Year of Award


Document Type


Degree Type

Master of Science (MS)

Degree Name

Health and Human Performance (Exercise Science Option)

Department or School/College

Integrative Physiology and Athletic Training

Committee Chair

Brent Ruby

Commitee Members

John Quindry Rich Willy


University of Montana



Previous studies have used the doubly labelled water (DLW) method to evaluate the total energy expenditure (TEE) during Ironman, ultra-marathon trail runs and competitive road cycling. However, the technique has not been applied to a 24-hour cross-country mountain bike event. This case study examined the TEE, cycling metrics and ad libitum nutrient/fluid intake in a trained male cyclist during a 24-hour cross-country mountain bike race. A trained male cyclist (41 y, 74.1 kg, 172.4 cm) received an oral dose of DLW prior to the 24-hour event for the calculations of TEE and water turnover (rH2O). Nude body weight and urine samples were collected pre, during, and post-race. Total nutrient (TNI) and fluid intake (TFI) and cycling metrics (speed, power output, cadence, HR) were continuously quantified during the event. The rider completed 383 km coupled with a vertical gain of ~7,737 m (GPS) during the 24-hour event. Average speed, power and HR were 16.3±2, 122±29 W, and 134±18 bpm, respectively. TEE and TNI were 41 and 23.5 MJ, respectively. Total carbohydrate intake was 1192 g with an average hourly intake of 58±22 Total body weight was 75.3 and 72.3 kg pre- and post-race, respectively with an ad libitum total fluid intake of 13.3 L. These data provide foundational measures of TEE, TEI and TFI during an ultra-endurance cross-country mountain biking event which can provide for future race/training strategies.



© Copyright 2022 Patrick S. Dodds