Magne Lund-Hansen

• Werkhausen, Amelie; Lund-Hansen, Magne; Wiedenbruch, Lucas; Peikenkamp, Klaus & Rice, Hannah (2024). Technologically advanced running shoes reduce oxygen cost and cumulative tibial loading per kilometer in recreational female and male runners. Scientific Reports. ISSN 2045-2322. 14(1). doi: 10.1038/s41598-024-62263-0.
• Holsbrekken, Eivind; Gløersen, Øyvind; Lund-Hansen, Magne & Losnegard, Thomas Johansen (2023). Competitive Cross-Country Skiers Have Longer Time to Exhaustion Than Recreational Cross-Country Skiers During Intermittent Work Intervals Normalized to Their Maximal Aerobic Power. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. 18(11), s. 1246–1253. doi: 10.1123/ijspp.2022-0487. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: To investigate differences in time to exhaustion (TTE), O2 uptake (˙VO2), and accumulated O2 deficit (Odef2) between competitive and recreational cross-country (XC) skiers during an intermittent-interval protocol standardized for maximal aerobic power (MAP). Methods: Twelve competitive (maximal ˙VO2 [˙VO2max]=76.5±3.8mL⋅kg−1⋅min−1) and 10 recreational (˙VO2max=63.5±6.3mL⋅kg−1⋅min−1) male XC skiers participated. All tests were performed on a rollerski treadmill in the V2 ski-skating technique. To quantify MAP and maximal accumulated oxygen deficit (MAOD), the skiers performed a steady-state submaximal test followed by a 1000-m time trial. After a 60-minute break, TTE, ˙VO2, and accumulated Odef2 were measured during an intermittent-interval protocol (40-s work and 20-s recovery), which was individually tailored to 120% and 60% of each subject’s MAP. Results: During the 1000-m time trial, the competitive skiers had 21% (95% CI, 12%–30%) shorter finish time and 24% (95% CI, 14%–34%) higher MAP (all P < .01) than the recreational skiers. No difference was observed in relative exercise intensity (average power/MAP; P = .28), MAOD (P = .18), or fractional utilization of ˙VO2max. During the intermittent-interval protocol, the competitive skiers had 34% (95% CI, 3%–65%) longer TTE (P = .03) and accumulated 61% (95% CI, 27%–95%) more Odef2 (P = .001) than the recreational skiers during work phases. Conclusions: Competitive XC skiers have longer TTE and accumulate more Odef2 than recreational XC skiers during an intermittent-interval protocol at similar intensity relative to MAP. This implies that performance in intermittent endurance sports is related to the ability to repeatedly recharge fractions of MAOD.

• Losnegard, Thomas Johansen; Lund-Hansen, Magne; Stubbe, Erland Vedeler; Granrud, Even Dahlen; Luchsinger, Harri Simon & Sandbakk, Øyvind Bucher [Vis alle 7 forfattere av denne artikkelen] (2023). Highly Trained Biathletes With a Fast-Start Pacing Pattern Improve Time-Trial Skiing Performance by Pacing More Evenly. International Journal of Sports Physiology and Performance (IJSPP). ISSN 1555-0265. doi: 10.1123/ijspp.2023-0211. Fulltekst i vitenarkiv Vis sammendrag

  Purpose: In sprint biathlon, a J-shaped pacing pattern is commonly used. We investigated whether biathletes with a fast-start pacing pattern increase time-trial skiing and shooting performance by pacing more evenly. Methods: Thirty-eight highly trained biathletes (∼21 y, 27 men) performed an individual 7.5 (3 × 2.5 km for women) or 10-km (3 × 3.3 km for men) time trial on roller skis with a self-selected pacing strategy (day 1). Prone (after lap 1) and standing shooting (after lap 2) stages were performed using paper targets. Based on their pacing strategy in the first time trial (ratio between the initial ∼800-m segment pace on lap 1 and average ∼800-m segment pace on laps 1–3), participants were divided into an intervention group with the fastest starting pace (INT, n = 20) or a control group with a more conservative starting pace (CON, n = 18). On day 2, INT was instructed to reduce their starting pace, while CON was instructed to maintain their day 1 strategy. Results: INT increased their overall time-trial performance more than CON from day 1 to day 2 (mean ± 95% CI; 1.5% ± 0.7% vs 0.0% ± 0.9%, P = .02). From day 1 to day 2, INT reduced their starting pace (5.0% ± 1.5%, P < .01), with reduced ratings of perceived exertion during lap 1 (P < .05). For CON, no change was found for starting pace (−0.8% ± 1.2%) or ratings of perceived exertion between days. No differences were found for shooting performance for either group. Conclusion: Highly trained biathletes with a pronounced fast-start pattern improve skiing performance without any change in shooting performance by pacing more evenly.

• Lund-Hansen, Magne; Gløersen, Øyvind; Rud, Bjarne & Losnegard, Thomas Johansen (2023). What is the optimal classical style sub-technique during uphill roller skiing in elite male cross-country skiers? European Journal of Applied Physiology. ISSN 1439-6319. 123, s. 2833–2842. doi: 10.1007/s00421-023-05261-w. Fulltekst i vitenarkiv
• Meyer, Frederic; Lund-Hansen, Magne; Kocbach, Jan Martin; Seeberg, Trine Margrethe; Sandbakk, Øyvind Bucher & Austeng, Andreas (2023). Inertial Sensor-Based Estimation of Temporal Events in Skating Sub-Techniques While In-Field Roller Skiing. Journal of Applied Biomechanics. ISSN 1065-8483. 39(3), s. 204–208. doi: 10.1123/jab.2022-0073. Vis sammendrag

  The aim of this study was to test and adapt a treadmill-developed method for determination of inner-cycle parameters and sub-technique in cross-country roller ski skating for a field application. The method is based on detecting initial and final ground contact of poles and skis during cyclic movements. Eleven athletes skied 4 laps of 2.5 km at low- and high-endurance intensities, using 2 types of skis with different rolling coefficients. Participants were equipped with inertial measurement units attached to their wrists and skis, and insoles with pressure sensors and poles with force measurements were used as reference systems. The method based on inertial measurement units was able to detect >97% of the temporal events detected with the reference system. The inner-cycle temporal parameters had a precision ranging from 49 to 59 milliseconds, corresponding to 3.9% to 13.7% of the corresponding inner-cycle duration. Overall, this study showed good reliability of using inertial measurement units on athletes’ wrists and skis to determine temporal events, inner-cycle parameters, and the performed sub-techniques in cross-country roller ski skating in field conditions.

• Meyer, Frederic; Lund-Hansen, Magne; Seeberg, Trine Margrethe; Kocbach, Jan; Sandbakk, Øyvind & Austeng, Andreas (2022). Inner-Cycle Phases Can Be Estimated from a Single Inertial Sensor by Long Short-Term Memory Neural Network in Roller-Ski Skating. Sensors. ISSN 1424-8220. 22(23). doi: 10.3390/s22239267. Fulltekst i vitenarkiv Vis sammendrag

  Objective: The aim of this study was to provide a new machine learning method to determine temporal events and inner-cycle parameters (e.g., cycle, pole and ski contact and swing time) in cross-country roller-ski skating on the field, using a single inertial measurement unit (IMU). Methods: The developed method is based on long short-term memory neural networks to detect the initial and final contact of the poles and skis with the ground during the cyclic movements. Eleven athletes skied four laps of 2.5 km at a low and high intensity using skis with two different rolling coefficients. They were equipped with IMUs attached to the upper back, lower back and to the sternum. Data from force insoles and force poles were used as the reference system. Results: The IMU placed on the upper back provided the best results, as the LSTM network was able to determine the temporal events with a mean error ranging from −1 to 11 ms and had a standard deviation (SD) of the error between 64 and 70 ms. The corresponding inner-cycle parameters were calculated with a mean error ranging from −11 to 12 ms and an SD between 66 and 74 ms. The method detected 95% of the events for the poles and 87% of the events for the skis. Conclusion: The proposed LSTM method provides a promising tool for assessing temporal events and inner-cycle phases in roller-ski skating, showing the potential of using a single IMU to estimate different spatiotemporal parameters of human locomotion.

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