Effects of Tart Cherry and Aronia Extract Supplementation on Selected Physiological Parameters in Endurance-Trained Men

This study is a randomized, placebo-controlled, crossover dietary intervention designed to evaluate the effects of four weeks of supplementation with CHG SPORT, a double-standardized extract of tart cherry (Prunus cerasus, Vistula) and aronia berry (Aronia melanocarpa, Michaux), on cardiopulmonary regulation, vascular function, and exercise performance in healthy endurance-trained men aged 40-75 years.

A total of 25 participants will be enrolled. Participants will be randomized to one of two intervention sequences. In one sequence, participants will receive CHG SPORT for four weeks, followed by a four-week washout period and then placebo for four weeks. In the alternative sequence, placebo will be administered first, followed by the washout period and subsequent CHG SPORT supplementation. The placebo consists of maltodextrin-containing capsules. Physiological assessments will be performed immediately before and at the end of each four-week intervention period, allowing within-participant comparison of responses to CHG SPORT and placebo.

At each assessment, resting cardiovascular and respiratory function will first be evaluated during a 15-20-minute recording in the supine position. Electrocardiography, arterial oxygen saturation, continuous non-invasive arterial blood pressure, inspiratory airflow, and end-tidal carbon dioxide will be recorded simultaneously. Derived variables will include heart rate, systolic, diastolic and mean arterial pressure, stroke volume, cardiac output, total peripheral resistance, tidal volume, respiratory rate, and minute ventilation. The resting recordings will also be used to assess cardiac autonomic regulation using heart rate variability analysis.

Peripheral chemoreflex function will be assessed using the transient hypoxia method. The test will be performed immediately after the resting recording using the same respiratory and cardiovascular monitoring system. While breathing through a face mask connected to a switching respiratory circuit, participants will be exposed to a series of brief periods of pure nitrogen inhalation lasting approximately 5-40 seconds. Individual nitrogen exposures will be separated by at least three minutes of room-air breathing to allow physiological variables to return toward baseline. Each test will include approximately 4-10 hypoxic stimuli of different intensity, producing a range of transient reductions in arterial oxygen saturation. The resulting ventilatory response, including changes in minute ventilation, and cardiovascular responses, including changes in heart rate and arterial blood pressure, will be quantified in relation to the magnitude of oxygen desaturation. This approach will be used to characterize peripheral chemoreflex sensitivity.

Endothelial function will subsequently be evaluated using brachial artery flow-mediated dilation (FMD). After 10-15 minutes of supine rest, the brachial artery will be visualized using high-resolution ultrasound with a linear transducer. The artery will be imaged approximately 3-10 cm above the antecubital fossa and baseline vessel diameter will be determined at end diastole. A pneumatic cuff will then be inflated to suprasystolic pressure, typically 200-250 mmHg, for five minutes. Following rapid cuff deflation, the artery will be continuously imaged for approximately 2-3 minutes during reactive hyperemia. FMD will be calculated as the percentage increase in maximal brachial artery diameter relative to baseline diameter and will be used as a functional measure of endothelium-dependent vasodilation.

Cardiorespiratory exercise capacity will be assessed using a symptom-limited cardiopulmonary exercise test (CPET) performed on a cycle ergometer with continuous analysis of oxygen and carbon dioxide in expired air. Following a one-minute warm-up at 0 W, workload will increase continuously using an individualized ramp protocol of approximately 15-30 W/min while participants maintain a cadence of approximately 60 revolutions per minute. The ramp rate will be selected according to the participant's expected exercise capacity. Variables assessed during CPET will include peak oxygen uptake (VO2), carbon dioxide output, minute ventilation, respiratory rate, heart rate, maximal workload, exercise duration, and aerobic and anaerobic thresholds. Capillary blood lactate will be measured immediately before and immediately after CPET to characterize the metabolic response to exercise.

Additional cardiovascular assessment will include 24-hour ambulatory blood pressure monitoring performed under usual daily living conditions. Tissue accumulation of advanced glycation end-products will also be assessed non-invasively by measurement of skin autofluorescence at the forearm.

Venous blood samples will be obtained immediately before and immediately after each CPET and again approximately 24 hours after exercise. The analyses include selected parameters of metabolic, inflammatory, endothelial, and oxidative-stress profile, including gene-expression markers.

The crossover design allows each participant to serve as his own control. The study will therefore compare changes occurring during four weeks of CHG SPORT supplementation with changes occurring during the corresponding placebo period. The overall objective is to determine whether supplementation with the tart cherry and aronia extract modifies cardiovascular and autonomic regulation, peripheral chemoreflex responsiveness, endothelial function, ambulatory blood pressure, exercise capacity, and selected biochemical responses in healthy endurance-trained men.