Effect of a global alteration of running technique on kinematics and economy

In this study, we examined the consequences of a global alteration in running technique on running kinematics and running economy in triathletes. Sixteen sub-elite triathletes were pre and post tested for running economy and running kinematics at 215 and 250 m.min-1. The members of the treatment group (n=8) were exposed to 12 weeks of instruction in the "pose method" of running, while the members of the control group (n=8) maintained their usual running technique. After the treatment period, the experimental group demonstrated a significant decrease in mean stride length (from 137.25+/-7.63 cm to 129.19+/-7.43 cm; P<0.05), a post-treatment difference in vertical oscillation compared with the control group (6.92+/-1.00 vs. 8.44+/-1.00 cm; P<0.05) and a mean increase in submaximal absolute oxygen cost (from 3.28+/-0.36 l.min-1 to 3.53+/-0.43 l.min-1; P<0.01). The control group exhibited no significant changes in either running kinematics or oxygen cost. The global change in running mechanics associated with 12 weeks of instruction in the pose method resulted in a decrease in stride length, a reduced vertical oscillation in comparison with the control group and a decrease of running economy in triathletes.     

Running Training,Instruction on Running Technique,and Running Economy in 10-year-old Males

Abstract

The purpose of the study was to determine the effects of running training, instruction on running technique, and a combination of instruction and running training on the running economy of 10-year-old children. Experimental treatments were randomly assigned to intact groups. Oxygen consumption was determined via the open circuit method during overground running at 161 m · min ^–1.Vertical displacement was determined utilizing cinematography. Stride rate was determined using 60-sec counts; stride length was calculated from stride rate and the distance covered. Subjects (n =40) required 38.9 ml · min ^–1 · kg ^–1 of O ₂ to sustain this pace and exhibited 3.71 cm vertical displacement. The mean stride length was 88 cm and the mean stride rate was 183 strides · min ^–1.No statistically significant alterations in running economy or technique were produced as a result of the various treatment regimens.     

中长跑途中跑适宜步长的影响因素

从影响跑速的基本因素和支撑阶段的运动学参数两个方面对中长跑途中跑适宜步长进行了分析。结果表明：步长指数和步频能力与适宜步长的确定直接相关，而支撑时间与腾空时间的比值、支撑腿离地瞬间膝关节角度、支撑阶段身体重心水平位移距离等运动学参数则是影响适宜步长的主要因素。采用专项耐力指数对运动员的专项能力进行了分级，给出了不同专项能力水平运动员步长指数的适宜范围。     

对中、外优秀竞走运动员关键动作技术特征的运动学分析

对影响和制约我国竞走运动员成绩发挥的因素进行分析和研究。研究发现,我国运动员小步幅,高步频技术风格依然存在。整体来看,我国运动员重心和头顶点垂直起伏较大,容易被裁判员判罚。我国部分运动员存在左、右腿力量分配不均衡现象,且上肢摆动幅度较小。     

The effect of a cadence retraining protocol on running biomechanics and efficiency: a pilot study

Many studies have documented the association between mechanical deviations from normal and the presence or risk of injury. Some runners attempt to change mechanics by increasing running cadence. Previous work documented that increasing running cadence reduces deviations in mechanics tied to injury. The long-term effect of a cadence retraining intervention on running mechanics and energy expenditure is unknown. This study aimed to determine if increasing running cadence by 10% decreases running efficiency and changes kinematics and kinetics to make them less similar to those associated with injury. Additionally, this study aimed to determine if, after 6 weeks of cadence retraining, there would be carryover in kinematic and kinetic changes from an increased cadence state to a runner’s preferred running cadence without decreased running efficiency. We measured oxygen uptake, kinematic and kinetic data on six uninjured participants before and after a 6-week intervention. Increasing cadence did not result in decreased running efficiency but did result in decreases in stride length, hip adduction angle and hip abductor moment. Carryover was observed in runners’ post-intervention preferred running form as decreased hip adduction angle and vertical loading rate.     

浅谈步频对青少年短跑运动成绩的影响

本文运用文献资料综合法和调查访问法,对短跑运动员步幅的大小和短跑运动成绩的影响进行了研究。分析短跑的技术对成绩的影响和如何解决步幅小的问题进行了阐明。从中发现我国短跑运动员的步幅还处于较落后的状态。原因是一方面部分教练员只能过直观分析认为我国男子100米运动员步频有余,步幅不足;另一方面是决定速度的两个因素没有充分认识。     

Biomechanical Effects of Fatigue on 10,000 Meter Running Technique

Abstract

A study of the effect of fatigue on the mechanical characteristics of running during a 10,000 meter race was undertaken using high speed cinematography and a computer analysis technique. Eight highly skilled male subjects were filmed at four intervals throughout the event. An analysis of variance for trends was conducted for each of the dependent variables indicating the adjustments made by the runners that accompanied fatigue over the four stages of the event. Runners countered fatigue by changing sections of their total gait pattern (stride length, stride rate, segmental body positions) and reducing running velocity. Toward the end of the race the runners became less competent in the positioning of the foot and leg at foot-strike, which increased the potential for a retarding effect. A more extended lower limb increased the energy requirements of the recovery phase during the latter stages of the race. Fatigue caused these highly skilled runners to systematically alter their technique throughout the race. These adjustments, however, were not excessive.     

Effect of Stride Length Variation on Oxygen Uptake during Level and Positive Grade Treadmill Running

Abstract

Sixteen men were studied during 6-min bouts of motorized treadmill running at 230 m · min^–1 and 0% and 4% grade to compare [Vdot]O₂ while using freely chosen stride lengths (CSL) and stride lengths approximately 8% shorter (SSL) and longer (LSL) than CSL. The study also attempted to determine whether stride length variations of these proportions altered [Vdot]O₂ differently at the two grades. CSL were greater (p<.05) at 0% than 4% with mean values of 133.5 and 131.5 cm, respectively. Two-way ANOVA (Stride x Grade) with repeated measures yielded significant F values (p<.05) for the main effects of both stride length and grade but not for interaction between the two factors. Mean [Vdot]O₂ values were 44.95 and 56.80 ml · kg¹ · min^–1 at 0% and 4% grade, respectively. The Tukey w procedure was used for comparing the main effect means across both grades for the three stride lengths. These means were 50.94, 49.88, and 51.80 ml · kg¹ · min^–1 for SSL, CSL, and LSL, respectively, with the CSL mean significantly less than the SSL and LSL means (p<.05). Stride length variations of approximately ±8% did not alter [Vdot]O₂ differently at the two grades, and although [Vdot]O₂ for SSL and LSL was not different, [Vdot]O₂ was significantly (p<.05) increased by 2.1% for SSL and 3.8% for LSL. Not all individual patterns followed the group norm, however, in that three subjects were more economical with short stride lengths and two were more economical with longer strides.     

不同步频和步幅的5km跑过程中运动员心率变化的对比研究

为了观察中长跑运动员长距离跑过程中步频和步幅的变化对身体机能反应的影响,8名运动员在跑台上分别采取主动加大步幅和主动减小步幅而增快步频的跑法,以相同的速度进行了两次5km跑,记录运动员在跑步过程中心率的变化并进行对比。结果显示,在相同速度5km跑的过程中,运动员采取主动减小步幅的跑法,其心率均值显著低于采取主动加大步幅的跑法。提示,长距离跑过程中,运动员采取主动减小步幅,或加大步频的跑法较为省力。     

Shoe cleat position during cycling and its effect on subsequent running performance in triathletes

Abstract

Research with cyclists suggests a decreased load on the lower limbs by placing the shoe cleat more posteriorly, which may benefit subsequent running in a triathlon. This study investigated the effect of shoe cleat position during cycling on subsequent running. Following bike-run training sessions with both aft and traditional cleat positions, 13 well-trained triathletes completed a 30?min simulated draft-legal triathlon cycling leg, followed by a maximal 5?km run on two occasions, once with aft-placed and once with traditionally placed cleats. Oxygen consumption, breath frequency, heart rate, cadence and power output were measured during cycling, while heart rate, contact time, 200?m lap time and total time were measured during running. Cardiovascular measures did not differ between aft and traditional cleat placement during the cycling protocol. The 5?km run time was similar for aft and traditional cleat placement, at 1084?±?80?s and 1072?±?64?s, respectively, as was contact time during km 1 and 5, and heart rate and running speed for km 5 for the two cleat positions. Running speed during km 1 was 2.1%?±?1.8 faster (P?<?0.05) for the traditional cleat placement. There are no beneficial effects of an aft cleat position on subsequent running in a short distance triathlon.     

对我国优秀男子标枪运动员投掷步技术的研究

本文以我国优秀男子标枪运动员为研究对象,通过影片解析及数据处理,获取其投掷步技术指标。然后与国外优秀运动员进行类比,找出规律及特点;同时具体阐述国内运动员的投掷步幅、投掷步节奏等动作存在的问题,较全面地对投掷步技术进行了定量分析,为促进该技术的教学和训练,提供了定量依据。     

Thinking about your running movement makes you less efficient: attentional focus effects on running economy and kinematics

A number of studies have shown that attentional focus instructions can effect running economy. This study assessed spiroergometry, as well as running kinematics as a possible mechanism to explain these effects. Twelve runners had to focus their attention on either their running movement, their breathing or on a video while running on a treadmill at a set, submaximum speed. Spiroergometry and running kinematics were measured. Results revealed worse running economy in both internal focus conditions (breathing and movement) compared to the external focus condition (video), replicating previous findings. In addition, vertical oscillation during the running movement was elevated in the movement compared to the video condition, indicating a less efficient running style. No changes in kinematics were found for the breathing compared to the video condition. Therefore, consciously focusing on the running movement moves runners away from their optimised running pattern and leads to detriments in economy. The decreases in running economy in the breathing condition can be better explained by changes in breathing patterns.     

世界优秀短跑运动员100m各分段步频、步长、平均速度变化规律的研究

利用数理统计法对世界优秀短跑运动员100m跑的各分段步频、步长等运动学指标进行评析，研究表明：世界优秀短跑运动员100m跑中长时间保持高速的途径是依靠自己的步长，而不是努力提高步频来保持；全程跑的加速节奏对全程的成绩有较大的影响；在各分段步长与步频对跑速的贡献具有显性差异。     

Reliabilities of leg and vertical stiffness during treadmill running

The aim of this study was to determine the intra-participant variabilities (i.e. intra-day and inter-day reliabilities) in leg and vertical stiffness, as well as related kinematic parameters, during treadmill running using the sine-wave method. Twenty-two healthy men ran on a treadmill at 4.44 m/s, and the flight and contact times were measured with a high-speed video camera. Three 30-s running bouts with 2-min inter-bout rests were performed to examine the intra-day reliability, and single 30-s running bouts on three separate days with 24- to 48-h inter-bout intervals were performed to examine the inter-day reliability. The reliability statistics included repeated-measure analyses of variance, average inter-trial correlations, intra-class correlation coefficients (ICCs), Cronbach's α reliability coefficient, and the coefficient of variation. Both leg and vertical stiffness produced high ICCs within 0.972 and 0.982, respectively, and between 0.922 and 0.873 days, respectively. High values were also observed for all of the reliability coefficients. Similar results were found regarding contact time, flight time, step length, and step rate. It was concluded that the measurements of leg and vertical stiffness, as well as related kinematic parameters, obtained using the sine-wave method during treadmill running at 4.44 m/s, were highly reliable, both within and across days.     

对短跑运动员步长与步频要素及成因的研究

通过文献资料法、比较分析法 ,对影响短跑运动员步长与步频的要素及成因进行了论证与分析 ,结果表明步长与步频对最高速度水平的发挥和各项跑成绩产生的影响很大。训练中在考虑外部要素时必须考虑内部因素发展的可能 ;在发展内在要素时 ,外在要素则应达到相应指标 ;并提出了最佳的指数范围和速度距离曲线 ,从而为短跑教学与训练提供参考。     

Effects of a verbal and visual feedback system on running technique,perceived exertion and running economy in female novice runners

The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty‐two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20‐min treadmill running sessions over a 5‐week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High‐speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P < 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non‐support. There were no significant differences between the groups in submaximal VO₂ or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.     

分析比较中外短跑运动员途中跑技术的差异

通过文献资料、分析对比等方法,对短跑途中跑技术进行分析,发现我国运动员在途中跑“后蹬屈膝式”技术及放松、步幅、节奏等技术方面与国外优秀选手存在一定差距。     

Effects of a verbal and visual feedback system on running technique, perceived exertion and running economy in female novice runners

The purpose of this study was to determine the effects of a verbal and visual feedback system on running technique, ratings of perceived exertion (RPE), and running economy. Twenty-two female novice runners were randomly assigned to experimental (n = 11) and control (n = 11) groups. The experimental subjects received verbal and visual feedback concerning their running technique prior to and during each training run. Training involved 15 20-min treadmill running sessions over a 5-week period. The control group adhered to the same training routine but did not receive feedback concerning their running technique. High-speed (100 Hz) photography was used to collect biomechanical data. A submaximal oxygen consumption test and Borg's RPE scale were used to collect data concerning running economy and perceived exertion, respectively. Statistical analysis using ANCOVA revealed that the proposed feedback system had a significant (P less than 0.01) effect on the experimental group's running technique by affecting the following desired changes relative to the control group: greater relative stride lengths, shorter support time, greater ankle dorsiflexion during support and greater knee flexion during support and non-support. There were no significant differences between the groups in submaximal VO2 or RPE. The results of this study suggest that verbal and visual feedback are effective means of eliciting modifications in running style in female novice runners. The link between modifications in running style and improvements in running economy and perceived exertion remains unclear.     

从步长、步频的角度分析我国男子百米跑成绩滞后原因

本文通过文献资料法收集国内外优秀男子百米运动员的运动技术参数,并加以统计,从影响跑速的步长、步频因素对我国男子百米跑运动员成绩滞后的因素进行分析。结果表明：我国百米运动员的步长能力不足是影响速度能力和成绩提高的主要原因,应在优化步长、步频关系的基础上,以提高步长能力为突破口,强调运动员整体训练水平的提高,从而提高最大速度能力和运动水平。     

对步长和步频合理组合与100m跑成绩相关性的研究

日本田联和国际田联生物力学课题组记录了在东京举行的第3届世界田径锦标赛男子100m决赛8名运动员包括速度、步长、步频在内的许多数据。作者通过对数据资料的分析处理,发现导致刘易斯等运动员的速度呈双高峰期的原因是步长和步频的合理组合模式遭到破坏,并得到如下结论:保持合理速度比追求最大速度更能提高100m运动成绩;建立步长和步频的合理组合模式是提高运动成绩的有效途径。