This research proposal aims to elucidate the physiological responses to pine bark extract supplementation during a single bout of high-intensity cycling exercise at 70% VO₂max and the subsequent recovery phase. Specifically, the study seeks to investigate the underlying mechanisms by which pine bark extract modulates exercise-induced fatigue and metabolic fitness, and to determine whether such supplementation may enhance endurance performance in the post-recovery period.
The primary active component of natural pine bark extract (PBE) is proanthocyanidins, which possess antioxidant, anti-inflammatory, and endothelial function-enhancing properties. These attributes suggest its potential as an ergogenic aid to improve exercise performance. In this study, 14 healthy participants will be randomly assigned to receive either 300 mg/day of PBE or a placebo for 4 consecutive days. Following supplementation, participants will consume a low-calorie meal (300 kcal) accompanied by either the placebo or PBE and rest for one hour. One hour after capsule ingestion, participants will perform a 60-minute cycling exercise at 70% VO₂max. Upon completion of the exercise challenge, they will consume a post-exercise meal adjusted to body weight. After a 3-hour recovery period, subjects will undergo an anaerobic power test followed by an endurance test at 75% VO₂max to volitional exhaustion. Gas exchange and blood samples will be collected at multiple time points: pre- and post-initial cycling session, during the recovery phase, and following the exhaustive endurance test. Gas samples will be analyzed to determine rates of fat and carbohydrate oxidation. Blood biomarkers will be assessed for glucose, superoxidase dismutase (SOD), malondialdehyde (MDA), interleukin-6 (IL-6), tumor necrosis factor-alpha (TNF-α), creatine kinase (CK), lactate dehydrogenase (LDH), and uric acid (UA).
Study Type
INTERVENTIONAL
Allocation
RANDOMIZED
Purpose
OTHER
Masking
QUADRUPLE
Enrollment
14
The Placebo capsule supplement was taken for 4 days (3 capsules per day)
The PBE capsule supplement was taken for 4 days, with a daily dosage of 300 mg of PBE (equivalent to 3 capsules per day, each containing 100 mg of PBE).
China Medical University
Taichung, Taiwan
Time to Exhaustion (TTE)
The total duration (in minutes) from the start of the graded exercise test until the participant reaches volitional exhaustion or can no longer maintain the required cadence of 60 RPM. Unit of Measure: Minutes
Time frame: Baseline and at the end of the 4-week crossover period.
Serum Tumor Necrosis Factor-alpha (TNF-alpha) Concentration
A pro-inflammatory cytokine measured in serum using a commercial ELISA kit (BioLegend) to evaluate the inflammatory response.Unit of Measure: Picograms per milliliter (pg/mL)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Superoxide Dismutase (SOD) Activity
biomarker used to evaluate total antioxidant capacity. Serum SOD activity is measured using a commercial colorimetric assay kit and read with an ELISA plate reader.Unit of Measure: Units per milliliter (U/mL).
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Blood Glucose Levels
Estimated from blood using the glucometer to assess glycemic response during the trials.
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Uric Acid (UA) Levels
Measured in serum as a marker of metabolic stress and muscle damage using commercial analytical reagents. Unit of Measure: Milligrams per deciliter (mg/dL).
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Lactate Dehydrogenase (LDH) Activity
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Description: A biomarker of muscle damage measured in serum using an automated clinical chemistry analyzer (Beckman Coulter AU5800). Unit of Measure: Units per Liter (U/L)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Serum Interleukin-6 (IL-6) Concentration
A pro-inflammatory cytokine measured in serum using a commercial ELISA kit (BioLegend) to evaluate the inflammatory response. Unit of Measure: Picograms per milliliter (pg/mL)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Malondialdehyde (MDA) Levels
A standard biomarker of lipid peroxidation. Serum MDA levels are determined using a commercial ELISA kit to assess oxidative stress status. Unit of Measure: micromolar (μM)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Serum Creatine Kinase (CK) Concentration
A biomarker of muscle damage measured in serum using an automated clinical chemistry analyzer (Beckman Coulter AU5800). Unit of Measure: Units per Liter (U/L)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Carbohydrate (CHO) Oxidation Rate
Determined using VO 2 and VCO 2 data collected during the cycling challenge. Calculated using the equation: 4.585×VCO2 -3.226×VO2 . Unit of Measure: grams per minute (g/min)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Fat Oxidation Rate
Determined using VO 2 and VCO 2 data collected during the cycling challenge. Calculated using the Frayn equation: 1.695×VO 2 -1.701×VCO 2 . Unit of Measure: grams per minute (g/min)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Respiratory Exchange Ratio (RER)
Calculated as the ratio of carbon dioxide production ($VCO\_2$) to oxygen consumption ($VO\_2$). It reflects the relative contribution of carbohydrates and fats to energy metabolism. Unit of Measure: Ratio (Unitless)
Time frame: 7 time points (Baseline, START, END, 0 min, 60 min, 120 min, 180 min in two ergometer trials) during each crossover trial.
Maximal Oxygen Consumption (VO2max)
Measured using a graded exercise test on a stationary ergometer. VO2max is defined as the plateau in oxygen uptake despite an increase in workload, confirmed when at least two of the following criteria are met: (1) RER \> 1.10, (2) VO2 plateau (\< 2 ml/kg/min change), or (3) attainment of age-predicted maximum heart rate. Unit of Measure: ml/kg/min
Time frame: Baseline and at the end of the 4-week crossover period.
Profile of Mood States (POMS) - Vigor Subscale Score
A subscale of the POMS brief version used to evaluate the positive mood state of vigor. It consists of specific adjectives scored on a 5-point scale (1-5). Higher scores indicate higher levels of vigor. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Self-esteem Subscale Score
A subscale of the POMS brief version used to evaluate the mood state of self-esteem. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of self-esteem. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Tension Subscale Score
A subscale of the POMS brief version used to evaluate the negative mood state of tension. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of tension. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Confusion Subscale Score
A subscale of the POMS brief version used to evaluate the negative mood state of confusion. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of confusion. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Anger Subscale Score
A subscale of the POMS brief version used to evaluate the negative mood state of anger. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of anger. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Fatigue Subscale Score
A subscale of the POMS brief version used to evaluate the negative mood state of fatigue. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of fatigue. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.
Profile of Mood States (POMS) - Depression Subscale Score
A subscale of the POMS brief version used to evaluate the negative mood state of depression. Scored on a 5-point scale (1-5). Higher scores indicate higher levels of depression. Unit of Measure: Units on a scale
Time frame: Measured immediately after each cycling challenge at baseline and at the end of the 4-week crossover trial.