REF-898 · Næss et al., 2021 · Frontiers in Physiology, Vol. 12, article · Paper · PubMed

Exercise Intensity and Pacing Pattern During a Cross-Country Olympic Mountain Bike Race

Blimited evidenceMeasured on highly trained athletesWritten before October 2026, being re-checked

Five male and two female national-level XCO riders raced a UCI Cat. 1 event (19 km, 5 laps for women; 23 km, 6 laps for men) with their own power meters, and were tested in the lab for critical power (CP), W′ and maximal aerobic power (MAP). Over 96 min, mean power was only 76% of CP and 63% of MAP, yet 40% of race time was above CP, in bouts of about 8 s at about 120% of CP.

From the first to the last lap, time above CP fell by 9% and W′ used per lap by 45%, and single bouts lost magnitude, while the number and duration of bouts did not change significantly. The authors conclude that XCO demands rapid changes in metabolic power through many short above-CP actions that shrink in size in later laps.

Participants

n=7 national competitive XCO cyclists: 5 men and 2 women.

Protocol

One UCI Cat. 1 XCO race: 19 km and 5 laps (women), 23 km and 6 laps (men).
Power output (PO) from each rider's personal power meter.
Two laboratory tests on their own bikes and power meters:
CP and W′ from three time trials of 12, 7 and 3 min
MAP from a 3-step submaximal test and the maximal oxygen uptake of the 7-min time trial

Key Results

Race duration 96 ± 7 min; mean PO 76 ± 9% of CP and 63 ± 4% of MAP.
40 ± 8% of race time with PO > CP; mean bout above CP lasted ~8 s at ~120% of CP.
First to last lap: time > CP per lap fell by 9 ± 6%; accumulated W′ per lap fell by 45 ± 17%.
Single bouts above CP: mean magnitude fell by 25 ± 8% and mean W′ expended by 38 ± 15% from the first to the last lap.
The number and duration of bouts did not change significantly between laps.

Practical Application

In 7 national-level XCO riders, a 96-min race averaged only 76% of critical power, yet 40% of race time was above CP in bouts of about 8 s at about 120% of CP; from first to last lap the bouts kept their number and length but lost 25% of their magnitude. To "why does my XCO race feel so hard when my average power is low?": the race is made of many short efforts above CP, and average power hides them.
The late-race fade is in the size of each surge, not in how often the rider surges: W′ spent per lap fell by 45% from first to last lap.
Inference, not tested here: training that repeats short efforts above CP late in a long session is the closest match to this pattern.
Not from this paper; the base's own practice: the XCO training framework is SYNTH-49. Granier's international riders (REF-897) were described against MAP and ventilatory thresholds rather than CP, so do not merge the two sets of numbers.

Limitations

n=7 (5 men, 2 women) in a single race; men and women raced different distances.
National level, not international elite.
CP and W′ from a three-trial model in the lab; field power meters were each rider's own.
Written from the abstract and record metadata only (full text not read).
How this entry was checked and changed
Why this level

n=7