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

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

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.

Study Overview

• Status: Completed
• Conditions: Vascular Function in Healthy Volunteers
• Intervention / Treatment: Dietary supplement: dark chocolate; Dietary supplement: milk chocolate; Behavioral: high-intensity resistance exercise

Detailed Description

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.

• Study Type: Interventional
• Enrollment (Actual): 31
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Taiwan
  • Chiayi County, Taiwan, Taiwan
    • National Chung Cheng University

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

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.

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Double

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Early Follicular; 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) phases of two menstrual cycles.	Dietary supplement: dark chocolate; 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.; Dietary supplement: milk chocolate; 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.; Behavioral: high-intensity resistance exercise; Participants performed high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles.
Active Comparator: Mid-Luteal; Participants consumed either 85% dark chocolate or milk chocolate (1g/kg body weight) before high-intensity resistance exercise during the mid-luteal (days 18-24) phases of two menstrual cycles.	Dietary supplement: dark chocolate; 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.; Dietary supplement: milk chocolate; 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.; Behavioral: high-intensity resistance exercise; Participants performed high-intensity resistance exercise during the early follicular (days 2-5) and mid-luteal (days 18-24) phases of two menstrual cycles.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Finger-Toe Pulse Wave Velocity (ftPWV)	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).	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.

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Arterial Index	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.	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.

Collaborators and Investigators

• Sponsor: National Cheng Kung University
• Investigators: Principal Investigator: Cheng-Shiun He Professor, National Chung Cheng University

Publications and helpful links

General Publications

• Gaynor-Metzinger SHA, Triplett NT, Meucci M, Fasczewski KS, Flinchum DH, Collier SR. Central arterial stiffness, wave reflection, and heart rate variability following 4-week high-intensity resistance training intervention in young active women. Eur J Appl Physiol. 2022 Oct;122(10):2283-2293. doi: 10.1007/s00421-022-05003-4. Epub 2022 Jul 19.

Helpful Links

• National Chung Cheng University Human Research Ethics Center

Study record dates

Study Major Dates

• Study Start (Actual): September 1, 2023
• Primary Completion (Actual): December 31, 2023
• Study Completion (Actual): July 31, 2024

Study Registration Dates

• First Submitted: March 19, 2025
• First Submitted That Met QC Criteria: March 26, 2025
• First Posted (Actual): April 3, 2025

Study Record Updates

• Last Update Posted (Actual): April 4, 2025
• Last Update Submitted That Met QC Criteria: April 2, 2025
• Last Verified: April 1, 2025

More Information

Terms related to this study

• Keywords: estrogen; cardiovascular function; dark chocolate
• Other Study ID Numbers: CCUREC111122101

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Study Data/Documents

1. Informed Consent Form
   Information identifier: CCUREC111122101
   Information comments: National Chung Cheng University Human Research Ethics Center

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No