We introduce a novel approach for computing gate-to-gate time automatically from audio recordings. In slalom skiing, gate-to-gate timing is a valuable metric for athletes and trainers, capturing the ...time elapsed between slalom gates. The availability of these measurements immediately after each run allows for prompt feedback. This study specifically concentrates on gate-to-gate timing in alpine slalom skating, serving as a foundational step towards its future application in slalom skiing. While existing methods for measuring gate-to-gate time vary in their feasibility, accuracy, and compliance with regulations, we propose a solution utilizing a convolutional neural network (CNN) to predict gate locations using the audio signals generated upon gate contact. By leveraging these predictions, we achieve fully automated computation of gate-to-gate timings. We conduct a comparative analysis between the CNN’s predictions and data obtained from an inertial measurement unit. Our findings reveal a strong predictive correlation between the two methods, with an R-squared value of 0.94 and a root mean squared error of 0.036. The majority of predictions demonstrate high accuracy, falling within a range of thousandths of a second. However, a few outliers negatively impact the overall performance. Notably, we observe no deterioration in predictive quality based on the distance between the camera and the gate. Finally, we delve into the challenges and limitations associated with our approach and provide a comprehensive discussion. To conclude, we outline potential avenues for future research and extensions of our methodology to the realm of slalom skiing.
Slalom chromatography (SC) was discovered in 1988 for analyzing double-stranded (ds) DNA. However, its progress was impeded by practical issues such as low-purity particles, sample loss, and lack of ...a clear retention mechanism. With the rise of cell and gene therapies and the availability today of bio-inert ultra-high-pressure liquid chromatography (UHPLC) columns and systems, SC has regained interest. In SC, the elution order is opposite to that observed in hydrodynamic chromatography (HDC): larger DNA molecules are more retained than small ones. Yet, the underlying SC retention mechanism remains elusive.
We provide the physicochemical background necessary to explain, at a microscopic scale, the full transition from a HDC to a SC retention mechanism. This includes the persistence length of the DNA macromolecule (representing DNA stiffness), their relaxation time (τR) from the non-equilibrium contour length to the equilibrium entropic configuration, and the relationship between the mobile phase shear rate (〈γ̇〉) in packed columns and the DNA extended length. We propose a relevant retention model to account for the simultaneous impact of hydrodynamic chromatography (HDC) and SC on the retention factors of a series of large and linear dsDNAs (ranging from 2 to 48 kbp). SC data were acquired using bio-inert MaxPeakTM Columns packed with 1.7μm BEHTM 45 Å, 1.8μm BEH 125 Å, 2.4μm BEH 125 Å, 5.3μm BEH 125 Å, and 11.3μm BEH 125 Å Particles, an ACQUITYTM UPLCTM I-class PLUS System, and either 1 × PBS (pH 7.4) or 100 mM phosphate buffer (pH 8) as the mobile phase. SC is a non-equilibrium retention mode that is dominant when the Weissenberg number (Wi=〈γ̇〉τR) is much larger than 10 and the average extended length of DNA exceeds the particle diameter. HDC, on the other hand, is an equilibrium retention mode that dominates when Wi<1 (DNA chains remaining in their non-extended configuration). Maximum dsDNA resolution is observed in a mixed HDC-SC retention mode when the extended length of the DNA is approximately half the particle diameter. This work facilitates the development of methods for characterizing various plasmid DNA mixtures, containing linear, supercoiled, and relaxed circular dsDNAs which all have different degree of molecular stiffness.
•Retention mechanism of dsDNA by slalom chromatography physically revisited.•SC fundamentals are based on shear flow and stiffness/relaxation of DNA.•Product of shear rate by DNA relaxation time (Weissenberg number) is critical.•SC dominant retention mode when the eluent/DNA Weissenberg number > 10.•HDC dominant retention mode when the eluent/ DNA Weissenberg number < 1.
In alpine skiing, intermediate times are usually measured with photocells. However, for practical reasons, the number of intermediate cells is limited to three⁻four, making a detailed timing analysis ...difficult. In this paper, we propose and validate a magnet-based timing system allowing for the measurement of intermediate times at each gate. Specially designed magnets were placed at each gate and the athletes wore small magnetometers on their lower back to measure the instantaneous magnetic field. The athlete's gate crossings caused peaks in the measured signal which could then be related to the precise instants of gate crossings. The system was validated against photocells placed at four gates of a slalom skiing course. Eight athletes skied the course twice and one run per athlete was included in the validation study. The 95% error intervals for gate-to-gate timing and section times were below 0.025 s. Each athlete's gate-to-gate times were compared to the group's average gate-to-gate times, revealing small performance differences that would otherwise be difficult to measure with a traditional photocell-based system. The system could be used to identify the effect of tactical choices and athlete specific skiing skills on performance and could allow a more efficient and athlete-specific performance analysis and feedback.
The primary aim of this study was to determine the morphology of elite canoe slalom paddlers and to identity if morphology differences existed between kayak and canoe paddlers. The survey included a ...total of 74 canoe slalom paddlers who competed in the 2018 European Championship. These competitors were assessed using a battery of anthropometric dimensions according to standardized anthropometric techniques and bioimpedance analysis using the multifrequency octopolar device Tanita MC-980. Elite slalom male competitors can be characterized to having average body height (~180 cm), average weight (~75 kg), with ectomorphic mesomorph somatotype (1.3 - 5.5 - 2.7), well developed trunk and arm muscles (biceps girth: 35.4 ± 1.8), low hypertrophy of legs and low body fat (8 ± 3.2 %). In addition, there are no significant differences between canoe (C1) and kayak (K1) paddlers. For female competitors we can conclude, there has been little change in anthropometric values through the decades. However, C1 competitors are younger, more mesomorphic and less ectomorphic.
To establish an alpine ski racing (ASR) specific dryland high intensity training protocol (HIT), we set out to analyze cardiorespiratory and metabolic responses of three ASR specific HIT modes using ...a ski ergometer compared with a running HIT.
Ten healthy international FIS level subjects (18 ± 1 years) performed an incremental running VO
test, three different ASR specific HIT modes slalom (SL), giant slalom (GS), and SL/GS mix and a running HIT with measurements of VO
, heart rate (HR), blood lactate, and rate of perceived exertion (RPE). The HIT protocols included 15 × 1-min intervals with >90% HR
and 30 s active rest. Furthermore, one elite alpine skier performed an 8-week, 17 session HIT block using the SL/GS mixed mode.
Running HIT resulted in greater VO
and whole-body RPE compared with the three ASR-specific HIT modes. During all four exercise modes participants were able to reach exercise intensities high enough to be classified as HIT (>90% HR
and >89% VO
). Legs RPE was similar between the four HIT modes, while arms RPE was higher for the ski-specific HIT. For all studied parameters, similar results for the three skiing specific HIT modes were observed. The 8-week HIT block was feasible for the athlete and resulted in an 11% increase in VO
at unchanged peak power output.
Across all HIT protocols high cardiorespiratory and metabolic responses were achieved. Therefore, the ASR specific HIT was shown to be feasible, thus could offer new possibilities for endurance training in elite alpine skiers. It is suggested to use the SL/GS mixed mode in terms of movement variety. The reduced VO
in the ski-specific modifications can be attributed to the concentric and eccentric muscle activity resulting in mechanical hindrance for O
extraction. The long-term effectiveness of ASR specific HIT in elite alpine skiers needs to be proven in a future study.
Canoe slalom is an Olympic discipline where athletes race down a whitewater course in kayaks (K1) or canoes (C1) navigating a set of down-stream and up-stream gates. Kayak paddles are symmetrical and ...have a blade at each end, whereas C1 paddles have only one blade that must be moved across the boat to perform strokes on either the right or left side. Asymmetries in paddle force between the two sides of the boat may lead to a reduction in predicted race time. The purpose of this study was to quantify asymmetries in the paddle forces between the two sides for slalom paddling. Paddle forces for 42 canoe slalom athletes (C1 and K1) were quantified from the straight sections of a flat-water figure-of-eight course. Paddle forces were measured using strain gauges embedded in the paddle shaft, stroke type was identified using video, and boat trajectory was tracked using inertial measurement units and high-speed GPS: data were fused using in-house analysis software. Paddle forces were quantified by their peak force, and impulse during the stroke. Paddle forces for the kayakers had asymmetries of 14.2 to 17.1% for the male K1M and 11.1 to 14.4% for the women K1W. Canoeists were no more asymmetrical than the kayakers for their 'on-side' strokes between the right and left sides. However, there were considerable differences for their 'off-side' strokes: male C1M off-side paddle forces were similar to their 'on-side' forces for the same side, but the women C1W had a significantly lower (-20.8% to -29.5%) paddle forces for their 'off-side' strokes compared to their 'on-side' strokes on that same side. Despite an increasing number of younger male athletes being introduced to the switching technique, and it being used by C1M athletes in international competitions since 2014, C1M paddlers still do not use switching transitions as much as C1W. The data from this study indicate that there is a biomechanical reason for this sex-based difference in the higher proportion of off-side strokes used by the C1M athletes compared to C1W athletes: and this needs to be considered for optimal technique development and race performance.
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