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.

Participants will receive CHG SPORT for four weeks, followed by a four-week washout period and then placebo for four weeks.

Dietary Supplement: Standardized Tart Cherry and Aronia Extract · Dietary Supplement: Placebo

Participants will receive placebo for four weeks, followed by a four-week washout period and then CHG SPORT for four weeks.

Dietary Supplement: Standardized Tart Cherry and Aronia Extract · Dietary Supplement: Placebo

Oral capsules containing 400 mg per capsule of a double-standardized extract of Prunus cerasus (Vistula) and Aronia melanocarpa (Michaux). The Prunus cerasus extract is standardized to a minimum of 15% polyphenols and 3% anthocyanins (DER 40:1), and the Aronia melanocarpa extract is standardized to a minimum of 50% polyphenols and 25% anthocyanins (DER 70:1). The intervention will be administered for four weeks during the active supplementation period.

Maltodextrin-based placebo capsules visually matched to CHG SPORT capsules and supplied in identical containers. The placebo will be administered according to the same dosing schedule and for the same four-week duration as the active intervention.

Time frame: Baseline and Day 28 of each intervention period

Change in resting total peripheral resistance (TPR) from baseline to the end of each 4-week intervention period. TPR will be derived from continuous non-invasive arterial blood pressure recordings obtained during the resting supine recording. Lower values after intervention indicate a reduction in resting TPR.

Time frame: Baseline and Day 28 of each intervention period

Change in brachial artery flow-mediated dilation (FMD), expressed as the percentage increase in maximal brachial artery diameter during reactive hyperemia relative to baseline diameter, from baseline to the end of each 4-week intervention period.

Time frame: Baseline and Day 28 of each intervention period

Total peripheral resistance (TPR) response to hypoxia will be quantified as the absolute value of the slope of the regression line relating TPR to arterial oxygen saturation (SpO2) during the transient hypoxia test. For each nitrogen-breathing episode, one pre-hypoxic and one post-hypoxic point will be included. The pre-hypoxic point will represent mean SpO2 and mean TPR during the 40-second period preceding nitrogen administration. The post-hypoxic point will represent the SpO2 nadir and the corresponding minimum TPR value within a window extending from 10 seconds before to 30 seconds after the SpO2 nadir. The regression will be fitted using all pre- and post-hypoxic points obtained during the test. The slope will be expressed as an absolute value; therefore, a higher value indicates a greater reduction in TPR in response to a given decrease in SpO2 and thus a stronger vascular response to hypoxia.

Time frame: Baseline and Day 28 of each intervention period

Hypoxic ventilatory response (HVR) will be quantified as the absolute value of the slope of the regression line relating inspiratory minute ventilation (VI) to arterial oxygen saturation (SpO2) during the transient hypoxia test. For each nitrogen-breathing episode, the pre-hypoxic point will represent mean SpO2 and mean VI during the 40-second period preceding nitrogen administration. The post-hypoxic point will represent the SpO2 nadir and the mean of the three highest VI values within a window extending from 10 seconds before to 30 seconds after the SpO2 nadir. The regression will be fitted using all pre- and post-hypoxic points obtained during the test. The slope will be expressed as an absolute value, with higher values indicating greater peripheral chemosensitivity.

Time frame: Baseline and Day 28 of each intervention period

Change in peak oxygen uptake (VO2peak) from baseline to the end of each 4-week intervention period. VO2max will be determined during symptom-limited cardiopulmonary exercise testing performed on a cycle ergometer using an individualized ramp protocol with continuous analysis of respiratory gases.

Time frame: Baseline and Day 28 of each intervention period

Change in the standard deviation of normal-to-normal RR intervals (SDNN) from baseline to the end of each 4-week intervention period. SDNN will be derived from resting electrocardiographic recordings as a time-domain measure of heart rate variability.

Time frame: Baseline and Day 28 of each intervention period

Change in plasma asymmetric dimethylarginine (ADMA) concentration from baseline to the end of each 4-week intervention period. ADMA is assessed as a circulating marker related to nitric oxide bioavailability and endothelial function.

Time frame: Baseline and Day 28 of each intervention period

Change in plasma interleukin-6 (IL-6) concentration from baseline to the end of each 4-week intervention period.

Time frame: Baseline and Day 28 of each intervention period

Change in skin advanced glycation end-products (AGEs) from baseline to the end of each 4-week intervention period. Tissue accumulation of AGEs will be assessed non-invasively by measurement of skin autofluorescence at the forearm.

Effects of Oral Supplementation With a Double-Standardized Extract of Tart Cherry (Prunus Cerasus (Vistula)) and Aronia Berry (Aronia Melanocarpa (Michaux)) on Selected Physiological Parameters in Healthy Endurance-Trained Men