| 1. |
- Ainegren, Mats, 1963-, et al.
(författare)
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Effects of Aerodynamic Drag and Drafting on Propulsive Force and Oxygen Consumption in Double Poling Cross-Country Skiing
- 2022
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Ingår i: Medicine & Science in Sports & Exercise. - 0195-9131 .- 1530-0315. ; 54:7, s. 1058-1065
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Tidskriftsartikel (refereegranskat)abstract
- Purpose This study aimed to investigate the effects of aerodynamic drag and drafting on propulsive force (FPROP), drag area (CDA), oxygen cost (V˙O2), metabolic rate (Ė), and heart rate (HR) during roller skiing on a treadmill in a wind tunnel using the double poling technique. A secondary aim was to investigate the effects of wind versus no-wind test conditions on the same physiological parameters. Methods Ten subjects of each gender participated in the experiments. One pair of skiers of the same gender roller skied simultaneously in line with the air flow; the distance between the skiers was 2.05 m. Each pair was tested as follows: I) with wind, leading; II) with wind, drafting; and III) without wind. The treadmill inclination was 0° throughout the tests. For the wind conditions, the air velocity was similar to the treadmill belt speed: 3 to 7 m·s-1 for men and 3 to 6 m·s-1 for women. Results Drafting resulted in significantly (P < 0.05) lower FPROP,CDA, V˙O2, and Ė, compared with leading, for both genders at racing speed but not at lower speeds, whereas HR was only affected for the male skiers at racing speed. The test without wind resulted in significantly lower FPROP, V˙O2, and Ė at all tested speeds compared with the tests with wind present, whereas HR was lower only at higher speeds. Conclusions At racing speed, but not at lower speeds, the positive effects of drafting behind a skier during double poling were obvious and resulted in a lower FPROP, CDA, V˙O2, Ė, and HR. Tests without wind present put even lower demands on the skiers' physiology, which was also evident at lower speeds.
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| 2. |
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| 3. |
- Ihalainen, Simo, et al.
(författare)
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Technical determinants of biathlon standing shooting performance before and after race simulation
- 2018
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 28:6, s. 1700-1707
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Tidskriftsartikel (refereegranskat)abstract
- The aim of this study was to identify performance determining factors in biathlon standing shooting in rest and after intense exercise. Eight Finnish national and nine junior team biathletes participated in the study. Participants fired 40 resting shots (REST) and 2*5 competition simulation shots (LOAD) after 5 min of roller skiing at 95% of peak heart rate. Hit percentage, aiming point trajectory and postural balance were measured from each shot. Cleanness of triggering (ATV, movement of the aiming point 0-0.2 s before the shot) and vertical stability of hold (DevY) were the most important components affecting shooting performance both in REST (DevY, R=-0.61, p<0.01; ATV, R=-0.65, p<0.01) and in LOAD (DevY, R=-0.50, p<0.05; ATV, R=-0.77, p<0.001). Postural balance, especially in shooting direction, was related to DevY and ATV. Stability of hold in horizontal (F(1,15)=7.025, p<0.05) and vertical (F(1,15)=21.285, p<0.001) directions, aiming accuracy (F(1,15)=9.060, p<0.01), and cleanness of triggering (F(1,15)=59.584, p<0.001) decreased from REST to LOAD, accompanied by a decrease in postural balance. National and junior team biathletes differed only in hit percentage in REST (92±8 % vs. 81±8 %, p<0.05) and left leg postural balance in shooting direction in LOAD (0.31±0.18 mm vs. 0.52±0.20 mm, p<0.05), and the intense exercise affected the shooting technical components similarly in both national and junior groups. Biathletes should focus on cleanness of triggering and vertical stability of hold in order to improve biathlon standing shooting performance. More stable postural balance in shooting direction could help to improve these shooting technical components.
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| 4. |
- Karczewska-Lindinger, Magdalena, et al.
(författare)
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Force Generation Profiles of Para-Nordic Sit-Skiers Representing Different Physical Impairments
- 2021
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Ingår i: Journal of Science in Sport and Exercise. - : Springer Science and Business Media LLC. - 2662-1371 .- 2096-6709. ; 3, s. 281-291
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Tidskriftsartikel (refereegranskat)abstract
- PurposeTo biomechanically profile force generation connected to the complex role of the trunk in double poling in a representative sample of Para-Nordic sit-skiers.MethodsTwelve male World Cup Para-Nordic sit-skiers (sport classes: LW10–12) were skiing on flat snow terrain at submaximal speed of 4.5 m/s (~ 73% maximum speed). 2D video (50 Hz) and pole force analyses (1000 Hz) were performed synchronously, examining angle, force and cycle characteristics to analyse the role of the trunk in generating propulsion.ResultsLW10–11.5 skiers lost between 21% and 4% propulsive force versus LW12 athletes only due to different geometrics of the trunk and pole angle at an equal axial pole force. While LW10–11 skiers indicated trunk extension or position maintenance during pole thrust, LW11.5–12 skiers showed strong trunk flexion combined with smaller pole angles to the ground. Hence, LW11.5–12 skiers could create larger propulsive forces and therefore greater cycle lengths at lower cycle rates at the same speed. Maximum speed increased from LW10 to LW12 and was significantly correlated to trunk flexion range of motion (r = 0.63) and cycle length (r = 0.59). Trunk flexion ROM showed a significant relationship to the impulse of propulsive force (r = 0.63) and pole angle to the ground (r = − 0.76) (all P < 0.05).ConclusionThe impact of impairment on the force production profiles and its physiological-biomechanical consequences need further investigation also in other terrains and at wider spectrums of skiing speeds. The evident problem of low numbers of LW10–11 skiers in World Cup needs creative future solutions for research.
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| 5. |
- Köykkä, Miika, et al.
(författare)
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Aiming strategy affects performance-related factors in biathlon standing shooting
- 2021
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 31:3, s. 573-585
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Tidskriftsartikel (refereegranskat)abstract
- This study focused on investigating differences in shooting performance and performance‐related factors between two different aiming strategies (HOLD, low radial velocity during the approach 0.4‐0.2 seconds before triggering, and TIMING, high radial velocity) in biathlon standing shooting. A total of 23 biathletes fired 8 × 5 standing shots at rest (REST) and 2 × 5 shots during a race simulation (RACE). Shooting performance (hit point distance from the center of the target), aiming point trajectory and postural balance were measured from each shot. Shooting performance was similar both at REST (HOLD 33 ± 5 mm vs TIMING 38 ± 8 mm, P = .111) and in RACE (40 ± 11 mm vs 47 ± 12 mm, P = .194). Better shooting performance was related to smaller distance of the aiming point mean location (REST r = 0.93, P < .001, RACE r = 0.72, P = .018) and higher time spent within ⅔ of the distance of the hit area edge from the center 0.6‐0.0 seconds before triggering (REST r=−0.88, P = .001, RACE r=−0.73, P = .016) in HOLD, and to lower aiming point total velocity 0.6‐0.0 seconds before triggering (REST r = 0.77, P = .009, RACE r = 0.88, P = .001) and less aiming point movement 0.2‐0.0 seconds before triggering (REST r = 0.82, P = .003, RACE r = 0.72, P = .012) in TIMING. Postural balance was related to shooting performance at REST in both groups and in RACE in TIMING. Biathletes using the hold strategy should focus on stabilizing the aiming point before triggering and aiming at the center, whereas biathletes using the timing strategy benefit of decreasing the total velocity during the final approach as well as minimizing the aiming point movement right before triggering.
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| 8. |
- Köykkä, Miika, et al.
(författare)
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Performance‐determining factors in biathlon prone shooting without physical stress
- 2022
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Ingår i: Scandinavian Journal of Medicine and Science in Sports. - : Wiley. - 0905-7188 .- 1600-0838. ; 32:2, s. 414-423
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the most important factors determining biathlon prone shooting performance. Ten female and 16 male biathletes (age 19.9 ± 2.9 years) from the national teams of Finland and Vuokatti-Ruka Sports Academy performed 6 × 5 biathlon prone shooting shots without physical stress under laboratory conditions. Shooting performance and multiple aiming point trajectory variables were measured together with an analysis of triggering force. Based on the aiming point trajectory data principal component analysis, we identified four technical components in biathlon prone shooting: stability of hold, aiming accuracy, cleanness of triggering, and timing of triggering. Multiple regression analysis (MRA) further determined that cleanness of triggering, aiming accuracy, and timing of triggering accounted for 80% of mean shooting performance (p < 0.001). Better stability of hold, aiming accuracy and cleanness of triggering were directly associated with better shooting performance (0.62 ≤ |r| ≥0.79, all p < 0.001). Better stability of hold measures were also associated with better cleanness of triggering, and higher pre-shot trigger force levels were associated with better stability of hold and cleanness of triggering. These results indicate that with both direct and indirect effects on performance, stability of hold seems to be a general prerequisite for successful biathlon shooting. The results also highlight the importance of aiming accuracy, cleanness and timing of triggering, along with a high pre-shot trigger force level. The variables identified in this study could be used to assess biathletes’ performance in the most relevant shooting technical aspects to guide the emphasis of their shooting training.
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| 9. |
- Köykkä, Miika, et al.
(författare)
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Rifle and aiming point accelerations do not differ between the most and least accurate shots in biathlon shooting within an athlete
- 2023
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Ingår i: Biomedical Human Kinetics. - : Walter de Gruyter GmbH. - 2080-2234. ; 15:1, s. 139-147
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Tidskriftsartikel (refereegranskat)abstract
- Study aim: As studies from shooting disciplines other than biathlon have observed associations between weapon accelerations and shooting performance, this study investigated whether accelerations of the rifle stock and aiming point (the point on the target where the rifle is aimed at) are associated with shooting performance, and differences in rifle and aiming point accelerations between the most and least accurate shots. Further, associations between rifle and aiming point accelerations were studied.Materials and methods: Shooting performance (Hit(Dist), hit point distance from the center of the target) along with rifle and aiming point accelerations were measured from nine biathletes who performed 6x5 biathlon prone and standing shots.Results: In the prone posture, rifle or aiming point accelerations were neither associated with shooting performance nor with each other. In the standing posture, vertical rifle accelerations right before triggering were negatively associated with Hit(Dist) (r = -0.70, p < 0.05), whereas aiming point accelerations were not associated with Hit(Dist). Horizontal rifle accelerations were positively associated with aiming point accelerations in standing (r = 0.74, p = 0.024), whereas vertical or resultant rifle accelerations did not demonstrate associations with aiming point accelerations. In both postures, rifle accelerations were of the same magnitude in the most and least accurate shots.Conclusion: Rifle and aiming point accelerations provide limited description of the technical level in biathlon shooting. Moreover, rifle accelerations alone do not appear to provide sufficient information to deduce the aiming point movements. Angular movement would likely be required for aiming point movement estimation.
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| 10. |
- Lajunen, Kimmo, et al.
(författare)
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Effect of Sitting Posture on Sit-Skiing Economy in Non-disabled Athletes.
- 2020
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Ingår i: Frontiers in sports and active living. - : Frontiers Media SA. - 2624-9367. ; 2
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Tidskriftsartikel (refereegranskat)abstract
- This study focused on resolving the differences in economy between two common sit-skiing postures used by disabled athletes, suspected to be the most and least effective. Ten experienced non-disabled male cross-country skiers went through an incremental testing protocol with an ergometer simulating double poling in two sitting postures "kneeing" and "knee-high." The protocol consisted of 3 × 4 min steady-state stages (13, 22, and 34% of maximal sprint power output). Subjects' respiratory gases and heart rate were measured and blood lactate concentrations were determined. In addition, pulling forces and motion capture recordings were collected. Oxygen consumption was 15.5% (p < 0.01) higher with "knee-high" compared to "kneeing" at stage three. At stage three cycle rate was 13.8% higher (p < 0.01) and impulse of force 13.0% (p < 0.05) and hip range of motion 46.6% lower (p < 0.01) with "knee-high" compared to "kneeing." "Kneeing" was found to be considerably more economical than "knee-high" especially at 34% of maximum sprint power output. This might have been due to higher cycle rate, lower impulse of force and smaller hip range of motion with "knee-high" compared to "kneeing." This indicates that sit-skiers should adopt, if possible, posture more resembling the "kneeing" than the "knee-high" posture. Combining such physiological and biomechanical measurements and to further develop them to integrated miniature wearable sensors could offer new possibilities for training and testing both in the laboratory and in the field conditions.
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