcode(s) [5]

2034 - Coogee

Recruitment postcode(s) [6]

2004 - Eastern Suburbs

Recruitment postcode(s) [7]

2035 - Maroubra

Funding & Sponsors

Funding source category [1]

University

Name [1]

UNSW Sydney

Address [1]

Wallace Wurth Building
High Street
UNSW Kensington Campus
NSW 2052

Country [1]

Australia

Primary sponsor type

Individual

Name

Dr. Amanda Hagstrom

Address

Wallace Wurth Building
High Street
UNSW Kensington Campus
NSW 2052

Country

Australia

Secondary sponsor category [1]

None

Name [1]

Address [1]

Country [1]

Ethics approval

Ethics application status

Approved

Ethics committee name [1]

The University of New South Wales Human Ethics Research Committee

Ethics committee address [1]

Rupert Myers Building
UNSW Sydney
NSW 2052

Ethics committee country [1]

Australia

Date submitted for ethics approval [1]

03/09/2021

Approval date [1]

02/12/2021

Ethics approval number [1]

HC210725

Summary

Brief summary

Improvements in skeletal muscle mass (SMM) have been linked to numerous health outcomes including lower risk of cardiovascular disease, better cancer survival, improved glucose control, and enhanced bone mineral content and density. Methods of increasing SMM are therefore of interest. Resistance training (RT) and creatine supplementation are respectively the established exercise and supplement methods for increasing SMM. However, the processes that underly these gains are unclear.

The gut microbiome has been identified as a potential influencer of SMM. However, no original research has investigated links between the gut microbiota and SMM. The primary purpose of this study is therefore to determine if the gut microbiome affects RT-based gains in SMM. The secondary purpose is to investigate the effects of creatine supplementation on the gut microbiome.

We hypothesise that the make up and function of the gut microbiome before the exercise intervention will effect the SMM growth response to RT, and that creatine supplementation will change the make-up of the gut microbiome.

Trial website

Trial related presentations / publications

Public notes

Resistance training (RT) is the gold standard mode of exercise for increasing muscular strength and size . Its benefits, however, are far reaching with skeletal muscle growth (hypertrophy) central to the benefits. Increases in muscle mass are associated with better survival in cancer patients and improved cardiovascular and all-cause mortality. Hypertrophy is also linked to better bone mineral content and density, improved dynamic balance and a decreased risk of falls in the elderly. Given the links between muscle and health, methods to augment RT adaptations are widely researched. These include whey protein and creatine supplementation, with creatine appearing to be superior. Although RT and creatine are recognised as the benchmarks for stimulating muscle growth, the underlying mechanisms are under explored. 

Recently, a group of researchers have proposed that the gut microbiota is a potential influencer of muscle size. This is based on research showing that the gut microbiome of athletes and people undertaking aerobic exercise is different to sedentary people, coupled with studies linking the gut microbiota to changes in host physiology. However, no original research has investigated links between the gut microbiota and hypertrophy. This presents a novel approach to understanding the factors that influence muscle growth. 

The gut microbiota comprises a complex eco system that requires a multidisciplinary approach to examining how it affects host physiology. This involves assessing both composition and function of the microbial community. Microbial DNA is extracted from stool and sequenced to determine species present, and their relative abundances. Function of the microbiota can be assessed by measuring metabolites, the small molecular products of microbial metabolism. This is of interest because changes to metabolites are direct consequences to changes in the function/s of the microbial community. Gut-derived metabolites, short-chain fatty acids (SCFAs), are the proposed link between the gut microbiota and muscle mass. Analysing both composition and function of the gut microbiota may therefore depict a clearer story of the interactions between human, environment, and microbial community, compared to only assessing either one.

The aims of the proposed study are therefore to 1) to investigate the effects of composition and function of the gut microbiota on the hypertrophy response to a 12-week RT intervention, and 2) determine the effects of creatine supplementation on composition and function of the gut microbiota. Including the discipline of microbiology into exercise physiology research is an innovative approach to elucidating the mechanisms of muscle growth, which may lead to updated or new avenues for increasing muscle mass.

Contacts

Principal investigator

Name

Dr Amanda Hagstrom

Address

Wallace Wurth Building
High Street
UNSW Sydney
2052
NSW

Country

Australia

Phone

+61 290653676

Fax

m.hagstrom@unsw.edu.au

Contact person for public queries

Name

Imtiaz Desai

Address

Wallace Wurth Building
High Street
UNSW Sydney
2052
NSW

Country

Australia

Phone

+61 432604119

Fax

i.desai@unsw.edu.au

Contact person for scientific queries

Name

Imtiaz Desai

Address

Wallace Wurth Building
High Street
UNSW Sydney
2052
NSW

Country

Australia

Phone

+61 432604119

Fax

i.desai@unsw.edu.au

Data sharing statement

Will individual participant data (IPD) for this trial be available (including data dictionaries)?

Yes

What data in particular will be shared?

De-identified individual participant data underlying published results only.

When will data be available (start and end dates)?

Immediately following publication, up until 15 years post publication of research results.

Available to whom?

Case-by-case basis at the discretion of the Primary Sponsor.

Available for what types of analyses?

Any purpose.

How or where can data be obtained?

Access will be provided subject to approval by the Principle Investigator (m.hagstrom@unsw.edu.au).

What supporting documents are/will be available?

No Supporting Document Provided

Results publications and other study-related documents

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No additional documents have been identified.

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