Baroreflex Sensitivity Response to Exercise

Summary

Males and females show distinct differences in cardiovascular function, especially during exercise. Evidence suggests that females generally have lower blood pressure due to hormonal influences that reduce blood vessel constriction. This protective effect may contribute to a lower risk of high blood pressure and cardiovascular diseases in females compared to males. Additionally, females tend to have different patterns of heart rate control and blood pressure regulation, largely due to differences in the autonomic nervous system and hormonal balance.

One key mechanism involved in blood pressure control is the baroreflex, which helps stabilize blood pressure by adjusting heart rate and blood vessel function. The sensitivity of the baroreflex (known as baroreflex sensitivity, or BRS) can vary between males and females. For instance, females may exhibit slower adjustments in heart rate in response to blood pressure changes, but they also tend to have better blood pressure regulation during moderate exercise.

The main purpose of this study is to explore whether these sex-specific differences extend to more intense exercise. Investigators will compare the responses of young, active males and females to cycling at two exercise intensities: moderate (50% of Heart Rate Reserve, HRR) and vigorous (80% HRR). As a secondary purpose, investigators we will assess the inter-day repeatability of HRV and BRS parameters measured at rest and during moderate and vigorous intensity exercise utilizing sequence and spectral indices in apparently healthy young adult males and females.

We hypothesize that:

1. Females will show higher HRV and BRS at rest compared to males, indicating better heart rate control.
2. During exercise, females will have greater cardiovagal (heart-related) activation than males, regardless of exercise intensity.
3. When exercise sessions are matched for blood pressure, there will be no significant sex differences in HRV and BRS responses.
4. Sequential methods techniques can be used to assess cardiovagal BRS and HRV changes between days during exercise in young adults, regardless of their sex. In addition, the inclusion of vigorous intensity may improve the repeatability of the outcome measure due to sympathetic outflow predominance.

Conditions

• Sex

Interventions

OTHER

Moderate Intensity Continuous Exercise

Participants perform a continuous cycling exercise session on a reclined ergometer at moderate intensity (50% HRR)

OTHER

Vigorous Intensity Continuous Exercise

Participants perform a continuous cycling exercise session on a reclined ergometer, at a vigorous intensity (80% HRR).

OTHER

Moderate Intensity Continuous Exercise Matched for Blood Pressure

Participants perform a cycling session where exercise intensity is adjusted to match the systolic blood pressure levels attained during the first visit at moderate intensity (50% HRR).

OTHER

Vigorous Intensity Continuous Exercise Matched for Blood Pressure

Participants perform a different cycling session where exercise intensity is adjusted to match the systolic blood pressure levels attained during the first visit at vigorous intensity (80% HRR).

Sponsors & Collaborators

• Faculdade de Motricidade Humana

  collaborator OTHER

• Egas Moniz - Cooperativa de Ensino Superior, CRL

  lead OTHER

Study Design

Allocation

NON_RANDOMIZED

Purpose

OTHER

Masking

SINGLE

Model

CROSSOVER

Eligibility

Min Age

18 Years

Max Age

44 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2023-01-02

Primary Completion

2023-07-28

Completion

2023-07-28

Countries

• Portugal

Study Locations