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- Stöggl, R., et al.
(författare)
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Motor abilities and anthropometrics in youth cross-country skiing
- 2015
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 25:1, s. E70-E81
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Tidskriftsartikel (refereegranskat)abstract
- The purposes were to validate whether general motor abilities and anthropometrics are determinants of youth cross-country (XC) skiing performance; evaluate gender-specific differences; and to establish noninvasive diagnostics. Fifty-one youth XC skiers (34 boys; 13.8 +/- 0.6 years and 17 girls; 13.4 +/- 0.9 years) performed motor skill and laboratory tests, and anthropometric data were collected and correlated with XC skiing performance. Anthropometrics and maturity status were related to boys but not to girls XC skiing performance. Push-ups and 20-m sprint were correlated to XC skiing performance in both boys and girls. XC skiing performance of boys was predominantly influenced by upper body and trunk strength capacities (medicine ball throw, push-ups, and pull-ups) and jumping power (standing long and triple jump), whereas XC skiing of girls was mainly influenced by aerobic capacities (3000-m run). Laboratory measures did not reveal greater correlations to XC skiing performance compared with simple test concepts of speed, strength, and endurance. Maturity was a major confounding variable in boys but not girls. Use of noninvasive simple test concepts for determination of upper body strength, speed, and endurance represent practicable support for ski clubs, schools, or skiing federations in the guidance and evaluation of young talent, being aware of the effect of maturity especially in boys.
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| 2. |
- Stöggl, Thomas, et al.
(författare)
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Automatic classification of the Sub-Techniques (Gears) used in cross-country ski skating employing a mobile phone
- 2014
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Ingår i: Sensors. - : MDPI AG. - 1424-8220. ; 14:11, s. 20589-20601
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of the current study was to develop and validate an automatic algorithm for classification of cross-country (XC) ski-skating gears (G) using Smartphone accelerometer data. Eleven XC skiers (seven men, four women) with regional-to-international levels of performance carried out roller skiing trials on a treadmill using fixed gears (G2left, G2right, G3, G4left, G4right) and a 950-m trial using different speeds and inclines, applying gears and sides as they normally would. Gear classification by the Smartphone (on the chest) and based on video recordings were compared. Formachine-learning, a collective database was compared to individual data. The Smartphone application identified the trials with fixed gears correctly in all cases. In the 950-m trial, participants executed 140 ± 22 cycles as assessed by video analysis, with the automatic Smartphone application giving a similar value. Based on collective data, gears were identified correctly 86.0% ± 8.9% of the time, a value that rose to 90.3% ± 4.1% (P < 0.01) with machine learning from individual data. Classification was most often incorrect during transition between gears, especially to or from G3. Identification was most often correct for skiers who made relatively few transitions between gears. The accuracy of the automatic procedure for identifying G2left, G2right, G3, G4left and G4right was 96%, 90%, 81%, 88% and 94%, respectively. The algorithm identified gears correctly 100% of the time when a single gear was used and 90% of the time when different gears were employed during a variable protocol. This algorithm could be improved with respect to identification of transitions between gears or the side employed within a given gear.
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| 3. |
- Andersson, Erik, et al.
(författare)
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Analysis of sprint cross-country skiing using a differential global navigation satellite system
- 2010
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 110:3, s. 585-595
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Tidskriftsartikel (refereegranskat)abstract
- The purpose was to examine skiing velocities, gear choice (G2-7) and cycle rates during a skating sprint time trial (STT) and their relationships to performance, as well as to examine relationships between aerobic power, body composition and maximal skiing velocity versus STT performance. Nine male elite cross-country skiers performed three tests on snow: (1) Maximum velocity test (Vmax) performed using G3 skating, (2) Vmax test performed using double poling (DP) technique and (3) a STT over 1,425 m. Additional measurements of VO2max during roller skiing and body composition using iDXA were made. Differential global navigation satellite system data were used for position and velocity and synchronized with video during STT. The STT encompassed a large velocity range (2.9-12.9 m s-1) and multiple transitions (21-34) between skiing gears. Skiing velocity in the uphill sections was related to gear selection between G2 and G3. STT performance was most strongly correlated to uphill time (r = 0.92, P < 0.05), the percentage use of G2 (r = -0.72, P < 0.05), and DP Vmax (r = -0.71, P < 0.05). The velocity decrease in the uphills from lap 1 to lap 2 was correlated with VO2max (r = -0.78, P < 0.05). Vmax in DP and G3 were related to percent of racing time using G3. In conclusion, the sprint skiing performance was mainly related to uphill performance, greater use of the G3 technique, and higher DP and G3 maximum velocities. Additionally, VO2max was related to the ability to maintain racing velocity in the uphills and lean body mass was related to starting velocity and DP maximal speed.
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| 4. |
- Andersson, Erik, 1984-, et al.
(författare)
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Biomechanical analysis of the herringbone technique as employed by elite cross-country skiers
- 2014
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley-Blackwell. - 0905-7188 .- 1600-0838. ; 24:3, s. 542-552
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Tidskriftsartikel (refereegranskat)abstract
- This investigation was designed to analyse the kinematics and kinetics of cross-country skiing at different velocities with the herringbone technique on a steep incline. Eleven elite male cross-country skiers performed this technique at maximal, high, and moderate velocities on a snow-covered 15° incline. They positioned their skis laterally (25 to 30°) with a slight inside tilt and planted their poles laterally (8 to 12°) with most leg thrust force exerted on the inside forefoot. Although 77% of the total propulsive force was generated by the legs, the ratio between propulsive and total force was approximately fourfold higher for the poles. The cycle rate increased with velocity (1.20 to 1.60 Hz), whereas the cycle length increased from moderate up to high velocity, but then remained the same at maximal velocity (2.0 to 2.3 m). In conclusion, with the herringbone technique, the skis were angled laterally without gliding, with the forces distributed mainly on the inside forefoot to enable grip for propulsion. The skiers utilized high cycle rates with major propulsion by the legs, highlighting the importance of high peak and rapid generation of leg forces.
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| 9. |
- Andersson, Erik P., 1984-, et al.
(författare)
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Anaerobic work capacity in cycling : the effect of computational method
- 2022
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Ingår i: European Journal of Applied Physiology. - : Springer Science and Business Media LLC. - 1439-6319 .- 1439-6327. ; 122, s. 2637-2650
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Tidskriftsartikel (refereegranskat)abstract
- Purpose To compare the anaerobic work capacity (AnWC, i.e., attributable anaerobic mechanical work) assessed using four different approaches/models applied to time-trial (TT) cycle-ergometry exercise. Methods Fifteen male cyclists completed a 7 x 4-min submaximal protocol and a 3-min all-out TT (TTAO). Linear relationships between power output (PO) and submaximal metabolic rate were constructed to estimate TT-specific gross efficiency (GE) and AnWC, using either a measured resting metabolic rate as a Y-intercept (7 + Y-LIN) or no measured Y-intercept (7-Y-LIN). In addition, GE of the last submaximal bout (GE(LAST)) was used to estimate AnWC, and critical power (CP) from TTAO (CP3'AO) was used to estimate mechanical work above CP (W', i.e., "AnWC"). Results Average PO during TTAO was 5.43 +/- 0.30 and CP was 4.48 +/- 0.23 W.kg(-1). The TT-associated GE values were similar to 22.0% for both 7 + Y-LIN and 7-Y-LIN and similar to 21.1% for GE(LAST) (both P < 0.001). The AnWC were 269 +/- 60, 272 +/- 55, 299 +/- 61, and 196 +/- 52 J.kg(-1) for the 7 + Y-LIN, 7 Y-LIN, GE(LAST), and CP3'AO models, respectively (7 + Y-LIN and 7-Y-LIN versus GE(LAST), both P <0.001; 7+ Y-LIN, 7 Y-LIN, and GE(LAST) versus CP3'AO, all P < 0.01). For the three pair-wise comparisons between 7+ Y-LIN, 7-Y-LIN, and GE(LAST), typical errors in AnWC values ranged from 7 to 11 J.kg(-1), whereas 7+ Y-LIN, 7-Y-LIN, and GE(LAST) versus CP3'AO revealed typical errors of 55-59 J.kg(-1). Conclusion These findings demonstrate a substantial disagreement in AnWC between CP3'AO and the other models. The 7 + Y-LIN and 7-Y-LIN generated 10% lower AnWC values than the GE(LAST) model, whereas 7 + Y-LIN and 7-Y-LIN generated similar values of AnWC.
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| 10. |
- Andersson, Erik P., 1984-, et al.
(författare)
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The effect of exercise hyperpnea on gross efficiency and anaerobic capacity estimates during a 3-min cycle time trial
- 2023
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Ingår i: Journal of applied physiology. - : American Physiological Society. - 8750-7587 .- 1522-1601. ; 134:2, s. 253-263
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Tidskriftsartikel (refereegranskat)abstract
- This study aimed to analyze the effect of exercise-induced hyperpnea on gross efficiency (GE) and anaerobic capacity estimates during a self-paced 3-min supramaximal cycle time trial (TT). Fourteen highly trained male cyclists performed 7 × 4-min submaximal stages, a 6-min passive rest, a 3-min TT, a 5-min passive rest, and a 6-min submaximal stage. Three models were based on the 7 × 4-min linear regression extrapolation method, using 1) the conventional model (7-YLIN); 2) the same 7-YLIN model but correcting for the additional ventilatory cost (i.e., hyperpnea) (7-YLIN-V-cor); and 3) accounting for linearly declining GE during the TT (7-YLIN-D). The other three models were based on GE from the last submaximal stage, using the conventional model (GELAST) and the same modifications as described for 7+YLIN, i.e., 1) GELAST, 2) GELAST-V-cor, and 3) GELAST-D. The GELAST model generated 18% higher values of anaerobic capacity than the 7-YLIN model (P < 0.05). During the TT, the hyperpnea-corrected model (i.e., 7-YLIN-V-cor or GELAST-V-cor) generated, compared with the respective conventional model (i.e., 7-YLIN or GELAST), ∼0.7 percentage points lower GE and ∼11% higher anaerobic capacity (all, P < 0.05). The post-TT GE was 1.9 percentage points lower (P < 0.001) and the 7-YLIN-D or GELAST-D model generated, compared with the respective conventional model, a lower GE (∼1.0 percentage points) and ∼17% higher anaerobic capacity during the TT (all, P < 0.05). In conclusion, the correction for a declining GE due to hyperpnea during a supramaximal TT resulted in an increased required total metabolic rate and anaerobic energy expenditure compared with the conventional models.NEW & NOTEWORTHY This study demonstrates that GE declines during a 3-min supramaximal cycle TT, which is possibly related to the hyperpneic response during supramaximal exercise. The finding from this study also provides novel insight into how the increased ventilatory energy cost from exercise-induced hyperpnea contributes to decreased GE, increased required total metabolic rate, and increased anaerobic energy expenditure during supramaximal exercise. Therefore, conventional linear models for estimating anaerobic capacity are likely to generate underestimated values.
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