Estimating Hemodynamic Responses to the Wingate Test Using Thoracic Impedance.

Area of Science:

• Exercise Physiology
• Cardiovascular Physiology
• Biomedical Engineering

Background:

• Assessing hemodynamic responses to exercise typically involves invasive methods like Fick or Doppler echocardiography.
• Thoracic impedance offers a noninvasive alternative for measuring stroke volume (SV) and cardiac output (CO) during graded exercise.
• The feasibility of thoracic impedance during supramaximal exercise, such as the Wingate test, remains less understood.

Purpose of the Study:

• To evaluate the use of thoracic impedance for estimating SV and CO during the Wingate anaerobic test (WAnT).
• To compare hemodynamic responses measured by thoracic impedance during WAnT with those from graded exercise testing (GXT).
• To determine the reliability of thoracic impedance measurements during repeated WAnT protocols.

Main Methods:

• Active men and women underwent two WAnTs and two GXTs on a cycle ergometer.
• Thoracic impedance was used for continuous estimation of heart rate (HR), SV, and CO during all exercise protocols.
• Repeated measures analysis of variance was employed to analyze hemodynamic differences across protocols.

Main Results:

• Maximal SV and CO were similar between repeated WAnTs, indicating high reliability.
• Mean maximal HR was higher during GXT compared to WAnT, while mean SV was higher during WAnT.
• Maximal cardiac output was comparable between WAnT and GXT, despite differences in intensity and duration.

Conclusions:

• Thoracic impedance is a feasible and reliable noninvasive method for assessing hemodynamic responses during supramaximal exercise (WAnT).
• The WAnT elicits similar maximal cardiac output compared to progressive cycling to VO2max.
• Thoracic impedance provides a simpler, noninvasive approach for continuous CO measurement in exercise physiology research.