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Holmberg, Hans-ChristerORCID iD iconorcid.org/0000-0002-3814-6246
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Publications (10 of 367) Show all publications
Supej, M. & Holmberg, H.-C. (2019). Recent Kinematic and Kinetic Advances in Olympic Alpine Skiing: Pyeongchang and Beyond. Frontiers in Physiology, 10, Article ID 111.
Open this publication in new window or tab >>Recent Kinematic and Kinetic Advances in Olympic Alpine Skiing: Pyeongchang and Beyond
2019 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 10, article id 111Article in journal (Refereed) Published
Abstract [en]

Alpine skiing has been an Olympic event since the first Winter Games in 1936. Nowadays, skiers compete in four main events: slalom, giant slalom, super-G and downhill. Here, we present an update on the biomechanics of alpine ski racers and their equipment. The technical and tactical ability of today's world-class skiers have adapted substantially to changes in equipment, snow conditions and courses. The wide variety of terrain, slopes, gate setups and snow conditions involved in alpine skiing requires skiers to continuously adapt, alternating between the carving and skidding turning techniques. The technical complexity places a premium on minimizing energy dissipation, employing strategies and ski equipment that minimize ski-snow friction and aerodynamic drag. Access to multiple split times along the racing course, in combination with analysis of the trajectory and speed provide information that can be utilized to enhance performance. Peak ground reaction forces, which can be as high as five times body weight, serve as a measure of the external load on the skier and equipment. Although the biomechanics of alpine skiing have significantly improved, several questions concerning optimization of skiers' performance remain to be investigated. Recent advances in sensor technology that allow kinematics and kinetics to be monitored can provide detailed information about the biomechanical factors related to success in competitions. Moreover, collection of data during training and actual competitions will enhance the quality of guidelines for training future Olympic champions. At the same time, the need to individualize training and skiing equipment for each unique skier will motivate innovative scientific research for years to come.

Keywords
downhill, giant slalom, performance, super-G, tactics, technique
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-35803 (URN)10.3389/fphys.2019.00111 (DOI)000459161800001 ()30842740 (PubMedID)
Available from: 2019-03-18 Created: 2019-03-18 Last updated: 2019-03-18Bibliographically approved
Supej, M., Nedergaard, N., Nord, J. & Holmberg, H.-C. (2019). The impact of start strategy on start performance in alpine skiing exists on flat, but not on steep inclines. Journal of Sports Sciences, 37(6), 647-655
Open this publication in new window or tab >>The impact of start strategy on start performance in alpine skiing exists on flat, but not on steep inclines
2019 (English)In: Journal of Sports Sciences, ISSN 0264-0414, E-ISSN 1466-447X, Vol. 37, no 6, p. 647-655Article in journal (Refereed) Published
Abstract [en]

Here, we explored the relationship between incline and start strategy during alpine skiing. Eight FIS skiers performed starts on a flat (3°) and steep (21°) incline employing five different strategies. Their times, trajectories and velocities were monitored with a GNSS system and video. A significant interaction was observed between slope incline and start strategy with respect to the skier’s exit velocity (p < 0.001, ƞ2 p = 0.716), but not for the start section time (p = 0.732, ƞ2 p = 0.037). On the almost flat incline, both section time (p = 0.022, ƞ2 p = 0.438) and exit velocity (p < 0.001, ƞ2 p = 0.786) were influenced significantly by start strategy, with four V2 skate-pushes being optimal. On the steep incline, neither section time nor exit velocity was affected significantly by start strategy, the fastest section time and exit velocity being attained with four and two V2 skate-pushes, respectively. In conclusion, these findings demonstrate that the start strategy exerts considerable impact on start performance on almost flat inclines, with strategies involving three or more V2 skate-pushes being optimal. In contrast, start performance on the steep incline was not influenced by strategy.

Keywords
Biomechanics, coach evaluation, kinematic, pole-push, skate stroke
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-35079 (URN)10.1080/02640414.2018.1522698 (DOI)000456817600006 ()30317917 (PubMedID)
Available from: 2018-12-17 Created: 2018-12-17 Last updated: 2019-03-18Bibliographically approved
Sperlich, B., Hahn, L.-S., Edel, A., Behr, T., Helmprobst, J., Leppich, R., . . . Holmberg, H.-C. (2018). A 4-Week Intervention Involving Mobile-Based Daily 6-Minute Micro-Sessions of Functional High-Intensity Circuit Training Improves Strength and Quality of Life, but Not Cardio-Respiratory Fitness of Young Untrained Adults. Frontiers in Physiology, 9, Article ID e423.
Open this publication in new window or tab >>A 4-Week Intervention Involving Mobile-Based Daily 6-Minute Micro-Sessions of Functional High-Intensity Circuit Training Improves Strength and Quality of Life, but Not Cardio-Respiratory Fitness of Young Untrained Adults
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2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, article id e423Article in journal (Refereed) Published
Abstract [en]

The present study was designed to assess the psycho-physiological responses of physically untrained individuals to mobile-based multi-stimulating, circuit-like, multiplejoint conditioning (CircuitHiu) performed either once (IxCircuitmu) or twice (2xCircuitHiu) daily for 4 weeks. In this single-center, two-arm randomized, controlled study, 24 men and women (age: 25 +/- 5 years) first received no training instructions for 4 weeks and then performed 4 weeks of either IxCircuitnirr or 2xCircuitHiu (5 men and 7 women in each group) daily. The IxCircuitnirr and 2xCircuitHiu participants carried out 90.7 and 85.7% of all planned training sessions, respectively, with average heart rates during the 6-min sessions of 74.3 and 70.8% of maximal heart rate. Body, fat and fat-free mass, and metabolic rate at rest did not differ between the groups or between time-points of measurement. Heart rate while running at 6 km h(-1) declined after the intervention in both groups. Submaximal and peak oxygen uptake, the respiratory exchange ratio and heart rate recovery were not altered by either intervention. The maximal numbers of push-ups, leg-levers, burpees, 45 degrees-one-legged squats and 30-s skipping, as well as perception of general health improved in both groups. Our IxCircuitHiu or 2xCircuitHiiT interventions improved certain parameters of functional strength and certain dimensions of quality of life in young untrained individuals. However, they were not sufficient to enhance cardio-respiratory fitness, in particular peak oxygen uptake.

Keywords
aerobic fitness, body composition, functional training, mHealth, power training, V800, wearable, Web-based apps
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33677 (URN)10.3389/fphys.2018.00423 (DOI)000431783900001 ()2-s2.0-85046654801 (Scopus ID)
Available from: 2018-05-30 Created: 2018-05-30 Last updated: 2018-06-10Bibliographically approved
Gejl, K. D., Vissing, K., Hansen, M., Thams, L., Rokkedal-Lausch, T., Plomgaard, P., . . . Ørtenblad, N. (2018). Changes in metabolism but not myocellular signaling by training with CHO-restriction in endurance athletes. Physiological Reports, 6(17), Article ID e13847.
Open this publication in new window or tab >>Changes in metabolism but not myocellular signaling by training with CHO-restriction in endurance athletes
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2018 (English)In: Physiological Reports, E-ISSN 2051-817X, Vol. 6, no 17, article id e13847Article in journal (Refereed) Published
Abstract [en]

Carbohydrate (CHO) restricted training has been shown to increase the acute training response, whereas less is known about the acute effects after repeated CHO restricted training. On two occasions, the acute responses to CHO restriction were examined in endurance athletes. Study 1 examined cellular signaling and metabolic responses after seven training-days including CHO manipulation (n = 16). The protocol consisted of 1 h high-intensity cycling, followed by 7 h recovery, and 2 h of moderate-intensity exercise (120SS). Athletes were randomly assigned to low (LCHO: 80 g) or high (HCHO: 415 g) CHO during recovery and the 120SS. Study 2 examined unaccustomed exposure to the same training protocol (n = 12). In Study 1, muscle biopsies were obtained at rest and 1 h after 120SS, and blood samples drawn during the 120SS. In Study 2, substrate oxidation and plasma glucagon were determined. In Study 1, plasma insulin and proinsulin C-peptide were higher during the 120SS in HCHO compared to LCHO (insulin: 0 min: +37%; 60 min: +135%; 120 min: +357%, P = 0.05; proinsulin C-peptide: 0 min: +32%; 60 min: +52%; 120 min: +79%, P = 0.02), whereas plasma cholesterol was higher in LCHO (+15-17%, P = 0.03). Myocellular signaling did not differ between groups. p-AMPK and p-ACC were increased after 120SS (+35%, P = 0.03; +59%, P = 0.0004, respectively), with no alterations in p-p38, p-53, or p-CREB. In Study 2, glucagon and fat oxidation were higher in LCHO compared to HCHO during the 120SS (+26-40%, P = 0.03; +44-76%, P = 0.01 respectively). In conclusion, the clear respiratory and hematological effects of CHO restricted training were not translated into superior myocellular signaling after accustomization to CHO restriction.

Keywords
Cycling, endurance performance, fat oxidation, glycogen, train-low
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34538 (URN)10.14814/phy2.13847 (DOI)000444544300018 ()30175557 (PubMedID)2-s2.0-85053290885 (Scopus ID)
Available from: 2018-09-27 Created: 2018-09-27 Last updated: 2018-10-16Bibliographically approved
Pellegrini, B., Stöggl, T. L. & Holmberg, H.-C. (2018). Developments in the Biomechanics and Equipment of Olympic Cross-Country Skiers. Frontiers in Physiology, 9(JUL), Article ID 976.
Open this publication in new window or tab >>Developments in the Biomechanics and Equipment of Olympic Cross-Country Skiers
2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no JUL, article id 976Article in journal (Refereed) Published
Abstract [en]

Here, our aim was to describe the major changes in cross-country (XC) skiing in recent decades, as well as potential future developments. XC skiing has been an Olympic event since the very first Winter Games in Chamonix, France, in 1924. Over the past decades, considerable developments in skiing techniques and improvements in equipment and track preparation have increased skiing speed. In contrast to the numerous investigations on the physiological determinants of successful performance, key biomechanical factors have been less explored. Today's XC skier must master a wide range of speeds, terrains, and race distances and formats (e.g., distance races with individual start, mass-start or pursuit; knock-out and team-sprint; relays), continuously adapting by alternating between various sub-techniques. Moreover, several of the new events in which skiers compete head-to-head favor technical and tactical flexibility and encourage high-speed techniques (including more rapid development of propulsive force and higher peak forces), as well as appropriate training. Moreover, the trends toward more extensive use of double poling and skiing without grip wax in classical races have given rise to regulations in connection with Olympic distances that appear to have preserved utilization of the traditional classical sub-techniques. In conclusion, although both XC equipment and biomechanics have developed significantly in recent decades, there is clearly room for further improvement. In this context as well, for analyzing performance and optimizing training, sensor technology has a potentially important role to play.

Keywords
performance, pole, poling force, ski, skiing technique, track preparation
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34228 (URN)10.3389/fphys.2018.00976 (DOI)000439607400002 ()30087621 (PubMedID)2-s2.0-85050637667 (Scopus ID)
Available from: 2018-08-13 Created: 2018-08-13 Last updated: 2018-09-28Bibliographically approved
Zoppirolli, C., Bortolan, L., Stella, F., Boccia, G., Holmberg, H.-C., Schena, F. & Pellegrini, B. (2018). Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered. Frontiers in Physiology, 9(JUL), Article ID 978.
Open this publication in new window or tab >>Following a Long-Distance Classical Race the Whole-Body Kinematics of Double Poling by Elite Cross-Country Skiers Are Altered
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2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no JUL, article id 978Article in journal (Refereed) Published
Abstract [en]

Introduction: Although short-term (approximately 10-min) fatiguing DP has been reported not to alter the joint kinematics or displacement of the centre of mass (COM) of high-level skiers, we hypothesize that prolonged DP does change these kinematics, since muscular strength is impaired following endurance events lasting longer than 2 h. Methods: During the 58-km Marcialonga race in 2017, the fastest 15 male skiers were videofilmed (100 fps, FHD resolution in the sagittal plane) on two 20-m sections (inclines: 0.7 +/- 0.1 degrees) 48 km apart (i.e., 7 and 55 km from the start), approximating 50-km Olympic races. The cameras were positioned perpendicular to and about 40 m from the middle of each section and spatial dimensions adjusted for each individual track skied. Pole and joint kinematics, as well as displacement of the COM during two DP cycles were assessed. Results: The 10 skiers who fulfilled our inclusion criteria finished the race in 2 h 09 min 19 s +/- 28 s. Displacements of the joints and COM were comparable to previous observations on skiers roller skiing on a flat treadmill at similar speeds in the laboratory. 55 km after the start, cycle velocity and length were lower (P < 0.001 and P = 0.002, respectively) and the angular range of elbow joint flexion during the initial part of the poling phase reduced, while shoulder angle was greater during the first 35% of the DP cycle (all P < 0.05). Moreover, the ankle angle was increased and forward displacement of the COM reduced during the first 80% of the cycle. Conclusion: Prolonged DP reduced the forward displacement of the COM and altered arm kinematics during the early poling phase. The inefficient utilization of COM observed after 2 h of competition together with potential impairment of the stretch-shortening of arm extensor muscles probably attenuated generation of poling force. To minimize these effects of fatigue, elite skiers should focus on maintaining optimal elbow and ankle kinematics and an effective forward lean during the propulsive phase of DP.

National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34272 (URN)10.3389/fphys.2018.00978 (DOI)000439827300001 ()30090070 (PubMedID)2-s2.0-85050587911 (Scopus ID)
Available from: 2018-08-17 Created: 2018-08-17 Last updated: 2018-09-28Bibliographically approved
Stöggl, T., Welde, B., Supej, M., Zoppirolli, C., Rolland, C. G., Holmberg, H.-C. & Pellegrini, B. (2018). Impact of incline, sex and level of performance on kinematics during a distance race in classical cross-country skiing. Journal of Sports Science and Medicine (JSSM), 17(1), 124-133
Open this publication in new window or tab >>Impact of incline, sex and level of performance on kinematics during a distance race in classical cross-country skiing
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2018 (English)In: Journal of Sports Science and Medicine (JSSM), ISSN 1303-2968, Vol. 17, no 1, p. 124-133Article in journal (Refereed) Published
Abstract [en]

Here, female and male elite cross-country (XC) skiers were compared on varying terrain during an official 10-km (women) and 15-km (men) Norwegian championship race. On the basis of race performance, 82 skiers were classified as fast (FS) (20 women, 20 men) or slower (SS) (21, 21) skiers. All were video recorded on flat (0°), intermediate (3.5°), uphill (7.1°) and steep uphill (11°) terrain during the race at a distance of 0.8, 1.2, 2.1 and 7.1 km from the start, respectively. All skiers employed exclusively double-poling (DP) on the flat section and, except for the male winner, exclusively diagonal stride (DIA) on the uphill sections. On the intermediate section, more men than women utilized DP and fewer DIA (p = 0.001), with no difference in kick double-poling (DPK). More FS than SS utilized DPK and fewer DIA (p = 0.001), with similar usage of DP. Males skied with faster and longer cycles but lower cycle rate compared with females (p < 0.001), with largest absolute sex differences on flat terrain (p < 0.001) and largest relative differences for cycle velocity and length on intermediate and uphill terrain. External power output rose with increasing incline, being higher for men and FS (p < 0.001). Cycle velocity on flat terrain was the best predictor of mean race velocity for the men, while cycle velocity on steep uphill was the best predictor for the women (both p < 0.001). In conclusion, incline, sex and level of performance influenced cycle characteristics and power output. Greatest absolute sex gap was on flat terrain, whereas the relative difference was greatest on intermediate and steep uphill terrain. We recommend usage of more DP and/or DPK, and less DIA and fewer transitions between techniques on intermediate terrain. Predictors of race performance are sex specific with greatest potential for enhancing performance on flat terrain for men and on steep uphill terrain for women. 

Keywords
Cycle characteristics, Diagonal stride, Double poling, Kick double poling, Power output, Video analysis
National Category
Sport and Fitness Sciences
Identifiers
urn:nbn:se:miun:diva-33275 (URN)000425786500015 ()2-s2.0-85042669483 (Scopus ID)
Available from: 2018-03-14 Created: 2018-03-14 Last updated: 2018-03-19Bibliographically approved
Düking, P., Achtzehn, S., Holmberg, H.-C. & Sperlich, B. (2018). Integrated framework of load monitoring by a combination of smartphone applications, wearables and point-of-care testing provides feedback that allows individual responsive adjustments to activities of daily living. Sensors, 18(5), Article ID 1632.
Open this publication in new window or tab >>Integrated framework of load monitoring by a combination of smartphone applications, wearables and point-of-care testing provides feedback that allows individual responsive adjustments to activities of daily living
2018 (English)In: Sensors, ISSN 1424-8220, E-ISSN 1424-8220, Vol. 18, no 5, article id 1632Article in journal (Refereed) Published
Abstract [en]

Athletes schedule their training and recovery in periods, often utilizing a pre-defined strategy. To avoid underperformance and/or compromised health, the external load during training should take into account the individual’s physiological and perceptual responses. No single variable provides an adequate basis for planning, but continuous monitoring of a combination of several indicators of internal and external load during training, recovery and off-training as well may allow individual responsive adjustments of a training program in an effective manner. From a practical perspective, including that of coaches, monitoring of potential changes in health and performance should ideally be valid, reliable and sensitive, as well as time-efficient, easily applicable, non-fatiguing and as non-invasive as possible. Accordingly, smartphone applications, wearable sensors and point-of-care testing appear to offer a suitable monitoring framework allowing responsive adjustments to exercise prescription. Here, we outline 24-h monitoring of selected parameters by these technologies that (i) allows responsive adjustments of exercise programs, (ii) enhances performance and/or (iii) reduces the risk for overuse, injury and/or illness.

Keywords
Biofeedback, eHealth, Individualized training, Injury prevention, IoT, Load management, Periodization
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-34112 (URN)10.3390/s18051632 (DOI)000435580300331 ()29783763 (PubMedID)2-s2.0-85047263268 (Scopus ID)
Available from: 2018-07-04 Created: 2018-07-04 Last updated: 2018-09-26
Marsland, F., Anson, J., Waddington, G., Holmberg, H.-C. & Chapman, D. W. (2018). Macro-Kinematic Differences Between Sprint and Distance Cross-Country Skiing Competitions Using the Classical Technique. Frontiers in Physiology, 9(MAY), Article ID 570.
Open this publication in new window or tab >>Macro-Kinematic Differences Between Sprint and Distance Cross-Country Skiing Competitions Using the Classical Technique
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2018 (English)In: Frontiers in Physiology, ISSN 1664-042X, E-ISSN 1664-042X, Vol. 9, no MAY, article id 570Article in journal (Refereed) Published
Abstract [en]

We compare the macro-kinematics of six elite female cross-country skiers competing in 1.1-km Sprint and 10.5-km Distance classical technique events on consecutive days under similar weather and track conditions. The relative use of double pole (DP), kick-double pole (KDP), diagonal stride (DS), tucking (Tuck) and turning (Turn) sub-techniques, plus each technique's respective velocities, cycle lengths and cycle rates were monitored using a single micro-sensor unit worn by each skier during the Sprint qualification, semi-final and finals, and multiple laps of the Distance race. Over a 1.0-km section of track common to both Sprint and Distance events, the mean race velocity, cyclical sub-technique velocities, and cycle rates were higher during the Sprint race, while Tuck and Turn velocities were similar. Velocities with KDP and DS on the common terrain were higher in the Sprint (KDP +12%, DS +23%) due to faster cycle rates (KDP +8%, DS +11 %) and longer cycle lengths (KDP +5%, DS +10%), while the DP velocity was higher (+8%) with faster cycle rate (+16%) despite a shorter cycle length (-9%). During the Sprint the percentage of total distance covered using DP was greater (+15%), with less use of Tuck (-19%). Across all events and rounds, DP was the most used sub-technique in terms of distance, followed by Tuck, DS, Turn and KDP. KDP was employed relatively little, and during the Sprint by only half the participants. Tuck was the fastest sub-technique followed by Turn, DP, KDP, and DS, These findings reveal differences in the macro-kinematic characteristics and strategies utilized during Sprint and Distance events, confirm the use of higher cycle rates in the Sprint, and increase our understanding of the performance demands of cross-country skiing competition.

Keywords
kinematics, cycle length, cycle rate, performance analysis, wearable sensors, Winter Olympics
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33689 (URN)10.3389/fphys.2018.00570 (DOI)000432411000001 ()2-s2.0-85047168901 (Scopus ID)
Available from: 2018-05-31 Created: 2018-05-31 Last updated: 2018-07-04Bibliographically approved
Messler, C. F., Holmberg, H.-C. & Sperlich, B. (2018). Multimodal Therapy Involving High-Intensity Interval Training Improves the Physical Fitness, Motor Skills, Social Behavior, and Quality of Life of Boys With ADHD: A Randomized Controlled Study. Journal of Attention Disorders, 22(8), 806-812
Open this publication in new window or tab >>Multimodal Therapy Involving High-Intensity Interval Training Improves the Physical Fitness, Motor Skills, Social Behavior, and Quality of Life of Boys With ADHD: A Randomized Controlled Study
2018 (English)In: Journal of Attention Disorders, ISSN 1087-0547, E-ISSN 1557-1246, Vol. 22, no 8, p. 806-812Article in journal (Refereed) Published
Abstract [en]

Objective: To compare the effects of multimodal therapy including supervised high-intensity interval training (HIIT) with those of standard multimodal therapy (TRAD) concerning key variables of physical fitness (peak power and oxygen uptake), motor skills, social behavior, and quality of life in boys with ADHD. Method: A single-center, two-arm randomized, controlled design was used, with 28 boys (8-13 years of age, IQ = 83-136) being randomly assigned to multimodal HIIT (three sessions/week, 4 x 4-min intervals at 95% of peak heart rate) or TRAD. The Movement Assessment Battery for Children II evaluated motor skills and the German version of the hyperkinetic disorder questionnaire for external evaluation by the guardians (FBB-HKS) or German version of the hyperkinetic disorder questionnaire for self-assessment by the children (SBB-HKS) and the KINDL-R questionnaires mental health and health-related quality of life. Results: Both interventions enhanced peak power, and HIIT also reduced submaximal oxygen uptake. HIIT was more effective than TRAD in improving the total score for motor skills (including manual dexterity and ball skills; p < .05), self-esteem, friends, and competence (p < .05) and, moreover, improved subjective ratings of attention. Conclusion: Three weeks of multimodal therapy including HIIT improved physical fitness, motor skills, certain aspects of quality of life, competence, and attention in boys with ADHD.

Keywords
ADHD, children, exercise, HIIT, training
National Category
Health Sciences
Identifiers
urn:nbn:se:miun:diva-33734 (URN)10.1177/1087054716636936 (DOI)000432874800010 ()27013028 (PubMedID)
Available from: 2018-06-10 Created: 2018-06-10 Last updated: 2018-06-10Bibliographically approved
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ORCID iD: ORCID iD iconorcid.org/0000-0002-3814-6246

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