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Kim Hébert-Losier, Kurt Jensen and Hans-Christer Holmberg

Purpose:

Jumping and hopping are used to measure lower-body muscle power, stiffness, and stretch-shortening-cycle utilization in sports, with several studies reporting correlations between such measures and sprinting and/or running abilities in athletes. Neither jumping and hopping nor correlations with sprinting and/or running have been examined in orienteering athletes.

Methods:

The authors investigated squat jump (SJ), countermovement jump (CMJ), standing long jump (SLJ), and hopping performed by 8 elite and 8 amateur male foot-orienteering athletes (29 ± 7 y, 183 ± 5 cm, 73 ± 7 kg) and possible correlations to road, path, and forest running and sprinting performance, as well as running economy, velocity at anaerobic threshold, and peak oxygen uptake (VO2peak) from treadmill assessments.

Results:

During SJs and CMJs, elites demonstrated superior relative peak forces, times to peak force, and prestretch augmentation, albeit lower SJ heights and peak powers. Between-groups differences were unclear for CMJ heights, hopping stiffness, and most SLJ parameters. Large pairwise correlations were observed between relative peak and time to peak forces and sprinting velocities; time to peak forces and running velocities; and prestretch augmentation and forest-running velocities. Prestretch augmentation and time to peak forces were moderately correlated to VO2peak. Correlations between running economy and jumping or hopping were small or trivial.

Conclusions:

Overall, the elites exhibited superior stretch-shortening-cycle utilization and rapid generation of high relative maximal forces, especially vertically. These functional measures were more closely related to sprinting and/or running abilities, indicating benefits of lower-body training in orienteering.

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Fabrice Vercruyssen, Mathieu Gruet, Serge S. Colson, Sabine Ehrstrom and Jeanick Brisswalter

Background:

Physiological mechanisms behind the use of compression garments (CGs) during off-road running are unknown.

Purpose:

To investigate the influence of wearing CGs vs conventional running clothing (CON) on muscle contractile function and running economy before and after short-distance trail running.

Methods:

Knee-extensor neuromuscular function and running economy assessed from two 5-min treadmill runs (11 and 14 km/h) were evaluated before and after an 18.6-km short-distance trail run in 12 trained athletes wearing either CGs (stocking + short-tight) or CON. Quadriceps neuromuscular function was assessed from mechanical and EMG recording after maximal percutaneous electrical femoral-nerve stimulations (single-twitch doublets at 10 [Db10] and 100 Hz [Db100] delivered at rest and during maximal quadriceps voluntary contraction [MVC]).

Results:

Running economy (in mL O2 · km–1 · kg–1) increased after trail running independent of the clothing condition and treadmill speeds (P < .001). Similarly, MVC decreased after CON and CGs conditions (–11% and –13%, respectively, P < .001). For both clothing conditions, a significant decrease in quadriceps voluntary activation, Db10, Db100, and the low-to-high frequency doublet ratio were observed after trail running (time effect, all P < .01), without any changes in rectus femoris maximal M-wave.

Conclusions:

Wearing CGs does not reduce physiological alterations induced during short-distance trail running. Further studies should determine whether higher intensity of compression pressure during exercises of longer duration may be effective to induce any physiological benefits in experienced trail runners.

Open access

Ricardo J.S. Costa, Beat Knechtle, Mark Tarnopolsky and Martin D. Hoffman

events and are typically either distance or time specific ( Hoffman et al., 2010 ). Trail running constitutes any off-road running event and can range from short distance fun runs to ultramarathon distance competitions. By nature, trail running is often associated with more harsh and challenging course