Trail running, where you run on dirt roads, single tracks, rocks and in the mountains has increased in popularity during the last few years. Compared to flat running, trail running is more technical challenging as the running takes place over rocks, roots as well as firm gravel roads or slippery tracks in the forest. Also, trail running often includes very steep uphill and downhill sections where it is too steep to run for most runners. The difference between track running and trail running is therefore significant and it is likely that biomechanical and physiological characteristics are different in specialized track runners compared to specialized trail runners. Hence, the purpose of the present study was to investigate the biomechanical and physiological characteristics for specialized trail runners compared to track runners, while running a typical trail running track. Method: Nine professional runners (3 women and 6 men) were recruited to the study. First, the runners performed an incremental lab test to determine running economy and VO2max. Thereafter, the group was divided into trail running specialists and track runners (5 trail runners and 4 flat runners). Second, all runners were equipped with 16 Inertial Measurements Units, IMU (MyoMotion, Noraxon Inc., Scottsdale, AZ, USA) and pressure insoles (MotiCon GmbH, Munich, Germany). Kinematic data was collected at 200 Hz and pressure data at 50 Hz. Each subject performed a 10-15 min long warm up before the data collection. The track consisted of two laps on a 3.5 km long technical loop which included a total vertical climb of 850 m. Ten continuing running cycles were analyzed during running on flat single track, moderate downhill and steep downhill. The subjects had one minute of rest between the two laps where all systems where checked and adjusted if necessary. Results: The trail running specialist showed a trend to complete the two runs on average 59.3 s faster than the track runners as well as loosing less time between the two runs compared to the track runners (54.0 s vs. 100.3 s. respectively). Step frequency and ground contact time were significant higher during steep downhill running compared to flat- and moderate downhill running (p<0.001). Steep downhill running generated lower peak forces than flat running (p<0.05). No differences in step kinetics were observed between flat- and moderate downhill running. A trend to increased hip and knee flexion was observed in the trail running specialists compared to the flat runners. Discussion: The present study showed clear differences in step kinetics when running in undulating terrain. Experienced trail runners completed the two laps on average 59.3 s. faster, even though all subjects have comparable VO2max (53±3 mL/kg/min for women and 65±5 mL/kg/min for men). Trail runners showed better ability to adapt to the surface and the kinematic data show increased joint flexion in the lower joints which is considered to decrease leg stiffness and contribute to "Groucho" running.
© Copyright 2015 20th Annual Congress of the European College of Sport Science (ECSS), 24th-27th June 2015, Malmö -Sweden. Book of Abstracts. Alle Rechte vorbehalten.