Metric Trails is a research lab developing quantitative methods to study trail runners and human movement in free-living conditions.

We work across geospatial science, sports analytics and artificial intelligence. Our methods are published in peer-reviewed research and released as open-source software.

Trail, mountain and ultra races deserve measurements that are fair, reproducible and comparable worldwide. Distance and elevation should be facts, not guesses. Good data and standardised practice protect athletes, organisers and the sport itself.

GNSS devices measure position, not distance. Distance and elevation gain are reconstructed from sampled points, and five sources of discrepancy shape the result.

Position drift

Forests, canyons and weather degrade the signal, and hardware design determines how well a device holds it.

Spatial resolution

Coarse sampling cuts corners and shortens distance. At 1 Hz, resolution depends on movement speed.

Elevation source

GNSS and barometric elevation fluctuate even at the same point. A digital elevation model gives a stable, repeatable reference.

Processing

2D or 3D distance, the distance formula and the coordinate reference system all change the result.

Field protocol

Device choice, placement, pace and conditions determine data quality.

Lost resolution cannot be recovered. Tracks are only comparable when they share the same resolution and elevation source, and that is what the MT standards provide.

Each standard is a spatial resolution. A track is assigned the finest standard its own sampling supports, and it is also valid for the coarser ones.

• 
  MT-5050 m resolution, expected for recreational use.
• 
  MT-55 m resolution, expected for competitive use.
• 
  MT-11 m resolution, expected for scientific use.

The level is set on the original file by its Nyquist resolution, the 90th percentile of the horizontal distance between consecutive readings, together with the geometric, topographic and kinematic properties of the track. Files without timestamps are assessed on less evidence, not excluded. The audit is fully automatable with the metrictrails R package.

• 2026Modeling heart rate (HR) dynamics to reconstruct missing HR data in trail runningSchnack, T., Sanchez, R. and Baca, A. BMC Sports Science, Medicine and Rehabilitation, 18(1), 298.
• 2026A post-processing methodology for improving kinematic consistency in GNSS-based running trajectoriesMartínez, C., Sanchez, R. and Diaz, C. 6th International Conference on Electrical, Computer and Energy Technologies (ICECET), Rome.
• 2025Human trajectory mapping in ecological contexts: a framework for reliable space-time localizationSanchez, R. ANZSCPB Conference 2025, Sippy Downs (abstract).
• 2025High-Precision Mapping of Mountain Terrain for Human Locomotion Research: A Multimodal Geospatial FrameworkSanchez, R., Nieto-Jimenez, C. and Riveros-Matthey, C. 15th IEEE International Conference on Pattern Recognition Systems (ICPRS), Viña del Mar.
• 2025Classifying physical activity types using only GPS data: towards improving fair play on fitness platformsDiaz, C., Sanchez, M., Arce, R. and Sanchez, R. IEEE International Geoscience and Remote Sensing Symposium (IGARSS), Brisbane.
• 2025How fractal complexity distorts distance and elevation gain in trail and mountain running: the case for course measurement standardizationSanchez, R., Egli, P. E., Jornet, K., Duggan, M. and Besomi, M. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology.
• 2025Evaluation of accelerometer placement for step frequency estimation in inclined locomotion: a pilot study in trail runningSanchez, R. and Flores, S. 5th International Conference on Electrical, Computer and Energy Technologies (ICECET), Paris.
• 2024Evaluación de la accesibilidad a la montaña en el Gran SantiagoSanchez, R., Zuniga, S., Morales, J., Monsalve, R. and Valenzuela, L. In Accesibilidad para ciudades equitativas (pp. 295–314). RIL Editores.
• 2024Assessing the impact of digital elevation model resolution on elevation gain estimations in trail runningSanchez, R., Egli, P., Besomi, M. and Truffello, R. International Conference on Electrical, Computer and Energy Technologies (ICECET), Sydney.
• 2024Analysing gait transition dynamics in uphill trail running from wearable devicesSanchez, R. 42nd International Society of Biomechanics in Sports Conference (ISBS), Salzburg.
• 2020Comparative evaluation of wearable devices for measuring elevation gain in mountain physical activitiesSánchez, R. and Villena, M. Proceedings of the Institution of Mechanical Engineers, Part P: Journal of Sports Engineering and Technology, 234(4), 312–319.
• 2020Use of digital devices to follow a Trail Runner. Case studySánchez, R. and Nieto-Jiménez, C. Retos, 38, 582–586.

Check a GPX file against the MT standards. The audit reports the file’s quality flags, its spatial resolution and the MT level it supports. It requires a free account, and audited files are stored by Metric Trails for analysis and anonymised scientific use. You can also run the same audit yourself with the metrictrails R package.

Audit a GPX file

• Raimundo Sanchez Principal Investigator Senior Research Fellow, Centre for Innovation in Pain and Health Research (CiPHeR), The University of Queensland Google ScholarORCID
• Claudio Díaz Research Fellow Assistant Professor, Faculty of Engineering and Science, Universidad Adolfo Ibáñez Google ScholarORCID

• Roberto Arce
• Arnold Baca
• Manuela Besomi
• Michael Duggan
• Pascal E. Egli
• Sebastian Flores
• Kilian Jornet
• Clovis Martínez
• Rafaella Monsalve
• Javier Morales
• Claudio Nieto-Jiménez
• Cristian Riveros-Matthey
• Matias Sanchez
• Tjorven Schnack
• Ricardo Truffello
• Luis Valenzuela
• Marcelo Villena
• Sofia Zuniga