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Completed

NCT Number: NCT06908941

The Cardiovascular Benefits of Resistance Training and Dark Chocolate in Female Adults

This study investigates the effects of 85% dark chocolate supplementation on vascular function and nitric oxide (NO) levels during high-intensity resistance exercise in healthy women across menstrual phases. Using a randomized crossover design, 31 women consumed either dark chocolate or milk chocolate before exercising during the early follicular and mid-luteal phases. Vascular markers, including pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels, were measured at multiple time points.

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Key information

Conditions

Vascular Function in Healthy Volunteers

Age range

20 year–30 year

Sex eligibility

Female

Study type

Interventional

Phase

Not applicable

Primary location

National Chung Cheng University

Chiayi County, Taiwan, Taiwan

About this study

Background:

Dark chocolate, rich in flavanols, may support vascular health by reducing arterial stiffness and blood pressure across menstrual phases. This study examined the effects of 85% dark chocolate on nitric oxide (NO) levels and vascular function during high-intensity resistance exercise in healthy women across the early follicular and mid-luteal phases.

Methods:

Thirty-one healthy women (aged 20-30 years) with regular menstrual cycles completed a randomized, crossover study (conducted at National Chung Cheng University, Sep-Dec 2023). Participants consumed either 85% dark chocolate or milk chocolate (1g/kg body weight) before high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles. Finger-toe pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

  • the healthy adult women,
  • aged 20-30 years, from a local university campus,
  • had a regular menstrual cycles in the past three months.

Exclusion criteria

  • (1) irregular menstrual cycles (menstrual cycle length < 21 or > 35 days in the past three months),
  • (2) pregnancy or lactation in the past year,
  • (3) history of cardiovascular or uterine surgery in the past six months,
  • (4) use of contraceptives or other female hormone medications,
  • (5) smoking or alcohol consumption habits,
  • (6) hypertension (blood pressure > 140/90 mmHg), chronic diseases, heart disease, or other cardiovascular conditions, (7) allergy to cocoa products, nuts, or fruits.

Treatment and study plan

Dark chocolate

Dietary Supplement

Participants consumed 85% dark chocolate (1g/kg body weight) before high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles. Finger-toe pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

Milk Chocolate

Dietary Supplement

Participants consumed milk chocolate (1g/kg body weight) before high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles. Finger-toe pulse wave velocity (ftPWV), arterial stiffness, blood pressure, and plasma NO levels were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

high-intensity resistance exercise

Behavioral

Participants performed high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles.

Primary outcomes

  1. Finger-Toe Pulse Wave Velocity (ftPWV)

    Time frame: Finger-toe pulse wave velocity (ftPWV) were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

    Measurements at other time points are taken while participants are resting in the laboratory. Firstly, sensors for photoplethysmography (PPG) were placed on the right index finger and right big toe of the participants. These sensors were marked with an oily pen to ensure consistent placement throughout the experiment. The signals were then amplified using a Biopec MP150 (MP150, Biopac Systems Inc., Goleta, CA, USA), with each physiological signal collected for at least 150 seconds. The signals were analyzed using MATLAB to calculate the time difference between the two pulse waves. The length of the participant's body segments ( sternum to the right index finger, and sternum to the big toe of the right foot) was measured, and this value was divided by the average difference between 10 pulse waves (in the stable interval of 150 seconds) to calculate the ftPWV value (m/s).

Secondary outcomes

  1. Arterial Index

    Time frame: Arterial index (API and AVI) were measured at rest, 2 hours after chocolate consumption (baseline), immediately post-exercise (T0), and at 60 (T60) and 120 (T120) minutes post-exercise.

    The arterial pressure volume index (API) and arterial velocity pulse index (AVI) are measured using the PASESA AVE-2000 (PASESA, Tokyo, Japan) with a wrapped around the right upper arm of seated participants. The API reflected the stiffness of peripheral arteries by assessing the pressure-volume relationship of the artery, while the AVI primarily reflected the stiffness of central arteries by analyzing the ratio of forward and reflected pressure waves. Each measurement was taken three times, and the average of the three readings was recorded.

Sponsors and collaborators

Lead sponsor

National Cheng Kung University

Other

Registry information

Official study title

The Cardiovascular Benefits of Dark Chocolate Supplementation Before High-intensity Resistance Exercise in the Early Follicular and Mid-luteal Phases of the Menstrual Cycle

Important dates

Study start
2023
Primary completion
2023
Study completion
2024
First posted
Apr 3, 2025
Registry last updated
Apr 4, 2025

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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