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- Björklund, Glenn, 1972-, et al.
(författare)
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Biomechanical Adaptations and Performance Indicators in Short Trail Running
- 2019
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Ingår i: Frontiers in Physiology. - : Frontiers Media S.A.. - 1664-042X. ; 10
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Tidskriftsartikel (refereegranskat)abstract
- Our aims were to measure anthropometric and oxygen uptake ((V)over dot O-2) variables in the laboratory, to measure kinetic and stride characteristics during a trail running time trial, and then analyse the data for correlations with trail running performance. Runners (13 men, 4 women: mean age: 29 +/- 5 years; stature: 179.5 +/- 0.8 cm; body mass: 69.1 +/- 7.4 kg) performed laboratory tests to determine (V)over dot O-2 (max), running economy (RE), and anthropometric characteristics. On a separate day they performed an outdoor trail running time trial (two 3.5 km laps, total climb: 486 m) while we collected kinetic and time data. Comparing lap 2 with lap 1 (19:40 +/- 1:57 min vs. 21:08 +/- 2:09 min, P < 0.001), runners lost most time on the uphill sections and least on technical downhills (-2.5 +/- 9.1 s). Inter-individual performance varied most for the downhills (CV > 25%) and least on flat terrain (CV < 10%). Overall stride cycle and ground contact time (GCT) were shorter in downhill than uphill sections (0.64 +/- 0.03 vs. 0.84 +/- 0.09 s; 0.26 +/- 0.03 vs. 0.46 +/- 0.90 s, both P < 0.001). Force impulse was greatest on uphill (248 +/- 46 vs. 175 +/- 24 Ns, P < 0.001) and related to GCT (r = 0.904, P < 0.001). Peak force was greater during downhill than during uphill running (1106 +/- 135 vs. 959 +/- 104 N, P < 0.01). Performance was related to absolute and relative (V)over dot O-2 (max) (P < 0.01), vertical uphill treadmill speed (P < 0.001) and fat percent (P < 0.01). Running uphill involved the greatest impulse per step due to longer GCT while downhill running generated the highest peak forces. (V)over dot O-2 (max), vertical running speed and fat percent are important predictors for trail running performance. Performance between runners varied the most on downhills throughout the course, while pacing resembled a reversed J pattern. Future studies should focus on longer competition distances to verify these findings and with application of measures of 3D kinematics.
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| 2. |
- Zinner, Christoph, et al.
(författare)
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Influence of Hypoxic Interval Training and Hyperoxic Recovery on Muscle Activation and Oxygenation in Connection with Double-Poling Exercise
- 2015
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 10:10
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Tidskriftsartikel (refereegranskat)abstract
- Here, we evaluated the influence of breathing oxygen at different partial pressures during recovery from exercise on performance at sea-level and a simulated altitude of 1800 m, as reflected in activation of different upper body muscles, and oxygenation of the m. triceps brachii. Ten well-trained, male endurance athletes (25.3 +/- 4.1 yrs; 179.2 +/- 4.5 cm; 74.2 +/- 3.4 kg) performed four test trials, each involving three 3-min sessions on a double-poling ergometer with 3-min intervals of recovery. One trial was conducted entirely under normoxic (No) and another under hypoxic conditions (Ho; FiO2 = 0.165). In the third and fourth trials, the exercise was performed in normoxia and hypoxia, respectively, with hyperoxic recovery (HOX; FiO2 = 1.00) in both cases. Arterial hemoglobin saturation was higher under the two HOX conditions than without HOX (p<0.05). Integrated muscle electrical activity was not influenced by the oxygen content (best d = 0.51). Furthermore, the only difference in tissue saturation index measured via near-infrared spectroscopy observed was between the recovery periods during the NoNo and HoHOX interventions (P<0.05, d = 0.93). In the case of HoHo the athletes' P-mean declined from the first to the third interval (P < 0.05), whereas P-mean was unaltered under the HoHOX, NoHOX and NoNo conditions. We conclude that the less pronounced decline in P-mean during 3 x 3-min double-poling sprints in normoxia and hypoxia with hyperoxic recovery is not related to changes inmuscle activity or oxygenation. Moreover, we conclude that hyperoxia (FiO2 = 1.00) used in conjunction with hypoxic or normoxic work intervals may serve as an effective aid when inhaled during the subsequent recovery intervals.
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