Maximizing recovery time between knock-out races improves sprint cross-country skiing performance

Background:In a sprint cross-country(XC)ski competition,the difference in recovery times separating the first and the second semi-final(SF)heats from the final(F)may affect performance.The aim of the current study was to compare the effects of longer vs.shorter recovery periods prescribed between the 3 knock-out races of a simulated sprint XC ski competition involving a prologue(P),quarter-final(QF),SF,and F.Methods:Eleven well-trained XC ski athletes completed 2 simulated sprint XC ski competitions on a treadmill involving 4×883-m roller-ski bouts at a 4°incline using the gear 3 ski-skating sub-technique.The first 3 bouts were completed at a fixed speed(PFIX,QFFIX,and SFFIX)corresponding to~96%of each individual’s previously determined maximal effort.The final bout was performed as a self-paced sprint time trial(FSTT).Test conditions differed by the time durations prescribed between the QFFIX,SFFIX,and FSTT,which simulated real-world XC ski competition conditions using maximum(MAX-REC)or minimum(MIN-REC)recovery periods.Results:The FSTT was completed 5.4±5.5 s faster(p=0.009)during MAX-REC(179.2±18.1 s)compared to MIN-REC(184.6±20.0 s),and this was linked to a significantly higher power output(p=0.010)and total metabolic rate(p=0.009).The pre FSTT blood lactate(BLa)concentration was significantly lower during MAX-REC compared to MIN-REC(2.5±0.8 mmol/L vs.3.6±1.6 mmol/L,respectively;p=0.027),and the pre-to-post FSTT increase in BLa was greater(8.8±2.1 mmol/L vs.7.1±2.3 mmol/L,respectively;p=0.024).No other differences for MAX-REC vs.MIN-REC reached significance(p>0.05).Conclusion:Performance in a group of well-trained XC skiers is negatively affected when recovery times between sprint heats are minimized which,in competition conditions,would occur when selecting the last QF heat.This result is combined with a higher pre-race BLa concentration and a reduced rise in BLa concentration under shorter recovery conditions.These findings may help inform decision making when XC skiers are faced with selecting a QF heat within a sprint competition.

Effect of Aerobic High-Intensity Interval Training on VO2max and Anaerobic Power in Cross-Country Skiers

The purpose of this study was to investigate whether eight weeks of aerobic high-intensity interval training with roller ski is effective in cross-country skiers. 10 male （age, 18.28 ± 2.1 years; height, 171.26 ± 4.12 cm; weight 61.39 ± 6.28 kg） and 8 female （age, 16.05 ± 0.3 years; height, 158.3 ± 6.47 cm; weight, 49.34 ± 0.7 kg） junior cross country skiers completed the study. All skiers performed a 2 × 2-kin all-out uphill intervals with roller-skis, 3 times a week, in addition to their traditional training program. Measurements included VO2max （maximal oxygen uptake）, anaerobic power, and also for 2-km roller ski. All values were listed as pre-to post-test mean （± SD）, significant level, and percentage changes （%）. Pre-to post-testing changes in VO2max, anaerobic power, and also 2-kin roller ski performance were significantly higher during all post-test trials in all groups （P 〈 0.005）. With reference to the training effects found in our study, we suggest that the skiers should integrate the roller ski aerobic high-intensity interval uphill models in their training programs for improving performance.

越野滑雪项目配速策略研究新方法:基于GNSS定位数据精细化分析

目的:分析我国优秀越野滑雪运动员短距离项目全程和分段的配速策略特征。方法:16名越野滑雪国家集训队男子运动员分别进行雪上最大速度测试和短距离1.5 km自由技术比赛。短距离1.5 km比赛场地分为6个段落(S1-S6),使用GNSS定位系统和计时设备测量运动员比赛中时间、速度和技术使用等指标数据。通过坐标映射程序的方法对其滑行位置和速度进行标准化处理,使用SPM 1D回归模型分析瞬时速度和分段时间的相关关系。结果:1)上坡段S3(339-476 m)、S3坡顶位置(517-537 m)、S5(1 127-1 167 m),平地段S1(13-84 m)、S6(1 223-1 400 m),下坡段S2(85-134 m)、S4的初始段(652-730 m)以及转弯区域的瞬时速度与其分段时间存在显著相关(P<0.01),不同区域内的速度出现显著变化(P<0.05)。后半程上坡段S5的平均滑行速度显著高于前半程上坡段S3(P<0.01)。2)技术动作周期总量、G3技术动作周期数量与比赛时间以及上坡段时间存在负相关关系(r>-0.65,P<0.01)。快速组运动员比赛中G3技术比例显著高于慢速组(P<0.01),更快的运动员上坡段和平地段的G3技术速度和步幅显著高于较慢的运动员(P<0.01),在S1—S2和S3—S4段的转换路段G3技术速度和步频显著增加(P<0.01)。结论:1)越野滑雪短距离比赛中不同路段的配速策略与运动员竞技表现密切相关。上坡段的爬升阶段和靠近终点的位置采用更加积极的配速策略。平地段快速启动和终点冲刺区域内更快的瞬时速度与其分段时间有关,较高的下坡段的转弯速度有利于获得更好的下坡段表现。2)较少的动作周期数量和较高的G3技术比例与更好的越野滑雪短距离竞技表现相关联。上坡和平地段中更快的运动员G3技术速度具有更长的步幅。在上坡坡顶衔接转换中提高步频有利于保持较高的滑行速度。

越野滑雪(短距离)项目战术体系的构建

运用观察法、专家访谈法和问卷调查法,构建出越野滑雪(短距离)战术体系,旨在探讨战术体系的结构,为战术训练提供依据。研究结果:越野滑雪(短距离)战术体系由4个一级指标、8个二级指标、28个三级指标构成。个人战术主要包括出发抢位、变速滑行、领先滑行、尾随滑行、超越滑行、冲刺滑行等。集体战术方法主要有掩护配合战术、进攻配合战术等。

世界级短距离越野滑雪运动员专项体能特征研究进展及启示

短距离越野滑雪是一项比赛强度高、轮次多、赛间间歇短的体能类项目,是我国备战2022年北京冬奥会的重要突破口。主要基于英文文献,探寻世界级短距离越野滑雪运动员专项体能特征,为提升我国该项目专项体能的科学训练水平提供参考。研究发现1)世界级短距离越野滑雪男女运动员的身高分别为175~188 vs.166~176 cm,体重为70~92 vs.55~70 kg,瘦体重占比接近83 vs.70%;2)比赛中的能量供应以有氧代谢为主,并呈现有氧无氧动态交替主导;3)具有较高平均滑行速度和连续“多赛”能力,在起滑和冲刺阶段的速度最快,高速滑行中上、下肢呈现明显的“爆发式”用力特征,躯干力量对各种技术动作运用具有重要影响。为此,国家队冬奥备战科技助力应围绕专项体能突破展开重点攻关,深入探寻影响比赛高速滑行保持能力的生理学与运动学因素,加快提升比赛表现水平。

Energetic Demands and Nutritional Strategies of Elite Cross-Country Skiers During Tour de Ski: A Narrative Review

The Tour de Ski(TDS:6-9 sprint and distance races across 9-11 days)represents the most intense competition series of the cross-country(XC)ski season and is characterized by accumulated stress from consecutive days of high-intensity(~85%-160% VO_(2max))racing,travel,cold temperatures and low to moderate altitude(500-1500 m above sea level).Here,nutritional strategies play a key supportive role for optimized health,recovery and performance.This narrative review aims to provide an evidence-based discussion on the energetic demands of the TDS and recommendations for nutritional strate-gies to optimize health and performance of XC skiers during and following the TDS.We highlight several challenges that may arise during the TDS,including the following:poor energy availability(EA)due to decreased appetite or a pressure to maintain a low body weight,suboptimal carbohydrate availability due to a failure to replenish muscle glycogen stores across consecutive-day racing and increased risk of illness due to a combination of factors,including high-intensity racing,poor nutrition,sleep,travel and hygiene.We encourage XC skiers to maintain optimal overall EA across the~1.5-week period,ensure high daily carbohydrate availability,as well as the use of strategies to maintain a healthy immune system.In addition,we include practical guidelines on the management of nutrition support prior to and during the TDS.We recognize that many nutritional questions remain unanswered both in the context of elite XC ski racing and specifically for extreme demands like the TDS that should be addressed in future investigations.

The Road to the Beijing Winter Olympics and Beyond: Opinions and Perspectives on Physiology and Innovation in Winter Sport

Beijing will host the 2022 Winter Olympics,and China strengthens research on various aspects to allow their athletes to compete successfully in winter sport.Simultaneously,Government-directed initiatives aim to increase public participation in recreational winter sport.These parallel developments allow research to advance knowledge and understanding of the physiological determinants of performance and health related to winter sport.Winter sport athletes often conduct a substan-tial amount of training with high volumes of low-to-moderate exercise intensity and lower volumes of high-intensity work.Moreover,much of the training occur at low ambient temperatures and winter sport athletes have high risk of developing asthma or asthma-related conditions,such as exercise-induced bronchoconstriction.The high training volumes require optimal nutrition with increased energy and dietary protein requirement to stimulate muscle protein synthesis response in the post-exercise period.Whether higher protein intake is required in the cold should be investigated.Cross-country ski-ing is performed mostly in Northern hemisphere with a strong cultural heritage and sporting tradition.It is expected that innovative initiatives on recruitment and training during the next few years will target to enhance performance of Chinese athletes in classical endurance-based winter sport.The innovation potential coupled with resourcing and population may be substantial with the potential for China to become a significant winter sport nation.This paper discusses the physiological aspects of endurance training and performance in winter sport highlighting areas where innovation may advance in athletic performance in cold environments.In addition,to ensure sustainable development of snow sport,a quality ski patrol and rescue system is recommended for the safety of increasing mass participation.

精英短距离越野滑雪运动员竞技表现特征及其关键影响因素分析

通过文献和逻辑分析法,对世界级精英短距离越野滑雪运动员在多轮次比赛中表现的配速策略、速度特征以及单轮赛中各赛段速度、技术特征进行分析并讨论影响短距离比赛竞技表现的关键因素。研究认为:生理机能系统、神经肌肉工作系统和身体形态特征是影响和决定短距离越野滑雪运动员竞技表现的重要因素;其中,有氧代谢能力、无氧代谢能力、工作效率、乳酸代谢和疲劳恢复能力是影响运动员多轮制比赛中高速均衡性配速策略的关键指标;上肢爆发力、上肢力量耐力、肌肉类型、神经协调能力是影响运动员选择更高档位滑行技术、高滑频、长滑长技术表现特征的关键指标;同时,身高、体质量和瘦体重尤其是上肢力量耐力表现是影响运动员速度耐力的关键指标。研究结合对世界级精英短距离年度、阶段训练模式的分析,对我国高水平短距离越野滑雪训练提出相关建议:1)以发展有氧代谢能力为基础,要高度重视中低强度有氧耐力训练;强化无氧耐力能力训练,尤其是以糖酵解无氧供能强度为主的高强度训练,提高以有氧代谢为根基的无氧耐力水平;2)注重发展专项力量与专项速度,加强专项力量耐力尤其是上肢专项力量耐力训练和单一技术的专项速度能力训练;3)重视滑行技术效率和动作经济性训练,特别是加强主要滑行技术动作、特定地形地段技术效率和经济性的专门性训练;4)加强科学训练监控、预防损伤和疲劳积累,积极防控重大公共卫生等事件,以保障高水平越野滑雪训练不间断。