Relationship Between Running Economy and Kinematic Parameters in Long-Distance Runners.

Pizzuto, F, Fonseca de Oliveira, C, Amorim Soares, TS, Rago, V, Silva, G, and Oliveira, J. Relationship between running economy and kinematic parameters in long-distance runners. J Strength Cond Res 33(7): 1921-1928, 2019-The purpose of this study was to explore the relationship between running economy (RE) and sagittal, frontal, and transverse plane kinematic parameters in long-distance runners. A secondary purpose was to identify the kinematic predictors of RE during running at the lowest RE value, representing an individual's most efficient running intensity. Twenty recreational long-distance runners ran 3 submaximal stages on a treadmill (65, 75, and 85% of velocity at maximum oxygen consumption). Respiratory data were collected using a portable gas analysis system. Kinematics were gathered using passive retroreflective markers and 8 high-resolution infrared cameras to collect the respective trajectories. Hip, knee, and ankle angles at foot strike and stance phase, as well as spatio-temporal parameters were calculated during each gait cycle. Knee flexion/extension range of motion (ROM), knee ab/adduction ROM, and hip ab/adduction ROM during the stance phase of the gait cycle showed positive moderate to large correlations with RE (r ± 90% confidence intervals = 0.51 ± 0.29; 0.49 ± 0.30; 0.53 ± 0.28, respectively). Knee and hip ab/adduction ROMs during the stance phase are predictors of RE, accounting for 44% of RE variance. Therefore, sagittal and frontal plane kinematics affect RE-inducing alterations in running performance. Coaches, athletic trainers, and anyone involved in running training prescription should consider a relationship between these parameters to ensure optimal technique and, consequently, to improve RE in recreational long-distance runners.

Acute kinematics changes in marathon runners using different footwear.

The effects of running with or without shoes on injury prevention have been extensively studied, and several investigations have assessed biomechanical differences between them. However, findings are not consensual and further insights on biomechanical load associated with differently shod or barefoot conditions may be needed. This study aimed to observe if habitually shod marathon runners show acute alterations when running barefoot or with minimalist shoes, and to determine whether the running kinematical adaptations of wearing minimalist shoes were similar to barefoot running. Twelve male marathon runners ran on the treadmill at their average marathon pace in different footwear conditions: habitual running shoes, minimalist shoes, and barefoot. High-resolution infrared cameras and visual 3D software were used to assess kinematic data. The following parameters were studied: foot strike angle, cycle time, stance time, normalized stride length, hip, knee, and ankle angular position at initial contact, and their respective range-of-motion (ROM) during stance phase. Contrary to the expectations, it was found that highly trained habitually shod elite marathon runners changed their lower limb kinematic pattern both when running barefoot or wearing minimalist shoes. Minimalist shoes showed a trend towards intermediate biomechanical effects between running with and without shoes.

Small-sided soccer games on sand are more physically demanding but less technically specific compared to games on artificial turf.

BACKGROUND: The use of sand has been suggested as fitness-enhancing surface in field-based team sports. However, concerns have arisen in regard whether physical responses associated to sand training are sport-specific. We compared physical and technical demands during small-sided soccer games (4 vs. 4 + goalkeeper; SSGs) played on artificial turf and on sand. METHODS: Movement patterns, rating of perceived exertion (RPE) and technical parameters were obtained from eight adult male soccerers (20.1±1.0 years, 176±4 cm and 70.1±2.0 kg) using Global Positioning Systems, Visual Analogue Scale questionnaires, and notational analysis. RESULTS: High-intensity actions (high intensity running, high intensity activities), low changes of speed, as well as peak and average speed were higher on artificial turf (P<0.05; effect sizes (ES) 0.41 to 0.82). In contrast, time spent by jogging as well as high and maximum changes of speed was higher on sand (P<0.05; ES: 0.59 to 0.82). Moreover, players perceived more demanding to play on sand (P<0.05; ES=0.72). Rating of successful actions was higher during turf SSGs than sand SSGs (P<0.05; ES: 0.44 to 0.73), whereas actions requiring lifting the ball were higher on sand (P<0.05; ES: 0.47 to 0.50). CONCLUSIONS: The use of sand can be considered as complemental to on-turf soccer training, when the training goal is to tax lower limb muscle strength or to require high-ball situations. Nonetheless, sand training is not appropriate when the achievement of maximal speed is desired. Further research should clarify the suitability of sand training within soccer conditioning programs.

Are the World Junior Championship Finalists for Middle- and Long-Distance Events Currently Competing at International Level?

PURPOSE: To analyze how many finalists of the International Association of Athletics Federations (IAAF) World Junior Championships (WJCs) in the middle- and long-distance track events had dropped out from high-level competitions. METHODS: Starting from 2002, the 8 male and the 8 female finalists in the middle- and long-distance events of 6 editions of the WJC were followed until 2015 to evaluate how many missed the IAAF rankings for 2 consecutive years starting from the year after WJC participation. For those still competing at elite level, their careers were monitored. RESULTS: In 2015, 61% of the 2002, 54.8% of the 2004, 48.3% of the 2006, 37.5% of the 2008, 26.2% of the 2010, and 29% of the 2012 WJC finalists were not present in the IAAF rankings. Of the 368 athletes considered, 75 (20.4%) were able to achieve the IAAF top 10 in 2.4 ± 2.2 y. There is evidence of relationships between dropout and gender (P = .040), WJC edition (P = .000), and nationality (P = .010) and between the possibility to achieve the IAAF top 10 and dropout (P = .000), continent (P = .001), relative age effect (P = .000), and quartile of birth (P = .050). CONCLUSIONS: Even if 23 of the finalists won a medal at the Olympic Games or at the World Championships, it is still not clear if participation at the WJC is a prerequisite to success at a senior level.