Photo by Kalen Emsley (Unsplash)

Trail running is an emergent endurance running discipline that takes place in open country on unpaved surfaces. It includes various distances, with ultramarathons (>42k) being the most popular.

Running on steep terrains alters the running parameters, with uphill running characterized by a concentric phase and downhill running dominated by an eccentric phase, being the concentric phase approximately 3–5 times more energetically demanding than the eccentric one.

Pacing strategy significantly affects ultratrail performance. Positive pacing, where runners slow down throughout the race, except for a final spurt, is commonly observed. Even pacing, with minimal speed variation, has been associated with better finish times.

Factors such as performance level, sex, and age can influence pacing strategy, although findings are inconsistent. Extrinsic factors like terrain also impact pacing strategy.

Previous studies have focused on specific races or factors, and a comprehensive analysis using a large dataset from multiple races is still missing. Such analysis would provide valuable information to optimize training and performance.

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The study

A recent study analyzed data from four popular trail running races held within the past five years:  the Ultra Trail Mont Blanc (UTMB), the Courmayeur-Champex-Chamonix (CCC), the Javelina 100 km and the Javelina 100 miles. A total of 16,518 athletes (14,330 male and 2,188 female) were included with the race course characteristics retrieved from the official event guides.

Regarding the athletes, they were categorized, and three datasets analysed: all finishers, elite men (top 10 men from each race), and elite women (top 10 women from each race).

As for the terrain, the analysis categorized it into uphill, downhill, or level sections based on the elevation profile between two consecutive checkpoints, and further categorized as belonging to the first or second half of the race. Sections characterized as mixed or flat were excluded.

Thus, three values were calculated:

  1. Average Race Speed (ARS)
  2. Average Speed of each Section (ASS)
  3. Pacing strategy, evaluated as Relative Section Speed percentage (RSS) and calculated as (ASS/ARS) × 100.



  • Faster finishers tended to run faster in downhill sections and slower in uphill ones.
  • Differences in pacing strategy between faster and slower finishers increased in later stages.
  • In later stages there was a general tendency to slow down more in downhill sections than in uphill sections.
  • Among elite athletes, no significant differences in pacing strategy were observed.
  • Women paced less evenly than men and slowed down more in downhill sections in the later race stages.



  • The study did not include flat sections and the steepness of uphill and downhill sections due to inconsistent data availability.

Future studies should focus on examining how terrain steepness and flat sections affect pacing strategy in ultratrail races.

Photo by Todd Diemer (Unsplash)


Downhill Sections Are Crucial for Performance in Trail Running Ultramarathons-A Pacing Strategy Analysis. Genitrini M, Fritz J, Zimmermann G, Schwameder H. J Funct Morphol Kinesiol. 2022 Nov 21;7(4):103. doi: 10.3390/jfmk7040103

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