The Bruce treadmill protocol: does walking or running during the fourth stage alter oxygen consumption values?

Area of Science:

• Exercise Physiology
• Cardiorespiratory Fitness Assessment

Background:

• The Bruce treadmill protocol is a standard method for assessing cardiorespiratory fitness.
• Understanding factors influencing measures like heart rate (HR) and oxygen consumption (VO2) is crucial for accurate assessment.

Purpose of the Study:

• To compare heart rate (HR) and relative oxygen consumption (VO2) during walking versus running stages of the Bruce treadmill protocol.
• To examine the influence of age and height on these physiological measures.

Main Methods:

• 27 male volunteers (ages 25-56) performed two randomly assigned Bruce treadmill tests to volitional fatigue.
• Heart rate and oxygen consumption were recorded at one-minute intervals and at exhaustion.

Main Results:

• Significant differences in VO2 and HR were observed between walking and running at minutes 11 and 12, with running yielding higher values.
• No significant differences in VO2 or HR were found between younger (<45) and older (>=45) subjects.
• Age, height, and modality did not significantly affect VO2 during the fourth stage of the protocol.
• Strong correlations were found for HR between protocols, but weaker correlations for VO2.
• Significant within-subject variability indicated a potential learning effect between test administrations.

Conclusions:

• Modality, age, and height are not significant factors influencing VO2 during the fourth stage of the Bruce treadmill test in endurance-trained males.
• A learning effect may influence physiological responses during repeated treadmill testing sessions.