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  • 1
    Language: English
    In: Sports Medicine, 2013, Vol.43(5), pp.355-366
    Description: BACKGROUND: Skiing and snowboarding are two activities that significantly contribute to the total number of sports-related injuries reported per year. Strength, endurance and cardiovascular fitness are central components in sports injury prevention. Providing exercises and training recommendations specific to recreational skiers and snowboarders is important in both injury prevention and reducing the prevalence and cost associated with alpine winter sports injuries.OBJECTIVE: The aim of this paper was to systematically review the literature for injury prevention recommendations specific to recreational alpine skiers and snowboarders. The focus was to discern recommendations that targeted physical fitness, exercise and/or training in the prevention of musculoskeletal injuries in these two sports.DATA SOURCES: Fourteen electronic databases were searched in October 2011 using relevant MeSH terms and key words.STUDY SELECTION: Articles were included if they addressed injury prevention, recreational alpine skiing or snowboarding and musculoskeletal injuries. Only original research articles published in peer-reviewed journals, and in the English-language, were reviewed. Articles on elite athletes were excluded.STUDY APPRAISAL AND SYNTHESIS METHODS: Two independent reviewers quality assessed articles meeting inclusion criteria using a modified version of the Downs and Black Quality Assessment Checklist. Data on study population, study design, study location and injury prevention recommendation(s) were extracted from articles using a standard form and subsequently categorized to facilitate data synthesis.RESULTS: A total of 30 articles met the inclusion criteria and were reviewed, having an average ± standard deviation quality score of 72% ± 17% (range: 23-100 %). Overall, 80 recommendations for the prevention of musculoskeletal injuries in recreational alpine skiers and snowboarders were identified and classified into five main groups: equipment (n = 24), education and knowledge (n = 11), awareness and behaviour (n = 15), experience (n = 10) and third-party involvement (n = 20). No recommendations pertained to physical fitness, exercise and/or training per se, or its role in preventing injury.LIMITATIONS: A comprehensive meta-analysis was not possible because several articles did not report data in sufficient detail.CONCLUSIONS: The importance of targeting physical fitness in injury prevention is accepted in sports medicine and rehabilitation; yet, there was a paucity of articles included in this review that explicitly investigated this aspect with regards to recreational alpine skiing and snowboarding. The most frequent recommendations for preventing skiing and snowboarding injuries concerned equipment or the involvement of third parties. The dominance of equipment-related measures in the injury prevention literature may be rationalized from a sports biomechanics viewpoint, as these activities involve high velocities and impact forces. Nonetheless, this also indicates a need for appropriate levels of strength, endurance and conditioning to meet the technical demands of these sports. Bearing this in mind, future research is encouraged to investigate the role of physical fitness, exercise and training in decreasing the incidence and severity of skiing and snowboarding injuries in recreational athletes.
    Keywords: Medicine;
    ISSN: 0112-1642
    E-ISSN: 1179-2035
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  • 2
    In: Medicine & Science in Sports & Exercise, 2013, Vol.45(8), pp.1569-1576
    Description: PURPOSE: In cross-country (XC) skiing, the V1 and V2 alternate skate techniques are asymmetric, and skiers can choose either the right or left side for pole support. The overall purpose of this study was to investigate V1 side preference in elite XC skiers, notably by documenting V1 skate side preference, dominant and nondominant V1peak speeds, left- to right-side differences (ΔL-R) in laboratory-based measurements, and relationships between side preference data. METHODS: Sixteen male elite XC skiers completed one incremental speed test using V1 on their dominant side and another incremental speed test using V1 on their nondominant side while roller-skiing on a treadmill. During these tests, V1peak speed, pole forces, and plantar forces were measured. A whole-body dual-energy x-ray absortiometry (DXA) scan measured anthropometric parameters and questionnaires established side preference for V2 alternate, overall laterality in XC skiing, handedness, footedness, and injury prevalence. RESULTS: Left-to-right V1 side preference was equally distributed among skiers. V1peak speed was approximately 4.5% greater on the dominant versus nondominant sides. V1peak ΔL-R were positively related to ΔL-R in V1-dominant peak pole forces only. Questionnaire data indicated that more skiers preferred V2 alternate right, with moderate correlations between preferred V1 and V2 alternate sides. The expression of a dominant side in V1 and V2 alternate increased as skiing speed increased from moderate to 15-km endurance-race to sprint-race speeds. However, no relationships were established between V1 or V2 side preference and handedness, footedness, or number of one-sided injuries. CONCLUSIONS: ΔL-R in measurements provide limited explanations for V1 side preferences in elite XC skiers. In fact, no systematic relations exist between V1 side preferences and anthropometric, biomechanical, or questionnaire data.
    Keywords: Absorptiometry, Photon–Physiology ; Adult–Physiology ; Anthropometry–Physiology ; Athletes–Physiology ; Biomechanical Phenomena–Physiology ; Exercise Test–Physiology ; Functional Laterality–Physiology ; Humans–Physiology ; Male–Physiology ; Muscle, Skeletal–Physiology ; Skiing–Physiology ; Surveys and Questionnaires–Physiology ; Young Adult–Physiology ; Space Life Sciences;
    ISSN: 0195-9131
    E-ISSN: 15300315
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  • 3
    In: Medicine & Science in Sports & Exercise, 2015, Vol.47(12), pp.2586-2594
    Description: PURPOSE: This study aims to investigate fluctuations in total mechanical energy of the body (Ebody) in relation to external ergometer work (Werg) during the poling and recovery phases of simulated double-poling cross-country skiing. METHODS: Nine male cross-country skiers (mean ± SD age, 24 ± 5 yr; mean ± SD body mass, 81.7 ± 6.5 kg) performed 4-min submaximal tests at low-intensity, moderate-intensity, and high-intensity levels and a 3-min all-out test on a ski ergometer. Motion capture analysis and load cell recordings were used to measure body kinematics and dynamics. From these, Werg, Ebody (sum of the translational, rotational, and gravitational potential energies of all segments), and their time differentials (power P) were calculated. Ptot—the rate of energy absorption or generation by muscles–tendons—was defined as the sum of Pbody and Perg. RESULTS: Ebody showed large fluctuations over the movement cycle, decreasing during poling and increasing during the recovery phase. The fluctuation in Pbody was almost perfectly out of phase with Perg. Some muscle–tendon energy absorption was observed at the onset of poling. For the rest of poling and throughout the recovery phase, muscles–tendons generated energy to do Werg and to increase Ebody. Approximately 50% of cycle Ptot occurred during recovery for all intensity levels. CONCLUSIONS: In double poling, the extensive contribution of the lower extremities and trunk to whole-body muscle–tendon work during recovery facilitates a “direct” transfer of Ebody to Werg during the poling phase. This observation reveals that double poling involves a unique movement pattern different from most other forms of legged terrestrial locomotion, which are characterized primarily by inverted pendulum or spring-mass types of movement.
    Keywords: Biomechanical Phenomena–Physiology ; Energy Metabolism–Physiology ; Ergometry–Physiology ; Humans–Physiology ; Lower Extremity–Physiology ; Male–Physiology ; Motor Skills–Physiology ; Movement–Physiology ; Muscle, Skeletal–Physiology ; Oxygen Consumption–Physiology ; Skiing–Physiology ; Tendons–Physiology ; Torso–Physiology ; Young Adult–Physiology;
    ISSN: 0195-9131
    E-ISSN: 15300315
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  • 4
    In: Medicine & Science in Sports & Exercise, 2015, Vol.47(6), pp.1232-1242
    Description: PURPOSE: To describe the detailed kinetics and kinematics associated with use of the V1 skating technique at high skiing speeds and to identify factors that predict performance. METHODS: Fifteen elite male cross-country skiers performed an incremental roller-skiing speed test (Vpeak) on a treadmill using the V1 skating technique. Pole and plantar forces and whole-body kinematics were monitored at four submaximal speeds. RESULTS: The propulsive force of the “strong side” pole was greater than that of the “weak side” (P 〈 0.01), but no difference was observed for the legs. The poles generated approximately 44% of the total propulsion, being more effective than the legs in this respect (∼59% vs 11%, P 〈 0.001). Faster skiers exhibited more well-synchronized poling, exhibited more symmetric edging by and forces from the legs, and were more effective in transformation of resultant forces into propulsion. Cycle length was not correlated with either Vpeak or the impulse of total propulsive forces. CONCLUSIONS: The present findings provide novel insights into the coordination, kinetics, and kinematics of the arm and leg motion by elite athletes while V1 skating at high speeds. The faster skiers exhibit more symmetric leg motion on the “strong” and “weak” sides, as well as more synchronized poling. With respect to methods, the pressure insoles and three-dimensional kinematics in combination with the leg push-off model described here can easily be applied to all skating techniques, aiding in the evaluation of skiing techniques and comparison of effectiveness.
    Keywords: Leg -- Physiology ; Skating -- Physiology ; Skiing -- Physiology;
    ISSN: 0195-9131
    E-ISSN: 15300315
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  • 5
    Language: English
    In: Medicine & Science in Sports & Exercise, 2016, Vol. 48(8), pp. 1580-1589
    Description: Introduction: In light of the recent revolutionary change in the use of the doublepoling (DP) technique in cross-country skiing, our purpose was to compare the associated kinetics and kinematics on flat (DPflat) and uphill terrain (DPup), as well as to identify factors that determine performance. Methods: Thirteen elite male cross-country skiers completed two incremental speed tests (V-peak) involving roller skiing with the DP technique at moderate (13 and 24 km.h(-1)) and high speed (15 and 28.5 km.h(-1)) on a treadmill that was flat (1 degrees) or tilted uphill (7 degrees). Pole forces and three-dimensional whole-body kinematics were monitored simultaneously. Results: In comparison to DPflat, during DPup, swing times were much shorter (-48%) and peak pole forces greater (+13%) and generated later during the poling phase (+68%), with higher impulses for all force components (+87%-123%). Furthermore, pole forces were 18% more effectively oriented for propulsion. During DPup, the skiers demonstrated more flexed elbows, as well as shoulder angles that were less flexed in the forward direction and less abducted throughout the poling phase, together with more highly flexed knee and ankle joints, a more upright thorax, less flexed hips, and a shortened backward swing after pole off. With DPup, the skiers raised their center of mass 25% more, attaining maximal heel raise and maximal vertical position at a timepoint closer to pole plant compared with flat. On the uphill incline, the magnitude of V-peak was positively related to body mass, relative pole length (% body height), and magnitude of heel raise. Conclusions: The present findings provide novel insights into the coordination, kinetics and kinematics of elite skiers while DP on flat and uphill terrain.
    Keywords: Medical And Health Sciences ; Health Sciences ; Medicin Och Hälsovetenskap ; Hälsovetenskaper
    ISSN: 0195-9131
    E-ISSN: 15300315
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  • 6
    In: Medicine & Science in Sports & Exercise, 2013, Vol.45(1), pp.206-211
    Description: : Several investigators have demonstrated that chronic eccentric leg cycling is an effective method for improving lower body neuromuscular function (e.g., quadriceps muscle size, strength, and mobility) in a variety of patient and athletic populations. To date, there are no reports of using eccentric arm cycling (ECarm) as an exercise modality, probably in large part because of the lack of commercially available ECarm ergometers. PURPOSE: Our purposes for conducting this study were to 1) describe the design and construction of an ECarm ergometer and 2) compare ECarm to traditional concentric arm cycling (CCarm). METHODS: All of the parts of a Monark 891E cycle ergometer (Monark Exercise AB, Vansbro, Sweden) were removed, leaving the frame and flywheel. An electric motor (2.2 kW) was connected to the flywheel via a pulley and a belt. Motor speed and pedaling rate were controlled by a variable frequency drive. A power meter quantified power and pedaling rate, and provided feedback to the individual. Eight individuals performed 3-min ECarm and CCarm trials at 40, 80, and 120 W (60 rpm) while V˙O2 was measured. RESULTS: The ECarm ergometer was simple to use, was adjustable, provided feedback on power output to the user, and allowed for a range of eccentric powers. V˙O2 during ECarm was substantially lower compared with CCarm (P 〈 0.001). At similar V˙O2 (0.97 ± 0.18 vs 0.91 ± 0.09 L·min, for ECarm and CCarm, respectively, P = 0.26), power absorbed during ECarm was approximately threefold greater than that produced during CCarm (118 ± 1 vs 40 ± 1 W, P 〈 0.001). CONCLUSION: This novel ECarm ergometer can be used to perform repetitive, high-force, multijoint, eccentric actions with the upper body at a low level of metabolic demand and may allow researchers and clinicians to use ECarm as a training and rehabilitation modality.
    Keywords: Exercise Test -- Instrumentation ; Resistance Training -- Instrumentation;
    ISSN: 0195-9131
    E-ISSN: 15300315
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  • 7
    In: Medicine & Science in Sports & Exercise, 2011, Vol.43(5 Suppl 1), pp.951-951
    ISSN: 0195-9131
    Source: Copyright © 2013 Lippincott Williams & Wilkins. All rights reserved.〈img src=http://exlibris-pub.s3.amazonaws.com/LWW%20logo.png style="vertical-align:middle;margin-left:7px"〉
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  • 8
    In: Journal of Strength and Conditioning Research, 2014, Vol.28(3), pp.843-855
    Description: ABSTRACT: Hébert-Losier, K and Holmberg, HC. Dynamometric indicators of fatigue from repeated maximal concentric isokinetic plantar flexion contractions are independent of knee flexion angles and age but differ for males and females. J Strength Cond Res 28(3): 843–855, 2014—Sex and age are reported to influence the maximal dynamometric performance of major muscle groups, inclusive of ankle plantar flexors. Knee flexion (KF) also impacts plantar flexion function from where stems use of 0° and 45° angles of KF for clinical assessment of gastrocnemius and soleus, respectively. The influence of KF, sex, and age on dynamometric indicators of plantar flexion fatigue was examined in 28 males and 28 females recruited in 2 different age groups (older and younger than 40 years). Each subject performed 50 maximal concentric isokinetic plantar flexions at 60-degree angle per·second with 0° and 45° angles of KF. Maximal voluntary isometric contractions were determined before and after isokinetic trials and maximal, minimal, and normalized linear slopes of peak power during testing. Main effects of and 2-way interactions between KF, sex, age, and order of testing were explored using mixed-effect models and stepwise regressions. At angles of 0° and 45°, the fatigue indicators in younger and older individuals were similar and not influenced by testing order. However, peak isokinetic power and isometric torque declined to greater extents in males than females and, moreover, KF exerted greater impacts on the absolute plantar flexion performance and maximal-to-minimal reduction in isokinetic power in males. Because KF wielded no pronounced effect on fatigue indicators, this test may perhaps be used over time with no major concern regarding the exact knee angle. Our findings indicate that sex, rather than age, should be considered when interpreting dynamometric indicators of fatigue from repeated maximal concentric isokinetic plantar flexions, for example, when establishing normative values or comparing outcomes.
    Keywords: Muscle Contraction -- Research ; Knee -- Physiological Aspects ; Leg Muscles -- Physiological Aspects ; Biomechanics -- Research ; Physiological Research;
    ISSN: 1064-8011
    E-ISSN: 15334287
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  • 9
    In: Journal of Strength and Conditioning Research, 2011, Vol.25(5), pp.1299-1305
    Description: Sandbakk, Ø, Welde, B, and Holmberg, H-C. Endurance training and sprint performance in elite junior cross-country skiers. J Strength Cond Res 25(5): 1299-1305, 2011-The purpose of the present study was to investigate the relationship between aerobic characteristics and sprint skiing performance, and the effects of high-intensity endurance training on sprint skiing performance and aerobic characteristics. Ten male and 5 female elite junior cross-country skiers performed an 8-week intervention training period. The intervention group (IG, n = 7) increased the volume of high-intensity endurance training performed in level terrain, whereas the control group (CG, n = 8) continued their baseline training. Before and after the intervention period, the skiers were tested for 1.5-km time-trial performance on roller skis outdoors in the skating technique. Maximal oxygen uptake (&OV0312;o2max) and oxygen uptake at the ventilatory threshold (&OV0312;o2VT) were measured during treadmill running. &OV0312;o2max and &OV0312;o2VT were closely related to sprint performance (r = ∼0.75, both p 〈 0.008). The IG improved sprint performance, &OV0312;o2max, and &OV0312;o2VT from pre to posttesting and improved sprint performance and &OV0312;o2VT when compared to the CG (all p 〈 0.01). This study shows a close relationship between aerobic power and sprint performance in cross-country skiing and highlights the positive effects of high-intensity endurance training in level terrain.
    Keywords: Skiers -- Physiological Aspects ; Skiers -- Psychological Aspects ; Endurance -- Demographic Aspects ; Sports Training -- Health Aspects ; Sports Training -- Psychological Aspects ; Sprinting -- Demographic Aspects ; Athletic Ability -- Research;
    ISSN: 1064-8011
    E-ISSN: 15334287
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  • 10
    Language: English
    In: European Journal of Applied Physiology, 2011, Vol.111(6), pp.1103-1119
    Description: The purpose of the study was to examine the biomechanical-physiological effects of different frequencies using the double poling technique in cross-country skiing. Nine elite skiers roller-skied using poling frequencies of 40, 60 and 80 cycles·min −1 (Pf 40, Pf 60 , Pf 80 ) at submaximal treadmill speeds (12, 18, 24 km·h −1 ). Cycle characteristics, pole forces, joint angles and physiological responses were measured. Comparing Pf 40 versus Pf 60 versus Pf 80 (all variables different at P  〈 0.05), absolute poling time decreased by up to 46%, as did absolute and relative (% cycle time) recovery times, at almost all speeds. Peak force, impulse of force and time to peak force decreased, whereas impact force increased with frequency at almost all speeds. Elbow ranges of motion and angular velocities, hip and knee angle maxima and flexion/extension ranges of motion per cycle decreased, whereas hip and knee angle minima, ranges of motion per minute and angular extension velocities during recovery phase all increased with frequency at nearly all speeds. Oxygen uptake and heart rate increased up to 13% (Pf 40–60 versus Pf 80 ) at all speeds. Pulmonary ventilation increased most distinctly at the highest speed. Blood lactate was lowest at Pf 60 and highest at Pf 80 (J-shape curve) at 24 km·h −1 . Gross efficiency decreased with higher frequency at all speeds. These results demonstrate different biomechanical and physiological demands at different frequencies with the beneficial effects of lower poling frequencies at submaximal speeds. For training purposes, we suggest that cross-country skiers would benefit by training with different poling frequencies to vary their training load.
    Keywords: Biomechanics ; Cadence ; Kinematics ; Kinetics ; Lactate ; Oxygen cost
    ISSN: 1439-6319
    E-ISSN: 1439-6327
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