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  • Author: Fernando Diefenthaeler x
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Tatiane Piucco, Rogério Soares, Fernando Diefenthaeler, Guillaume Y. Millet and Juan M. Murias

Purpose: To compare the oxygen-uptake (V˙O2) kinetics during skating on a treadmill and skating on a slide board and to discuss potential mechanisms that might control the V˙O2 kinetics responses during skating. Methods: Breath-by-breath pulmonary V˙O2 and near-infrared spectroscopy–derived muscle deoxygenated hemoglobin and myoglobin ([HHbMb]) were monitored continuously in 12 well-trained, young, long-track speed skaters. On-transient V˙O2 and [HHbMb] responses to skating on a treadmill and skating on a slide board at 80% of the estimated gas exchange threshold were fitted as monoexponential function. The signals were time-aligned, and the individual [HHbMb]-to-V˙O2 ratio was calculated as the average value from 20 to 120 s after exercise starts. Results: The time constants for the adjustment of phase II V˙O2V˙O2) and [HHbMb] (τ [HHbMb]) were low and similar between slide board and treadmill skating (18.1 [3.4] vs 18.9 [3.6] for τ V˙O2 and 12.6 [4.0] vs 12.4 [4.0] s for τ [HHbMb]). The [HHbMb]:V˙O2 ratio was not different from 1.0 (P > .05) in both conditions. Conclusions: The fast V˙O2 kinetics during skating suggest that chronic adaptation to skating might overcome any possible restriction in leg blood flow during low-intensity exercise. The V˙O2 ratio values also suggest a good matching of O2 delivery to O2 utilization in trained speed skaters. The similar τ V˙O2 and τ [HHbMb] values between slide board and treadmill further reinforce the validity of using a slide board for skating testing and training purposes.

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Tatiane Piucco, Fernando Diefenthaeler, Rogério Soares, Juan M. Murias and Guillaume Y. Millet

Purpose: To investigate the criterion validity of a maximal incremental skating test performed on a slide board (SB). Methods: Twelve subelite speed skaters performed a maximal skating test on a treadmill and on a SB. Gas exchange threshold (GET), respiratory compensation point (RCP), and maximal variables were determined. Results: Oxygen uptake (V˙O2) (31.0 ± 3.2 and 31.4 ± 4.1 mL·min−1·kg−1), percentage of maximal V˙O2 (V˙O2max) (66.3 ± 4 and 67.7 ± 7.1%), HR (153 ± 14 and 150 ±12 bpm), and ventilation (59.8 ± 11.8 and 57.0 ± 10.7 L·min−1) at GET, and V˙O2 (42.5 ± 4.4 and 42.9 ± 4.8 mL·min−1·kg−1), percentage of V˙O2max (91.1 ± 3.3 and 92.4 ± 2.1%), heart rate (HR) (178 ± 9 and 178 ± 6 bpm), and ventilation (96.5 ± 19.2 and 92.1 ± 12.7 L·min−1) at RCP were not different between skating on a treadmill and on a SB. V˙O2max (46.7 ± 4.4 vs 46.4 ±6.1 mL·min−1·kg−1) and maximal HR (195 ± 6 vs 196 ± 10 bpm) were not significantly different and correlated (r = .80 and r = .87, respectively; P < .05) between the treadmill and SB. V˙O2 at GET, RCP, and V˙O2max obtained on a SB were correlated (r > .8) with athletes’ best times on 1500 m. Conclusions: The incremental skating test on a SB was capable to distinguish maximal (V˙O2 and HR) and submaximal (V˙O2, % V˙O2max, HR, and ventilation) parameters known to determine endurance performance. Therefore, the SB test can be considered as a specific and practical alternative to evaluate speed skaters.

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Fábio J. Lanferdini, Rodrigo R. Bini, Pedro Figueiredo, Fernando Diefenthaeler, Carlos B. Mota, Anton Arndt and Marco A. Vaz

Purpose:

To employ cluster analysis to assess if cyclists would opt for different strategies in terms of neuromuscular patterns when pedaling at the power output of their second ventilatory threshold (POVT2) compared with cycling at their maximal power output (POMAX).

Methods:

Twenty athletes performed an incremental cycling test to determine their power output (POMAX and POVT2; first session), and pedal forces, muscle activation, muscle–tendon unit length, and vastus lateralis architecture (fascicle length, pennation angle, and muscle thickness) were recorded (second session) in POMAX and POVT2. Athletes were assigned to 2 clusters based on the behavior of outcome variables at POVT2 and POMAX using cluster analysis.

Results:

Clusters 1 (n = 14) and 2 (n = 6) showed similar power output and oxygen uptake. Cluster 1 presented larger increases in pedal force and knee power than cluster 2, without differences for the index of effectiveness. Cluster 1 presented less variation in knee angle, muscle–tendon unit length, pennation angle, and tendon length than cluster 2. However, clusters 1 and 2 showed similar muscle thickness, fascicle length, and muscle activation. When cycling at POVT2 vs POMAX, cyclists could opt for keeping a constant knee power and pedal-force production, associated with an increase in tendon excursion and a constant fascicle length.

Conclusions:

Increases in power output lead to greater variations in knee angle, muscle–tendon unit length, tendon length, and pennation angle of vastus lateralis for a similar knee-extensor activation and smaller pedal-force changes in cyclists from cluster 2 than in cluster 1.