Beetroot Juice: a Natural Aid for Boosting the Health Benefits of Exercise in Post-menopausal Women?

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.

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).

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.

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.

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.

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.

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.

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.

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.

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 %.

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.

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.

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.