Indirect calorimetry during ultradistance running: a case report

Area of Science:

• Exercise Physiology
• Sports Science
• Human Performance

Background:

• Ultradistance trail running presents unique physiological demands.
• Accurate assessment of energy expenditure is crucial for performance and health in endurance athletes.
• Previous research may underestimate the metabolic cost of challenging trail running conditions.

Purpose of the Study:

• To quantify the energy expenditure during a segment of an ultradistance trail running race.
• To compare the energy cost of running in race conditions versus non-competitive settings.
• To determine the implications for nutritional strategies in ultradistance events.

Main Methods:

• A portable metabolic unit was used to measure oxygen consumption and other metabolic parameters in a male runner during a 64.5 km section of the Western States 100.
• Calibrations were performed under race-specific environmental conditions (temperature, humidity, altitude).
• Energy expenditure was calculated and compared to the subject's baseline energy cost of running.

Main Results:

• Average oxygen consumption was 34.0 ± 6.8 ml·kg(-1)·min(-1), representing 51% of VO2max.
• Energy expenditure was 12.6 ± 2.5 kcals·min(-1), or 82.7 ± 16.6 kcals·km(-1).
• This energy expenditure was higher than the subject's typical energy cost of running on non-undulating terrain.

Conclusions:

• Ultradistance trail running significantly elevates energy expenditure compared to running on level terrain.
• The increased energy cost may lead to underestimation of caloric requirements during such events.
• Adequate energy intake is critical to prevent undernourishment and maintain performance in ultradistance trail races.