Intensity profile during an ultra-endurance triathlon in relation to testing and performance

Area of Science:

• Sports Science
• Exercise Physiology
• Cardiovascular Physiology

Background:

• Ultra-endurance triathlons (UET) demand sustained physiological effort across multiple disciplines.
• Understanding the intensity profile and cardiovascular strain during UET is crucial for optimizing performance.
• Heart rate (HR) and oxygen uptake (VO2) are key physiological markers of exercise intensity.

Purpose of the Study:

• To examine the HR-based intensity profile during an UET.
• To relate this intensity profile to race performance in male ultra-endurance triathletes.
• To identify predictors of final race time in UET.

Main Methods:

• Nine male ultra-endurance triathletes underwent graded exercise tests for cycling, running, and swimming to establish individual HR-VO2 relationships.
• Exercise-specific HR-VO2 regression equations were developed.
• Mean race HR was compared across disciplines, and HR differences were correlated with race times.

Main Results:

• Mean race HR was significantly higher during swimming (149.2 bpm) compared to cycling (137.1 bpm) and running (136.2 bpm).
• During cycling and running, HR was maintained below ventilatory threshold (VT).
• The HR difference between swimming and cycling correlated with overall race, cycling, and running times, with larger differences predicting worse performance in subsequent stages.

Conclusions:

• Ultra-endurance triathletes perform the swimming leg at a higher relative intensity than cycling or running.
• This higher swimming intensity is inversely correlated with performance in subsequent race stages.
• Weight-adjusted VO2max and the HR difference between cycling and swimming were the best predictors of final UET race time.