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Ergometry with respiratory gas analysis, also known as cardiopulmonary exercise testing (CPET), allows measurement of oxygen consumption (VO2), carbon dioxide production (VCO2) and other respiratory parameters during exercise. To determine the anaerobic threshold, these steps are followed:

Patient Preparation:

The patient is placed on a cycloergometer or treadmill.

Respiratory gas measurement equipment, such as a mask or mouthpiece connected to a gas analyzer, is attached.

Heart rate monitors and other devices needed to measure blood pressure and electrocardiogram (ECG) are attached.

  1. Exercise Protocol: Exercise begins at a low intensity and is gradually increased in defined stages, generally every 1-3 minutes. The workload increases progressively to ensure a smooth transition between intensity levels. Respiratory Gas Measurement: During exercise, VO2 and VCO2 are measured continuously, as well as other parameters such as ventilation (VE), respiratory rate (FR) and tidal volume (VT). Anaerobic Threshold Determination: Respiratory Ratio Method (RER): one of the most common methods is to observe the point at which the respiratory quotient (RER), which is the ratio of VCO2 to VO2, reaches a value of approximately 1.0. However, this value may vary depending on the individual and the intensity of exercise. Ventilatory Threshold (VT) method: The ventilatory threshold (VT) is identified, the point where a disproportionate increase in ventilation relative to VO2 is observed. This can be visualized on a VE/VO2 graph, where an inflection point is seen. Ventilatory Equivalent Method: A significant increase in the VE/VO2 slope is observed without a parallel change in VE/VCO2, indicating that the body is increasing ventilation in an attempt to compensate for lactic acid accumulation.

Interpretation of Results

  • Graphs and Data: The collected data are graphed, noting the relationship between VO2, VCO2, and VE. The interpretation of these graphs and data allows the identification of the anaerobic threshold point.

  • Reporting and Follow-up: A detailed report with the results of the anaerobic threshold is prepared and provided to the patient along with personalized recommendations to improve performance and aerobic capacity.

The anaerobic threshold is a crucial value for athletes and patients in cardiac rehabilitation programs, as it helps to personalize training plans and evaluate physical capacity and progress over time.


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