| 1. |
- Bortolan, Lorenzo, et al.
(författare)
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Development of Equipment for Ski Mountaineering, a New Olympic Event
- 2023
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 13:9
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Tidskriftsartikel (refereegranskat)abstract
- Ski mountaineering, a new Olympic winter sport involving both climbing and descending snowy slopes, requires considerable physical and technical abilities, as well as highly specialized equipment. Herein, we briefly describe this equipment and its influence on performance and consider potential future advances. Skis, boots, and bindings must be light enough to facilitate climbing uphill (in which as much as 85% of the total racing time is spent) and, at the same time, provide stability and safety in often-challenging descents. A skier must be able to easily and rapidly attach and remove the adhesive skins under the skis that provide grip while skiing uphill. Poles and their baskets must be designed optimally to transfer propulsive force and help maintain balance. Despite the popularity of ski mountaineering, research on this sport is scarce, and we indicate a number of areas wherein improvements in equipment could potentially advance both performance and safety. Such advances must be based on a better understanding of the biomechanics of ski mountaineering, which could be obtained with novel sensor technology and can be best achieved via more extensive collaboration between researchers, skiers and their coaches, and manufacturers of ski mountaineering equipment.
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| 2. |
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| 3. |
- Drobnič, Miha, et al.
(författare)
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The Validity of a Three-Dimensional Motion Capture System and the Garmin Running Dynamics Pod in Connection with an Assessment of Ground Contact Time While Running in Place
- 2023
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Ingår i: Sensors. - : Multidisciplinary Digital Publishing Institute (MDPI). - 1424-8220. ; 23:16
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Tidskriftsartikel (refereegranskat)abstract
- A three-dimensional motion capture system (MoCap) and the Garmin Running Dynamics Pod can be utilised to monitor a variety of dynamic parameters during running. The present investigation was designed to examine the validity of these two systems for determining ground contact times while running in place by comparing the values obtained with those provided by the bilateral force plate (gold standard). Eleven subjects completed three 20-s runs in place at self-selected rates, starting slowly, continuing at an intermediate pace, and finishing rapidly. The ground contact times obtained with both systems differed significantly from the gold standard at all three rates, as well as for all the rates combined (p < 0.001 in all cases), with the smallest mean bias at the fastest step rate for both (11.5 ± 14.4 ms for MoCap and −81.5 ± 18.4 ms for Garmin). This algorithm was developed for the determination of ground contact times during normal running and was adapted here for the assessment of running in place by the MoCap, which could be one explanation for its lack of validity. In conclusion, the wearables developed for monitoring normal running cannot be assumed to be suitable for determining ground contact times while running in place.
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| 4. |
- Majerič, Matej, et al.
(författare)
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Application of Experimental Measurements in a Wind Tunnel to the Development of a Model for Aerodynamic Drag on Elite Slalom and Giant Slalom Alpine Skiers
- 2022
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 12:2
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Tidskriftsartikel (refereegranskat)abstract
- Aerodynamic drag is a major cause of energy losses during alpine ski racing. Here we developed two models for monitoring the aerodynamic drag on elite alpine skiers in the technical disciplines. While 10 skiers assumed standard positions (high, middle, tuck) with exposure to different wind speeds (40, 60, and 80 km/h) in a wind tunnel, aerodynamic drag was assessed with a force plate, shoulder height with video-based kinematics, and cross-sectional area with interactive image segmentation. The two regression models developed had 3.9–7.7% coefficients of variation and 4.5–16.5% relative limits of agreement. The first was based on the product of the coefficient of aerodynamic drag and cross-sectional area (Cd·S) and the second on the coefficient of aerodynamic drag Cd and normalized cross-sectional area of the skier Sn, both expressed as a function of normalized shoulder height (hn). In addition, normative values for Cd (0.75 ± 0.09–1.17 ± 0.09), Sn (0.51 ± 0.03–0.99 ± 0.05), hn (0.48 ± 0.03–0.79 ± 0.02), and Cd·S (0.23 ± 0.03–0.66 ± 0.09 m2) were determined for the three different positions and wind speeds. Since the uncertainty in the determination of energy losses due to aerodynamic drag relative to total energy loss with these models is expected to be <2.5%, they provide a valuable tool for analysis of skiing performance.
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| 5. |
- Podlogar, T., et al.
(författare)
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Addition of Fructose to a Carbohydrate-Rich Breakfast Improves Cycling Endurance Capacity in Trained Cyclists
- 2022
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Ingår i: International Journal of Sport Nutrition & Exercise Metabolism. - : Human Kinetics. - 1526-484X .- 1543-2742. ; 32:6, s. 439-445
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Tidskriftsartikel (refereegranskat)abstract
- It was previously demonstrated that postexercise ingestion of fructose-glucose mixtures can lead to superior liver and equal muscle glycogen synthesis as compared with glucose-based carbohydrates (CHOs) only. After an overnight fast, liver glycogen stores are reduced, and based on this we hypothesized that addition of fructose to a glucose-based breakfast would lead to improved subsequent endurance exercise capacity. In this double-blind cross-over randomized study (eight males, peak oxygen uptake: 62.2 ± 5.4 ml·kg-1·min-1), participants completed two experimental trials consisting of two exercise bouts. In the afternoon of Day 1, they completed a cycling interval training session to normalize glycogen stores after which a standardized high-CHO diet was provided for 4 hr. On Day 2, in the morning, participants received 2 g/kg of CHOs in the form of glucose and rice or fructose and rice, both in a CHO ratio of 1:2. Two hours later they commenced cycling exercise session at the intensity of the first ventilatory threshold until task failure. Exercise capacity was higher in fructose and rice (137.0 ± 22.7 min) as compared with glucose and rice (130.06 ± 19.87 min; p = .046). Blood glucose and blood lactate did not differ between the trials (p > .05) and neither did CHO and fat oxidation rates (p > .05). However, due to the duration of exercise, total CHO oxidation was higher in fructose and rice (326 ± 60 g vs. 298 ± 61 g, p = .009). Present data demonstrate that addition of fructose to a glucose-based CHO source at breakfast improves endurance exercise capacity. Further studies are required to determine the mechanisms and optimal dose and ratio.
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| 6. |
- Podlogar, Tim, et al.
(författare)
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Commercially available carbohydrate drink with menthol fails to improve thermal perception or cycling exercise capacity in males
- 2022
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Ingår i: European Journal of Sport Science. - : Informa UK Limited. - 1746-1391 .- 1536-7290. ; 22:11, s. 1705-1713
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Tidskriftsartikel (refereegranskat)abstract
- The purpose of this double-blinded, crossover randomized and counterbalanced study was to compare the effects of ingesting a tepid commercially available carbohydrate-menthol-containing sports drink (menthol) and an isocaloric carbohydrate-containing sports drink (placebo) on thermal perception and cycling endurance capacity "in a simulated home virtual cycling environment". It was hypothesized that the addition of menthol would improve indicators of thermal perception and improve endurance exercise capacity. Twelve healthy, endurance-trained males (age 29 +/- 5 years, height 181 +/- 6 cm, body mass 79 +/- 2 kg and V?O(2)max 57.3 +/- 6.4 mL kg(-1) min(-1)) completed two experimental trials on a stationary bicycle without external air flow. Each trial consisted of (1) cycling for 60 min at 90% of the first ventilatory threshold while receiving a fixed amount of menthol or placebo every 10 min followed immediately by (2) cycling until volitional exhaustion (TTE) at 105% of the intensity corresponding to the respiratory compensation point. TTE did not differ between both conditions (541 +/- 177 and 566 +/- 150 s for menthol and placebo; p > 0.05) and neither did ratings of perceived thermal comfort or thermal sensation (p > 0.05). Also, the rectal temperature at the end of TTE was comparable between menthol and placebo trials (38.7 +/- 0.2 degrees C and 38.7 +/- 0.3 degrees C, respectively; p > 0.05). The present results demonstrate that the addition of menthol to commercially available sports drink does not improve thermal comfort or endurance exercise capacity during similar to 65 min of intense virtual cycling.
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| 7. |
- Supej, Matej, et al.
(författare)
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The Contribution of Ski Poles to Aerodynamic Drag in Alpine Skiing
- 2023
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Ingår i: Applied Sciences. - : MDPI. - 2076-3417. ; 13:14
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Tidskriftsartikel (refereegranskat)abstract
- The present study was designed to determine the contribution of the cross-sectional area of the ski poles (Sp) to the total aerodynamic drag during alpine skiing. At three different wind speeds in a wind tunnel, 10 skiers assumed typical alpine skiing postures (high, middle, and tuck), and their frontal aerodynamic drag was assessed with a force plate and their cross-sectional area, along with that of their ski poles, determined by interactive image segmentation. The data collected were utilized to examine intra-subject variation in Sp, the effects of Sp on the coefficient of aerodynamic drag (Cd), and the product of Cd and total cross-sectional area (Cd∙S. The major findings were as follows: (i) Sp ranged from 0.0067 (tuck position) to 0.0262 m2 (middle position), contributing 2.2–4.8% of the total cross-sectional area, respectively; (ii) Sp was dependent on wind speed in the high and middle positions; (iii) intra-subject variations ranged from 0.0018 m2 (27.6%) in the tuck position to 0.0072 m2 (30.5%) in the high position; (iv) Sp exerted a likely effect on Cd and Cd∙S. The extensive intra- and inter-skier variability in Sp can account for as much as ~5% of the total frontal cross-sectional area and future investigations on how elite skiers optimize their positioning of the poles in a manner that reduces aerodynamic drag are warranted.
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| 8. |
- Verdel, Nina, et al.
(författare)
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A Comparison of a Novel Stretchable Smart Patch for Measuring Runner’s Step Rates with Existing Measuring Technologies
- 2022
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 22:13
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Tidskriftsartikel (refereegranskat)abstract
- A novel wearable smart patch can monitor various aspects of physical activity, including the dynamics of running, but like any new device developed for such applications, it must first be tested for validity. Here, we compare the step rate while running in place as measured by this smart patch to the corresponding values obtained utilizing ‘‘gold standard’’ MEMS accelerometers in combination with bilateral force plates equipped with HBM load cells, as well as the values provided by a three-dimensional motion capture system and the Garmin Dynamics Running Pod. The 15 healthy, physically active volunteers (age = 23 ± 3 years; body mass = 74 ± 17 kg, height = 176 ± 10 cm) completed three consecutive 20-s bouts of running in place, starting at low, followed by medium, and finally at high intensity, all self-chosen. Our major findings are that the rates of running in place provided by all four systems were valid, with the notable exception of the fast step rate as measured by the Garmin Running Pod. The lowest mean bias and LoA for these measurements at all rates were associated consistently with the smart patch.
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| 9. |
- Verdel, Nina, et al.
(författare)
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Reliability and validity of running step rate derived from a novel wearable Smart Patch
- 2024
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Ingår i: IEEE Sensors Journal. - : IEEE. - 1530-437X .- 1558-1748. ; 24:9, s. 14343-14351
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Tidskriftsartikel (refereegranskat)abstract
- A novel, wearable, stretchable Smart Patch can monitor various aspects of physical activity, including the dynamics of running. However, like any new device developed for such applications, it must first be tested for validity and reliability. Here, we compare the step rate while running on a treadmill measured by this smart patch with the corresponding values obtained with the ”gold standard” OptoGait, as well as with other devices commonly used to assess running dynamics, i.e., the MEMS accelerometer and commercially available and widely used Garmin Running Dynamic Pod. The 14 healthy, physically active volunteers completed two identical sessions with a 5-minute rest between. Each session involved two one-minute runs at 11 km/h and 14 km/h separated by a one-min rest. The major finding was that the Smart Patch demonstrated fair to good test-retest reliability. The best test-retest reliability for the Running Pod was observed in connection with running at 11 km/h and both velocities combined (good and excellent, respectively) and for the OptoGait when running at 14 km/h (good). The best concurrent validity was achieved with the Smart Patch, as reflected in the highest Pearson correlation coefficient for this device when running at 11 or 14 km/h, as well as for both velocities combined. In conclusion, this study demonstrates that the novel wearable Smart Patch shows promising reliability and excellent concurrent validity in measuring step rate during treadmill running, making it a viable tool for both research and practical applications in sports and exercise science.
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| 10. |
- Verdel, Nina, et al.
(författare)
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Reliability and Validity of the CORE Sensor to Assess Core Body Temperature during Cycling Exercise
- 2021
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Ingår i: Sensors. - : MDPI. - 1424-8220. ; 21:17
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring core body temperature (Tc) during training and competitions, especially in a hot environment, can help enhance an athlete’s performance, as well as lower the risk for heat stroke. Accordingly, a noninvasive sensor that allows reliable monitoring of Tc would be highly beneficial in this context. One such novel non-invasive sensor was recently introduced onto the market (CORE, greenTEG, Rümlang, Switzerland), but, to our knowledge, a validation study of this device has not yet been reported. Therefore, the purpose of this study was to evaluate the validity and reliability of the CORE sensor. In Study I, 12 males were subjected to a low-to-moderate heat load by performing, on two separate occasions several days apart, two identical 60-min bouts of steady-state cycling in the laboratory at 19 °C and 30% relative humidity. In Study II, 13 males were subjected to moderate-to-high heat load by performing 90 min of cycling in the laboratory at 31 °C and 39% relative humidity. In both cases the core body temperatures indicated by the CORE sensor were compared to the corresponding values obtained using a rectal sensor (Trec). The first major finding was that the reliability of the CORE sensor is acceptable, since the mean bias between the two identical trials of exercise (0.02 °C) was not statistically significant. However, under both levels of heat load, the body temperature indicated by the CORE sensor did not agree well with Trec, with approximately 50% of all paired measurements differing by more than the predefined threshold for validity of ≤0.3 °C. In conclusion, the results obtained do not support the manufacturer’s claim that the CORE sensor provides a valid measure of core body temperature.
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