Comment on Dissociation between running economy and running performance in elite Kenyan distance runners

Mooses and colleagues suggest that running economy alone does not explain superior distance running performance in elite Kenyan runners. Whilst we agree with the multi-factorial hypothesis for Kenyan running success, we do not believe that running economy can be overlooked to the extent that it was based on this particular study. Based on the methods used and the range of athletes tested, in this response letter we question whether this study provides any basis for downplaying the influence of running economy or suggesting that other factors compensate for it to enable superior performance.     

Letter to the editor

Santos-Concejero and Tucker argued in their letter to the editor that in our study the running economy in achieving superior performance was overlooked due to some methodological aspects. Having given the remarks of Santos-Concejero and Tucker appropriate consideration, in this letter to the editor, we argue that our paper does not downplay the influence of running economy on the determinants of the East African running phenomenon, but rather adds novel insights into the interaction between running economy, maximal oxygen uptake and performance.     

Muscle co-activation and its influence on running performance and risk of injury in elite Kenyan runners

The relationship between muscle co-activation and energy cost of transport and risk of injury (initial loading rate and joint stiffness) has not been jointly studied. Fourteen elite Kenyan male runners were tested at two speeds (12 and 20 km · h^?1), where oxygen consumption, kinematic, kinetic and electromyography were recorded. Electromyography of seven lower limb muscles was recorded. Pre-activation and ground contact of agonist:antagonist co-activation was determined. All muscles displayed higher activity during pre-activation except rectus femoris (RF). Conversely, no differences were found during ground contact except for higher biceps femoris (BF) at 20 km · h^?1. Knee stiffness was correlated to RF–BF co-activation during both pre-activation and ground contact at both running speeds. However, energy cost of transport was only positively correlated to the above-mentioned muscle pairs at 20 km · h^?1 (r = 0620, P = 0.032; r = 0.682, P = 0.015, respectively). These findings emphasise the influence of neuromuscular control and performance and its support to musculoskeletal system to optimise function and modulate risk of injury. Further, neuromuscular activity during terminal swing is also important and necessary to execute and maintain performance.     

The effect of foot orthoses and insoles on running economy and performance in distance runners: A systematic review and meta-analysis

ABSTRACT

Foot orthoses and insoles are prescribed to runners, however their impact on running economy and performance is uncertain. The aim of this systematic review and meta-analysis was to determine the effect of foot orthoses and insoles on running economy and performance in distance runners. Seven electronic databases were searched from inception until June 2018. Eligible studies investigated the effect of foot orthoses or insoles on running economy (using indirect calorimetry) or running performance. Standardised mean differences (SMDs) were computed and meta-analyses were conducted using random effects models. Methodological quality was assessed using the Quality Index. Nine studies met the criteria and were included: five studies investigated the effect of foot orthoses on running economy and four investigated insoles. Foot orthoses were associated with small negative effects on running economy compared to no orthoses (SMD 0.42 [95% CI 0.17,0.72] p = 0.007). Shock absorbing insoles were also associated with negative effects on running economy, but an imprecise estimate (SMD 0.26 [95% CI ?0.33,0.84] p = 0.83). Quality Index scores ranged from 4 to 15 out of 17. Foot orthoses and shock absorbing insoles may adversely affect running economy in distance runners. Future research should consider their potential effects on running performance.     

Effect of resistance training regimens on treadmill running and neuromuscular performance in recreational endurance runners

Abstract

The purpose of this study was to assess the effects of heavy resistance, explosive resistance, and muscle endurance training on neuromuscular, endurance, and high-intensity running performance in recreational endurance runners. Twenty-seven male runners were divided into one of three groups: heavy resistance, explosive resistance or muscle endurance training. After 6 weeks of preparatory training, the groups underwent an 8-week resistance training programme as a supplement to endurance training. Before and after the 8-week training period, maximal strength (one-repetition maximum), electromyographic activity of the leg extensors, countermovement jump height, maximal speed in the maximal anaerobic running test, maximal endurance performance, maximal oxygen uptake ([Vdot]O_2max), and running economy were assessed. Maximal strength improved in the heavy (P = 0.034, effect size ES = 0.38) and explosive resistance training groups (P = 0.003, ES = 0.67) with increases in leg muscle activation (heavy: P = 0.032, ES = 0.38; explosive: P = 0.002, ES = 0.77). Only the heavy resistance training group improved maximal running speed in the maximal anaerobic running test (P = 0.012, ES = 0.52) and jump height (P = 0.006, ES = 0.59). Maximal endurance running performance was improved in all groups (heavy: P = 0.005, ES = 0.56; explosive: P = 0.034, ES = 0.39; muscle endurance: P = 0.001, ES = 0.94), with small though not statistically significant improvements in [Vdot]O_2max (heavy: ES = 0.08; explosive: ES = 0.29; muscle endurance: ES = 0.65) and running economy (ES in all groups < 0.08). All three modes of strength training used concurrently with endurance training were effective in improving treadmill running endurance performance. However, both heavy and explosive strength training were beneficial in improving neuromuscular characteristics, and heavy resistance training in particular contributed to improvements in high-intensity running characteristics. Thus, endurance runners should include heavy resistance training in their training programmes to enhance endurance performance, such as improving sprinting ability at the end of a race.     

跑节省化、无氧阈和最大摄氧量评价篮球运动员有氧能力的比较研究

以天津商务职业学院24名男篮球队员为研究对象,通过跑台测试、因子分析法等,采用跑节省化、无氧阈和最大摄氧量对篮球运动员进行评价分析。结果显示:篮球运动员跑节省化的修正值在第一公因子中载荷最大,在第二、第三公因子中跑节省化相关指标的载荷量处于相对重要位置,在第四公因子中只有跑节省化时通气量;跑节省化、无氧阈和最大摄氧量三指标在评价篮球运动员有氧耐力时,跑节省化指标优势明显。提示:跑节省化可以作为评价篮球运动员有氧耐力的首选指标。     

Ventilatory Threshold,Running Economy and Distance Running Performance of Trained Athletes

Abstract

The purpose of this study was to assess the relationships among ventilatory threshold T(vent), running economy and distance running performance in a group (N=9) of trained experienced male runners with comparable maximum oxygen uptake ([Vdot]O₂ max). Maximal oxygen uptake and submaximal steady state oxygen uptake were measured using open circuit spirometry during treadmill exercise. Ventilatory threshold was determined during graded treadmill exercise using non-invasive techniques, while distance running performance was assessed by the best finish time in two 10-kilometer (km) road races. The subjects averaged 33.8 minutes on the 10km runs, 68.6 ml · kg ^-1 · min ^-1 for [Vdot]O₂ max, and 48.1 ml · kg ^-1 · min ^-1 for steady state [Vdot]O₂ running at 243 meters · min ^-1. The T(vent) (first deviation from linearity of [Vdot]_E, [Vdot]CO ₂ ) occurred at an oxygen consumption of 41.9 ml · kg ^-1 · min ^-1. The relationship between running economy and performance was r = .51 (p>0.15) and the relationship between T(vent) and performance was r = .94 (p < 0.001). Applying stepwise multiple linear regression, the multiple R did not increase significantly with the addition of variables to the T(vent); however, the combination of [Vdot]O₂ max, running economy and T(vent) was determined to account for the greatest amount of total variance (89%). These data suggest that among trained and experienced runners with similar [Vdot]O₂ max, T(vent) can account for a large portion of the variance in performance during a 10km race.     

中跑运动员跑步经济性与运动成绩的相关性研究

探索中跑运动员跑步经济性(running economy,RE)与运动成绩的相关性,通过实验探索出中跑运动员RE测试的最佳负荷。根据.VO2max相对值及800 m运动成绩,最终确定7人为研究对象。研究结果发现,7名受试者运动成绩的排序和RE12的排序相关性呈现出高度显著性(r=0.98,P=0.00)。研究结论表明,800 m运动成绩越好,RE12水平越好;同时也发现,选择12.0 km/h的测试速度评价中跑运动员的RE水平比较适合。     

Effect of downhill running grade on lower extremity loading in female distance runners

ABSTRACT

Hill running is often used as a foundational training mechanism to build strength and speed. Distance runners in particular are at an increased likelihood of encountering steep hills during training runs. There is limited research regarding downhill running, and there is no research available on the biomechanics of females specifically during downhill running. The purpose of this study was to quantify the differences in loading when running downhill at different grades compared to a level surface in female distance runners to determine the potential risk for injury. Fifteen female distance runners (age: 23.5 ± 4.9 y), who ran 56.3 ± 20.9 km a week participated in this study. Participants ran on a force-instrumented treadmill at 4.0 m/s for 2 min at 0%, ?5%, ?10%, ?15%, and ?20% grades, with 5 min of rest between conditions. Study findings showed increased impact forces (p < 0.001), and increased loading rates (p < 0.001) with increasing downhill grades compared to level. These results indicate a significantly greater risk of overuse injury to the lower extremity with steeper downhill grades. Individuals need to be aware of these risks to plan and implement training programmes that will increase performance while minimising injury risk.     

我国优秀中跑运动员体能特征的研究

运用文献资料法、专家调查法、测试法和数理统计法，对影响我国优秀中跑运动员的专项能力的体能因素进行综合分析.确定了影响中跑运动员运动成绩的体能指标，包括身体形态指标、身体机能指标、运动素质指标.分析了我国优秀中跑运动员的体能特征，以期能为科学选材和对运动员体能训练提供参考。     

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.     

Effects of a minimalist shoe on running economy and 5-km running performance

The purpose of this study was to determine if minimalist shoes improve time trial performance of trained distance runners and if changes in running economy, shoe mass, stride length, stride rate and footfall pattern were related to any difference in performance. Twenty-six trained runners performed three 6-min sub-maximal treadmill runs at 11, 13 and 15 km·h^?1 in minimalist and conventional shoes while running economy, stride length, stride rate and footfall pattern were assessed. They then performed a 5-km time trial. In the minimalist shoe, runners completed the trial in less time (effect size 0.20 ± 0.12), were more economical during sub-maximal running (effect size 0.33 ± 0.14) and decreased stride length (effect size 0.22 ± 0.10) and increased stride rate (effect size 0.22 ± 0.11). All but one runner ran with a rearfoot footfall in the minimalist shoe. Improvements in time trial performance were associated with improvements in running economy at 15 km·h^?1 (r = 0.58), with 79% of the improved economy accounted for by reduced shoe mass (P < 0.05). The results suggest that running in minimalist shoes improves running economy and 5-km running performance.     

The efficacy of downhill running as a method to enhance running economy in trained distance runners

Running downhill, in comparison to running on the flat, appears to involve an exaggerated stretch-shortening cycle (SSC) due to greater impact loads and higher vertical velocity on landing, whilst also incurring a lower metabolic cost. Therefore, downhill running could facilitate higher volumes of training at higher speeds whilst performing an exaggerated SSC, potentially inducing favourable adaptations in running mechanics and running economy (RE). This investigation assessed the efficacy of a supplementary 8-week programme of downhill running as a means of enhancing RE in well-trained distance runners. Nineteen athletes completed supplementary downhill (?5% gradient; n?=?10) or flat (n?=?9) run training twice a week for 8 weeks within their habitual training. Participants trained at a standardised intensity based on the velocity of lactate turnpoint (vLTP), with training volume increased incrementally between weeks. Changes in energy cost of running (E_C) and vLTP were assessed on both flat and downhill gradients, in addition to maximal oxygen uptake (?O_2max). No changes in E_C were observed during flat running following downhill (1.22?±?0.09 vs 1.20?±?0.07?Kcal?kg^?1?km^?1, P?=?.41) or flat run training (1.21?±?0.13 vs 1.19?±?0.12?Kcal?kg^?1?km^?1). Moreover, no changes in E_C during downhill running were observed in either condition (P?>?.23). vLTP increased following both downhill (16.5?±?0.7 vs 16.9?±?0.6?km?h^?1 _, P?=?.05) and flat run training (16.9?±?0.7 vs 17.2?±?1.0?km?h^?1, P?=?.05), though no differences in responses were observed between groups (P?=?.53). Therefore, a short programme of supplementary downhill run training does not appear to enhance RE in already well-trained individuals.     

Aerobic fitness and running performance of male and female recreational runners

The purpose of the present study was to assess fitness and running performance in a group of recreational runners (men, n = 18; women, n = 13). ‘Fitness’ was determined on the basis of their physiological and metabolic responses during maximal and submaximal exercise. There were strong correlations between VO₂ max and treadmill running speeds equivalent to blood lactate concentrations of 2 mmol 1^‐1’ (V‐2 mM) or 4 mmol 1^‐1 (V‐4 mM), ‘relative running economy’ and 5 km times (r = 0.84), but modest and non‐significant correlations between muscle fibre composition and running performance. The results of the submaximal exercise tests suggested that the female runners were as well trained as the male runners. However, the men still recorded faster 5 km times (19.20 ± 1.97 min vs 20.97 ± 1.70 min; P <0.05). Therefore the results of the present study suggest that the faster performance times recorded by the men were best explained by their higher VO₂ max values, rather than their training status per se.     

耐力训练、神经骨骼肌系统适应与跑步经济性

跑步经济性和运动成绩密切相关。进行专项运动训练,下肢运动肌募集方式更为精炼。耐力训练可诱导神经骨骼肌系统发生适应,降低代谢需求,提高运动成绩。自行车运动单项与多项组合项目相比,下肢运动肌募集方式存在差异。目前,研究非常关注单项与多项组合项目诱导神经骨骼肌系统适应间的差异。但是,并不清楚这些特异性神经骨骼肌系统适应是否有助于提高或损害耐力性项目的运动成绩？神经骨骼肌系统适应可能在影响耐力性项目的运动成绩。力量训练和超等长训练可提高运动的经济性,但这些适应性的变化对跑步时运动肌募集方式产生多少有益的影响并不清楚。当前,尚没有充足的证据显示拉伸训练和运动鞋可提高运动的经济性。     

力量训练提升马拉松跑者耐力运动表现的研究进展及训练策略

有氧能力的高低是马拉松跑者能否取得优异成绩的关键。最大摄氧量、乳酸阈和跑步经济性是衡量运动员有氧能力和耐力运动表现的关键指标,也是长跑训练效果的核心考量。由于力量和耐力训练对机体产生不同的训练刺激,教练员和运动员很少将力量训练作为提升耐力运动表现的手段,以防止有氧能力受到负面影响。通过对大量文献梳理发现,力量训练可以在不影响机体最大摄氧量和乳酸阈值的前提下,通过改善神经肌肉功能、转换肌纤维类型以及增强肌肉肌腱刚度和利用弹性势能的能力,提高跑步经济性和无氧能力,改善运动员耐力运动表现。本文基于对力量、耐力训练的生理学适应的探讨,总结不同形式力量训练对耐力运动表现的影响与作用机制,并为马拉松选手科学安排力量训练提出建议,从而优化其耐力运动表现。     

中长跑运动员赛前训练的调控研究

运用实验法对参加全国第七届大学生运动会的江苏省大学生中长跑运动员和参加第十届全运会江苏队中长跑运动员的赛前训练期间的生理学指标进行跟踪测定、评价，对训练进行了调控。研究表明：用心率、心功能指数、尿蛋白、最大吸氧量、无氧功率、斯坦格试验与汉契试验、无氧闽等指标评定中长跑运动员赛前的机能状态有较强的实用性和针对性，但需结合项目的特点和训练实际，加强监控和调控，进行综合分析；中长跑赛前训练安排应以专项素质为主，突出速度和速度耐力的训练，速度力量在中长跑项目赛前训练要给予重视，负荷的安排是赛前训练的关键。     

The relationship between critical power and running performance

Critical power is a theoretical concept that presumes there is a certain work‐rate which may be maintained without exhaustion. The extent to which critical power predicts running performance over varying distances has not been determined, and so the aim of this study was to correlate measurements of critical power in the laboratory to running performances in the field at 40 m and 1, 10 and 21.1 km in a group of 17 male longdistance runners (mean ± s.d. age = 31.7 ± 7.3 years). Each subject ran to exhaustion on the treadmill in the laboratory at six different speeds, ranging from 17 to 25 km h^‐1. Least squares analyses were used to fit an exponential decay to the relationship between the running speed (y) versus time to exhaustion (x). Critical power was calculated as the running speed (y) coinciding with the asymptote or C parameter of the y = A‐e^(‐Bx) + C relationship. The VO₂ max was also measured in all subjects. For the data in the field, each subject was timed over 40 m and 1 km and participated in 10‐ and 21.1‐km races. The mean critical power of die subjects in this study was 18.5 ± 1.6 km h^‐1. The test‐retest correlation coefficient for the determination of critical power was r = 0.99. The mean VO₂ max, measured in a progressive exercise protocol starting at 13 km h^‐1 and increasing by 1 km h^‐1 every minute, was 59.2 ± 4.6 ml O₂ kg^‐1 min^‐1. The 40‐m times ranged from 5.57 to 6.95 s, the 1‐km times from 2:46 to 3:55 min:s, the 10‐km times from 30:43 to 42:02 min:s and the 21‐km times from 67:00 to 95:45 min:s. Critical power predicted running times over 1 km (r = ‐0.75, P< 0.001), 10 km (r = ‐ 0.85, P< 0.00001) and 21.1 km (r = ‐ 0.79, P< 0.001) in this heterogeneous group of runners. The correlation coefficients for VO₂ max and running performances were similar to the above at all distances. Even in the best relationship between critical power and the time taken to run 10 km, only 72% of the variation in the 10‐km running time could be accounted for by differences in critical power. While the test of critical power may be repeatable and correlate significantly with VO₂ max (r = 0.77, P< 0.001), the measurement lacks the degree of specificity required to predict running performance in trained subjects of varying ability.     

中长跑运动员跑台跑与场地跑下肢肌肉工作情况的比较分析

目的:通过EMG记录分析跑台跑和场地跑肌肉用力情况特征,比较这两种状态跑时肌肉用力方式的各自特点。方法:11名中长跑运动员,每名运动员分两天测试,随机让其以10 km/h、12 km/h、14 km/h、16 km/h、18 km/h的速度在场地和跑台(0%、5%、10%坡度)运动6min,每种速度跑之间间歇10min。使用便携式Megawin ME-6000肌电仪记录其下肢肌群(臀大肌、股外侧肌、股二头肌、腓肠肌内侧头、胫骨前肌)EMG变化情况。结果表明:在肌肉用力方面,5%坡度的跑台跑可以模拟场地跑,而10%坡度的跑台跑则可以给予下肢肌群更强的刺激,以满足训练的需要;跑台跑时,胫骨前肌需要比在场地跑时动员更多的运动单位参与工作,而跑台的坡度和速度增加对动员更多的运动单位影响不大。     

中长跑运动员步频步幅与摄氧量关系的研究

通过分析研究中长跑运动员的跑速和步频步幅与摄氧量、肺通气量和心率等心肺功能的关系,以及心肺功能和身体状况探讨长跑运动员跑步中生理特点与运动规律,为改进运动员的长跑运动技术,提高训练效果和运动成绩,科学有效制定训练计划和比赛的战术提供理论依据。