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Trial registered on ANZCTR


Registration number
ACTRN12622001363774
Ethics application status
Approved
Date submitted
17/10/2022
Date registered
24/10/2022
Date last updated
24/10/2022
Date data sharing statement initially provided
24/10/2022
Type of registration
Prospectively registered

Titles & IDs
Public title
The influence of cow or soy milk on circulating blood sex hormones following a single session of resistance exercise.
Scientific title
Effect of Cow’s or Soy milk on sex hormones following resistance training in males who engage in regular resistance training.
Secondary ID [1] 308200 0
Nil
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Reproductive hormones 327943 0
Muscle hypertrophy 327944 0
Condition category
Condition code
Musculoskeletal 325010 325010 0 0
Other muscular and skeletal disorders

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Study overview

Eligible participants will attend the Illawarra Health and Medical Research Institute (IHMRI) on three occasions in total. The first visit to IHMRI will be for a maximal strength assessment (1-Repition Maximum [1-RM]). The maximal strength assessment (visit 1) will be followed by two subsequent visits to complete two identical resistance exercise training sessions where either cow or soy milk will ensue followed by blood collection (visits 2 and 3). An experienced trainer will supervise all resistance exercise sessions.

Visit 1.
A single testing session will be conducted at IHMRI to determine 1- repetition max strength for several resistance exercises including: barbell bench press, latissimus dorsi pulldowns, seated barbell shoulder press, standing barbell biceps curl, and seated machine triceps extension. 1-RM will be established from the best of 4 attempts at each exercise, each separated by 5 min of rest. Upon completion of 1-RM for each exercise, 10 min will be permitted before testing the next exercise. Standardised instructions on testing procedures will be provided to all participants and verbal encouragement will be offered throughout the testing session. Visit one is expected to take approximately 1.5 hours to complete

Visits 2 and 3.
Participants will be able to perform their usual exercise training regimen until 48 h prior to resistance exercise training sessions. All participants will complete resistance exercise training sessions at the same time of day (between 0600 and 0900) to control for diurnal hormonal fluctuations. Participants will begin with a warm-up consisting of 2 sets of 20 repetitions for barbell bench press at 40% of their predetermined 1-RM load. Three sets at 70% of 1-RM will then be completed for the same exercises used in the maximal strength assessment: barbell bench press, lat pulldown, seated dumbbell shoulder press, standing barbell biceps curl, and seated machine triceps extension. Participants will be instructed to perform repetitions until voluntary exhaustion, and verbal encouragement will be provided. Pausing between the eccentric and concentric phases of each repetition will not be permitted. There will be 2 min of passive rest between each of the sets of exercises (barbell bench press, latissimus dorsi pulldown, seated dumbbell shoulder press, standing barbell biceps curl, and seated machine triceps extension) and 2 minutes of passive rest between each exercise. Session attendance checklists will be completed at visits 2 and 3 to monitor training output. The second resistance exercise training condition, which is identical to the first will proceed within 7 days after completion of the first. Visits 2 and 3 are anticipated to take approximately 3 hours to complete. All subjects will be asked to maintain their usual activities of daily living throughout the study. Participants will consume either soy or cow's milk following both visits 2 and 3 and have blood samples collected to test their reproductive hormone levels (details below).

Nutritional intervention

Utilising a randomised crossover design, all subjects will complete each treatment condition: dairy milk and soy milk following resistance exercise (70% of 1 repetition maximum).
The dairy milk will be organic, grass-fed, locally procured whole milk. Soy milk will also be organic. A single serve of 600 mL/m2 of milk will be provided, a quantity administered in previous research yielding 33-40g protein. Milk will be provided at 45 minutes post-exercise and all milk will be consumed within 10 min to ensure intake within the “post-workout anabolic window of opportunity,”. A registered dietitian will provide the nutritional intervention (soy or cow’s milk) to participants.

Participants will be instructed to continue with their habitual dietary patterns 2 days prior to each visit and will be advised on how to record all food items consumed including the amounts and recipes. A registered dietitian will be available to answer questions as needed throughout the food diary collection periods. Intake of dairy (including dairy from cow, goat, and sheep) and soy products as well as alcohol and more than 1 cup of coffee per day will be prohibited for 2 days prior to each experimental condition and the investigators will emphasise the importance of abstaining from supplements and ergogenic aids throughout the course of the study. The ‘Meallogger’ smartphone application will be used to assess/monitor participants adherence to the nutritional restrictions. Participants will be instructed to refrain from food consumption for 12 h prior to each experimental condition. Water consumption will be permitted however, in order to maintain euhydration.

Hormone testing and analysis

At both resistance exercise training sessions (visits 2 and 3) blood samples will be obtained to quantify the plasma concentration of selected sex hormones (total testosterone, progesterone and estrogen) immediately following exercise and at additional time points. Approximately 4 mL of blood will be drawn from the antecubital vein and will be collected with subjects in a seated, slightly reclined position upon exercise completion and 30, 45, 60, 80, 100, 120 min thereafter following milk consumption.
Samples will be centrifuged at 3500 rpm at 4°C for 10 min for separation of plasma, which will be aliquoted and stored at -80°C with 1 thaw for analysis. Plasma hormone levels will be measured in duplicate by Cardinal laboratory.
Intervention code [1] 324651 0
Treatment: Other
Intervention code [2] 324652 0
Lifestyle
Comparator / control treatment
As this is a cross-over design, participants will act as their own control. Consumption of the soy milk will act as the control treatment.
Control group
Active

Outcomes
Primary outcome [1] 332827 0
Total testosterone determined from blood samples
Timepoint [1] 332827 0
time 0, 30, 45, 60, 80, 100, 120 min thereafter following milk consumption
Secondary outcome [1] 414806 0
Total estrogen determined from blood samples
Timepoint [1] 414806 0
Time 0, 30, 45, 60, 80, 100, 120 min thereafter following milk consumption.
Secondary outcome [2] 414807 0
Total progesterone determined from blood samples
Timepoint [2] 414807 0
Time 0, 30, 45, 60, 80, 100, 120 min thereafter following milk consumption.

Eligibility
Key inclusion criteria
Inclusion criteria
- Resistance training for > 2 years, 3 times/week.
- Male aged 18-30
- Normal BMI range (18.5-30kg/m2)
Males have been selected to avoid any potential confounding effects of fluctuating progesterone and estrogen levels associated with monthly menstrual cycles and/ or use of the oral contraceptive pill in females.
Minimum age
18 Years
Maximum age
30 Years
Sex
Males
Can healthy volunteers participate?
Yes
Key exclusion criteria
Exclusion criteria
- Participants using dietary ergogenic aids
- Lactose intolerance or allergy
- Smokers
- Suffering from, or with a history of, cardiac, hepatic, pulmonary, renal, neurological, haematological, psychiatric or gastrointestinal illness
- Participants on medications

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)
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using a randomisation table created by computer software (i.e. computerised sequence generation)
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Crossover
Other design features
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis

Recruitment
Recruitment status
Not yet recruiting
Date of first participant enrolment
Anticipated
25/10/2022
Actual
Date of last participant enrolment
Anticipated
23/01/2023
Actual
Date of last data collection
Anticipated
13/02/2023
Actual
Sample size
Target
26
Accrual to date
Final
Recruitment in Australia
Recruitment state(s)
NSW

Funding & Sponsors
Funding source category [1] 312456 0
Charities/Societies/Foundations
Name [1] 312456 0
Switch4Good Inc
Country [1] 312456 0
United States of America
Primary sponsor type
University
Name
University of Wollongong
Address
Northfields Avenue, Wollongong NSW 2522
Country
Australia
Secondary sponsor category [1] 314034 0
Charities/Societies/Foundations
Name [1] 314034 0
Illawarra Health and Medical Research Institution
Address [1] 314034 0
Building 32, University of Wollongong,
Northfields Ave, Keiraville NSW 2522
Country [1] 314034 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 311802 0
Joint University of Wollongong and Illawarra Shoalhaven Local Health District Health and Medical Human Research Ethics Committee
Ethics committee address [1] 311802 0
Northfields Avenue, Wollongong NSW 2522
Ethics committee country [1] 311802 0
Australia
Date submitted for ethics approval [1] 311802 0
Approval date [1] 311802 0
21/09/2022
Ethics approval number [1] 311802 0
2022/211

Summary
Brief summary
Recreational exercisers often participate in weight training to increase their strength and muscle size. Cow’s milk has been suggested as a suitable recovery drink following weight training due to its high protein and carbohydrate composition which can help build muscle strength. Although, cow’s milk may not be appropriate for many as it contains lactose, a sugar many individuals are intolerant or allergic to. Plant-based milks such as soy milk might provide an alternative recovery drink.

Soy foods are associated with many health benefits, but some athletes participating in weight training believe soy to be disadvantageous for building muscle as soy milk contains phytoestrogens. Phytoestrogens are naturally occurring components of many plant foods and are especially concentrated in soy. The concern arises as estrogen can influence muscle adaptions and body composition and some resistance athletes worry the phytoestrogen found in soy could similarly inhibit muscle adaptions.

Whilst the phytoestrogens found in soy have a similar structure to human estrogen, their effects appear to be substantially weaker. On the other hand, the estrogen concentrations in cow’s milk is considerable. Limited research has compared the influence of soy milk and cow’s milk on reproductive hormones, particularly after resistance exercise which is the aim of this study.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 122414 0
Dr Joel Craddock
Address 122414 0
School of Medical, Indigenous and Health Sciences
University of Wollongong.
Northfields Avenue, Wollongong NSW 2522
Country 122414 0
Australia
Phone 122414 0
+61 2 4221 3218
Fax 122414 0
Email 122414 0
[email protected]
Contact person for public queries
Name 122415 0
Joel Craddock
Address 122415 0
School of Medical, Indigenous and Health Sciences
University of Wollongong.
Northfields Avenue, Wollongong NSW 2522
Country 122415 0
Australia
Phone 122415 0
+61 2 4221 3218
Fax 122415 0
Email 122415 0
[email protected]
Contact person for scientific queries
Name 122416 0
Joel Craddock
Address 122416 0
School of Medical, Indigenous and Health Sciences
University of Wollongong.
Northfields Avenue, Wollongong NSW 2522
Country 122416 0
Australia
Phone 122416 0
+61 2 4221 3218
Fax 122416 0
Email 122416 0
[email protected]

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 data of primary outcomes only
When will data be available (start and end dates)?
Following publication. There will not be an end date
Available to whom?
researchers who provide sound response
Available for what types of analyses?
IPD meta-analysis
How or where can data be obtained?
Contact PI [email protected]


What supporting documents are/will be available?

No Supporting Document Provided



Results publications and other study-related documents

Documents added manually
No documents have been uploaded by study researchers.

Documents added automatically
No additional documents have been identified.