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Trial registered on ANZCTR


Registration number
ACTRN12621000432819
Ethics application status
Approved
Date submitted
2/03/2021
Date registered
16/04/2021
Date last updated
1/03/2024
Date data sharing statement initially provided
16/04/2021
Type of registration
Prospectively registered

Titles & IDs
Public title
Effects of glycogen availability on human skeletal muscle molecular responses to exercise
Scientific title
Effects of glycogen availability on skeletal muscle molecular responses to exercise in healthy adults
Secondary ID [1] 303560 0
None
Universal Trial Number (UTN)
Trial acronym
Linked study record

Health condition
Health condition(s) or problem(s) studied:
Metabolic disorders 320917 0
Obesity 320918 0
Condition category
Condition code
Metabolic and Endocrine 318728 318728 0 0
Metabolic disorders
Diet and Nutrition 318729 318729 0 0
Obesity
Musculoskeletal 319265 319265 0 0
Normal musculoskeletal and cartilage development and function

Intervention/exposure
Study type
Interventional
Description of intervention(s) / exposure
Ten healthy and recreationally active males aged between 18 – 30 years old with a body mass index (BMI) of 18.5 – 27.0 kg/m2 will be recruited to participate in this study to investigate the effects of skeletal muscle glycogen availability on molecular responses to exercise.

Preliminary testing (week -2)
VISIT 1 (~30 mins):
At the first visit, participants will meet the trial coordinator, go through the participant information letter and have an opportunity to ask any questions they may have about the study.
1. Prior to any measurement participants will sign the study consent and muscle biopsy consent forms.
2. The Exercise and Sports Science Australia (ESSA) pre-exercise screening tool will be completed with trial coordinator.
3. Three-day food record explained: Participants will be asked to record ALL food and fluid consumed over a three-day period prior to the experimental period to establish habitual dietary intake using the ‘Easy Diet Diary’ or ‘My Fitness Pal’ phone application. To assist with compliance and reduce participant burden, household measures will be recorded.
4. Anthropometric measurements: Height will be measured using a wall mounted stadiometer. Weight will be measured using digital scales. Hip, waist and neck circumferences will be measured with a metal tape measure. All measures will be taken at the Australian Catholic University (ACU) lab in duplicate.

VISIT 2 (~2 h; week -1):
At the second visit, participants will participate in the following measures:
1. Body composition assessment: A dual-energy x-ray absorptiometry scan (DXA) is a specialised x-ray technique used to provide a measure of body composition (i.e. total body mass, fat mass and lean mass). Participants are required to lay supine on the scanning bed based at ACU for the duration of the scan, which is approximately 15 min and will be one to two scans depending on body shape. The machine uses small doses (<1% of the yearly radiation dose) of radiation to estimate tissue density. This test requires participants to be fasted with no food, fluid or exercise/activity prior to the test and requires participants to wear light clothing with no metal items (i.e. zips, domes, clips, underwire etc.) and remove all jewellery. Measures will be obtained by trained researchers who hold radiation licenses with Victorian Government and comply to the Code of Practice set out by the Australian Radiation Protection and Nuclear Safety Agency.
2. Maximum effort cycling exercise test [VO2 peak]: An experienced exercise physiologist will assess aerobic capacity at the ACU lab by measuring the maximum volume of oxygen (VO2) participants can breathe in and transport to the working muscles while exercising at maximal intensity. After a light 10 min warm-up on a cycling ergometer (exercise bike), participants will pedal at a fixed intensity (watts) that will increase every 1-2.5 min until volitional fatigue. During this test participants will wear a mouthpiece and headpiece that is connected to a metabolic cart for the collection of expired air. Following the warm-up, the test will last for 10-15 min where the last few minutes should be perceived as exhaustive, with recovery at low intensity for 2-3 min.

VISIT 3 (~2 h; > 72 h post Visit 2):
At the third visit, participants will participate in the following protocol:
1. One-legged glycogen depletion and two legged high intensity cycling exercise familiarization: Subjects will arrive at the ACU lab mid-afternoon to be familiarised with both one-legged cycling (to be used during glycogen depletion session) and two-legged interval cycling (to be used for exercise trial day) as practice runs for the glycogen depletion and exercise experimental trial day. Between each exercise protocol familiarisation performed with an experienced exercise physiologist, participants will rest for 15-30 min.

VISIT 4 (~3 h; > 72 h post Visit 3):
At the fourth visit, participants will participate in the following measures:
1. Continuous glucose monitoring (CGM): Participants will be provided with a continuous glucose monitor to assess circulating glucose levels before the glycogen depletion protocol, and this monitor will remain on the participant until the next morning following the experimental exercise session. These monitors enable detection of blood glucose changes associated with glycogen depletion and diet to ensure the participant has not consumed any food other than what was provided for their evening standardised meal.
2. One-legged muscle glycogen depletion exercise protocol: The exercise glycogen depletion protocol will be performed with an experienced exercise physiologist at the ACU lab and consist of repeated 10-min work bouts with 2 min recovery between work bouts. The time spent completing these work bouts will be ~100 min. This work-to-rest ratio will continue until volitional fatigue at which time power output will be decreased by 10W. Subjects then will repeat the same work-to-rest ratio until fatigue at this reduced work rate. Following a 10 min rest, subjects then will complete a series of 90-s one-leg maximal sprints (with 60-s recovery) on a Repco RE7100 Ergo cycle ergometer until volitional fatigue, defined as the inability to maintain 70 revolutions/min. When participants successfully complete the entire duration of this glycogen depletion exercise protocol, they will achieve the final eligibility component of this study and be formally enrolled to complete the experimental day.
3. Standardised meal: Subjects will consume a low-CHO meal with macronutrient targets based on body mass by an Accredited Practicing Dietician (APD) to minimise glycogen re-synthesis in the 'low glycogen' leg after the glycogen depletion exercise. Prior to undertaking the glycogen depletion, subjects will be instructed to refrain from exercise training and vigorous physical activity, and avoid any alcohol, caffeine and/or food consumption until completing the experimental day.

Experimental day and blood/biopsy collection
VISIT 5 (~5 h; 12 h post Visit 4):
At the fifth visit, participants will participate in the following measures:
1. Muscle biopsy sampling (pre-exercise, immediately post-exercise, 3 h post-exercise):
A total of 6 muscle biopsies will be taken over the entire study period by an experienced sports medicine physician, with 3 biopsies taken from each leg on this experimental visit. Samples will immediately be placed in liquid nitrogen for freezing and stored at -80 °C.
In preparation for a biopsy, a small amount of local anaesthetic is injected under the skin, which may result in a mild burning sensation while the fluid is injected. A small, 4-5 mm incision is then made into the skin to create an opening for the biopsy needle. There is often a small amount of bleeding from the incision; however, this bleeding is generally minimal. The biopsy needle is then inserted through the incision site. Participants may feel the sensation of deep pressure in the biopsy site, and on some occasions this is moderately painful. However, the discomfort very quickly passes and participants are capable of performing exercise and daily activities within minutes. There may also be some minimal bleeding when the needle is removed which may require the application of pressure for a few minutes. After each biopsy, the incision will be closed with sterile tape and wrapped with a bandage.
2. Blood sampling and analysis (pre-exercise, immediately post-exercise, and 3 h post-exercise):
A total of 3 blood samples will be collected over the entire study period via an in-dwelling venous cannula inserted by the sports medicine physician: 12ml blood samples will be taken at 3 time points only for the two-legged high intensity exercise protocol on the experimental day. A total volume of 36 mL of blood will be collected for the whole study across, which is minimal compared to the standard 500 mL for a Red Cross donation. Samples will be collected in two 6 mL vacutainers, with one containing EDTA for plasma and one uncoated for serum. Samples will then be centrifuged and aliquots of plasma/serum will be stored at -80 °C.
3. Experimental Exercise Session (20 x 1 min two-legged high intensity cycling exercise, interspersed with 20 x 1 min active recovery)
Participants will have previously completed the glycogen depletion exercise during Visit 4, and the following morning they will complete the following experimental two-legged high intensity cycling exercise protocol with an experienced exercise physiologist in Visit 5:
4. Two legged high intensity cycling exercise protocol: Subjects will report to the ACU lab at 0700 h on the morning of an experiment having completed the glycogen depletion protocol the previous evening. Resting biopsies from the vastus lateralis of the L and R legs will be taken under local anaesthesia. To determine the effects of muscle glycogen availability on exercise-regulated protein and gene responses, subjects will then undertake two-legged cycling 20 x 1 min at a maximum of 110-125% PPO interspersed 20 x 1 min active recovery at 50% PPO. This protocol provides sufficient stimulus to activate proteins and genes in both legs and is the maximum intensity that is sustainable in the ‘low’ glycogen limb. Two further biopsies from both legs will be taken: one immediately upon cessation of exercise to examine the acute protein responses and another 3 h later for the subsequent gene responses.
5. Removal of CGM.
6. Follow up care: Shortly after the completion of the final muscle biopsy sampling at 3 h post-exercise, participants will be offered a light snack (e.g. raisin toast, cereal, Up n' Go). A waterproof dressing will be applied to the muscle biopsy sites on each leg by the sports medicine physician. Participants can shower normally, and for those who may be swimming or sweating heavily, additional dressings and instruction can be provided. Wounds from the muscle biopsies normally heal within four days.
Intervention code [1] 319850 0
Lifestyle
Intervention code [2] 320232 0
Prevention
Comparator / control treatment
Participants will serve as their own control. We will use a healthy human model whereby glycogen concentration in the control leg of the individual is differentiated (as having not undergone glycogen depletion) the evening prior to the experimental day. This design allows us to distinguish between possible systemic and local effects because the systemic concentrations of circulating hormones and metabolites are the same for both legs, yet the local (muscle) glycogen availability is markedly different. The use of the human single-limb model permits paired-analyses in the same individual, reducing the variability in exercise-regulated protein and gene responses to exercise.
Control group
Active

Outcomes
Primary outcome [1] 326675 0
Determine the effects of a single session of exercise on protein post-translational modifications (i.e. protein phosphorylation) in skeletal muscle with low versus high glycogen availability.
Timepoint [1] 326675 0
Skeletal muscle biopsy samples will be obtained before and immediately following exercise from both the low and high glycogen legs to measure protein post-translational modifications (i.e. phosphorylation).
Primary outcome [2] 326676 0
Determine the effects of a single session of exercise on protein content in skeletal muscle with low versus high glycogen availability.
Timepoint [2] 326676 0
Skeletal muscle biopsy samples will be obtained before and immediately following exercise from both the low and high glycogen legs to measure protein content.
Secondary outcome [1] 392338 0
Determine the effects of a single session of exercise on gene expression (i.e. transcription) in skeletal muscle with low versus high glycogen availability.
Timepoint [1] 392338 0
Skeletal muscle biopsy samples will be obtained before, immediately following and 3 h post-exercise from both the low and high glycogen legs to measure gene expression (i.e. transcription).
Secondary outcome [2] 393984 0
Determine the effects of a exercise on plasma hormone and metabolite concentrations. This is a composite and exploratory secondary outcome.
Timepoint [2] 393984 0
Blood samples will be obtained before, immediately following and 3 hours following two-legged exercise to measure the effects of exercise on plasma hormones and metabolites.

Eligibility
Key inclusion criteria
Participants will be recruited if they meet the following criteria:
• Male
• Aged 18-30 y
• BMI: 18.5-27 kg/m2
• Recreationally active (i.e. target V02 max approximately between 40-45 ml/kg)
• No cardiopulmonary abnormalities
• No injuries
• Pass the ESSA pre-exercise screening tool and/or obtain GP clearance to exercise
• Able to ride a stationary cycle ergometer at high intensity and successfully complete the entire duration of the glycogen depletion exercise protocol
Minimum age
18 Years
Maximum age
30 Years
Sex
Males
Can healthy volunteers participate?
Yes
Key exclusion criteria
Exclusion criteria:
• Known cardiovascular disease or diabetes mellitus
• Known bleeding disorder (i.e. hemophilia A [factor VIII deficiency]
• Hemophilia B [factor IX deficiency]
• von Willebrand disease, or other rare factor deficiencies including I, II, V, VII, X, XI, XII and XIII)
• Major or chronic illness that impairs mobility or eating/digestion
• Taking prescription medications (i.e. beta-blockers, anti-arrhythmic drugs, statins, insulin sensitising drugs, or drugs that increase the risk of bleeding [i.e. anticoagulants, antiplatelets, novel oral anticoagulants [NOAs], nonsteroidal anti-inflammatory drugs [NSAIDs], selective norepinephrine reuptake inhibitors [SNRI], or selective serotonin reuptake inhibitors [SSRIs]
• Unable or unwilling to have a muscle biopsy
• Weight has changed more than 5 kg in past 3 months
• Currently on a restrictive diet
• Unable to attend the lab based on ACU's campus in Fitzroy (inner suburb of Melbourne), Victoria for the 5 study visits for completion of study protocol

Study design
Purpose of the study
Prevention
Allocation to intervention
Randomised controlled trial
Procedure for enrolling a subject and allocating the treatment (allocation concealment procedures)
Sealed opaque envelopes.
Methods used to generate the sequence in which subjects will be randomised (sequence generation)
Simple randomisation using computer-generated, randomised sequence. An independent third party will prepare the computer-generated randomisation lists and sealed envelopes for randomisation. Once informed consent is obtained, the sealed randomisation envelope will be opened revealing the leg-condition order.
Masking / blinding
Open (masking not used)
Who is / are masked / blinded?



Intervention assignment
Other
Other design features
Both conditions (low and high muscle glycogen) will be studied in the two legs from the same participant on a single experimental day. The only randomisation involved will be the sequence of muscle biopsy collection from each leg and the single leg assigned for glycogen depletion.
Phase
Not Applicable
Type of endpoint/s
Statistical methods / analysis
Statistical analysis: Data obtained from each of the participants' two legs with differential glycogen content will be analysed using Generalised Linear Mixed Models. Statistics will analyse factor (time: pre-exercise, immediately post-exercise, and/or 3 h post-exercise) and glycogen availability condition (low versus high glycogen leg). Statistical significance will be set at P<0.05. Statistical power calculations (minimum power of 80%, P<0.05, 2 dependent means (matched pairs), 2-tailed test) were undertaken using G*Power version 3 software using raw data from previously reported effect size changes in post-exercise signaling (i.e. AMPK and p38 MAPK pathway protein phosphorylation) related to our primary outcome measures. Estimated sample size was calculated at n=10 participants.

Recruitment
Recruitment status
Recruiting
Date of first participant enrolment
Anticipated
26/04/2021
Actual
18/10/2021
Date of last participant enrolment
Anticipated
17/12/2024
Actual
Date of last data collection
Anticipated
31/12/2024
Actual
Sample size
Target
10
Accrual to date
5
Final
Recruitment in Australia
Recruitment state(s)
VIC

Funding & Sponsors
Funding source category [1] 307983 0
University
Name [1] 307983 0
Australian Catholic University
Country [1] 307983 0
Australia
Primary sponsor type
Individual
Name
Dr Nolan Hoffman
Address
Exercise and Nutrition Research Program
Mary MacKillop Institute for Health Research
Level 5, 215 Spring Street
Melbourne, VIC 3000
Country
Australia
Secondary sponsor category [1] 308703 0
Individual
Name [1] 308703 0
Professor John Hawley
Address [1] 308703 0
Exercise and Nutrition Research Program
Mary MacKillop Institute for Health Research
Level 5, 215 Spring Street
Melbourne, VIC 3000
Country [1] 308703 0
Australia

Ethics approval
Ethics application status
Approved
Ethics committee name [1] 307974 0
Australian Catholic University Human Research Ethics Committee (ACU HREC)
Ethics committee address [1] 307974 0
Manager, Ethics
c/o Office of the Deputy Vice Chancellor (Research)
Australian Catholic University
North Sydney Campus
PO Box 968
North Sydney, NSW 2059
Ethics committee country [1] 307974 0
Australia
Date submitted for ethics approval [1] 307974 0
05/03/2020
Approval date [1] 307974 0
17/07/2020
Ethics approval number [1] 307974 0
2020-56H

Summary
Brief summary
The energy status of skeletal muscle is tightly coupled to the activity of proteins and genes within the network of molecular responses to exercise and the resulting health benefits of exercise. This research project will investigate how protein and gene responses to a single session of exercise are changed when skeletal muscle glycogen levels are altered in healthy adults. A total of 10 healthy, recreationally active males, 18-30 yr of age with a body mass index (BMI) of 18.5-27 kg/m2 will be recruited after providing written informed consent. In the fortnight before the experimental two-legged high intensity exercise session, all participants will complete preliminary testing including a 3-day food record, body composition scan (DXA), fitness testing (VO2 peak test), exercise session familiarisation and one-legged glycogen depletion exercise. This study will use a healthy human model whereby glycogen concentration in the right and left legs of the same individual are differentiated (low versus high glycogen) the evening prior to the experimental day. This experimental design allows us to distinguish between possible systemic and local effects because the systemic concentrations of circulating hormones and metabolites are the same for both legs, yet the local (muscle) glycogen availability is markedly different. On the experimental day, a total of 6 muscle biopsies (including 3 from each leg) and a total of 3 blood samples will be obtained from each participant. These samples will be utilised to determine how exercise-induced changes in protein post-translational modifications (i.e. phosphorylation), protein content and gene expression in skeletal muscle are influenced by glycogen availability. We hypothesise that a single session of exercise with low skeletal muscle glycogen availability will result in greater increases in exercise-stimulated muscle protein post-translational modifications (i.e. phosphorylation) and muscle gene expression (i.e. transcription), but comparable changes in muscle protein content, compared to high glycogen availability.
Trial website
Trial related presentations / publications
Public notes

Contacts
Principal investigator
Name 109106 0
Dr Nolan Hoffman
Address 109106 0
Exercise and Nutrition Research Program
Mary MacKillop Institute for Health Resarch
Level 5, 215 Spring Street
Melbourne, VIC 3000
Country 109106 0
Australia
Phone 109106 0
+61 03 9230 8277
Fax 109106 0
Email 109106 0
nolan.hoffman@acu.edu.au
Contact person for public queries
Name 109107 0
Dr Nolan Hoffman
Address 109107 0
Exercise and Nutrition Research Program
Mary MacKillop Institute for Health Resarch
Level 5, 215 Spring Street
Melbourne, VIC 3000
Country 109107 0
Australia
Phone 109107 0
+61 03 9230 8277
Fax 109107 0
Email 109107 0
nolan.hoffman@acu.edu.au
Contact person for scientific queries
Name 109108 0
Dr Nolan Hoffman
Address 109108 0
Exercise and Nutrition Research Program
Mary MacKillop Institute for Health Resarch
Level 5, 215 Spring Street
Melbourne, VIC 3000
Country 109108 0
Australia
Phone 109108 0
+61 03 9230 8277
Fax 109108 0
Email 109108 0
nolan.hoffman@acu.edu.au

Data sharing statement
Will individual participant data (IPD) for this trial be available (including data dictionaries)?
No
No/undecided IPD sharing reason/comment


What supporting documents are/will be available?

Doc. No.TypeCitationLinkEmailOther DetailsAttachment
10833Study protocol  Nolan.hoffman@acu.edu.au
10834Ethical approval  Nolan.hoffman@acu.edu.au



Results publications and other study-related documents

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