[Does the modified Bruce protocol induce physiological stress equal to that of the Bruce protocol?]

Area of Science:

• Cardiology
• Exercise Physiology
• Sports Medicine

Background:

• The Bruce protocol is a standard exercise stress test for assessing cardiovascular health.
• Modifications to the Bruce protocol are sometimes implemented to suit specific patient populations or clinical settings.
• Understanding the physiological stress differences between protocols is crucial for accurate patient assessment.

Purpose of the Study:

• To compare the physiological stress induced by the standard Bruce protocol versus a modified Bruce protocol.
• To evaluate differences in heart rate, blood pressure, and double product progression between the two protocols.
• To determine the adequacy of each protocol for different levels of physical capacity.

Main Methods:

• Retrospective analysis of clinical data from 80 apparently healthy individuals undergoing cardiac check-ups.
• Comparison of physiological parameters (heart rate, blood pressure, double product, exercise time) between individuals tested with the original Bruce protocol (n=51) and a modified Bruce protocol (n=29).
• Sequential sampling and data analysis of stress test results.

Main Results:

• The original Bruce protocol elicited significantly higher physiological stress in the initial stages compared to the modified protocol (p < 0.01 for heart rate, p < 0.0001 for blood pressure).
• At peak exercise, the original protocol group achieved higher systolic blood pressure (p < 0.001), double product (p = 0.01), and corrected exercise time (p = 0.02).
• A greater percentage of participants in the original protocol group completed higher exercise stages (76% vs. 48%, p = 0.02).

Conclusions:

• The modified Bruce protocol results in a less intense initial physiological stress but may lead to reduced peak exercise capacity due to peripheral fatigue.
• The original Bruce protocol induces a higher initial stress and allows for greater peak exercise intensity attainment.
• The original Bruce protocol is recommended for individuals with good physical capacity, while the modified protocol may be more suitable for those with moderate functional limitations.