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  • 1.
    Hebert-Losier, Kim
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sports Science, National Sports Institute of Malaysia, National Sports Complex, Bukit Jalil, Kuala Lumpur, Malaysia.
    Zinner, Christoph
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. Department of Sport Science, Julius-Maximilians-University Würzburg, Würzburg, Germany.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Stöggl, Thomas
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences. University of Salzburg, Salzburg, Austria.
    Holmberg, Hans-Christer
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Factors that Influence the Performance of Elite Sprint Cross-Country Skiers2017In: Sports Medicine, ISSN 0112-1642, E-ISSN 1179-2035, Vol. 47, no 2, p. 319-342Article in journal (Refereed)
    Abstract [en]

    Background: Sprint events in cross-country skiing are unique not only with respect to their length (0.8–1.8 km), but also in involving four high-intensity heats of ~3 min in duration, separated by a relatively short recovery period (15–60 min). Objective: Our aim was to systematically review the scientific literature to identify factors related to the performance of elite sprint cross-country skiers. Methods: Four electronic databases were searched using relevant medical subject headings and keywords, as were reference lists, relevant journals, and key authors in the field. Only original research articles addressing physiology, biomechanics, anthropometry, or neuromuscular characteristics and elite sprint cross-country skiers and performance outcomes were included. All articles meeting inclusion criteria were quality assessed. Data were extracted from each article using a standardized form and subsequently summarized. Results: Thirty-one articles met the criteria for inclusion, were reviewed, and scored an average of 66 ± 7 % (range 56–78 %) upon quality assessment. All articles except for two were quasi-experimental, and only one had a fully-experimental research design. In total, articles comprised 567 subjects (74 % male), with only nine articles explicitly reporting their skiers’ sprint International Skiing Federation points (weighted mean 116 ± 78). A similar number of articles addressed skating and classical techniques, with more than half of the investigations involving roller-skiing assessments under laboratory conditions. A range of physiological, biomechanical, anthropometric, and neuromuscular characteristics was reported to relate to sprint skiing performance. Both aerobic and anaerobic capacities are important qualities, with the anaerobic system suggested to contribute more to the performance during the first of repeated heats; and the aerobic system during subsequent heats. A capacity for high speed in all the following instances is important for the performance of sprint cross-country skiers: at the start of the race, at any given point when required (e.g., when being challenged by a competitor), and in the final section of each heat. Although high skiing speed is suggested to rely primarily on high cycle rates, longer cycle lengths are commonly observed in faster skiers. In addition, faster skiers rely on different technical strategies when approaching peak speeds, employ more effective techniques, and use better coordinated movements to optimize generation of propulsive force from the resultant ski and pole forces. Strong uphill technique is critical to race performance since uphill segments are the most influential on race outcomes. A certain strength level is required, although more does not necessarily translate to superior sprint skiing performance, and sufficient strength-endurance capacities are also of importance to minimize the impact and accumulation of fatigue during repeated heats. Lastly, higher lean mass does appear to benefit sprint skiers’ performance, with no clear advantage conferred via body height and mass. Limitations: Generalization of findings from one study to the next is challenging considering the array of experimental tasks, variables defining performance, fundamental differences between skiing techniques, and evolution of sprint skiing competitions. Although laboratory-based measures can effectively assess on-snow skiing performance, conclusions drawn from roller-skiing investigations might not fully apply to on-snow skiing performance. A low number of subjects were females (only 17 %), warranting further studies to better understand this population. Lastly, more training studies involving high-level elite sprint skiers and investigations pertaining to the ability of skiers to maintain high-sprint speeds at the end of races are recommended to assist in understanding and improving high-level sprint skiing performance, and resilience to fatigue. Conclusions: Successful sprint cross-country skiing involves well-developed aerobic and anaerobic capacities, high speed abilities, effective biomechanical techniques, and the ability to develop high forces rapidly. A certain level of strength is required, particularly ski-specific strength, as well as the ability to withstand fatigue across the repeated heats of sprint races. Cross-country sprint skiing is demonstrably a demanding and complex sport, where high-performance skiers need to simultaneously address physiological, biomechanical, anthropometric, and neuromuscular aspects to ensure success.

  • 2.
    Hébert-Losier, Kim
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Hopkins, William G.
    Victoria Univ, Coll Sport & Exercise Sci, Melbourne, Vic 8001, Australia.
    Sources of Variability in Performance Times at the World Orienteering Championships2015In: Medicine & Science in Sports & Exercise, ISSN 0195-9131, E-ISSN 1530-0315, Vol. 47, no 7, p. 1523-1530Article in journal (Refereed)
    Abstract [en]

    Purpose An improvement equal to 0.3 of the typical variation in an elite athlete's race-to-race performance estimates the smallest worthwhile enhancement, which has not yet been determined for orienteers. Moreover, much of the research in high-performance orienteering has focused on physical and cognitive aspects, although course characteristics might influence race performance. Analysis of race data provides insights into environmental effects and other aspects of competitive performance. Our aim was to examine such factors in relation to World Orienteering Championships performances. Methods We used mixed linear modelling to analyze finishing times from the three qualification rounds and final round of the sprint, middle-distance, and long-distance disciplines of World Orienteering Championships from 2006 to 2013. Models accounted for race length, distance climbed, number of controls, home advantage, venue identity, round (qualification final), athlete identity, and athlete age. Results Within-athlete variability (coefficient of variation, mean SD) was lower in the final (4.9% +/- 1.4%) than in the qualification (7.3% +/- 2.4%) rounds and provided estimates of smallest worthwhile enhancements of 1.0%-3.5%. The home advantage was clear in most disciplines, with distance climbed particularly impacting sprint performances. Small to very large between-venue differences were apparent. Performance predictability expressed as intraclass correlation coefficients was extremely high within years and was high to very high between years. Age of peak performance ranged from 27 to 31 yr. Conclusions Our results suggest that elite orienteers should focus on training and strategies that enhance performance by at least 1.0%-3.5% for smallest worthwhile enhancement. Moreover, as greater familiarity with the terrain likely mediated the home advantage, foreign athletes would benefit from training in nations hosting the World Orienteering Championships for familiarization.

  • 3.
    McGawley, Kerry
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Beaven, Martyn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Björklund, Glenn
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    The validity and reliability of a four-minute running time trial in assessing VO2max and performance2015Conference paper (Refereed)
    Abstract [en]

    INTRODUCTION: Incremental tests to volitional exhaustion are widely used to assess VO2max. However, the need to establish starting workloads, stage durations, and step increments make administration problematic. Moreover, the validity of such tests has been questioned (Beltrami et al., 2012, Br J Sports Med, 46:23-29; Mauger & Sculthorpe, 2012, Br J Sports Med, 46:59-63). Short time trials represent a simpler and more ecologically valid alternative to assess VO2max and performance across exercise modes (Crouter et al., 2001, Med Sci Sports Exerc, 33:644-647; Ansley et al., 2004, Med Sci Sports Exerc, 36:1819-1825; McGawley & Holmberg, 2014, Int J Sports Physiol Perform 9:32-40). The aim of the current study was to assess the reliability and validity of a treadmill running time trial (RunTT) for the assessment of VO2max and performance.

     

    METHODS: Ten recreational athletes (5 males, 5 females; 32 ± 7 y) completed five incremental tests to exhaustion (INC) including a verification phase (VER) on a treadmill and five, 4-min RunTTs. The order of INC+VER and RunTT trials was alternated and counter-balanced. The INC and VER protocols were externally controlled, with incline increasing by 1% every minute during the INC. By contrast, the RunTT protocol was athlete controlled, with running speed self-adjusted via a laser system fitted to the treadmill (and incline fixed at 1%). Performance was measured as time to exhaustion for INC and VER and distance covered for RunTT. Heart rate (HR) was monitored continuously throughout each protocol. RPE and lactate were assessed immediately post-exercise and at 1-min intervals for four minutes post-exercise, respectively.

     

    RESULTS: The CV for VO2max was not significantly different between INC, VER and RunTT (1.9, 2.2 and 1.7%, respectively) but for performance was significantly different between all types of test (4.5, 9.7 and 1.8% for INC, VER and RunTT, respectively; P<0.005). VO2max was significantly higher for INC compared with VER and RunTT (59.2 versus 58.0 and 57.6 mL/kg/min, respectively; P<0.001) and Bland-Altman limits of agreement showed a bias ± 95% of 1.5 ± 3.1 mL/kg/min for INC versus RunTT. Peak HR was also significantly higher for INC compared with RunTT (181 versus 177 beats/min; P<0.001), while peak RER and RPE were not different. Peak lactate was higher after RunTT compared with INC (10.13 versus 9.22 mmol/L; P<0.001).

     

    CONCLUSION: A RunTT appears to provide more reliable performance data in comparison to INC; however, VO2max values were ~ 1.5 mL/kg/min lower and peak lactate was significantly higher.

  • 4.
    McGawley, Kerry
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Watkins, Jonathan
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Optimal Pacing Strategies And Associated Metabolic Responses During 4-Min Self-Paced Running Time-Trials2016Conference paper (Refereed)
  • 5.
    Watkins, Jonathan
    et al.
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Platt, Simon
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Andersson, Erik
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    McGawley, Kerry
    Mid Sweden University, Faculty of Human Sciences, Department of Health Sciences.
    Pacing Strategies and Metabolic Responses During 4-Minute Running Time-Trials2017In: International Journal of Sports Physiology and Performance, ISSN 1555-0265, E-ISSN 1555-0273, Vol. 12, no 9, p. 1143-1150Article in journal (Refereed)
    Abstract [en]

    Purpose: The aim of the current study was to investigate pacing strategies and the distributionof physiological resources in best versus worst performances during a series of 4-minute, self-paced running time-trials (RunTTs). Methods: Five male and five female recreational runners(age 32 ± 7 years) completed a sub-maximal ramp test and five RunTTs on a motor-driventreadmill fitted with a speed-controlling laser system. The supramaximal V̇ O2 demand wasestimated by linear extrapolation from the sub-maximal relationship between V̇ O2 and speed,enabling computation of the accumulated oxygen deficit (AOD). Results: There were nosignificant differences between the five RunTTs for any of the performance, physiological orsubjective responses (P > 0.05). The trial-to-trial variability in pacing (i.e., separate quarters)was typically low, with an average within-athlete CV of 3.3%, being highest at the start andend of the 4 minutes. Total distance covered and distance covered over the first and last 2minutes for best and worst performances were 1137 ± 94 and 1090 ± 89 m (P < 0.001), 565 ±53 and 526 ± 40 m (P = 0.002), and 572 ± 47 and 565 ± 54 m (P = 0.346), respectively.Conclusions: Negative pacing strategies were evident during both the best and worstperformances of the RunTT. Best performances were characterised by more aggressive pacingover the first 2 minutes compared with worst performances. In addition, the relatively low trial-to-trial variability in running speed suggests that pacing strategies are similar during a seriesof 4-minute, self-paced running time-trials.

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