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Menopause and ageing bring several changes to women's health, partly due to a decline in the hormone estrogen. This reduction affects multiple systems in the body, including muscles and bones, and also influences the production of nitric oxide, a molecule that plays a key role in regulating blood flow and blood pressure. An reduced ability to produce nitric oxide is associated with higher blood pressure and an increased risk of cardiovascular and metabolic diseases.
Many women also experience lower levels of physical activity and changes in body composition during midlife, such as increased body fat and reduced muscle mass and strength, which may further decrease exercise capacity.
This PhD project investigates whether a simple, natural strategy, combining exercise with beetroot juice, can help postmenopausal women achieve greater benefits from exercise. Beetroot juice is naturally rich in nitrates, which the body can convert into nitric oxide, thereby enhancing blood flow. Exercise itself also stimulates nitric oxide production, and together these approaches may have additive or even synergistic effects.
The study examines whether consuming beetroot juice before exercise can enhance training adaptations and health outcomes in postmenopausal women. Key outcomes include cardiovascular function, body composition, musculoskeletal function, and aerobic capacity.
Some evidence suggests that beetroot juice may amplify the body's response to exercise, which could be particularly beneficial for postmenopausal women, who often face greater barriers to physical activity. By exploring this combined approach, the project aims to evaluate a safe, non-pharmacological strategy to improve physical function and overall health in women after menopause.
Menopause and ageing are associated with significant changes in women's health, partly due to the decline in estrogen production. Estrogen contributes to the regulation of cardiovascular function and metabolism, as well as the maintenance of musculoskeletal health, in part by stimulating nitric oxide (NO) production, a key signalling molecule involved in vascular function. Ageing per se is also linked to reduced NO bioavailability, meaning that postmenopausal women may experience a combined decline driven by both lower estrogen levels and age-related physiological changes. Together, these factors are associated with an increased risk of cardiometabolic dysfunction, reduced exercise tolerance, and potential declines in quality of life.
This PhD project examines a non-pharmacological approach: the combination of beetroot juice (BRJ) supplementation and exercise (BRJ+EX). Both BRJ and exercise can enhance NO production through different pathways, which may result in additive effects. This approach may be relevant for postmenopausal women, in whom both estrogen-related and age-related NO production are reduced.
The study will investigate whether BRJ+EX can influence exercise-induced adaptations, including changes in cardiometabolic health, body composition, musculoskeletal function, and exercise tolerance, compared with placebo beetroot juice combined with exercise (BRJplacebo+EX). Some recent evidence suggests that BRJ ingestion prior to combined exercise training may enhance certain training responses, which could be particularly relevant for postmenopausal women who may experience barriers to exercise. Thus, building on this evidence, this study aim to test the hypothesis that pre-workout ingestion of BRJ enhances exercise adaptions in post-menopausal women comprehensively.
Furthermore, given the lack of information on the impact of hormone replacement therapy (HRT), this study also aim to explore whether HRT modulates exercise adaptions by also including women taking HRT.
Overall, this project aims to contribute to the evidence base on non-pharmacological approaches to supporting health and physical function in postmenopausal women.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Nitrate rich | Experimental |
| |
| Nitrate depleted | Placebo Comparator |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| Beetroot Juice (Beet-It Stamina Shot) & Supervised Exercise Training | Dietary Supplement | Intervention includes 3 sessions per week of combined strength and resistance exercise. Two of the sessions are supervised, while the third session is unsupervised-home-based. |
| Measure | Description | Time Frame |
|---|---|---|
| Maximal oxygen uptake | Maximal oxygen uptake (VO₂max) will be measured using a standardized incremental exercise test to volitional exhaustion on a cycle ergometer, with continuous analysis of expired gases (indirect calorimetry). VO₂max will be determined as the highest VO₂ value achieved during the test and reported as ml/min and ml/kg/min. Validity of test will be determined based on established criteria such as a plateau in oxygen uptake despite increasing workload, a respiratory exchange ratio above a predefined threshold (e.g., ≥1.10), and/or attainment of age-predicted maximal heart rate. When a clear plateau is not observed, the highest recorded VO₂ (VO₂peak) will be reported. | Before and after 12 weeks of intervention |
| Measure | Description | Time Frame |
|---|---|---|
| Skeletal muscle strength | Maximal upper- and lower-body strength will be determined using a Keiser pneumatic leg press and chest press machine as well as handgrip dynamometer using standardized protocols. Maximal strength for will be defined as the highest load achieved and will be reported in kilograms (kg). | Before and after 12 weeks of intervention |
| Measure | Description | Time Frame |
|---|---|---|
| Arterial stiffness | Arterial stiffness will be assessed by carotid-femoral pulse wave velocity (cfPWV) in accordance with established expert consensus guidelines. Pulse wave velocity will be determined from the transit time of the arterial pulse waveform between the carotid and femoral arteries, measured in the supine position following a standardized rest period. Arterial stiffness will be reported as cfPWV in meters per second (m/s), with higher values indicating greater arterial stiffness. |
Inclusion Criteria:
Exclusion Criteria:
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| Name | Role | Phone | Extension | |
|---|---|---|---|---|
| Ann-Katrin Grotle, PhD | Contact | +4790960580 | ann-katrin.grotle@hvl.no | |
| Brit Jorun Liseth, MSc | Contact | +4790013513 | brit.jorun.fossan.liseth@hvl.no |
| Name | Affiliation | Role |
|---|---|---|
| Ann-Katrin Grotle, PhD | Western Norway University of Applied Sciences | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Western Norway University of Applied Sciences | Recruiting | Bergen | 5063 | Norway |
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| ID | Term |
|---|---|
| D009043 | Motor Activity |
| ID | Term |
|---|---|
| D001519 | Behavior |
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| Exercise economy | Exercise economy will be assessed during a standardized incremental lactate threshold test using indirect calorimetry. Oxygen consumption (VO₂) will be measured during submaximal exercise stages below the lactate threshold, and exercise economy will be defined as the steady-state oxygen cost at a given absolute workload. Exercise economy will be reported as oxygen consumption relative to workload (e.g., mL·kg-¹·min-¹ or L·min-¹ at a standardized power output or speed), with lower oxygen cost indicating better exercise economy. | Before and after 12 weeks of intervention |
| Lean mass | Lean mass changes will be assessed using validated body composition analysis methods, including dual-energy X-ray absorptiometry (DXA), according to site-specific standard operating procedures. Measurements will be performed at baseline and after 12 weeks of exercise training under standardized conditions. Total and regional lean mass will be measured and reported in kilograms and % of total mass. | Before and after 12 weeks of intervention |
| Resting blood pressure | Resting blood pressure control will be assessed after >15 minutes of supine rest under standardized condition by measuring systolic and diastolic blood pressure five times during a 10 minute resting period, with at least one minute between measurements. A validated automated device will be used. The average of five systolic and diastolic blood pressure measurements will be used for reporting and is reported in mmHg. | Before and after 12 weeks of intervention |
| Blood pressure reactivity | Blood pressure reactivity will be assessed as the change in mean arterial pressure (MAP) in response to standardized stress tasks (e.g., isometric handgrip exercise and cold pressor test). Reactivity will be quantified as the difference between resting baseline MAP and peak MAP achieved during each stress task and will be reported in mmHg. | Before and after 12 weeks of intervention |
| Before and after 12 weeks of intervention |
| Endothelial function | Endothelial function will be assessed by brachial artery flow-mediated dilation (FMD) in accordance with current expert consensus guidelines. FMD will be measured using high-resolution ultrasound following a standardized period of forearm occlusion and subsequent reactive hyperemia. Endothelial function will be quantified as the percentage change in brachial artery diameter from baseline to peak post-occlusion diameter and reported as FMD (%), with higher values indicating better endothelial function. | Before and after 12 weeks of intervention |
| Pelvic floor strength | Pelvic floor muscle strength will be assessed using a vaginal pressure manometer (Camtech manometer). Participants will be examined in a supine position and covered with a towel for privacy. A small pressure-sensitive vaginal probe will be inserted into the vagina, and participants will perform three maximal voluntary pelvic floor muscle contractions. The highest recorded value will be used for analysis and reported in cmH₂O, with higher values indicating greater muscle strength. The Camtech manometer has demonstrated validity and normative reference values are available for the relevant age group. | Before and after 12 weeks of intervention |
| Fat mass | Fat mass changes will be assessed using validated body composition analysis methods, including dual-energy X-ray absorptiometry (DXA), according to site-specific standard operating procedures. Measurements will be performed at baseline and after 12 weeks of exercise training under standardized conditions. Total and regional fat mass will be measured and reported in kilograms and %. | Before and after 12 weeks of intervention |
| Visceral fat | Visceral adipose tissue will be assessed from whole-body dual-energy X-ray absorptiometry (DXA) scans using manufacturer-specific software algorithms for estimation of abdominal visceral fat. Visceral adipose tissue will be reported in grams (g) or volume (cm³), with higher values indicating greater visceral fat accumulation. | Before and after 12 weeks of intervention |
| Fasting triglyserides | Fasting triglyceride concentrations will be assessed from venous blood samples collected following an overnight fast. Blood samples will be analyzed using standard enzymatic laboratory methods. Fasting triglyceride levels will be reported in mmol/L, with lower values indicating a more favorable lipid profile. | Before and after 12 weeks of intervention |
| Fasting glukose | Fasting glucose concentrations will be assessed from venous blood samples collected following an overnight fast. Blood samples will be analyzed using standard clinical laboratory methods. Fasting glucose levels will be reported in mmol/L, with lower values indicating better glycemic control. | Before and after 12 weeks of intervention |