Sex Differences in Baroreflex Sensitivity Response to Different Constant-load Submaximal Exercise Intensities
试验速览
- 阶段
- 不适用
- 状态
- 已完成
- 发起方
- 入组人数
- 40
- 试验地点
- 1
- 主要终点
- Changes in Heart Rate Variability
研究概览
简要总结
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:
- Females will show higher HRV and BRS at rest compared to males, indicating better heart rate control.
- During exercise, females will have greater cardiovagal (heart-related) activation than males, regardless of exercise intensity.
- When exercise sessions are matched for blood pressure, there will be no significant sex differences in HRV and BRS responses.
- 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.
详细描述
Forty healthy and physically active participants (20 males and 20 females) aged 18-31 were recruited for this study. All participants reported to the laboratory in a fasted state (>4 hours) and refrained from consuming foods or drinks containing caffeine or alcohol for at least 12 hours. They also avoided strenuous exercise for at least 24 hours prior to the testing sessions. The menstrual cycle was not controlled for female participants. All participants provided written informed consent after receiving a detailed explanation of the study's aims and experimental procedures.
This study was constructed as a crossover trial. Participants attended 4 separate intervention sessions. On the first visit, participants had their body composition evaluated by a clinical bioimpedance device using 8 electrodes positioned on each hand and foot. Each participant also performed a ramp incremental cycle ergometer test to exhaustion on a recumbent stationary cycle ergometer (Excite Recline Med, TechnoGym, Italy). On the second and third visit, participants quietly rested for 15 min in the supine position to evaluate heart rate variability (HRV) using a 5-ECG lead module (Nova, Finapres Measurement Systems, Amsterdam, The Netherlands), carotid (Arietta V60 ultrasound; Aloka/Hitachi Medical Systems) and aortic (Complior Analyse software (ALAM Medical, Paris, France) arterial stiffness. Participants then performed a 6 minutes bout of moderate intensity continuous exercise (MICE) at 50% heart rate reserve [HRR= 0.5*(HRmax- HRrest) + HRrest] followed by a 6 minutes vigorous intensity continuous exercise (VICE) bout at 80% HRR on a recumbent stationary bike, while having their HRV, beat-by-beat blood pressure and carotid arterial stiffness evaluated at HR steady state at each intensity. Visits 2 and 3 provided the data for the repeatability objective and hypothesis. On the fourth visit, the participants performed an acute bout of MICE and VICE, but this time at the corresponding average blood pressure at each intensity from visits 2 and 3. As men show higher blood pressure values during exercise, in the fourth visit we matched their intensity of exercise with the average blood pressure attained by women during steady state at each intensity.
Blood pressure and HR were monitored beat-by-beat and carotid arterial stiffness was measured at BP steady-state.
All visits were conducted in the morning with each participant performing sessions at the same time of the day to minimize any potential diurnal variation.
研究设计
- 研究类型
- Interventional
- 分配方式
- Non Randomized
- 干预模型
- Crossover
- 主要目的
- Other
- 盲法
- Single (Participant)
盲法说明
Participants were blinded to the order of the visits until arrival at the laboratory.
入排标准
- 年龄范围
- 18 Years 至 44 Years（Adult）
- 性别
- All
- 接受健康志愿者
- 是
入选标准
- •Males and females aged 18 to 44 years old.
- •Physical active as assessed by the International Physical Activity Questionnaire (IPAQ).
- •Low risk to increase physical Activity as assessed by the Physical Activity Readiness Questionnaire (PAR-Q+).
排除标准
- •Diagnosed with cardiac, metabolic or renal diseases
- •Taking cardioactive medication
- •Resting hypertension (systolic blood pressure >140 mmHg, diastolic blood pressure > 90 mmHg).
研究组 & 干预措施
Heart Rate Reserve (HRR)-Based Exercise Intensity Prescription
The exercise intensity is based solely on HRR.
干预措施: Moderate Intensity Continuous Exercise (Other)
Heart Rate Reserve (HRR)-Based Exercise Intensity Prescription
The exercise intensity is based solely on HRR.
干预措施: Vigorous Intensity Continuous Exercise (Other)
Blood Pressure-Matched Exercise Intensity Prescription
Instead of relying on HRR, exercise intensity is tailored to replicate the average systolic blood pressure achieved in the initial HRR-based session.
干预措施: Moderate Intensity Continuous Exercise Matched for Blood Pressure (Other)
Blood Pressure-Matched Exercise Intensity Prescription
Instead of relying on HRR, exercise intensity is tailored to replicate the average systolic blood pressure achieved in the initial HRR-based session.
干预措施: Vigorous Intensity Continuous Exercise Matched for Blood Pressure (Other)
结局指标
主要结局
Changes in Heart Rate Variability
时间窗: At rest and in the last 2 minutes of the 6 minutes bout of MICE and VICE
R-R intervals were derived from beat-to-beat blood pressure pulse intervals using finger plethysmography (Finapres® Nova, Amsterdam, Netherlands) at rest and during exercise across all visits. The pressure signal's upstroke was identified with a 2 ms resolution, and the interval between consecutive upstrokes was measured. In the frequency domain, low-frequency (LF; 0.04-0.15 Hz) reflected sympathetic and parasympathetic modulation, while high-frequency (HF; 0.15-0.40 Hz) served as a marker of parasympathetic modulation. The LF/HF ratio indicated sympathovagal dominance. Data acquisition and analysis were conducted following the Task Force guidelines of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology.
Changes in Baroreflex sensitivity
时间窗: At rest and in the last 2 minutes of the 6 minutes bout of moderate intensity continuous exercise and high intensity continuous exercise
A spectral method was used to compute baroreflex sensitivity as the transfer gain of the cross-spectra between pressure and interval at rest and during exercise across all visits. Coherence was typically high in the 10 s rhythm band (0.06-0.15 Hz) and at ventilatory frequencies (0.15-0.5 Hz). Spectral estimates of the recordings were computed using the Finapres® Nova device software (Amsterdam, Netherlands), which provided an easy-to-use interface. A discrete Fourier transform, requiring no interpolation or zero padding, was applied. Triangular spectral smoothing was set at a width of 10, reflecting the 10-minute duration of the recordings. Spectral density, coherence, pressure-interval transfer gain, and phase plots were displayed on the device screen, with a cursor allowing manual selection of bands with high coherence and spectral power. An output program listed the resultant data and all selections made for subsequent analysis.
次要结局
- Regional Arterial Stiffness(At rest in each visit to the laboratory, just before the 6 minutes bouts of MICE and VICE)
- Central Blood Pressure(At rest and in the last 2 minutes of the 6 minutes bout of moderate intensity continuous exercise and high intensity continuous exercise)
- Changes in Local Arterial Stiffness(At rest and in the last 2 minutes of the 6 minutes bout of moderate intensity continuous exercise and high intensity continuous exercise)
- Changes in Carotid Blood Pressure Wave Intensity(At rest and in the last 2 minutes of the 6 minutes bout of moderate intensity continuous exercise and high intensity continuous exercise)