Physiological comparisons among three maximal treadmill exercise protocols in trained and untrained individuals

Area of Science:

• Exercise Physiology
• Sports Science
• Cardiorespiratory Fitness

Background:

• Maximal oxygen uptake (VO2max) and anaerobic threshold (AT) are key indicators of cardiorespiratory fitness.
• Standardized exercise protocols are crucial for reliable physiological measurements.
• The influence of different exercise protocols on VO2max and AT in trained versus untrained individuals requires further investigation.

Purpose of the Study:

• To investigate the impact of three distinct incremental treadmill exercise protocols (Astrand, Bruce, Costill/Fox) on VO2max and AT.
• To determine if training status (trained vs. untrained) modifies the protocol-specific effects on these physiological parameters.

Main Methods:

• Fifteen untrained men, 10 untrained women, and 12 trained men participated.
• Subjects completed all three protocols in a randomized order.
• VO2max was determined by averaging the highest consecutive oxygen uptake measurements, and AT was identified using the V-slope method.

Main Results:

• VO2max was not significantly different across protocols in untrained individuals.
• In untrained individuals, AT was lower with the Bruce protocol compared to the Astrand protocol.
• In trained individuals, both VO2max and AT were lower with the Bruce protocol compared to Astrand or Costill/Fox protocols.

Conclusions:

• Treadmill exercise protocol does not affect VO2max measurements in healthy individuals.
• Short-duration protocols (approx. 5 min) are time-efficient for assessing VO2max in untrained subjects.
• The anaerobic threshold (AT) is protocol-dependent, irrespective of training status, with the Bruce protocol yielding lower values.